MULTICS DESIGN DOCUMENT MDD-003
To: MDD Distribution
From: W. Olin Sibert
Date: July 1, 1975
Subject: Overview of the Multics TCB
Abstract:
Overview of the Multics Virtual Memory System, Metering, and the
Supervisor.
Revisions:
REVISION DATE AUTHOR
initial 85-07-01 W. Olin Sibert
_________________________________________________________________
Multics Design Documents are the official design descriptions of
the Multics Trusted Computing Base. They are internal documents,
which may be released outside of Multics System Development only
with the approval of the Director.
i
MDD-003 Overview of the Multics TCB
CONTENTS
Page
Topic I Multics Design Philosophy . . . . . . . . . 1-1
Major Design Goals . . . . . . . . . . . 1-1
Virtual Memory Organization . . . . . . 1-3
Selective, Controlled Sharing . . . . . 1-5
Security. . . . . . . . . . . . . . . .. 1-6
Open-Ended, Modular System. . . . . . . 1-10
Decentralized Administration. . . . . . 1-11
Flexible User Interfaces.. . . . . . . . 1-13
Continuous Operation.. . . . . . . . . . 1-14
Reliable File System.. . . . . . . . . . 1-15
Remote Access .. . . . . . . . . . . . . 1-16
Efficient Service to Large/Small Users . 1-17
Topic II Overview of the Operating System.. . . . . . 2-1
Structure of the Operating System .. . . 2-1
What is the Multics Supervisor.. . . . . 2-3
The Major Supervisor Subsystems .. . . . 2-5
Name Space/Address Space Management .. . 2-9
Directory Control .. . . . . . . . . . . 2-13
Volume Management .. . . . . . . . . . . 2-15
Segment Control .. . . . . . . . . . . . 2-19
Page Control.. . . . . . . . . . . . . . 2-21
Traffic Control .. . . . . . . . . . . . 2-27
Fault and Interrupt Handling.. . . . . . 2-28
System Initialization .. . . . . . . . . 2-31
File System Salvagers .. . . . . . . . . 2-34
Metering & Tuning .. . . . . . . . . . . 2-37
Initializer.SysDaemon .. . . . . . . . . 2-39
Topic III The Multics Environment .. . . . . . . . . . 3-1
What is a Process .. . . . . . . . . . . 3-1
Cooperating Processes .. . . . . . . . . 3-4
The PL/I Operators.. . . . . . . . . . . 3-7
Interfaces to System Modules.. . . . . . 3-9
Deadlock Prevention .. . . . . . . . . . 3-10
Types of Locks.. . . . . . . . . . . . . 3-16
Topic IV Name Space and Address Space Management .. . 4-1
Name/Address Space Overview .. . . . . . 4-1
Name/Address Space Terminology.. . . . . 4-5
Name/Address Space Concepts .. . . . . . 4-7
Name/Address Space Data Bases .. . . . . 4-12
Reference Name Table (RNT).. . . . . 4-12
Known Segment Table (KST) .. . . . . 4-13
Descriptor Segment (DSEG) .. . . . . 4-14
ii MDD-003
Overview of the Multics TCB MDD-003
Typical Address Space .. . . . . . . . . 4-16
Name/Address Space Meters .. . . . . . . 4-32
system_link_meters.. . . . . . . . . 4-32
link_meters .. . . . . . . . . . . . 4-33
Name/Address Space Commands .. . . . . . 4-34
display_kst_entry .. . . . . . . . . 4-34
Topic V Directory Control .. . . . . . . . . . . . . 5-1
Directory Control Overview.. . . . . . . 5-1
Directory Control Terminology .. . . . . 5-3
Directory Control Data Bases.. . . . . . 5-6
Directory Segments.. . . . . . . . . 5-6
Directory Header.. . . . . . . . . . 5-9
Directory Entries .. . . . . . . . . 5-12
Directory Control Commands.. . . . . . . 5-16
display_branch.. . . . . . . . . . . 5-16
Topic VI Volume Management .. . . . . . . . . . . . . 6-1
Volume Management Overview.. . . . . . . 6-1
The New Storage System.. . . . . . . . . 6-4
Volume Management Terminology .. . . . . 6-13
Volume Management Data Bases.. . . . . . 6-16
Volume Label.. . . . . . . . . . . . 6-16
Volume Map.. . . . . . . . . . . . . 6-20
Dumper Bit Map.. . . . . . . . . . . 6-23
VTOC Map.. . . . . . . . . . . . . . 6-25
Physical Volume Table (PVT) .. . . . 6-26
Logical Volume Table (LVT).. . . . . 6-29
Physical Volume Hold Table.. . . . . 6-32
Volume Management Operations.. . . . . . 6-34
Acceptance of Physical Volumes.. . . 6-35
Demounting of Physical Volumes.. . . 6-37
Logical Volume Management .. . . . . 6-39
Volume Management Commands.. . . . . . . 6-40
print_configuration_deck.. . . . . . 6-40
list_vols .. . . . . . . . . . . . . 6-42
display_label .. . . . . . . . . . . 6-44
display_pvte.. . . . . . . . . . . . 6-46
Volume Management Meters.. . . . . . . . 6-48
disk_meters .. . . . . . . . . . . . 6-48
device_meters .. . . . . . . . . . . 6-49
disk_queue.. . . . . . . . . . . . . 6-50
Topic VII Segment Control .. . . . . . . . . . . . . . 7-1
Segment Control Overview.. . . . . . . . 7-1
Segment Control Terminology .. . . . . . 7-4
Segment Control Data Bases.. . . . . . . 7-5
Volume Table of Contents (VTOC) .. . 7-5
Active Segment Table (AST).. . . . . 7-11
iii MDD-003
MDD-003 Overview of the Multics TCB
Services of Segment Control .. . . . . . 7-25
Creating Segments .. . . . . . . . . 7-25
Segment Fault .. . . . . . . . . . . 7-28
Segment Activation.. . . . . . . . . 7-29
Segment Trailers.. . . . . . . . . . 7-30
Boundsfault Handling.. . . . . . . . 7-32
Segment Deactivation.. . . . . . . . 7-35
Summary of Major Services .. . . . . 7-37
Encacheability.. . . . . . . . . . . 7-38
Truncating Segments .. . . . . . . . 7-38
Deleting Segments .. . . . . . . . . 7-40
Other Services.. . . . . . . . . . . 7-42
Segment Control Meters.. . . . . . . . . 7-44
file_system_meters.. . . . . . . . . 7-44
vtoc_buffer_meters.. . . . . . . . . 7-46
Segment Control Commands.. . . . . . . . 7-47
print_aste_ptp.. . . . . . . . . . . 7-47
dump_vtoce.. . . . . . . . . . . . . 7-48
Topic VIII Page Control.. . . . . . . . . . . . . . . . 8-1
Page Control Overview .. . . . . . . . . 8-1
Page Control Terminology.. . . . . . . . 8-5
Page Control Data Bases .. . . . . . . . 8-6
Page Tables .. . . . . . . . . . . . 8-6
Core Map.. . . . . . . . . . . . . . 8-9
System Segment Table (SST) Header .. 8-11
Other Data Bases.. . . . . . . . . . 8-13
Services of Page Control.. . . . . . . . 8-15
Page Fault Handling .. . . . . . . . 8-15
Post Purging.. . . . . . . . . . . . 8-27
Page Control Meters .. . . . . . . . . . 8-28
file_system_meters.. . . . . . . . . 8-28
Topic IX Traffic Control .. . . . . . . . . . . . . . 9-1
Traffic Control Overview.. . . . . . . . 9-1
Traffic Control Terminology .. . . . . . 9-3
Traffic Control Data Bases.. . . . . . . 9-5
tc_data .. . . . . . . . . . . . . . 9-5
Services of Traffic Control .. . . . . . 9-8
Wait Locks.. . . . . . . . . . . . . 9-8
Processor Multiplexing.. . . . . . . 9-9
Traffic Control Meters.. . . . . . . . . 9-18
total_time_meters .. . . . . . . . . 9-18
traffic_control_meters.. . . . . . . 9-19
traffic_control_queue .. . . . . . . 9-21
work_class_meters .. . . . . . . . . 9-23
respons_meters.. . . . . . . . . . . 9-24
post_purge_meters .. . . . . . . . . 9-26
iv MDD-003
Overview of the Multics TCB MDD-003
Traffic Control Commands.. . . . . . . . 9-27
print_tuning_parameters .. . . . . . 9-27
print_apt_entry .. . . . . . . . . . 9-28
Topic X Fault and Interrupt Handling.. . . . . . . . 10-1
Fault and Interrupt Handling Overview .. 10-1
Fault and Interrupt Data Bases.. . . . . 10-4
Fault and Interrupt Vectors .. . . . 10-4
Fault Data Save Areas .. . . . . . . 10-6
Important Types of Faults .. . . . . 10-8
Fault/Interrupt Meters.. . . . . . . . . 10-13
fim_meters.. . . . . . . . . . . . . 10-13
interrupt_meters.. . . . . . . . . . 10-14
Topic XI System Initialization/Shutdown.. . . . . . . 11-1
System Initialization Overview.. . . . . 11-1
System Initialization Terminology .. . . 11-4
Initialization Data Bases .. . . . . . . 11-7
Environment Passed to Initialization.. . 11-10
Collection 0.. . . . . . . . . . . . . . 11-11
Collection 1.. . . . . . . . . . . . . . 11-12
Collection 2.. . . . . . . . . . . . . . 11-14
Collection 3.. . . . . . . . . . . . . . 11-16
Normal Shutdown .. . . . . . . . . . . . 11-17
File System Shutdown.. . . . . . . . . . 11-18
Emergency Shutdown.. . . . . . . . . . . 11-20
Topic XII File System Salvagers .. . . . . . . . . . . 12-1
Overview of Salvagers .. . . . . . . . . 12-1
Directory Salvager.. . . . . . . . . . . 12-4
Quota Salvaging .. . . . . . . . . . . . 12-7
Physical Volume Scavenger .. . . . . . . 12-9
Physical Volume Salvager.. . . . . . . . 12-11
sweep_pv.. . . . . . . . . . . . . . . . 12-12
Topic XIII The Initializer.SysDaemon Process .. . . . . 13-1
Initializer Overview . . . . . . . . . . 13-1
Services of Initializer .. . . . . . . . 13-3
Topic XIV Metering and Tuning .. . . . . . . . . . . . 14-1
Meter and Tuning Overview .. . . . . . . 14-1
Analyzing Performance Problems.. . . . . 14-3
Detailed Problem Analysis .. . . . . . . 14-6
Output From Metering Commands .. . . . . 14-8
total_time_meters .. . . . . . . . . 14-8
interrupt_meters.. . . . . . . . . . 14-9
file_system_meters.. . . . . . . . . 14-10
v MDD-003
MDD-003 Overview of the Multics TCB
file_system_meters.. . . . . . . . . 14-12
device_meters .. . . . . . . . . . . 14-14
disk_meters .. . . . . . . . . . . . 14-15
disk_queue.. . . . . . . . . . . . . 14-16
print_configuration_deck.. . . . . . 14-17
list_vols .. . . . . . . . . . . . . 14-19
traffic_control_queue .. . . . . . . 14-21
traffic_control_meters.. . . . . . . 14-23
print_tuning_parameters .. . . . . . 14-25
work_class_meters .. . . . . . . . . 14-26
respons_meters.. . . . . . . . . . . 14-27
system_performance_graph.. . . . . . 14-29
meter_gate.. . . . . . . . . . . . . 14-31
Topic XV Evolution of Memory Addressing/Management .. 15-1
Conventional Memory .. . . . . . . . . . 15-1
Structure .. . . . . . . . . . . . . 15-1
Address Formation .. . . . . . . . . 15-1
Characteristics .. . . . . . . . . . 15-2
Problems.. . . . . . . . . . . . . . 15-4
Single Virtual Memory .. . . . . . . . . 15-7
Structure .. . . . . . . . . . . . . 15-7
Address Formation .. . . . . . . . . 15-7
Characteristics .. . . . . . . . . . 15-7
Solved Problems .. . . . . . . . . . 15-9
Problems.. . . . . . . . . . . . . . 15-11
Multiple Virtual Memories .. . . . . . . 15-12
Structure .. . . . . . . . . . . . . 15-12
Address Formation .. . . . . . . . . 15-11
Characteristics .. . . . . . . . . . 15-13
Solved Problems .. . . . . . . . . . 15-14
Problems.. . . . . . . . . . . . . . 15-15
Multics Virtual Memory.. . . . . . . . . 15-16
Structure .. . . . . . . . . . . . . 15-16
Address Formation .. . . . . . . . . 15-16
Characteristics .. . . . . . . . . . 15-17
Solved Problems .. . . . . . . . . . 15-18
Problems.. . . . . . . . . . . . . . 15-20
vi MDD-003
Overview of the Multics TCB MDD-003
TOPIC I
Multics Design Philosophy
Page
Major Design Goals. . . . . . . . . . . . . . 1-1
Virtual Memory Organization . . . . . . . . . 1-3
Selective, Controlled Sharing . . . . . . . . 1-5
Security. . . . . . . . . . . . . . . . . . . 1-6
Open-Ended, Modular System. . . . . . . . . . 1-10
Decentralized Administration. . . . . . . . . 1-11
Flexible User Interfaces. . . . . . . . . . . 1-13
Continuous Operation. . . . . . . . . . . . . 1-14
Reliable File System. . . . . . . . . . . . . 1-15
Remote Access . . . . . . . . . . . . . . . . 1-16
Efficient Service to Large or Small Users . . 1-17
1-i MDD-003
.
_M_A_J_O_R__D_E_S_I_G_N__G_O_A_L_S
ox _M_U_L_T_IPLEXED _INFORMATION AND _COMPUTING _SERVICE (MULTICS)
ox MULTICS WAS ONE OF THE FIRST OPERATING SYSTEMS TO BE THOROUGHLY
DESIGNED FROM THE TOP DOWN. THE DEVELOPERS:
[] STARTED WITH A SET OF GOALS
[] CREATED A SYSTEM WHICH WOULD SATISFY THESE GOALS
[] DEVELOPED GENERAL SOLUTIONS INSTEAD OF SPECIFIC SOLUTIONS
(MAKING THE PRODUCT EXTENDABLE)
[] PRODUCED A VIABLE AND MARKETABLE PRODUCT
Not To Be Reproduced 1-1 MDD-003
_M_A_J_O_R__D_E_S_I_G_N__G_O_A_L_S
ox THESE GOALS WERE CAREFULLY CHOSEN TO CHARACTERIZE A 'UTILITY-GRADE'
COMPUTER SYSTEM, AND ARE OUTLINED BELOW:
[] VIRTUAL MEMORY ORGANIZATION
[] SELECTIVE, CONTROLLED SHARING
[] SECURITY
[] OPEN-ENDED, MODULAR SYSTEM
[] DECENTRALIZED ADMINISTRATION
[] FLEXIBLE USER INTERFACES, END-USER ORIENTATION
[] CONTINUOUS OPERATION
[] RELIABLE FILE SYSTEM
[] REMOTE ACCESS
[] EFFICIENT SERVICE TO LARGE AND SMALL USER
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_V_I_R_T_U_A_L__M_E_M_O_R_Y__O_R_G_A_N_I_Z_A_T_I_O_N
ox MOTIVATION
[] INFORMATION STORED ON-LINE IN LARGE INFORMATION UTILITIES OFTEN
EXCEEDS THE SIZE OF AVAILABLE MAIN MEMORY
[] THIS INFORMATION SHOULD BE DIRECTLY (AND CONTINUOUSLY)
ACCESSIBLE BY THE USER COMMUNITY
[] THE SIZE OF MAIN MEMORY SHOULD ONLY AFFECT PROCESSING TIME, NOT
PROCESSING CAPABILITY
[] MAIN MEMORY MANAGEMENT SHOULD BE A TASK FOR THE OPERATING
SYSTEM, NOT THE PROGRAMMER
ox IMPLEMENTATION
[] ALL ON-LINE INFORMATION IS _P_R_O_C_E_S_S_O_R__A_D_D_R_E_S_S_A_B_L_E
[] _A_L_L INFORMATION (PROCEDURE AND DATA) IS COMPARTMENTALIZED INTO
UNITS CALLED "SEGMENTS" ALLOWING THE ASSOCIATION OF ATTRIBUTES
WITH EACH SEGMENT(1)
______________________________________________________________________
(1) THROUGHOUT THIS DOCUMENT, GENERIC REFERENCES TO "SEGMENTS" INCLUDE
DIRECTORIES AS WELL, SINCE DIRECTORIES ARE SIMPLY A SPECIAL KIND
OF SEGMENT
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_V_I_R_T_U_A_L__M_E_M_O_R_Y__O_R_G_A_N_I_Z_A_T_I_O_N
[] SEGMENTS ARE MADE _P_R_O_C_E_S_S _A_D_D_R_E_S_S_A_B_L_E AS THEY ARE REFERENCED
[] ALL SEGMENTS ARE DIVIDED INTO AN INTEGRAL NUMBER OF 1024 WORD
PAGES. THESE PAGES ARE BROUGHT INTO MAIN MEMORY IF AND ONLY IF
THEY ARE REFERENCED (NEEDED)-AT THE TIME THEY ARE REFERENCED BY
ANY PROCESS
[] THE MULTICS HARDWARE INTERPRETS ALL ADDRESSES AS OFFSETS WITHIN
A SPECIFIED SEGMENT (SEGNO|OFFSET)
[] THE HARDWARE MAKES NO DISTINCTION BETWEEN PROCEDURE AND DATA
SEGMENTS. BOTH ARE PAGED IN THE SAME MANNER, BOTH ARE ADDRESSED
IN THE SAME MANNER
[] ALL COMPILERS PRODUCE LOAD MODULES - _N_O MODIFICATION IS REQUIRED
TO EXECUTE PROCEDURE CODE
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_S_E_L_E_C_T_I_V_E_,__C_O_N_T_R_O_L_L_E_D__S_H_A_R_I_N_G
ox MOTIVATION
[] USERS SHOULD BE ABLE TO USE COMMON PROCEDURE AND DATA SEGMENTS
DIRECTLY (NOT COPIES)
[] USERS SHOULD BE ABLE TO SHARE PRIVATE CODE IN A SELECTIVE MANNER
ox IMPLEMENTATION
[] PURE, REENTRANT CODE IS ALWAYS GENERATED BY THE COMPILERS
(ALLOWING SHARING OF PROCEDURE CODE IN A MULTI-PROCESS
ENVIRONMENT)
[] EVERYTHING THE USER TOUCHES (EXECUTE OR REFERENCE) WILL BE A
SEGMENT HAVING ITS OWN ATTRIBUTES
[] THE ACCESS ATTRIBUTES OF EACH SEGMENT ARE ESTABLISHED BY THE
OWNER OF THAT SEGMENT
Not To Be Reproduced 1-5 MDD-003
_S_E_C_U_R_I_T_Y
ox MOTIVATION
[] IN AN ENVIRONMENT OF SEVERAL COEXISTING PROCESSES, USERS MUST BE
PROTECTED FROM ACCIDENTALLY OR INTENTIONALLY INTERFERING WITH
EACH OTHER
[] THE SUPERVISOR MUST BE PROTECTED FROM DAMAGE BY USERS
[] CHANGES IN ACCESS TO INFORMATION MUST BE IMMEDIATELY EFFECTIVE
[] DISCLOSURE OF INFORMATION SHOULD BE ALLOWED IN A SELECTIVE AND
CONTROLLED MANNER (VERSUS ALL-OR-NONE APPROACH)
[] UNWARRANTED DENIAL OF ACCESS TO INFORMATION MUST BE PROHIBITED
ox IMPLEMENTATION
[] PER-SEGMENT ACCESS CONTROL LIST (ACL) - SPECIFYING BY WHOM AND
HOW THE SEGMENT MAY BE ACCESSED
[] RING PROTECTION MECHANISM - ISOLATES SEGMENTS AND PROCESSES
[] ACCESS ISOLATION MECHANISM (AIM) - ISOLATES SEGMENTS ACCORDING
TO CATEGORIES AND SECURITY LEVELS
Not To Be Reproduced 1-6 MDD-003
_S_E_C_U_R_I_T_Y
[] PASSWORDS AND AUDIT TRAILS
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_S_E_C_U_R_I_T_Y
==================================
INSERT Access Control DIAGRAM HERE
==================================
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_O_P_E_N_-_E_N_D_E_D_,__M_O_D_U_L_A_R__S_Y_S_T_E_M
ox MOTIVATION
[] SOFTWARE SHOULD BE EASY TO MODIFY AND EXTEND
[] THE OPERATING SYSTEM SHOULD BE MODULAR, AND THE MODULES SHOULD
BE COMPREHENSIBLE
ox IMPLEMENTATION
[] MODULAR DESIGN OF OPERATING SYSTEM AND USER PROGRAMS (COMPILERS,
PROGRAMMING ENVIRONMENT ENCOURAGE MODULAR DESIGN)
[] UNIFORM PROGRAMMING CONVENTIONS ARE FOLLOWED THROUGHOUT MOST
SYSTEM CODE
[] MORE THAN 92% OF THE OPERATING SYSTEM OBJECT CODE ORIGINATED
FROM PL/I SOURCE
[] DYNAMIC LINKING (ELIMINATES RE-COMPILING, RE-EDITING WHEN
UN-BOUND MODULES ARE REPLACED)
[] ON-LINE MODIFICATION, TESTING AND INSTALLATION OF SYSTEM MODULES
(MULTICS INSTALLATION FACILITY - MIS)
[] PATCH-FREE SYSTEM
Not To Be Reproduced 1-9 MDD-003
_O_P_E_N_-_E_N_D_E_D_,__M_O_D_U_L_A_R__S_Y_S_T_E_M
[] LIBRARY MANAGEMENT TOOLS AND LIBRARY CONVENTIONS
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_D_E_C_E_N_T_R_A_L_I_Z_E_D__A_D_M_I_N_I_S_T_R_A_T_I_O_N
ox MOTIVATION
[] SYSTEM RESOURCES MUST BE EFFECTIVELY ADMINISTERED
[] RESOURCE ALLOCATION, ACCOUNTING, REGISTRATION, BILLING, ETC, IS
TOO MUCH FOR SINGLE INDIVIDUAL
[] DIFFERENT GROUPS OF USERS HAVE DIFFERENT ADMINISTRATIVE NEEDS
ox IMPLEMENTATION
[] GROUPING OF USERS, BY FUNCTION OR MANAGEMENT, INTO PROJECTS
[] THREE-LEVEL HIERARCHY OF ADMINISTRATION
[] SYSTEM ADMINISTRATOR: DISTRIBUTES RESOURCES AND ASSIGNS
ATTRIBUTES TO PROJECTS
[] PROJECT ADMINISTRATORS: DISTRIBUTES RESOURCES AND ASSIGNS
ATTRIBUTES TO USERS
[] USERS: HAS FULL CONTROL OVER ALLOCATED RESOURCES, MODIFIED
BY ASSIGNED ATTRIBUTES
[] THE PROJECT ADMINISTRATOR MAY PASS DOWNWARD ONLY THOSE RESOURCES
AND ATTRIBUTES THAT HAVE BEEN GIVEN TO THE PROJECT
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_D_E_C_E_N_T_R_A_L_I_Z_E_D__A_D_M_I_N_I_S_T_R_A_T_I_O_N
===========================
INSERT SAT/PDT DIAGRAM HERE
===========================
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_F_L_E_X_I_B_L_E__U_S_E_R__I_N_T_E_R_F_A_C_E_S
ox MOTIVATION
[] THE STANDARD USER ENVIRONMENT SHOULD BE EXTENSIVELY
USER-MODIFIABLE
[] THE CAPABILITY SHOULD EXIST TO DEVELOP AND IMPOSE CLOSED
SUBSYSTEMS WHICH CAN PROVIDE ANY DESIRED ENVIRONMENT
ox IMPLEMENTATION
[] USER HAS ABILITY TO CHANGE OR REPLACE CONTROL PROGRAMS IN THE
USER'S RING
[] PROJECT ADMINISTRATOR CAN IMPOSE A CLOSED SUBSYSTEM ENVIRONMENT
OR A DIFFERENT process_overseer ON USERS
[] start_up.ec, ABBREV PROCESSOR, general_ready, ready_off,
add_search_rules, CONDITION HANDLING, ETC.
[] OTHER TOOLS PROVIDE SIMULATION, ENCAPSULATION CAPABILITY
(enter_lss, project_start_up_)
[] STANDARD INTERFACE FOR INTERACTIVE SUBSYSTEMS (ssu_) ENCOURAGES
UNIFORM, FAMILIAR BEHAVIOUR OF USER SUBSYSTEMS.
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_C_O_N_T_I_N_U_O_U_S__O_P_E_R_A_T_I_O_N
ox MOTIVATION
[] UTILITY CONCEPT: SYSTEM SHOULD BE AVAILABLE ON DEMAND AT ALL
TIMES
ox IMPLEMENTATION
[] ON-LINE SOFTWARE INSTALLATION
[] ON-LINE MAINTENANCE: MOVE MORE AND MORE BOS CAPABILITY INTO
MULTICS (EG: RE-BOOT FNP FROM MULTICS)
[] ON-LINE FILE BACKUP AND RECOVERY
[] ON-LINE ACCOUNTING AND BILLING
[] DYNAMIC RECONFIGURATION
[] DYNAMIC FAILSOFT DECONFIGURATION OF FAILING HARDWARE
[] UNATTENDED SERVICE
[] AUTOMATIC REBOOT
Not To Be Reproduced 1-14 MDD-003
_R_E_L_I_A_B_L_E__F_I_L_E__S_Y_S_T_E_M
ox MOTIVATION
[] MUST PROVIDE USERS SOME ASSURANCE THAT THEIR ON-LINE INFORMATION
IS SAFE
[] MUST PROVIDE CHECKPOINT CAPABILITY FOR RECOVERY FROM USER ERROR
OR SYSTEM DISASTER
ox IMPLEMENTATION
[] AUTOMATIC BACKUP/RETRIEVAL FACILITY
[] CONSOLIDATED STORAGE SYSTEM DUMPS
[] PHYSICAL AND LOGICAL SAVE/RESTORE
[] ALL STORAGE SYSTEM RECOVERY PROCEDURES RUN WHILE SYSTEM IS UP
[] DAMAGE RECOVERY RUN AUTOMATICALLY FOLLOWING SYSTEM FAILURE
Not To Be Reproduced 1-15 MDD-003
_R_E_M_O_T_E__A_C_C_E_S_S
ox MOTIVATION
[] UTILITY CONCEPT: FULL ACCESS FROM ANY PHONE IN THE WORLD VIA
ANY REMOTE DEVICE
[] WISH TO PROVIDE _O_N_E "COMMAND LANGUAGE", TO SERVE ALL USERS,
WHETHER LOCAL OR REMOTE, INTERACTIVE OR BATCH
ox IMPLEMENTATION
[] MULTICS COMMUNICATION SYSTEM (MCS)
[] _I_N__P_R_I_N_C_I_P_L_E, ANY REMOTE DEVICE/TERMINAL IS CONNECTABLE
[] SINGLE COMMAND LANGUAGE
[] REMOTE JOB ENTRY (RJE) AND BULK I/O CAPABILITIES
[] DIRECT ATTACHMENTS TO PUBLIC DATA NETWORKS VIA X.25
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_E_F_F_I_C_I_E_N_T__S_E_R_V_I_C_E__T_O__L_A_R_G_E__O_R__S_M_A_L_L__U_S_E_R_S
ox MOTIVATION
[] UTILITY CONCEPT: SYSTEM SHOULD BE AVAILABLE FOR, AND CAPABLE
OF, ANY SIZE TASK
[] RUNNING BOTH LARGE AND SMALL TASKS TOGETHER SHOULD NOT IMPACT
THE EFFICIENCY OF EITHER
ox IMPLEMENTATION
[] DYNAMIC RESOURCE ALLOCATION (DON'T HAVE TO PRE-ALLOCATE OR
GUESS-TIMATE RESOURCES REQUIRED)
[] SERVICE ON DEMAND
[] DYNAMIC SYSTEM TUNING TO ACCOMMODATE CHANGING SYSTEM WORKLOADS
Not To Be Reproduced 1-17 MDD-003
_E_F_F_I_C_I_E_N_T__S_E_R_V_I_C_E__T_O__L_A_R_G_E__O_R__S_M_A_L_L__U_S_E_R_S
TOPIC II
Overview of the Operating System
Page
Structure of the Operating System . . . . . . 2-1
What is the Multics Supervisor. . . . . . . . 2-3
The Major Supervisor Subsystems . . . . . . . 2-5
Name Space/Address Space Management . . . . . 2-9
Directory Control . . . . . . . . . . . . . . 2-13
Volume Management . . . . . . . . . . . . . . 2-15
Segment Control . . . . . . . . . . . . . . . 2-19
Page Control. . . . . . . . . . . . . . . . . 2-21
Traffic Control . . . . . . . . . . . . . . . 2-27
Fault and Interrupt Handling. . . . . . . . . 2-28
System Initialization . . . . . . . . . . . . 2-31
File System Salvagers . . . . . . . . . . . . 2-34
Metering & Tuning . . . . . . . . . . . . . . 2-37
Initializer.SysDaemon . . . . . . . . . . . . 2-39
2-i MDD-003
_S_T_R_U_C_T_U_R_E__O_F__T_H_E__O_P_E_R_A_T_I_N_G__S_Y_S_T_E_M
ox THE MULTICS OPERATING SYSTEM IS A HIGHLY STRUCTURED COLLECTION OF
SOME 5050 MODULES SUMMING TO MORE THAN SIX MILLION WORDS OF OBJECT
CODE
[] MORE THAN 92% OF THIS OBJECT CODE ORIGINATED FROM PL/I SOURCE
(1,930,000 LINES)
[] THE REMAINDER IS WRITTEN IN MULTICS ASSEMBLER LANGUAGE, ALM
(310,000 LINES)
ox THE MULTICS OPERATING SYSTEM CONSISTS OF THE FOLLOWING MAJOR
COMPONENTS:
[] THE SUPERVISOR (THE PRINCIPAL TARGET OF THIS COURSE)
[] FREQUENTLY CALLED "HARDCORE" - BUT DOES NOT NECESSARILY IMPLY
WIRED IN CORE. IF MULTICS WAS NOT A VIRTUAL SYSTEM, THEN THE
TERM "HARDCORE" WOULD PROPERLY DEFINE THE SUPERVISOR
[] CONSIST OF MORE THAN 750 SEGMENTS AND USES MORE THAN 380
INCLUDE FILES
[] USER COMMANDS AND ACTIVE FUNCTIONS (600)
[] DESCRIBED IN THE MPM MANUAL "Multics Commands and Active
Functions" (AG92)
Not To Be Reproduced 2-1 MDD-003
_S_T_R_U_C_T_U_R_E__O_F__T_H_E__O_P_E_R_A_T_I_N_G__S_Y_S_T_E_M
[] SUBROUTINES (550)
[] DESCRIBED IN THE MPM MANUALS "Multics Subroutines" (AG93) AND
"Subsystems Writer's Guide" (OFTEN ABBREVIATED AS "SWG")
(AK92)
[] TOOLS (220)
[] DESCRIBED IN THE MPM MANUAL "Multics Commands and Active
Functions" (AG92)
[] ADMINISTRATIVE ROUTINES (200)
[] DESCRIBED IN THE MAM MANUALS "System Administrator" (AK50),
"Registration & Accounting Administrator" (AS68), "Project
Administrator" (AK51)
[] OPERATOR COMMANDS (150)
[] DESCRIBED IN THE MANUAL "Operator's Handbook" (AM81)
Not To Be Reproduced 2-2 MDD-003
_W_H_A_T__I_S__T_H_E__M_U_L_T_I_C_S__S_U_P_E_R_V_I_S_O_R
ox WHAT IS THE MULTICS SUPERVISOR?
[] A COLLECTION OF MANY LOGICAL SUBSYSTEMS WHICH IMPLEMENT THE
FUNCTIONS OF MULTICS
[] THE PRIMARY PURPOSE OF MULTICS IS TO RUN PROGRAMS, WHICH ACCESS
DATA, AND THUS THE MAJOR PURPOSE OF THE MULTICS SUPERVISOR IS TO
MAKE THAT DATA ACCESSIBLE
[] THESE SUBSYSTEMS FALL INTO FOUR MAJOR GROUPS:
[] THE FILE SYSTEM
[] SUPPORT SERVICES FOR THE FILE SYSTEM
[] MISCELLANEOUS SUPERVISOR SERVICES
[] SUBSYSTEMS RELATED TO, BUT NOT STRICTLY PART OF THE
SUPERVISOR
[] THESE DIVISIONS ARE SOMEWHAT ARTIFICIAL, BECAUSE THE SUBSYSTEMS
ARE ALL INTIMATELY RELATED TO EACH OTHER. THE DIVISIONS
REPRESENT A PARTICULAR VIEWPOINT OF SYSTEM FUNCTION.
[] A MULTICS SUBSYSTEM IS A SET OF PROGRAMS PERFORMING A SPECIFIC
SERVICE FOR THE USER COMMUNITY - AND FOR THE OPERATING SYSTEM
ITSELF
[] TOGETHER, ALL THESE SUBSYSTEMS IMPLEMENT THE FUNCTIONS DESCRIBED
Not To Be Reproduced 2-3 MDD-003
_W_H_A_T__I_S__T_H_E__M_U_L_T_I_C_S__S_U_P_E_R_V_I_S_O_R
IN THE MPM SUBROUTINES AND SWG MANUALS, (ESSENTIALLY hcs_ AND
THE VIRTUALS MEMORY).
Not To Be Reproduced 2-4 MDD-003
_T_H_E__M_A_J_O_R__S_U_P_E_R_V_I_S_O_R__S_U_B_S_Y_S_T_E_M_S
ox MAJOR MULTICS SUPERVISOR SUBSYSTEMS: FOUR GROUPS OF ABOUT FOUR
SUBSYSTEMS EACH
[] THE FILE SYSTEM - THOSE SUBSYSTEMS WHICH ARE CONCERNED WITH
STORING DATA, MANAGING DATA, AND MAKING IT AVAILABLE TO USERS.
FIVE MAJOR COMPONENTS:
[] NAME SPACE / ADDRESS SPACE CONTROL
[] DIRECTORY CONTROL
[] VOLUME MANAGEMENT
[] SEGMENT CONTROL
[] PAGE CONTROL
[] SERVICES TO SUPPORT THE FILE SYSTEM, WHICH MULTIPLEX ITS
FACILITIES BETWEEN DIFFERENT USERS, AND ENSURE ITS RELIABILITY.
FOUR MAJOR COMPONENTS:
[] TRAFFIC CONTROL
[] FAULT AND INTERRUPT HANDLING
[] SYSTEM INITIALIZATION
[] THE FILE SYSTEM SALVAGERS
Not To Be Reproduced 2-5 MDD-003
_T_H_E__M_A_J_O_R__S_U_P_E_R_V_I_S_O_R__S_U_B_S_Y_S_T_E_M_S
[] MISCELLANEOUS SUPERVISOR SERVICES - THESE ARE THINGS DONE IN THE
SUPERVISOR FOR REASONS OF ACCESS CONTROL AND SHARING, BUT NOT
DIRECTLY RELATED TO THE FILE SYSTEM
[] BECAUSE THEY ARE NOT DIRECTLY RELATED, THEY WILL NOT BE COVERED
IN ANY DETAIL
[] MULTICS COMMUNICATIONS SYSTEM
[] RESOURCE CONTROL
[] USER DEVICE I/O - ioi_
[] LOW LEVEL SUPERVISOR I/O
[] RECONFIGURATION
[] SYSTEM ERROR HANDLING (syserr / verify_lock)
[] RELATED SUBSYSTEMS - THESE ARE NOT ACTUALLY PART OF THE
SUPERVISOR, BUT ARE CLOSELY RELATED
[] METERING AND TUNING
[] THE Initializer.SysDaemon
ox THE MULTICS SUPERVISOR IS DESIGNED AROUND THE "LAYERED MACHINE"
CONCEPT
Not To Be Reproduced 2-6 MDD-003
_T_H_E__M_A_J_O_R__S_U_P_E_R_V_I_S_O_R__S_U_B_S_Y_S_T_E_M_S
[] CONSTRUCT A SIMPLE SET OF OPERATIONS CALLED A "KERNEL" WHICH
IMPLEMENTS THE MOST FUNDAMENTAL (PRIMITIVE) OPERATIONS REQUIRED
[] CONSTRUCT A SLIGHTLY MORE SOPHISTICATED SET OF OPERATIONS WHICH
ASSUMES AND RELIES ON THE CORRECT FUNCTIONING OF THE KERNEL -
ANOTHER "LAYER"
[] CONSTRUCT A MORE SOPHISTICATED LAYER WHICH ASSUMES AND RELIES ON
THE CORRECT FUNCTIONING OF THE PREVIOUS MACHINES
[] ETC
ox THE "LAYERS" OF THE MULTICS SUPERVISOR PARTIALLY MAP INTO THE ABOVE
SUBSYSTEMS
ox THE FOLLOWING DIAGRAM REPRESENTS THIS MAPPING:
Not To Be Reproduced 2-7 MDD-003
_T_H_E__M_A_J_O_R__S_U_P_E_R_V_I_S_O_R__S_U_B_S_Y_S_T_E_M_S
======================================
INSERT Multics Supervisor DIAGRAM HERE
======================================
Not To Be Reproduced 2-8 MDD-003
_N_A_M_E__S_P_A_C_E_/_A_D_D_R_E_S_S__S_P_A_C_E__M_A_N_A_G_E_M_E_N_T
ox FUNCTION
[] IMPLEMENT THE PER PROCESS VIRTUAL MEMORY
ox BASIC PHILOSOPHY
[] AS A NEWLY LOGGED IN USER ATTEMPTS TO TOUCH VARIOUS SEGMENTS A
CONSIDERABLE AMOUNT OF MANAGEMENT INFORMATION MUST BE
(TRANSPARENTLY) FOUND AND/OR COMPUTED BEFORE THE USER'S
REFERENCE IS ACTUALLY ACCOMPLISHED
[] FOR EVERY SEGMENT REFERENCED BY THE USER, THE SUPERVISOR:
[] ASSIGNS A SEGMENT NUMBER (FOR REASON OF HARDWARE ADDRESSING),
AND
[] RECORDS (REMEMBERS) THE MANAGEMENT INFORMATION (FOR REASON OF
SOFTWARE EFFICIENCY AND CONTROL)
[] SUCH SEGMENTS ARE SAID TO BE "KNOWN TO THE PROCESS"
[] THE MANAGEMENT INFORMATION IS MAINTAINED ON A PER PROCESS BASIS
Not To Be Reproduced 2-9 MDD-003
_N_A_M_E__S_P_A_C_E_/_A_D_D_R_E_S_S__S_P_A_C_E__M_A_N_A_G_E_M_E_N_T
IN THREE COMPLEMENTING AREAS: DSEG, KST, AND RNT
[] MANAGES TWO DISTINCT SETS OF INFORMATION:
[] ADDRESS SPACE - CORRESPONDENCE BETWEEN SEGMENT NUMBERS AND
THE SEGMENTS THEMSELVES
[] NAME SPACE - CORRESPONDENCE BETWEEN SEGMENT NUMBERS AND NAMES
THE USER REFERS TO THEM BY
[] CALLS DIRECTORY CONTROL TO LOCATE SEGMENTS INITIALLY
[] NAME SPACE / ADDRESS SPACE MANAGEMENT IS INVOKED BY SUBROUTINE
CALLS, AND BY LINKAGE FAULTS (THE "DYNAMIC LINKER")
ox PRINCIPAL USER INTERFACES
[] COMMAND LEVEL
[] initiate, terminate, terminate_segno, terminate_ref_name,
terminate_single_ref_name, list_ref_name
[] THE COMMAND PROCESSOR ITSELF - WHICH USES THESE SERVICES TO
LOCATE COMMANDS
[] SUBROUTINE LEVEL
[] hcs_$initiate, hcs_$initiate_count_, hcs_$terminate_file,
hcs_$terminate_seg, hcs_$terminate_name,
hcs_$terminate_noname, term_
Not To Be Reproduced 2-10 MDD-003
_N_A_M_E__S_P_A_C_E_/_A_D_D_R_E_S_S__S_P_A_C_E__M_A_N_A_G_E_M_E_N_T
ox MAJOR DATA BASES
[] DESCRIPTOR SEGMENT (DSEG) - ONE PER PROCESS
[] SEGMENT DESCRIPTOR WORD (SDW) - ONE PER KNOWN SEGMENT
[] DEFINES THE USER'S ADDRESS SPACE TO THE HARDWARE
[] KNOWN SEGMENT TABLE (KST) - ONE PER PROCESS
[] KNOWN SEGMENT TABLE ENTRY (KSTE) - ONE PER KNOWN SEGMENT
(EXCEPT SUPERVISOR SEGMENTS)
[] DEFINES THE USER'S ADDRESS SPACE TO THE SUPERVISOR AND THE
USER
[] EACH KSTE ASSOCIATES A USER'S SEGMENT NUMBER WITH THE SEGMENT
CONTROL ATTRIBUTES OF THAT SEGMENT
[] THE SEARCH FOR AN AVAILABLE KSTE DETERMINES A SEGMENT'S
NUMBER
[] REFERENCE NAME TABLE (RNT) - ONE PER EACH RING IN EACH PROCESS
[] NOT A SEGMENT - KEPT AS A REGION ALLOCATED IN THE "LINKAGE
AREA" FOR EACH RING
[] REFERENCE NAME TABLE ENTRY (RNTE) - ONE PER REFERENCE NAME
Not To Be Reproduced 2-11 MDD-003
_N_A_M_E__S_P_A_C_E_/_A_D_D_R_E_S_S__S_P_A_C_E__M_A_N_A_G_E_M_E_N_T
[] USED BY THE DYNAMIC LINKER TO IMPLEMENT THE
"initiated_segments" SEARCH RULE
[] DEFINES THE USER'S NAME SPACE TO THE USER
[] NAME SPACE MAY BE DIFFERENT IN DIFFERENT RINGS OF THE SAME
PROCESS
Not To Be Reproduced 2-12 MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L
ox FUNCTION
[] DIRECTORY CONTROL IS A SET OF HARDCORE MODULES RESPONSIBLE FOR
THE MAINTENANCE OF THE MULTICS DIRECTORY STRUCTURE -- IE: THE
HIERARCHY
[] ITS TASKS INCLUDE CREATING, MANIPULATING AND INTERPRETING THE
CONTENTS OF DIRECTORY SEGMENTS, TO INCLUDE:
[] ACCESS CONTROL LISTS (ACL'S), NAMES, AND VTOCE POINTERS OF
ENTRIES DESCRIBED THEREIN
[] ONLY DIRECTORY CONTROL IS ALLOWED TO ALTER THE CONTENTS OF
DIRECTORY SEGMENTS
[] DIRECTORY CONTROL IMPLICITLY RELIES UPON THE SERVICES OF OTHER
SUBSYSTEMS SUCH AS SEGMENT CONTROL AND PAGE CONTROL, AND ALSO
INVOKES THEM DIRECTLY BY SUBROUTINE CALL
[] DIRECTORIES ARE SIMPLY SEGMENTS TO THESE SUBSYSTEMS
[] DIRECTORY CONTROL IS INVOKED ONLY BY SUBROUTINE CALLS
ox PRINCIPAL USER INTERFACES
Not To Be Reproduced 2-13 MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L
[] COMMAND LEVEL
[] create, create_dir, link, set_acl, delete_acl, status, list,
add_name, rename
[] SUBROUTINE LEVEL
[] hcs_$append_branch, hcs_$add_acl_entries, hcs_$append_link,
hcs_$delete_acl_entries, hcs_$status_, hcs_$chname_file
ox MAJOR DATA BASES
[] DIRECTORY SEGMENTS
[] CONTAIN THE ATTRIBUTES AND OTHER INFORMATION ABOUT THEIR
SEGMENTS (NEEDED TO FIND SEGMENTS, RETURN STATUS INFORMATION,
AND BUILD VTOCE'S AT SEGMENT CREATION)
[] THE DIRLOCKT_SEG
[] SEGMENT WHERE DIRECTORY LOCKING IS MANAGED
Not To Be Reproduced 2-14 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T
ox FUNCTION
[] VOLUME MANAGEMENT IS RESPONSIBLE FOR THE MANAGEMENT OF PHYSICAL
AND LOGICAL VOLUMES
[] ITS TASKS INCLUDE:
[] ACCEPTANCE AND DEMOUNTING OF PHYSICAL VOLUMES
[] MAINTAINING THE ASSOCIATION BETWEEN PHYSICAL VOLUMES, LOGICAL
VOLUMES, AND DISK DRIVES
[] ENSURING THE INTEGRITY OF VOLUME CONTENTS
[] MAKING VOLUME CONTENTS ACCESSABLE TO PAGE CONTROL (PAGES) AND
SEGMENT CONTROL (VTOC ENTRIES)
[]
Not To Be Reproduced 2-15 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T
VOLUME MANAGEMENT IS INVOKED ONLY BY SUBROUTINE CALLS
ox MAJOR DATA BASES
[] PHYSICAL VOLUME TABLE (PVT) - ONE PER SYSTEM
[] PHYSICAL VOLUME TABLE ENTRY (PVTE) - ONE PER DISK DRIVE KNOWN
TO THE SYSTEM
[] EACH PVTE IDENTIFIES A DRIVE'S DEVICE NUMBER, SUBSYSTEM NAME,
DEVICE TYPE, AND INFORMATION ABOUT THE PHYSICAL VOLUME
CURRENTLY MOUNTED
[] USED TO MAP REFERENCES TO PAGES OF SEGMENTS INTO AN I/O
REQUEST TO THE CORRECT DISK DRIVE
[] LOGICAL VOLUME TABLE (LVT) - ONE PER SYSTEM
[] LOGICAL VOLUME TABLE ENTRY (LVTE) - ONE PER MOUNTED LOGICAL
VOLUME
[] EACH LVTE CONTAINS THE LOGICAL VOLUME ID, POINTERS TO MEMBER
PVTE'S, AIM CLASS LIMITS, ETC.
[] USED TO DETERMINE A USER'S ACCESS TO A LOGICAL VOLUME
(PRIVATE OR PUBLIC) AND TO LOCATE MEMBER PHYSICAL VOLUMES
[] VOLUME HEADER - ONE PER PACK
[] VOLUME LABEL (REGISTRATION AND ACCEPTANCE INFORMATION)
Not To Be Reproduced 2-16 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T
[] VOLUME MAP (OCCUPIED/VACANT INFORMATION FOR VOLUME CONTENTS)
[] RECORD STOCKS - ONE PER MOUNTED VOLUME
[] ONLINE CACHE OF INFORMATION ABOUT USED / UNUSED RECORDS ON
THE VOLUME
[] THIS INFORMATION IS DERIVED FROM THE VOLUME MAP, BUT KEPT
ONLINE TO AVOID THE NECESSITY OF REFERRING TO THE VOLUME MAP
ON DISK EVERY TIME A RECORD IS ALLOCATED OR FREED
[] WHEN THE CACHE BECOMES COMPLETELY EMPTY OR COMPLETELY FULL,
IT MUST BE UPDATED FROM/TO DISK - A PROTOCOL ENSURES THAT THE
COPY ON DISK IS ALWAYS CONSISTENT
[] PROVIDED BY VOLUME MANAGEMENT, BUT USED BY PAGE CONTROL
[] VTOCE STOCKS - ONE PER VOLUME
[] SIMILAR TO RECORD STOCKS, BUT MAINTAINS INFORMATION ABOUT
USED / UNUSED VTOC ENTRIES ON THE VOLUME
[] PROVIDED BY VOLUME MANAGEMENT, BUT USED BY SEGMENT CONTROL
[] PHYSICAL VOLUME HOLD TABLE (PVHT) - ONE PER SYSTEM
[] RECORDS THE COMMENCEMENT OF COMPOUND I/O OPERATIONS UPON A
PHYSICAL VOLUME
[] THIS INFORMATION PREVENTS A VOLUME FROM BEING DEMOUNTED WHILE
SUCH AN OPERATION IS IN PROGRESS
Not To Be Reproduced 2-17 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L
ox FUNCTION
[] SEGMENT CONTROL IS RESPONSIBLE FOR THE MANAGEMENT OF _L_O_G_I_C_A_L
_M_E_M_O_R_Y
[] ITS TASKS INCLUDE:
[] MAINTAINING THE DISK RESIDENT MAPS OF SEGMENTS (IE: THEIR
VTOCE'S)
[] SEGMENT CREATION, TRUNCATION AND DELETION
[] SEGMENT ACTIVATION AND DEACTIVATION (ASTE MULTIPLEXING)
[] SEGMENT CONTROL CAN BE INVOKED EITHER BY SUBROUTINE CALLS OR BY
SEGMENT FAULTS
ox BASIC PHILOSOPHY OF ACTIVATION/DEACTIVATION
[] OF ALL SEGMENTS RESIDENT WITHIN THE SYSTEM'S MOUNTED PHYSICAL
VOLUMES, ONLY A SMALL SUBSET WILL REQUIRE ACCESSING AT ANY ONE
TIME. SUCH SEGMENTS WILL BE CALLED "ACTIVE SEGMENTS"
[] A PART OF MAIN MEMORY, CALLED THE "ACTIVE SEGMENT TABLE" (AST),
WILL BE RESERVED TO HOLD MANAGEMENT INFORMATION FOR THESE ACTIVE
SEGMENTS (IDENTITY, PVT INDEX, LOCATION OF PAGES, ETC.)
Not To Be Reproduced 2-18 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L
[] AS SEGMENTS FALL INTO DISUSE, THEIR "MANAGEMENT INFORMATION" IN
THE AST WILL BE REPLACED WITH INFORMATION OF OTHER SEGMENTS
REQUIRING ACTIVATION
ox USER INTERFACE
[] COMMAND LEVEL
[] create, delete, truncate, etc.
[] SUBROUTINE LEVEL
[] hcs_$append_branch, hcs_$append_branchx, hcs_$delentry_seg,
hcs_$delentry_file, hcs_$truncate_seg, hcs_$truncate_file,
hcs_$force_write, etc
ox MAJOR DATA BASES
[] SYSTEM SEGMENT TABLE (SST) - ONE PER SYSTEM, SHARED WITH PAGE
CONTROL. ONE MAJOR COMPONENT IS "OWNED" BY SEGMENT CONTROL:
[] ACTIVE SEGMENT TABLE (AST) - ONE PER SYSTEM
[] THE AST IS A LIST OF ACTIVE (CURRENTLY BEING USED) SEGMENTS
[] ACTIVE SEGMENT TABLE ENTRY (ASTE) - ONE PER ACTIVE SEGMENT
[] ASTES CONTAIN PHYSICAL VOLUME ID'S (PVID'S) AND VTOC
Not To Be Reproduced 2-19 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L
INDEX'S (VTOCX'S) OF SEGMENTS. NEEDED BY SEGMENT CONTROL
TO FIND THE SEGMENT ON DISK (HARDWARE)
[] AST HASH TABLE
[] ALLOWS EFFICIENT SEARCHING OF ASTE'S
[] LOGICALLY PART OF THE AST, BUT ELSEWHERE FOR HISTORICAL
REASONS
[] DIRECTORY SEGMENTS
[] CONTAIN LOCATIONS AND ATTRIBUTES OF SEGMENTS. LOCATION
INFORMATION FROM DIRECTORY SEGMENTS IS PROVIDED TO SEGMENT
CONTROL BY DIRECTORY CONTROL
[] VOLUME TABLE OF CONTENTS (VTOC) - ONE PER PHYSICAL VOLUME
[] VOLUME TABLE OF CONTENTS ENTRY (VTOCE) - ONE PER
DISK-RESIDENT SEGMENT
[] EACH VTOCE CONTAINS THE SEGMENT'S UNIQUE ID, CURRENT LENGTH,
FILE MAP, ETC (NEED TO BUILD ASTE'S AND PT'S)
[] VTOCES ARE READ AND WRITTEN ONLY BY SEGMENT CONTROL
[] VTOCE STOCKS - FROM VOLUME MANAGEMENT
[] USED WHEN CREATING AND DELETING VTOCES FOR SEGMENTS
Not To Be Reproduced 2-20 MDD-003
_P_A_G_E__C_O_N_T_R_O_L
ox FUNCTION
[] PAGE CONTROL IS RESPONSIBLE FOR THE MANAGEMENT OF _P_H_Y_S_I_C_A_L
_M_E_M_O_R_Y TO INCLUDE THE MULTIPLEXING OF MAIN MEMORY FRAMES, AND
THE MANAGEMENT OF DISK STORAGE
[] ITS TASKS INCLUDE:
[] TRANSFERRING THE PAGES OF SEGMENTS BETWEEN THE MEMORY
DEVICES, AND RECORDING THE LOCATION OF "THE" COPY OF THESE
PAGES
[] REPORTING THE STATUS AND FILE MAPS OF SEGMENTS TO SEGMENT
CONTROL
[] PAGE CONTROL IS LARGELY CODED IN MULTICS ASSEMBLER LANGUAGE
(ALM)
[] PAGE CONTROL CAN BE INVOKED EITHER BY SUBROUTINE CALLS OR BY
PAGE FAULTS
[]
Not To Be Reproduced 2-21 MDD-003
_P_A_G_E__C_O_N_T_R_O_L
THERE ARE NO EXPLICIT USER INTERFACES TO PAGE CONTROL
ox BASIC PHILOSOPHY
[] OF ALL THE SEGMENTS ACTIVE AT A GIVEN TIME, ONLY A SMALL SUBSET
OF THEIR TOTAL PAGES WILL BE REQUIRED FOR ACCESSING
[] PAGES WILL BE READ INTO MAIN MEMORY AS THEY ARE REQUIRED
[] THE READING OF A PAGE INTO MAIN MEMORY WILL (PROBABLY) REQUIRE
THE EVICTION OF A PREVIOUSLY REQUIRED PAGE
[] THE CHOICE OF A PAGE FOR EVICTION WILL BE BASED ESSENTIALLY UPON
A "LEAST RECENTLY USED" CRITERIA
[] AN EVICTED PAGE NEED BE WRITTEN BACK TO DISK _O_N_L_Y IF IT WAS
MODIFIED DURING ITS RESIDENCY IN MAIN MEMORY
ox MAJOR DATA BASES
[] PHYSICAL VOLUME TABLE (PVT) - ONE PER SYSTEM. PROVIDED BY
VOLUME MANAGEMENT
[] PHYSICAL VOLUME TABLE ENTRY (PVTE) - ONE PER DISK DRIVE
CONFIGURED
[] EACH PVTE CONTAINS:
Not To Be Reproduced 2-22 MDD-003
_P_A_G_E__C_O_N_T_R_O_L
[] THE DEVICE ID (DISK DRIVE ID) AND THE ID OF THE PHYSICAL
VOLUME (DISK PACK) CURRENTLY MOUNTED
[] THE NUMBER OF RECORDS LEFT UNALLOCATED ON THE PHYSICAL
VOLUME, POINTER TO THE RECORD STOCK, ETC
[] RECORD STOCKS - ONE PER MOUNTED PHYSICAL VOLUME, PROVIDED BY
VOLUME MANAGEMENT
[] CONTAINS AN IN-MEMORY CACHE OF THE IN-USE STATUS OF RECORDS
ON THE VOLUME, FROM THE VOLUME MAP, USED WHEN ALLOCATING OR
FREEING PAGES
[] ACCESSED BY A COMPLEX MECHANISM WHICH USES NORMAL PAGE I/O
BUT HAS A PROTOCOL TO ENSURE SYNCHRONIZATION OF DISK CONTENTS
AND RECORD STOCK CONTENTS
[] SYSTEM SEGMENT TABLE (SST) - ONE PER SYSTEM. SHARED WITH
SEGMENT CONTROL. CONTAINS THE FOLLOWING FIVE DATA BASES USED BY
PAGE CONTROL:
[] SYSTEM SEGMENT TABLE (SST) HEADER - ONE PER SYSTEM
[] CONTAINS A LARGE NUMBER OF COUNTERS AND POINTERS VITAL TO
THE MAINTENANCE AND METERING OF THE STORAGE SYSTEM
[] CONTAINS LOCKWORDS USED TO SYNCHRONIZE PAGE CONTROL AND
SEGMENT CONTROL OPERATIONS
[] CORE MAP - THE core_map SEGMENT - ONE PER SYSTEM
[] CORE MAP ENTRY (CME) - ONE PER FRAME (1024 WORDS) OF
CONFIGURED MAIN MEMORY
[] EACH CME REPRESENTS A FRAME OF MAIN MEMORY AND IDENTIFIES
THE CURRENT OCCUPANT OF THAT FRAME
[]
Not To Be Reproduced 2-23 MDD-003
_P_A_G_E__C_O_N_T_R_O_L
NOT PART OF THE SST SEGMENT ANY MORE, BUT LOGICALLY PART
OF THE SST
[] ACTIVE SEGMENT TABLE (AST) - ONE PER SYSTEM
[] ACTIVE SEGMENT TABLE ENTRY (ASTE) - ONE PER ACTIVE SEGMENT
[] LIST OF ACTIVE (CURRENTLY BEING USED) SEGMENTS
[] PAGE TABLES (PT) - ONE PER ACTIVE SEGMENT, THE OTHER HALF OF
EACH ASTE
[] PAGE TABLE WORD (PAGE PTW) - EITHER 4, 16, 64, OR 256 PER
PAGE TABLE
[] EACH PTW DEFINES THE CURRENT LOCATION OF A PAGE OF THE
SEGMENT: DISK, MAIN MEMORY ADDRESS, OR NULL
Not To Be Reproduced 2-24 MDD-003
_P_A_G_E__C_O_N_T_R_O_L
===============================
INSERT File System DIAGRAM HERE
===============================
Not To Be Reproduced 2-25 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L
ox FUNCTION
[] TRAFFIC CONTROL (OR THE "TRAFFIC CONTROLLER") IS RESPONSIBLE FOR
MANAGING THE ASSIGNMENT OF PHYSICAL PROCESSORS TO MULTICS
PROCESSES AND IMPLEMENTING THE SYSTEM'S WAIT/NOTIFY AND
INTERPROCESS COMMUNICATION PRIMITIVES
[] THE FUNCTIONS ASSUMED BY THE TRAFFIC CONTROLLER ARE KNOWN AS
MULTIPROGRAMMING, MULTIPROCESSING, SCHEDULING, DISPATCHING,
PROCESSOR MANAGEMENT, AND INTERPROCESS COMMUNICATION.
[] ITS MAJOR FUNCTION IS ALLOWING PROCESSES TO AWAIT THE COMPLETION
OF FILE SYSTEM OPERATIONS, SUCH AS PAGE I/O
[] TRAFFIC CONTROL CAN BE INVOKED BY SUBROUTINE CALLS AND
INTERRUPTS
[] THERE ARE NO IMPORTANT USER SUBROUTINE INTERFACES, BUT THERE ARE
PRIVILEGED SUBROUTINE INTERFACES FOR PROCESS CREATION,
ADJUSTMENT OF SCHEDULING PARAMETERS, ETC.
ox MAJOR DATA BASES
[] TC_DATA SEGMENT - ONE PER SYSTEM. CONTAINS THE FOLLOWING FOUR
DATA BASES:
[] TC_DATA HEADER - ONE PER SYSTEM
Not To Be Reproduced 2-26 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L
[] CONTAINS VARIOUS METERS, COUNTERS AND POINTERS USED BY THE
TRAFFIC CONTROLLER
[] ACTIVE PROCESS TABLE (APT) - ONE PER SYSTEM
[] ACTIVE PROCESS TABLE ENTRY (APTE) - ONE OCCUPIED PER
ACTIVE PROCESS (TOTAL NUMBER IS DETERMINED BY CONFIG DECK)
[] EACH APTE CONTAINS VARIOUS ATTRIBUTES OF AN ACTIVE PROCESS
INCLUDING THE PROCESS ID, STATE, THE VALUE OF ITS
DESCRIPTOR BASE REGISTER (DBR), SCHEDULING PARAMETERS, AND
A POINTER TO THE PROCESS'S ITT ENTRIES
[] THE APTE CONTAINS ALL INFORMATION THE SUPERVISOR NEEDS TO
KNOW ABOUT A PROCESS WHEN THE PROCESS IS NOT RUNNING
[] INTERPROCESS TRANSMISSION TABLE (ITT) - ONE PER SYSTEM
[] ITT ENTRY - ONE OCCUPIED PER OUTSTANDING IPC WAKEUP
[] A QUEUE FOR TEMPORARILY STORING IPC WAKEUP INFORMATION
(CHANNEL NAME, RANDOM DATA, PROCESS ID, ETC)
[] WORK CLASS TABLE (WCT) - ONE PER SYSTEM
[] WORK CLASS TABLE ENTRY (WCTE) - ONE PER WORKCLASS
[] EACH WCTE CONTAINS ADMINISTRATOR DEFINED PARAMETERS OF THE
WORKCLASS, VARIOUS METERS AND POINTERS
Not To Be Reproduced 2-27 MDD-003
_F_A_U_L_T__A_N_D__I_N_T_E_R_R_U_P_T__H_A_N_D_L_I_N_G
ox FUNCTION
[] RESPONSIBLE FOR HANDLING ALL EXCEPTIONS IN A CPU WHETHER
INTERNAL TO THE PROCESSOR (REFERRED TO AS _F_A_U_L_T_S) OR EXTERNAL
(REFERRED TO AS _I_N_T_E_R_R_U_P_T_S)
[] ESTABLISHES THE SUPERVISOR ENVIRONMENT AT FAULT AND INTERRUPT
TIME. SAVES THE MACHINE CONDITIONS AND TRANSFERS TO THE
APPROPRIATE HANDLER
[] MAJOR COMPONENTS: THE FAULT INTERCEPT MODULE (fim), WIRED-FAULT
INTERCEPT MODULE (wired_fim), I/O INTERRUPT HANDLER
(io_interrupt), sys_trouble, page_fault
ox MAJOR DATA BASES
[] INTERRUPT VECTORS - ONE SET PER SYSTEM (WIRED)
[] INTERRUPT PAIR (2 INSTRUCTIONS) - ONE PAIR PER DEFINED
INTERRUPT TYPE
[] LOCATED AT ABSOLUTE ADDRESS 0. A HARDWARE RECOGNIZED DATA
BASE
[] DESCRIBE WHERE TO SAVE THE CONTEXT, AND WHERE TO TRANSFER TO
TO PROCESS THE INTERRUPT (ALWAYS io_interrupt)
Not To Be Reproduced 2-28 MDD-003
_F_A_U_L_T__A_N_D__I_N_T_E_R_R_U_P_T__H_A_N_D_L_I_N_G
[] FAULT VECTORS - ONE SET PER SYSTEM (WIRED)
[] VECTOR PAIR (2 INSTRUCTIONS) - ONE PAIR PER DEFINED FAULT
TYPE
[] LOCATED AT ABSOLUTE ADDRESS 100 (OCTAL) IMMEDIATELY ABOVE THE
INTERRUPT VECTORS. A HARDWARE RECOGNIZED DATA BASE
[] DESCRIBE WHERE TO SAVE THE CONTEXT, AND WHERE TO TRANSFER TO
TO PROCESS THE FAULT (fim, wired_fim, page_fault)
[] _P_R_O_C_E_S_S DATA SEGMENT (PDS) - ONE PER PROCESS (WIRED WHEN
ELIGIBLE)
[] CONTAINS PROCESS RELEVANT INFO SUCH AS PROCESS ID, USER ID,
HOME/WORKING/PROCESS DIRECTORIES, AIM CLASSIFICATION, INITIAL
RING, ETC
[] CONTAINS ALL INFORMATION ABOUT THE PROCESS NEEDED BY THE
SUPERVISOR CODE WHEN THE PROCESS IS RUNNING
[] CONTAINS SAVE AREAS FOR CONTEXT INFORMATION ABOUT FAULTS
WHICH CAN RESULT IN GIVING UP THE PROCESSOR: PAGE FAULTS,
SEGMENT FAULTS, AND ALL FAULTS NOT HANDLED BY THE SUPERVISOR
[] _P_R_O_C_E_S_S_O_R DATA SEGMENT (PRDS) - ONE PER CONFIGURED CPU (WIRED)
[] SERVES AS RING-ZERO STACK FOR PAGE CONTROL AND TRAFFIC
CONTROL
[] ALSO CONTAINS SAVE AREAS FOR CONTEXT INFORMATION ABOUT FAULTS
WHICH USUALLY DO NOT MEAN GIVING UP THE PROCESSOR: CONNECT
FAULTS AND INTERRUPTS.
Not To Be Reproduced 2-29 MDD-003
_F_A_U_L_T__A_N_D__I_N_T_E_R_R_U_P_T__H_A_N_D_L_I_N_G
[] FIM_TABLE
[] A TABLE IN THE FIM PROGRAM WHICH DESCRIBES THE ACTION TO BE
TAKEN FOR VARIOUS TYPES OF FAULTS
Not To Be Reproduced 2-30 MDD-003
_S_Y_S_T_E_M__I_N_I_T_I_A_L_I_Z_A_T_I_O_N
ox FUNCTION
[] PREPARE THE SYSTEM TO OPERATE, STARTING FROM A COMPLETELY EMPTY
MACHINE
[] READS IN SUPERVISOR PROGRAMS FROM SYSTEM TAPE, SNAPS LINKS
BETWEEN SUPERVISOR COMPONENTS, VERIFIES AND INITIALIZES HARDWARE
CONFIGURATION, SETS UP SYSTEM DATABASES, ACCEPTS STORAGE SYSTEM
DISKS AND PREPARES THEM FOR USE BY THE FILE SYSTEM
[] MOST PROGRAMS IN SYSTEM INITIALIZATION ARE DELETED AFTER
INITIALIZATION IS COMPLETE.
[] SUPERVISOR PROGRAMS ARE LOADED IN THREE "COLLECTIONS", EACH OF
WHICH DEPENDS ON THE MECHANISMS SET UP BY THE PREVIOUS ONE
ox MAJOR DATA BASES
[] THESE DATA BASES ARE ALL BUILT DURING THE PROCESS OF
INITIALIZATION (EXCEPT FOR THE CONFIG DECK) AND KEPT AFTER
INITIALIZATION IS FINISHED
[] SEGMENT LOADING TABLE (>sl1>slt)
[] CONTAINS AN ENTRY DESCRIBING THE ATTRIBUTES OF EACH SEGMENT
IN THE SUPERVISOR
Not To Be Reproduced 2-31 MDD-003
_S_Y_S_T_E_M__I_N_I_T_I_A_L_I_Z_A_T_I_O_N
[] NAME TABLE (>sl1>name_table)
[] CONTAINS A LIST OF NAMES FOR EACH OF THE SEGMENTS IN THE
SUPERVISOR
[] DEFINITIONS SEGMENT (>sl1>definitions_)
[] CONTAINS THE DEFINITIONS SECTIONS FOR ALL THE SEGMENTS IN THE
SUPERVISOR, WHICH ARE USED IN ORDER TO SNAP LINKS BETWEEN THE
SUPERVISOR MODULES
[] CONFIG DECK (>sl1>config_deck)
[] CONTAINS A DESCRIPTION OF THE HARDWARE CONFIGURATION AND
CERTAIN SOFTWARE PARAMETERS
[] PROVIDED TO SYSTEM INITIALIZATION BY BOS
ox SHUTDOWN -- TERMINATES THE ACTIVITIES OF THE SYSTEM IN AN ORDERLY
FASHION
[] TWO TYPES OF SHUTDOWN:
[] NORMAL -- REQUESTED BY THE INITIALIZER, RUNS IN THE USUAL
SUPERVISOR ENVIRONMENT
[] EMERGENCY -- USED AFTER A CRASH, MUST MAKE THE SUPERVISOR
ENVIRONMENT OPERABLE BEFORE PROCEEDING
Not To Be Reproduced 2-32 MDD-003
_S_Y_S_T_E_M__I_N_I_T_I_A_L_I_Z_A_T_I_O_N
[] BOTH TYPES EXIST PRIMARILY TO SHUT DOWN THE FILE SYSTEM -- THAT
IS, TO WRITE ALL DATA IN MEMORY INTO ITS PROPER HOME ON DISK
[] INCLUDES PAGES OF SEGMENTS, VTOCES, VOLUME AND VTOC MAPS
[] SHUTDOWN ESSENTIALLY RUNS THE STEPS OF INITIALIZATION BACKWARDS,
BUT WITH A LOT OF SHORTCUTS
Not To Be Reproduced 2-33 MDD-003
_F_I_L_E__S_Y_S_T_E_M__S_A_L_V_A_G_E_R_S
ox FUNCTION
[] ENSURE THE CONSISTENCY OF THE FILE SYSTEM DATABASES AND PERFORM
PERIODIC PREVENTIVE MAINTENANCE OPERATIONS
[] THERE ARE SEVERAL SALVAGERS, EACH WITH A DIFFERENT FUNCTION
[] BECAUSE OF THE COMPLICATED INTERACTIONS THEY HAVE WITH THE REST
OF THE FILE SYSTEM, THE SALVAGERS ARE PERHAPS THE MOST
COMPLICATED SINGLE PROGRAMS IN THE SUPERVISOR
[] SOME SALVAGING IS DONE AUTOMATICALLY, WHEN THE SYSTEM DETECTS AN
INCONSISTENCY. OTHER SALVAGE OPERATIONS ARE EXPLICITLY
REQUESTED, BY PRIVILEGED USERS.
[] EXCEPT FOR SUPERVISOR BUGS, THE ONLY TIME DAMAGE OCCURS THAT
REQUIRES SALVAGING TO FIX IS AFTER A CRASH WHERE EMERGENCY
SHUTDOWN FAILS
ox THE SALVAGERS:
[] DIRECTORY SALVAGER
[] CORRECTS INCONSISTENCIES IN DIRECTORY SEGMENTS BY REBUILDING
THEM
Not To Be Reproduced 2-34 MDD-003
_F_I_L_E__S_Y_S_T_E_M__S_A_L_V_A_G_E_R_S
[] THIS IS THE ONLY SALVAGER INVOKED AUTOMATICALLY IN USER
PROCESSES: ANY ATTEMPT TO LEAVE RING ZERO WITH A DIRECTORY
LOCKED FOR WRITING WILL CAUSE IT TO BE SALVAGED
[] DIRECTORY SALVAGING ALSO RECLAIMS WASTED SPACE IN THE
DIRECTORY, AND IS RUN PERIODICALLY TO COMPACT DIRECTORIES
[] QUOTA SALVAGER
[] CORRECTS INCONSISTENCIES IN THE QUOTA SYSTEM
[] PHYSICAL VOLUME SCAVENGER
[] RECONSTRUCTS RECORD AND VTOCE STOCK INFORMATION FROM THE
VTOCES ON A VOLUME, THEREBY RECLAIMING ANY RECORDS OR VTOCES
WHICH MIGHT HAVE BEEN LOST
[] RUNS ENTIRELY ONLINE WHILE THE SYSTEM IS UP FOR USERS (NEW IN
MR10.1)
[] THIS TYPE OF DAMAGE IS USUALLY BENIGN, SO RUNNING THE
SCAVENGER CAN BE DELAYED.
[] PHYSICAL VOLUME SALVAGER
[] RECONSTRUCTS RECORD AND VTOCE STOCK INFORMATION
[] RUNS ONLY DURING INITIALIZATION, AND THEREFORE DELAYS CRASH
RECOVERY
[] NOW USED ONLY FOR RARE CASES WHERE THERE IS NOT ENOUGH FREE
SPACE LEFT FOR THE SCAVENGER TO RUN. IN THESE RARE CASES, IT
IS INVOKED AUTOMATICALLY BY SYSTEM INITIALIZATION.
Not To Be Reproduced 2-35 MDD-003
_F_I_L_E__S_Y_S_T_E_M__S_A_L_V_A_G_E_R_S
[] SWEEP_PV
[] DELETES UNUSED VTOC ENTRIES WHICH HAVE NO DIRECTORY ENTRY
POINTING TO THEM
[] RUNS ENTIRELY IN USER RING, EXCEPT FOR ACTUALLY READING VTOC
ENTRIES AND DIRECTORY ENTRIES
[] PURELY A HOUSEKEEPING FUNCTION, AND RUN ONLY RARELY.
Not To Be Reproduced 2-36 MDD-003
_M_E_T_E_R_I_N_G__&__T_U_N_I_N_G
ox WHILE NOT A SUBSYSTEM ITSELF, METERING AND TUNING IS A POLICY AND
CAPABILITY COMMON TO ALL OF THE SUPERVISOR'S SUBSYSTEMS
ox FUNCTION
[] METERING (CONSISTS OF THREE ACTIVITIES)
[] ACCUMULATING DATA: THIS IS PERFORMED THROUGHOUT THE
SUPERVISOR BY CODE WHICH
[] RECORDS THE NUMBER OF TIMES AN EVENT HAPPENS OR A
PARTICULAR PIECE OF CODE IS EXECUTED; AND/OR
[] RECORDS THE TIME REQUIRED TO PERFORM A TASK
[] SUCH DATA IS STORED IN AREAS REFERRED TO AS "METERING
CELLS"
[] EXTRACTING DATA: THIS IS PERFORMED BY NUMEROUS METERING
COMMANDS WHICH (WHEN INVOKED)
[] READ AND STORE THE CURRENT VALUES OF RELEVANT METERING
CELLS
[] REPORTING THE DATA: THIS IS PERFORMED BY THE METER COMMANDS
WHICH (WHEN INVOKED)
[] COMPARE CURRENT METERING CELL VALUES WITH PREVIOUSLY READ
VALUES
[] PERFORM THE APPROPRIATE ARITHMETIC COMPUTATIONS UPON THE
DATA IN ORDER TO ARRIVE AT THE DESIRED STATISTIC
[] ARRANGE THE DATA IN A USEFUL FORMAT (A REPORT OR DIAGRAM)
AND PRINT IT
Not To Be Reproduced 2-37 MDD-003
_M_E_T_E_R_I_N_G__&__T_U_N_I_N_G
[] TUNING
[] CHANGING THE SYSTEM'S OPERATING PARAMETERS AND/OR
CONFIGURATION BASED UPON THE DATA AND INSIGHTS FROM THE
SYSTEM'S METERS
ox MAJOR DATA BASES
[] SST HEADER, TC_DATA HEADER, ETC.
Not To Be Reproduced 2-38 MDD-003
_I_N_I_T_I_A_L_I_Z_E_R_._S_Y_S_D_A_E_M_O_N
ox FUNCTION
[] THE SYSTEM'S INITIALIZATION, ADMINISTRATIVE AND CONTROL PROCESS
(Initializer.SysDaemon.z), RESPONSIBLE FOR:
[] INITIALIZING THE OPERATING SYSTEM AT BOOTLOAD, FOLLOWING
SUCCESSFUL INITIALIZATION OF THE SUPERVISOR
[] ANSWERING SERVICE (login and logout)
[] PROCESS CREATION AND DESTRUCTION
[] MESSAGE COORDINATOR (DAEMON COORDINATION)
[] SYSTEM ADMINISTRATION FUNCTIONS
[] SYSTEM ACCOUNTING FUNCTIONS
ox MAJOR DATA BASES, ALL KEPT IN >sc1
[] ANSWER_TABLE
[] ABSENTEE_USER_TABLE
[] DAEMON_USER_TABLE
Not To Be Reproduced 2-39 MDD-003
_I_N_I_T_I_A_L_I_Z_E_R_._S_Y_S_D_A_E_M_O_N
[] MASTER GROUP TABLE (MGT)
[] CHANNEL DEFINITION TABLE (CDT)
[] SYSTEM ADMINISTRATION TABLE (SAT)
[] PERSON NAME TABLE (PNT)
[] PROJECT DEFINITION TABLES (PDT'S)
TOPIC III
The Multics Environment
Page
What is a Process . . . . . . . . . . . . . . 3-1
Cooperating Processes . . . . . . . . . . . . 3-4
The PL/I Operators. . . . . . . . . . . . . . 3-7
Interfaces to System Modules. . . . . . . . . 3-9
Deadlock Prevention . . . . . . . . . . . . . 3-10
Types of Locks. . . . . . . . . . . . . . . . 3-16
3-i MDD-003
.
_W_H_A_T__I_S__A__P_R_O_C_E_S_S
ox A MULTICS PROCESS IS A WELL DEFINED COLLECTION OF SEGMENTS, EACH
WITH DEFINED ACCESS, OVER WHICH A SINGLE EXECUTION POINT IS FREE TO
ROAM (I.E., FETCH INSTRUCTIONS AND MAKE DATA REFERENCES)
ox THE ADDRESS SPACE OF A PROCESS IS THE ABOVE "COLLECTION OF
SEGMENTS". SUCH SEGMENTS ARE SAID TO BE KNOWN TO THE PROCESS
ox EVERY LOGGED IN USER HAS A PROCESS
ox VERY IMPORTANT CONCEPT: THE MULTICS SUPERVISOR RUNS IN THE _U_S_E_R_'_S
PROCESS (IE: IN THE USER'S ADDRESS SPACE), BUT IN A DIFFERENT RING
ox A PROCESS TAKES ON THE IDENTITY OF THE SOFTWARE IT IS EXECUTING
WHERE EVER IT GOES
[] WHEN A USER WISHES TO CREATE A SEGMENT, IT IS THE USER'S PROCESS
WHICH EXECUTES THE SUPERVISOR CODE hcs_$append, CREATING THE
SEGMENT
ox A PROCESS CAN BE VIEWED AS A CONTINUAL FLOW OF EXECUTION
FLUCTUATING BETWEEN DIFFERENT RINGS: PRIMARILY RING FOUR AND RING
ZERO
Not To Be Reproduced 3-1 MDD-003
_W_H_A_T__I_S__A__P_R_O_C_E_S_S
=============================================
INSERT Process Flow of Execution DIAGRAM HERE
=============================================
ox ALL PROCEDURE CODE (WHETHER SUPERVISOR OR USER CODE) MUST HAVE A
STACK FRAME CONTAINING ITS ARGUMENTS AND ENVIRONMENT DATA
ox FOR REASONS OF SECURITY, MULTICS REQUIRES ONE STACK PER RING OF
EXECUTION. WHEN EXECUTING RING "N" PROCEDURES, THERE WILL EXIST A
RING "N" STACK CONTAINING STACK FRAMES FOR THESE PROCEDURES
Not To Be Reproduced 3-2 MDD-003
_W_H_A_T__I_S__A__P_R_O_C_E_S_S
==================================
INSERT Stack per Ring DIAGRAM HERE
==================================
Not To Be Reproduced 3-3 MDD-003
_C_O_O_P_E_R_A_T_I_N_G__P_R_O_C_E_S_S_E_S
ox ALL ACTIVE PROCESSES (INTERACTIVE, ABSENTEE, AND DAEMONS) APPEAR TO
BE AUTONOMOUS AND INDEPENDENT OF ONE ANOTHER
ox IN REALITY, ALL PROCESSES ARE CONTINUALLY COOPERATING, COMPETING
AND SHARING
[] EXAMPLES OF COOPERATION
[] VOLUNTARY
[] THE SENDING AND ACCEPTING OF MESSAGES AND MAIL
[] PREPLANNED BY SYSTEM PROGRAMMERS
[] EVERY PROCESS, BEFORE RELINQUISHING A PROCESSOR, CHOOSES
THE MOST DESERVING REPLACEMENT AND EXECUTES THE CODE WHICH
DISPATCHES THE CHOSEN PROCESS
[] EVERY PROCESS, WHEN RUNNING, WILL SERVICE ALL INTERRUPTS
FIELDED BY ITS PROCESSOR. THESE INTERRUPTS ARE GENERALLY
THE REPLIES TO THE REQUESTS OF _O_T_H_E_R PROCESSES (IE: THE
ARRIVAL OF A PAGE REQUESTED SOME TIME EARLIER)
[] PREPLANNED BY APPLICATION PROGRAMMERS
[] THE MULTICS TRANSACTION PROCESSOR IS COMPOSED OF MANY
COOPERATING, INTER-DEPENDENT PROCESSES
[] EXAMPLES OF COMPETITION
[] ALL PROCESSES COMPETE FOR PROCESSOR TIME AND MAIN MEMORY
RESOURCES
Not To Be Reproduced 3-4 MDD-003
_C_O_O_P_E_R_A_T_I_N_G__P_R_O_C_E_S_S_E_S
[] THIS COMPETITION IS HIGHLY REGULATED IN ORDER FOR ALL
PROCESSES TO BE TREATED FAIRLY
[] THE COMPETITION IS ALSO SUBJECT TO VERSATILE ADMINISTRATIVE
CONTROLS
[] EXAMPLES OF SHARING
[] BY DESIGN, A SIGNIFICANT PART OF THE ADDRESS SPACE OF ALL
PROCESSES IS _I_D_E_N_T_I_C_A_L (THE SUPERVISOR SEGMENTS)
[] BY DEFAULT, REFERENCES TO SEGMENT foo BY TWO DIFFERENT
PROCESSES WILL RESULT IN REFERENCES TO THE _S_A_M_E SEGMENT
(LOGICALLY, PHYSICALLY, ACTUALLY AND ABSOLUTELY)
ox THERE IS NO SEPARATE ENTITY IN MULTICS LIKE AN EXECUTIVE DOING
THINGS ON BEHALF OF THE USER. THE Initializer.SysDaemon IS _N_O_T THE
TIME-SHARE EXECUTIVE OF MULTICS
Not To Be Reproduced 3-5 MDD-003
_C_O_O_P_E_R_A_T_I_N_G__P_R_O_C_E_S_S_E_S
=========================================
INSERT Cooperating Processes DIAGRAM HERE
=========================================
Not To Be Reproduced 3-6 MDD-003
_T_H_E__P_L_/_I__O_P_E_R_A_T_O_R_S
ox OPERATORS ARE LANGUAGE DEPENDENT PIECES OF CODE WHICH IMPLEMENT
HARDWARE OR OPERATING-SYSTEM DEPENDENT FUNCTIONS SUCH AS CALLING
AND SIGNALLING
ox CURRENTLY THERE ARE OPERATORS FOR PL/I, COBOL, AND BASIC. ALM AND
FORTRAN SHARE THE PL/I OPERATORS
ox ALL OPERATORS IN MULTICS ARE PURE, SHARED AND RE-ENTRANT ALM CODE
ox OPERATORS COULD BE GENERATED BY THE COMPILERS AND PLACED IN LINE
WITH OTHER CODE, HOWEVER, THERE ARE DISADVANTAGES:
[] SOME OPERATORS ARE TOO BULKY TO BE INCLUDED WITH EACH USE (SUCH
AS COMPLICATED I/O STATEMENTS)
[] SOME OPERATORS MIGHT CHANGE IN THE FUTURE (SUCH AS ENTRY AND
RETURN SEQUENCES)
ox OPERATORS ARE SIMILAR TO QUICK INTERNAL PROCEDURES IMPLEMENTING
WHAT IS OFTEN CALLED "LIBRARY FUNCTIONS" IN OTHER OPERATING SYSTEMS
Not To Be Reproduced 3-7 MDD-003
_T_H_E__P_L_/_I__O_P_E_R_A_T_O_R_S
ox INSTEAD OF PASSING ARGUMENT LIST, ARGUMENTS ARE USUALLY PASSED TO
THE OPERATORS IN THE CPU'S REGISTERS
ox INSTEAD OF BEING CALLED BY A PROCEDURE CALL, A SINGLE TRANSFER
INSTRUCTION IS USED (tsx0 or tsp3)
ox THE PL/I OPERATORS IMPLEMENT THE SUPPORT FUNCTIONS FOR THE PL/I
ENVIRONMENT
ox SINCE A MULTICS PROCESS IS A PL/I ENVIRONMENT, THE PL/I OPERATORS
ARE VITAL TO THE MULTICS SUPERVISOR (AND ANY OTHER PROGRAMS WRITTEN
IN PL/I)
Not To Be Reproduced 3-8 MDD-003
_I_N_T_E_R_F_A_C_E_S__T_O__S_Y_S_T_E_M__M_O_D_U_L_E_S
ox UNLIKE OTHER SUPERVISORS, THE MULTICS SUPERVISOR IS _N_O_T SEQUENTIAL
- THAT IS, THE CONCEPT OF "JOB FLOW" DOES NOT REALLY APPLY
[] INSTEAD, THE SUBSYSTEMS PERFORM ASYNCHRONOUSLY, BEING 'INVOKED'
BY THOSE PROCESSES WHO REQUIRE THEIR SERVICES
[] THESE SUBSYSTEMS ARE INVOKED BY THE USER'S PROCESS IN ONE OF
THREE WAYS:
[] EXPLICITLY - VIA A SUBROUTINE CALL OR A COMMAND
[] IMPLICITLY - VIA A FAULT
[] IMPLICITLY - VIA AN INTERRUPT
============================
INSERT Triangle DIAGRAM HERE
============================
Not To Be Reproduced 3-9 MDD-003
_D_E_A_D_L_O_C_K__P_R_E_V_E_N_T_I_O_N
ox WHAT IS DEADLOCK?
[] DEADLOCK CAN OCCUR IN ANY MULTI-PROGRAMMING ENVIRONMENT WHEN TWO
OR MORE PROCESSES COMPETE RANDOMLY FOR SERIALLY REUSABLE
RESOURCES
[] THE CLASSIC EXAMPLE OF DEADLOCK IS THE "DEADLY EMBRACE"
==================================
INSERT Deadly Embrace DIAGRAM HERE
==================================
Not To Be Reproduced 3-10 MDD-003
_D_E_A_D_L_O_C_K__P_R_E_V_E_N_T_I_O_N
ox DEADLOCK SOLUTIONS
[] DETECTION AND UNLOCKING
[] SOME SYSTEMS EMPLOY SCHEMES WHICH DETECT THE OCCURRENCE OF
DEADLOCK AND "UNTANGLE" THE INVOLVED PROCESSES
[] DETECTION SCHEMES ARE USUALLY DIFFICULT TO IMPLEMENT AND
EXPENSIVE IN TERMS OF OVERHEAD
[] THE ACT OF UNTANGLING THE INVOLVED PROCESSES USUALLY RESULTS
IN AT LEAST ONE OF THEM LOSING RESOURCES, PRIORITY, OR EVEN
ITS LIFE
[] PREVENTION
[] MOST SYSTEMS ADOPT SOME FORM OF PREVENTION INSTEAD OF
DETECTION
[] PREVENTION SCHEMES NORMALLY TAKE ONE OF TWO FORMS:
[] CHECKING: WHEREBY REQUESTS FOR RESOURCES ARE SCREENED FOR
DEADLOCK POTENTIAL PRIOR TO ACCEPTANCE
[] IMPOSED POLICY: WHEREBY REQUESTS FOR MORE THAN ONE
RESOURCE _M_U_S_T BE MADE:
[] TOGETHER AS ONE TOTAL REQUEST BEFORE THE "JOB" OR
"JOB-STEP" COMMENCES (ALL OR NOTHING); OR
[] SERIALLY, IN A FIXED, PRE-DEFINED ORDER
Not To Be Reproduced 3-11 MDD-003
_D_E_A_D_L_O_C_K__P_R_E_V_E_N_T_I_O_N
ox MULTICS, IN GENERAL, ADOPTS THE FOLLOWING DEADLOCK PREVENTION
SCHEME:
[] USER ASSIGNABLE RESOURCES (SUCH AS TAPE DRIVES, CARD PUNCHES,
ETC)
[] WHEN THE USER IS INTERACTIVE NO POLICY IS ENFORCED. THE USER
IS INFORMED IF THE RESOURCE IS BUSY AND MAY EITHER TRY AGAIN
OR GIVE UP
[] WHEN THE USER IS NOT INTERACTIVE, THE "ALL" OR "NONE"
APPROACH SHOULD BE USED. THE AVAILABILITY OF ALL REQUIRED
RESOURCES BECOMES THE DETERMINING FACTOR IN SCHEDULING THE
USER (SEE THE "RESOURCE CONTROL PACKAGE")
[] SHOULD A NON-INTERACTIVE USER ATTEMPT SERIAL REQUESTS FOR
RESOURCES, A DEADLOCK SITUATION COULD POTENTIALLY ARISE AND
EXIST UNTIL THE AUTOMATIC LOGOUT DUE TO INACTIVITY OCCURS
[] USER ACCESSIBLE RESOURCES (SUCH AS FILES, DATA BASES, ETC)
[] IN GENERAL, USER SEGMENTS IN THE HIERARCHY POSE NO DEADLOCK
PROBLEM SINCE THEY ARE A SIMULTANEOUSLY USABLE RESOURCE (IE:
THERE IS NO DEFAULT CONCURRENCY MECHANISM ASSOCIATED WITH
USER SEGMENTS)
[] SEGMENTS MAY BE PROTECTED FROM POTENTIAL CONCURRENCY PROBLEMS
THROUGH USE OF LOCK WORDS AND THE set_lock_ MECHANISM. THIS
REQUIRES MUTUAL AGREEMENT AMONG ALL PROCESSES ACCESSING SUCH
SEGMENTS
[] SOME SEGMENTS SUCH AS THOSE USED BY THE MULTICS DATA BASE
Not To Be Reproduced 3-12 MDD-003
_D_E_A_D_L_O_C_K__P_R_E_V_E_N_T_I_O_N
MANAGER (MDBM), USE A "COMMITMENT/ROLLBACK" SCHEME
[] SUPERVISOR RESOURCES (SUCH AS HARDCORE DATABASE)
[] LOCKWORDS (OR SIMPLY "LOCKS") ARE USED IN MULTICS TO
IMPLEMENT CONCURRENT ACCESS CONTROL IN THE MULTI-PROCESS
ENVIRONMENT
===================================
INSERT Locking Concept DIAGRAM HERE
===================================
[] THE SUPERVISOR LOCKS ARE ARRANGED IN A PARTIAL ORDER AND A
CODING CONVENTION PREVENTS WAITING ON A LOCK _I_F THE PROCESS
HAS A HIGHER LOCK LOCKED
[] THIS PARTIAL ORDER IS DETERMINED BY AN ANALYSIS OF THE
OPERATING SYSTEM'S BEHAVIOR. FOR EXAMPLE: SINCE A PAGE
FAULT MAY PROPERLY OCCUR WHILE A PROCESS HAS THE ACTIVE
SEGMENT TABLE (AST) LOCKED, AND PAGE FAULT HANDLING REQUIRES
THE LOCKING OF THE PAGE TABLE LOCK, THE PAGE TABLE LOCK MUST
BE PLACED "HIGHER" IN THE PARTIAL ORDER THAN THE AST LOCK
[] TO THE DEGREE THAT THE SYSTEM PROGRAMMERS OBEY THIS PARTIAL
ORDER, A DEADLY EMBRACE CANNOT OCCUR WITHIN THE MULTICS
SUPERVISOR
Not To Be Reproduced 3-13 MDD-003
_D_E_A_D_L_O_C_K__P_R_E_V_E_N_T_I_O_N
=====================================
INSERT Locking Hierarchy DIAGRAM HERE
=====================================
Not To Be Reproduced 3-14 MDD-003
_T_Y_P_E_S__O_F__L_O_C_K_S
ox LOCKS WITHIN MULTICS:
[] ARE 36 BIT WORDS CONTAINING EITHER ZERO (UNLOCKED) OR A
PROCESS_ID (LOCKED)
[] CONTROL PROCESSES, _N_O_T PROCESSORS
[] ARE MUTUALLY EXCLUSIVE LOCKS
[] THE HARDWARE SUPPORTS SEVERAL INDIVISIBLE INSTRUCTIONS USED IN
IMPLEMENTING THE LOCKING PRIMITIVES. FOR EXAMPLE:
[] STAC (_S_TORE _A _CONDITIONAL)
[] IF C(Y)=0 THEN C(A) -> C(Y)
[] TYPICAL USE: LOCKING. IF THE LOCKWORD (Y) IS UNLOCKED (=0)
THEN LOCK THE LOCK BY STORING THE PROCESS_ID (WHICH IS IN A)
INTO THE LOCKWORD
[] SPECIAL HARDWARE PROHIBITS SIMILAR REFERENCES BY OTHER
PROCESSORS DURING THE TEST AND DATA TRANSFER WINDOW
[] ALSO STACQ (_S_TORE _A _CONDITIONAL ON _Q), LDAC (_LOA_D _A AND _CLEAR),
LDQC (_LOA_D _Q AND _CLEAR), SZNC (_SET _Z AND _N AND _CLEAR)
Not To Be Reproduced 3-15 MDD-003
_T_Y_P_E_S__O_F__L_O_C_K_S
ox WITHIN THE MULTICS SUPERVISOR EXISTS TWO TYPES OF LOCKS: LOOP
LOCKS AND WAIT LOCKS
[] LOOP LOCKS
==============================
INSERT Loop Locks DIAGRAM HERE
==============================
[] SIMPLIFIED PL/I ANALOGY:
do while (lockword ^=0);
end;
lockword = process_id;
<update data>
lockword = 0;
[] LOOP LOCKS ARE USED WHEN IT WOULD NOT BE ACCEPTABLE TO GIVE
UP THE PROCESSOR BEFORE LOCKING THE LOCK.
[] LOOP LOCKS TYPICALLY PROTECT THE LOWEST LEVEL OF CRITICAL
SUPERVISOR DATABASES: TRAFFIC CONTROL, PAGE CONTROL, ETC.
Not To Be Reproduced 3-16 MDD-003
_T_Y_P_E_S__O_F__L_O_C_K_S
[] WAIT LOCKS
===========================================
INSERT Wait Locks (Simplified) DIAGRAM HERE
===========================================
[] SIMPLIFIED PL/I ANALOGY:
do while (lockword ^=0);
<GIVE UP PROCESSOR>
<WAIT FOR NOTIFICATION>
end;
Lockword = process_id;
<update data>
Lockword = 0
<SEND NOTIFICATION>
[] MOST SUPERVISOR LOCKS ARE WAIT LOCKS
[] IN GENERAL, A PROCESS IS ALLOWED TO GIVE UP ITS PROCESSOR
WHEN IT HAS WAIT LOCKS LOCKED
[] THE WAIT LOCK MECHANISM WILL BE DESCRIBED IN MORE DETAIL IN
TOPIC 9
Not To Be Reproduced 3-17 MDD-003
_T_Y_P_E_S__O_F__L_O_C_K_S
TOPIC IV
Name Space and Address Space Management
Page
Name/Address Space Overview . . . . . . . . . 4-1
Name/Address Space Terminology. . . . . . . . 4-5
Name/Address Space Concepts . . . . . . . . . 4-7
Name/Address Space Data Bases . . . . . . . . 4-12
Reference Name Table (RNT). . . . . . . . 4-12
Known Segment Table (KST) . . . . . . . . 4-13
Descriptor Segment (DSEG) . . . . . . . . 4-14
Typical Address Space . . . . . . . . . . . . 4-16
Name/Address Space Meters . . . . . . . . . . 4-32
system_link_meters. . . . . . . . . . . . 4-32
link_meters . . . . . . . . . . . . . . . 4-33
Name/Address Space Commands . . . . . . . . . 4-34
display_kst_entry . . . . . . . . . . . . 4-34
4-i MDD-003
_N_A_M_E_/_A_D_D_R_E_S_S__S_P_A_C_E__O_V_E_R_V_I_E_W
ox FUNCTION
[] IMPLEMENT THE PER PROCESS VIRTUAL MEMORY
ox BASIC PHILOSOPHY
[] AS A NEWLY LOGGED IN USER ATTEMPTS TO TOUCH VARIOUS SEGMENTS A
CONSIDERABLE AMOUNT OF MANAGEMENT INFORMATION MUST BE
(TRANSPARENTLY) FOUND AND/OR COMPUTED BEFORE THE USER'S
REFERENCE IS ACTUALLY ACCOMPLISHED
[] FOR EVERY SEGMENT REFERENCED BY THE USER, THE SUPERVISOR:
[] ASSIGNS A SEGMENT NUMBER (FOR REASON OF HARDWARE ADDRESSING),
AND
[] RECORDS (REMEMBERS) THE MANAGEMENT INFORMATION (FOR REASON OF
SOFTWARE EFFICIENCY AND CONTROL)
[] SUCH SEGMENTS ARE SAID TO BE "KNOWN TO THE PROCESS"
[] THE MANAGEMENT INFORMATION IS MAINTAINED ON A PER PROCESS BASIS
Not To Be Reproduced 4-1 MDD-003
_N_A_M_E_/_A_D_D_R_E_S_S__S_P_A_C_E__O_V_E_R_V_I_E_W
IN THREE COMPLEMENTING AREAS: DSEG, KST, AND RNT
[] MANAGES TWO DISTINCT SETS OF INFORMATION:
[] ADDRESS SPACE - CORRESPONDENCE BETWEEN SEGMENT NUMBERS AND
THE SEGMENTS THEMSELVES
[] NAME SPACE - CORRESPONDENCE BETWEEN SEGMENT NUMBERS AND NAMES
THE USER REFERS TO THEM BY
[] CALLS DIRECTORY CONTROL TO LOCATE SEGMENTS INITIALLY
[] NAME SPACE / ADDRESS SPACE MANAGEMENT IS INVOKED BY SUBROUTINE
CALLS, AND BY LINKAGE FAULTS (THE "DYNAMIC LINKER")
ox PRINCIPAL USER INTERFACES
[] COMMAND LEVEL
[] initiate, terminate, terminate_segno, terminate_ref_name,
terminate_single_ref_name, list_ref_name
[] THE COMMAND PROCESSOR ITSELF - WHICH USES THESE SERVICES TO
LOCATE COMMANDS
[] SUBROUTINE LEVEL
[] hcs_$initiate, hcs_$initiate_count_, hcs_$terminate_file,
hcs_$terminate_seg, hcs_$terminate_name,
hcs_$terminate_noname, term_
Not To Be Reproduced 4-2 MDD-003
_N_A_M_E_/_A_D_D_R_E_S_S__S_P_A_C_E__O_V_E_R_V_I_E_W
ox MAJOR DATA BASES
[] DESCRIPTOR SEGMENT (DSEG) - ONE PER PROCESS
[] SEGMENT DESCRIPTOR WORD (SDW) - ONE PER KNOWN SEGMENT
[] DEFINES THE USER'S ADDRESS SPACE TO THE HARDWARE
[] KNOWN SEGMENT TABLE (KST) - ONE PER PROCESS
[] KNOWN SEGMENT TABLE ENTRY (KSTE) - ONE PER KNOWN SEGMENT
(EXCEPT SUPERVISOR SEGMENTS)
[] DEFINES THE USER'S ADDRESS SPACE TO THE SUPERVISOR AND THE
USER
[] EACH KSTE ASSOCIATES A USER'S SEGMENT NUMBER WITH THE SEGMENT
CONTROL ATTRIBUTES OF THAT SEGMENT
[] THE SEARCH FOR AN AVAILABLE KSTE DETERMINES A SEGMENT'S
NUMBER
[] REFERENCE NAME TABLE (RNT) - ONE PER EACH RING IN EACH PROCESS
[] NOT A SEGMENT - KEPT AS A REGION ALLOCATED IN THE "LINKAGE
AREA" FOR EACH RING
[] REFERENCE NAME TABLE ENTRY (RNTE) - ONE PER REFERENCE NAME
Not To Be Reproduced 4-3 MDD-003
_N_A_M_E_/_A_D_D_R_E_S_S__S_P_A_C_E__O_V_E_R_V_I_E_W
[] USED BY THE DYNAMIC LINKER TO IMPLEMENT THE
"initiated_segments" SEARCH RULE
[] DEFINES THE USER'S NAME SPACE TO THE USER
[] NAME SPACE MAY BE DIFFERENT IN DIFFERENT RINGS OF THE SAME
PROCESS
Not To Be Reproduced 4-4 MDD-003
_N_A_M_E_/_A_D_D_R_E_S_S__S_P_A_C_E__T_E_R_M_I_N_O_L_O_G_Y
SEGMENT DESCRIPTOR WORD (SDW):
A TWO WORD PAIR USED BY THE HARDWARE WHEN REFERENCING A
SEGMENT.
DESCRIPTOR SEGMENT (DSEG):
THE MOST FUNDAMENTALLY IMPORTANT SEGMENT IN A PROCESS.
CONTAINS AN ARRAY OF SDW'S DEFINING THE ADDRESS SPACE
OF THE PROCESS
ADDRESS SPACE:
THE SET OF ALL SEGMENTS (PROCEDURE AND DATA) FOR WHICH
THE PROCESS HAS A SEGMENT NUMBER AND A CORRESPONDING
SDW. THE ADDRESS SPACE EXPANDS AND CONTRACTS DURING A
SEGMENT'S LIFE
SEGMENT NUMBER:
AN OCTAL NUMBER 0-1777 (0-1023 DECIMAL) ASSIGNED
UNIQUELY TO A SEGMENT. USED BY THE HARDWARE AS AN
OFFSET INTO THE ARRAY OF SDW'S WHEN REFERENCING A
SEGMENT
MAKING KNOWN:
THE ACT OF ASSIGNING A SEGMENT NUMBER TO A SEGMENT,
THEREBY ADDING IT TO THE ADDRESS SPACE. SEGMENTS MUST
BE MADE KNOWN BEFORE THEY CAN BE REFERENCED
Not To Be Reproduced 4-5 MDD-003
_N_A_M_E_/_A_D_D_R_E_S_S__S_P_A_C_E__T_E_R_M_I_N_O_L_O_G_Y
NAME SPACE:
THE SET OF ALL SEGMENTS FOR WHICH THE PROCESS HAS A
REFERENCE NAME. THE REFERENCE NAME MAY BE DIFFERENT
THAN THE SEGMENTS ACTUAL NAME (ITS ENTRYNAME). SINCE
SOME SEGMENTS IN THE ADDRESS SPACE HAVE NO REFERENCE
NAME, THE NAME SPACE IS A PROPER SUBSET OF THE ADDRESS
SPACE
Not To Be Reproduced 4-6 MDD-003
_N_A_M_E_/_A_D_D_R_E_S_S__S_P_A_C_E__C_O_N_C_E_P_T_S
ox A MULTICS PROCESS IS A WELL DEFINED COLLECTION OF UNIQUE SEGMENTS,
EACH WITH DEFINED ACCESS, OVER WHICH A SINGLE EXECUTION POINT IS
FREE TO ROAM (I.E., FETCH INSTRUCTIONS AND MAKE DATA REFERENCES)
ox THE ADDRESS SPACE OF A PROCESS IS THE ABOVE "COLLECTION OF
SEGMENTS". SUCH SEGMENTS ARE SAID TO BE KNOWN TO THE PROCESS
[] ALL SUPERVISOR (RING 0) SEGMENTS ARE PLACED INTO THE ADDRESS
SPACE AT PROCESS CREATION TIME. THIS ADDRESS SPACE IS SAID TO
BE "CLONED" FROM THE INITIALIZER ADDRESS SPACE
[] THE RING ZERO ADDRESS SPACE IN ANY PROCESS IS THE SAME AS THE
INITIALIZER'S RING ZERO ADDRESS SPACE, EXCEPT FOR THE DSEG,
KST, PDS, PRDS, AND STACK_0
[] THE RING ZERO ADDRESS SPACE HAS NO RNT, BECAUSE IT IS SET UP
DURING SYSTEM INITIALIZATION, AND DOES NOT CHANGE
[] OTHER SEGMENTS ARE MADE KNOWN AND UNKNOWN DURING THE LIFE OF THE
PROCESS
[] IMPLICITLY BY THE DYNAMIC LINKER (LINKAGE FAULT) OR A SYSTEM
COMMAND
print my_dir>my_seg
tester
[] EXPLICITLY BY COMMANDS OR SUBROUTINES THAT MANAGE THE ADDRESS
SPACE
initiate my_prog call hcs_$terminate_segno
Not To Be Reproduced 4-7 MDD-003
_N_A_M_E_/_A_D_D_R_E_S_S__S_P_A_C_E__C_O_N_C_E_P_T_S
[] MAKING A SEGMENT KNOWN IS SIMILAR TO DECLARING A VARIABLE IN A
PL/I PROGRAM. IT SIGNIFIES INTENT, BUT NOT USAGE
[] THE PRESENCE OF ONE OR MORE PAGES OF A SEGMENT IN MAIN MEMORY
IMPLIES THAT THE SEGMENT IS KNOWN TO (AND IS BEING USED BY) AT
LEAST ONE USER
[] BEING KNOWN DOES NOT IMPLY PRESENCE IN MAIN MEMORY
ox NOTE THAT THIS SET OF SEGMENTS, THE EXECUTION POINT, AND THE
REGISTERS AND INDICATORS OF THE PROCESSOR, UNIQUELY DEFINES THE
STATE OF THE PROCESS
Not To Be Reproduced 4-8 MDD-003
_N_A_M_E_/_A_D_D_R_E_S_S__S_P_A_C_E__C_O_N_C_E_P_T_S
==========================================
INSERT N/A Space Manipulation DIAGRAM HERE
==========================================
Not To Be Reproduced 4-9 MDD-003
_N_A_M_E_/_A_D_D_R_E_S_S__S_P_A_C_E__C_O_N_C_E_P_T_S
========================================
INSERT NS and AS Management DIAGRAM HERE
========================================
Not To Be Reproduced 4-10 MDD-003
_N_A_M_E_/_A_D_D_R_E_S_S__S_P_A_C_E__C_O_N_C_E_P_T_S
====================================================
INSERT Multics Virtual Memory Structure DIAGRAM HERE
====================================================
Not To Be Reproduced 4-11 MDD-003
_N_A_M_E_/_A_D_D_R_E_S_S__S_P_A_C_E__D_A_T_A__B_A_S_E_S
_R_E_F_E_R_E_N_C_E__N_A_M_E__T_A_B_L_E__(_R_N_T_)
========================================
INSERT Reference Name Table DIAGRAM HERE
========================================
Not To Be Reproduced 4-12 MDD-003
_N_A_M_E_/_A_D_D_R_E_S_S__S_P_A_C_E__D_A_T_A__B_A_S_E_S
_K_N_O_W_N__S_E_G_M_E_N_T__T_A_B_L_E__(_K_S_T_)
=======================================
INSERT Known Segment Table DIAGRAM HERE
=======================================
Not To Be Reproduced 4-13 MDD-003
_N_A_M_E_/_A_D_D_R_E_S_S__S_P_A_C_E__D_A_T_A__B_A_S_E_S
_D_E_S_C_R_I_P_T_O_R__S_E_G_M_E_N_T__(_D_S_E_G_)
======================================
INSERT Descriptor Segment DIAGRAM HERE
======================================
Not To Be Reproduced 4-14 MDD-003
_N_A_M_E_/_A_D_D_R_E_S_S__S_P_A_C_E__D_A_T_A__B_A_S_E_S
_D_E_S_C_R_I_P_T_O_R__S_E_G_M_E_N_T__(_D_S_E_G_)
========================================================
INSERT States of Segments and Pages (short) DIAGRAM HERE
========================================================
Not To Be Reproduced 4-15 MDD-003
_T_Y_P_I_C_A_L__A_D_D_R_E_S_S__S_P_A_C_E
ox COLLECTION ZERO
[] SEGMENTS WHICH MUST BE PRESENT TO RUN THE VERY FIRST LOADING
PROGRAM
[] SEGMENTS WHICH HAVE FIXED ABSOLUTE ADDRESSES TO INTERFACE WITH
HARDWARE
[] ALL DESCRIBED IN template_slt_.cds
0 [pd]>dseg (ring 0)
The descriptor segment. The Initializer's dseg
comes from the system tape and is built during
system initialization; all others are created by
process creation.
1 fault_vector (ring 0, perm-wired)
Contains the interrupt vector, fault vector, and the
ITS pairs for SCU and TRA instructions. Located at
absolute locations 0-577. Used by the CPU hardware.
2 iom_mailbox (ring 0, perm-wired)
Mailboxes (communications areas) for up to four
IOMs. Located at locations 1200-3377 absolute.
Used by the IOM hardware.
3 >sl1>config_deck (ring 0, deciduous)
The online copy of the config deck. This is built
from the config deck provided by BOS during system
initialization, but it is not the copy BOS actually
uses.
4 dn355_mailbox (ring 0)
Mailboxes (communications areas) for up to eight
FNPs. Located at absolute locations 3400-6377.
Used by the FNP hardware.
Not To Be Reproduced 4-16 MDD-003
_T_Y_P_I_C_A_L__A_D_D_R_E_S_S__S_P_A_C_E
5 bos_toehold (ring 0, perm-wired)
The segment containing the tiny program used to
switch between Multics and BOS at crash time.
Located at absolute locations 10000-11777.
6 flagbox (ring 0, perm-wired)
A region inside the bos_toehold segment (yes, it
really overlaps the toehold) used to access the
BOS/Multics communication region.
7 >sl1>slt (ring 0, deciduous)
10 >sl1>name_table (ring 0, deciduous)
The two primary databases of system initialization.
The SLT contains one entry for every supervisor
segment read from the system boot tape, containing
all its attributes. The separate name_table is used
to hold the names, because each segment may have
several
This marks the end of Collection Zero. All the rest of the segments in the
address space are either read from the system tape or found in the online
system.
Not To Be Reproduced 4-17 MDD-003
_T_Y_P_I_C_A_L__A_D_D_R_E_S_S__S_P_A_C_E
ox COLLECTION ONE
[] FIRST BATCH OF SEGMENTS READ FROM SYSTEM TAPE
[] ALL THE PROGRAMS AND DATABASES NEEDED TO MAKE PAGING RUN
[] ALL SEGMENTS WHICH MUST BE "perm-wired" -- PERMANENTLY ALLOCATED IN
LOW MEMORY, WITHOUT PAGE TABLES
11 lot (ring 0)
The supervisor's linkage offset table. Used to find
linkage sections. Built as the segments are read in
from tape.
12 as_linkage (ring 0)
13 ws_linkage (ring 0)
The permanent supervisor combined linkage regions.
The names mean "Active Supervisor Linkage" and
"Wired Supervisor Linkage", respectively. The
linkage sections of all permanent supervisor
segments are put in one of these as the segments are
read from the tape.
14 >sl1>definitions_ (ring 0, deciduous)
The segment containing all the definitions sections
of supervisor programs. The definitions sections
are placed here as the programs are read from the
tape, and used by the hardcore prelinker.
15 sst_seg (ring 0, perm-wired)
The segment containing all ASTEs and page tables.
Covered in under Page and Segment Control. This
segment is allocated at the very top end of the
bootload SCU.
16 core_map (ring 0, perm-wired)
All the core map entries, describing all system
memory. Covered under Page Control. This used to
Not To Be Reproduced 4-18 MDD-003
_T_Y_P_I_C_A_L__A_D_D_R_E_S_S__S_P_A_C_E
be part of the SST, but was moved out to make more
room for page tables.
17 abs_seg (ring 0, abs-seg)
An abs-seg used for complex call-side operations in
page control, such as evict_page and
reconfiguration.
20 abs_seg1 (ring 0, abs-seg)
An abs-seg used only by page control for checking
page frame contents for zeros, and zeroing newly
allocated page frames.
21 backup_abs_seg (ring 0, abs-seg)
An abs-seg used to access the segment being dumped
in a Volume Dumper process. It is given an SDW
which refers to any ordinary segment. This is a
very special hardcore segment, because it has
trailer entries, and it is special-cased by the
trailer manipulation program, setfaults. Normal
hardcore segments never receive trailers, since they
are never activated or deactivated.
22 fim_abs_seg (ring 0, abs-seg)
An abs-seg used by the FIM to scan the cache when
attempting to diagnose cache parity errors.
23 isolts_abs_seg (ring 0, abs-seg)
An abs-seg used by ISOLTS, which gives it an SDW
describing the low 64K of the SCU being used for
ISOLTS testing.
24 volmap_abs_seg (ring 0, abs-seg)
An abs-seg used by page control to access record
stocks. It is given the SDW of whichever volume's
stock is needed.
25 bound_active_1 (ring 0)
26 bound_disk_util (ring 0)
27 bound_disk_util_wired (ring 0, perm-wired)
30 bound_error_active (ring 0)
31 bound_error_wired (ring 0, perm-wired)
32 bound_interceptors (ring 0, perm-wired)
This is where the FIM lives.
33 bound_io_wired (ring 0, perm-wired)
34 bound_iom_support (ring 0, perm-wired)
35 bound_page_control (ring 0, perm-wired)
36 bound_priv_1 (ring 0, perm-wired)
37 >sl1>bound_sss_wired_ (ring 0, deciduous)
This is where pl1_operators_ and a whole host of
Not To Be Reproduced 4-19 MDD-003
_T_Y_P_I_C_A_L__A_D_D_R_E_S_S__S_P_A_C_E
other miscellaneous subroutines live. It is wired
in a very special way, because not all of its
contents need to be wired. In particular, only
about half of pl1_operators_ needs to be wired, and
there is a special hack in make_sdw.pl1 which finds
the definition in the middle of pl1_operators_ which
marks the end of the wired portion, and makes an
ASTE for bound_sss_wired_ which has all its pages up
to and including that definition wired, and the rest
unwired.
40 bound_tc_priv (ring 0, perm-wired)
41 bound_tc_wired (ring 0, perm-wired)
42 bound_unencacheable (ring 0, perm-wired)
43 dir_seg (ring 0, abs-seg)
An abs-seg now used only at process termination time
to loop through the dead process's KST in order to
flush any trailers it had for active segments.
44 disk_post_queue_seg (ring 0, perm-wired)
The segment where the core address queue lives: see
core_queue_man.alm. This is discussed under Page
Control.
45 disk_seg (ring 0, perm-wired)
The segment containing the disk DIM's databases:
device table, channel table, and I/O queues.
46 dn355_data (ring 0, perm-wired)
The segment containing software communications
regions for the FNPs. This is not where FNP buffers
are kept, but only the mailboxes that describe the
buffers, and some control information.
47 ds_seg (ring 0, abs-seg)
The segment used by setfaults when accessing another
process's DSEG in order to remove a trailer.
Covered under Segment Control.
50 emergency_shutdown (ring 0, perm-wired)
The procedure segment which starts an ESD. It is a
separate segment because BOS has to be able to find
it and transfer to it.
51 hardcore_sct_seg (ring 0)
The segment containing the static condition table
for ring zero; it's just like the one which is kept
in an outer ring stack header. The only static
handlers in ring zero are those used to invoke the
copy_on_write mechanism.
Not To Be Reproduced 4-20 MDD-003
_T_Y_P_I_C_A_L__A_D_D_R_E_S_S__S_P_A_C_E
52 idle_dsegs (ring 0, perm-wired)
53 idle_pdses (ring 0, perm-wired)
Two similar segments: they contain the DSEG and PDS
segments for all the idle processes, all in a row.
When an idle process is constructed, the SDWs for
its DSEG and PDS are set up to point into the middle
of one of these segments.
54 init_processor (ring 0)
55 inzr_stk0 (ring 0)
The stack segment used by the Initializer during
initialization and shutdown. During normal
operation, the Initializer participates in ordinary
ring zero stack sharing.
56 iobm_data (ring 0, perm-wired)
The database of iobm.pl1, the I/O Buffer Manager.
57 ioi_abs_seg (ring 0, abs-seg)
The abs-seg used by ioi_interrupt.pl1 to access a
user ioi_ buffer at interrupt time, for storing
status information.
60 ioi_data (ring 0, perm-wired)
The database for ioi_ -- describes all
user-accessable, or potentially user-accessable
devices. See the programs in bound_io_active and
bound_io_wired.
61 iom_data (ring 0, perm-wired)
Describes the configuration of the IOMs, and
software information about IOM channels. Contains
assignment information, software status queue
location, and metering cells.
62 oc_data (ring 0, perm-wired)
The database for the ring zero operator's console
mechanism. This is used by syserr in ring zero, and
by the Initializer to write on the system console
(but not message coordinator consoles).
63 [pd]>pds (ring 0, deciduous)
The Process Data Segment. This contains all the
miscellaneous information that makes a process
unique to the supervisor, and need not be readily
accessable to other processes. Most per-process
variables are referenced symbolically, such as
pds$processid, pds$page_fault_data (machine
conditions for last page fault), etc.
Not To Be Reproduced 4-21 MDD-003
_T_Y_P_I_C_A_L__A_D_D_R_E_S_S__S_P_A_C_E
64 >sl1>prds (ring 0, deciduous)
Like the PDS, but per-processor. Contains the same
sort of miscellaneous information, and is also used
as the ring zero stack for certain types of faults
(page faults, connects, and timer runouts) and all
interrupts. There is a PRDS per processor, named
>sl1>cpu_A.prds, cpu_B.prds, etc. The PRDS segment
in ring zero is changed at LDBR time to indicate the
actual PRDS of the processor that the process is
going to run on; thus, it's sort of an abs-seg. All
PRDS's are wired, but have page tables.
65 >sl1>pvt (ring 0, deciduous)
The Physical Volume Table. Described under Volume
Management and Page Control.
66 rdisk_seg (ring 0, abs-seg)
A PTW-type abs-seg (the only one where the PTW ever
changes). Used only by the program read_disk, which
does I/O to arbitrary pages on any disk, its
aste.pvtx and PTW are switched around to indicate
the right page, which is faulted on and (if needed)
written back out by pc$cleanup.
67 restart_fault (ring 0)
70 return_to_ring_0_ (ring 0)
These two procedures are used to implement the
restarting of faults (such as a QUIT signal) from
the user ring. When a fault occurs, a frame is
pushed on the user ring stack, with its owner set to
be return_to_ring_0_. Additionally, the machine
conditions for the fault are saved in ring zero (in
the PDS) so that when restart_fault is called to
restart a possibly modified set of conditions, it
can compare and validate.
71 scas (ring 0, abs-seg)
The System Controller Addressing Segment. This
segment has a page overlaid on a page of every
system controller. No data is ever accessed through
this segment; its page table is not even in the SST,
but in the SCS. It is used only for certain
privileged instructions which require an effective
address in an particular SCU in order to read or set
control registers in the SCU.
72 scs (ring 0, perm-wired)
The System Configuration Segment. It describes most
of the hardware configuration, and contains various
control words used by privileged control
instructions.
Not To Be Reproduced 4-22 MDD-003
_T_Y_P_I_C_A_L__A_D_D_R_E_S_S__S_P_A_C_E
73 signaller (ring 0)
The procedure which implements user ring fault
signalling.
74 >sl1>sst_names_ (ring 0, deciduous)
The SST name table. This is a debugging feature; it
contains (when in use) the primary name
corresponding to every segment in the AST. It can
be maintained online, by use of the PARM ASTK config
card, but usually is not. It is always filled in by
FDUMP after a crash if it was not already in use.
75 stack_0_data (ring 0, perm-wired)
Data segment describing the available segments for
use in ring zero stack sharing. These segments,
seen later on as segment 230, are recorded here and
multiplexed among eligible processes.
76 stock_seg (ring 0, perm-wired)
The segment containing all in-core record and VTOCE
stocks for use by page control and segment control,
and covered under those topics.
77 >sl1>sys_boot_info (ring 0, deciduous)
A data segment containing information about the I/O
devices (tape and disk) used during bootload.
100 >sl1>sys_info (ring 0, deciduous)
Contains assorted global wired information shared by
the user ring and supervisor. Some is set during
bootload, and some comes off the tape; none is
modified after initialization is complete.
101 syserr_data (ring 0, perm-wired)
Data segment for the lowest level of the syserr
mechanism. Syserr messages are built and queued
here, and sent to the console. They are also copied
out by the syserr logger hardcore process, into the
syserr_log.
102 syserr_log (ring 0, abs-seg)
This segment overlays the LOG partition on some
disk, which is used to reliably store syserr
messages until they can be copied into the
perm_syserr_log maintained in the Hierarchy.
103 tc_data (ring 0)
The traffic control data segment; contains all
traffic control data. Covered under Traffic
Control.
Not To Be Reproduced 4-23 MDD-003
_T_Y_P_I_C_A_L__A_D_D_R_E_S_S__S_P_A_C_E
104 wired_hardcore_data (ring 0, perm-wired)
Miscellaneous data used by the wired supervisor.
Not To Be Reproduced 4-24 MDD-003
_T_Y_P_I_C_A_L__A_D_D_R_E_S_S__S_P_A_C_E
ox COLLECTION TWO
[] THE UNWIRED PORTION OF THE SUPERVISOR
[] READ IN BY COLLECTION ONE, DIRECTLY INTO PAGED
SEGMENTS IN THE HARDCORE PARTITIONS
105 >sl1>active_all_rings_data (ring 0, deciduous)
Miscellaneous data shared between the unwired
supervisor and the outer rings.
106 active_hardcore_data (ring 0)
Miscellaneous data used by the unwired portion of
the supervisor: system-wide locks, size constants
for directory control, system search rule info, and
metering for directory control and the dynamic
linker.
107 >sl1>admin_gate_ (ring 0, deciduous)
110 ast_lock_meter_seg (ring 0)
A segment used to collect AST lock metering,
normally off (enabled by the ast_lock_metering
tuning parameter).
111 >sl1>audit_gate_ (ring 0, deciduous)
112 bound_355_wired (ring 0)
113 bound_file_system (ring 0)
114 bound_hc_backup (ring 0)
115 bound_hc_reconfig (ring 0)
116 bound_hc_tuning (ring 0)
117 bound_imp_dim_ (ring 0)
120 bound_imp_status (ring 0)
121 bound_io_active (ring 0)
122 bound_mcs_util (ring 0)
123 bound_priv_mpx (ring 0)
124 bound_network0_ (ring 0)
125 bound_priv_procs (ring 0)
126 bound_process_creation (ring 0)
127 bound_salvager (ring 0)
130 bound_scavenger (ring 0)
Not To Be Reproduced 4-25 MDD-003
_T_Y_P_I_C_A_L__A_D_D_R_E_S_S__S_P_A_C_E
131 >sl1>bound_sss_active_ (ring 0, deciduous)
132 bound_system_faults (ring 0)
133 bound_tty_active (ring 0)
134 bound_vtoc_man (ring 0)
135 bound_x25_mpx (ring 0)
136 dbm_seg (ring 0)
The segment used to hold the dumper bit maps for
volumes being volume-dumped. The bitmaps are read
from the volume header when a dump begins, and
written back when finished.
137 dirlockt_seg (ring 0)
The segment used to keep track of all directory
locks. Directory locks are kept in a supervisor
segment, rather than in directories themselves.
140 >sl1>dm_hcs_ (ring 0, deciduous)
141 >sl1>dm_journal_seg_ (ring 0, deciduous)
142 >sl1>error_table_ (ring 0, deciduous)
143 fnp_dump_seg (ring 0)
Segment used for data buffering by FNP dump and
patch operations (but not bootload).
144 hasp_mpx (ring 0)
145 >sl1>hc_backup_ (ring 0, deciduous)
146 >sl1>hcs_ (ring 0, deciduous)
147 >sl1>hphcs_ (ring 0, deciduous)
150 ibm3270_mpx (ring 0)
151 imp_data (ring 0)
152 imp_dim_buf_ (ring 0)
153 imp_tables (ring 0)
154 imp_wired_buffers (ring 0)
These four segments were used by the ring zero IMP
DIM (part of the ARPAnet support), which has since
been decomissioned.
155 initializer_abs_seg (ring 0, abs-seg)
An abs-seg used solely in order to copy a process's
stack_0 segment into its process directory on
process termination.
156 >sl1>initializer_gate_ (ring 0, deciduous)
157 io_page_tables (ring 0)
The segment which contains page tables used for I/O
if the IOM is operating in Paged mode. It is
initialized by ioi_init and used only for ioi_ I/O.
160 ioat (ring 0)
The I/O attach table. This is a largely obsolete
database, the relic of an earlier I/O device
Not To Be Reproduced 4-26 MDD-003
_T_Y_P_I_C_A_L__A_D_D_R_E_S_S__S_P_A_C_E
attachment scheme. It is now used only for loading
and dumping FNPs.
161 >sl1>ioi_ (ring 0, deciduous)
62 [pd]>kst_seg (ring 0, deciduous)
The Known Segment Table. Described in Name &
Address Space Management.
163 lvt (ring 0)
The Logical Volume Table. Described in Volume
Management.
164 >sl1>mhcs_ (ring 0, deciduous)
165 ncp_tables_ (ring 0)
Another part of the now-decommissioned ring zero
ARPAnet support, no longer used.
166 >sl1>net_ring0_admin_ (ring 0, deciduous)
167 >sl1>net_ring0_sys_ (ring 0, deciduous)
170 >sl1>net_ring0_user_ (ring 0, deciduous)
171 >sl1>phcs_ (ring 0, deciduous)
172 polled_vip_mpx (ring 0)
173 pv_salv_seg (ring 0)
This data segment is created in order to run the
physical volume salvager (now rarely used). It
contains various databases used by the salvager. It
is created (by calling grab_aste.pl1) and destroyed
for each volume salvage, in each process running a
salvage, rather than being a shared segment.
174 salv_abs_seg_00 (ring 0, abs-seg)
175 salv_abs_seg_01 (ring 0, abs-seg)
176 salv_abs_seg_02 (ring 0, abs-seg)
177 salv_abs_seg_03 (ring 0, abs-seg)
200 salv_abs_seg_04 (ring 0, abs-seg)
These five segments are used to overlay the VTOC of
a volume being salvaged, and are set up and
referenced by vm_vio.pl1. Covered under File System
Salvagers.
201 salv_dir_space (ring 0)
202 salv_data (ring 0)
203 salv_temp_dir (ring 0)
These three segments are used by the directory
salvager when invoked as the online salvager, in
response to a crawlout or bad_dir_ condition. Only
one instance of the online salvager may be running
at a time, and this is ensured by a lock on
salv_data. The online salvager does not interfere
with demand directory salvages, however. Covered
under File System Salvagers.
Not To Be Reproduced 4-27 MDD-003
_T_Y_P_I_C_A_L__A_D_D_R_E_S_S__S_P_A_C_E
204 scavenger_data (ring 0)
The segment containing the tables used when running
the online volume scavenger. As many volumes as
tables can be fit here may be scavenged at one time.
The in-use portion of the segment is wired while a
scavenge is being done. Covered under File System
Salvagers.
205 >sl1>shcs_ (ring 0, deciduous)
206 str_seg (ring 0)
The segment trailer segment. The trailers in this
segment record which processes have an SDW for any
particular non-supervisor segment, and the
backup_abs_seg (see above). Covered under Segment
Control.
207 syserr_daemon_dseg (ring 0)
210 syserr_daemon_pds (ring 0)
211 syserr_daemon_stack (ring 0)
The DSEG, PDS, and ring zero stack of the syserr
logging daemon. They are filled in when the daemon
processs (which runs entirely in ring zero) is
created. They are in the global system address
space primarily for debugging and recordkeeping
purposes.
212 >sl1>system_privilege_ (ring 0, deciduous)
213 >sl1>tandd_ (ring 0, deciduous)
214 template_pds (ring 0)
A template for the PDS, used when creating a
process. It is a copy of the pds template which
came off the system tape, but which was used to
create the Initializer's PDS.
215 tty_area (ring 0)
An unwired database used by ring zero communications
system, used primarily for saved metering
information on each channel.
216 tty_buf (ring 0)
The important segment in the ring zero
communications system. Contains the logical channel
table, all communications I/O buffers, and all
multiplexer databases.
217 tty_tables (ring 0)
An unwired database used by ring zero communications
system to keep the tables used for input and output
translation/conversion.
Not To Be Reproduced 4-28 MDD-003
_T_Y_P_I_C_A_L__A_D_D_R_E_S_S__S_P_A_C_E
220 vtoc_buffer_seg (ring 0)
The segment containing all buffers for VTOC I/O, and
a small amount of control information. Covered
under Segment Control.
221 <<unused>>
222 <<unused>>
223 <<unused>>
224 <<unused>>
225 <<unused>>
226 <<unused>>
227 <<unused>>
These segments are unused, since the first segment
after the supervisor address space is the ring zero
stack, and its segment number must be zero mod 8.
230 >sl1>stack_0.016 (ring 0, deciduous)
The ring zero stack. One is allocated from a pool
(>sl1>stack_0.NNN) whenever a process becomes
eligible. When a process is not eligible (blocked,
usually), it has no ring zero context, and needs no
ring zero stack.
231 [pd]>stack_1
232 <<not used>>
232 <<not used>>
234 [pd]>stack_4
The rest of the stacks. There would be others if
other rings were being used. A stack is created for
each ring as it is needed; the segment number is
automatically generated by the CALL6 instruction
(from DBR.stack), and when a segment fault occurs on
a stack not yet extant (pds$stacks(ring) is null),
seg_fault.pl1 calls makestack.pl1 to create one.
Not To Be Reproduced 4-29 MDD-003
_T_Y_P_I_C_A_L__A_D_D_R_E_S_S__S_P_A_C_E
ox NON-SUPERVISOR SEGMENTS
[] REMAINDER OF A PROCESS ADDRESS SPACE.
[] BUILT BY THE NORMAL NAME AND ADDRESS SPACE MANAGEMENT
MECHANISMS AS THE PROCESS GETS GOING AND RUNS
[] DIFFERENT IN DIFFERENT PROCESSES; THIS IS ONLY AN
EXAMPLE
240 > (the ROOT)
The ROOT directory. The recursive nature of the
initiate/segment fault mechanism ensures that this
will be the first non-supervisor segment in the
address space.
241 >pdd (directory)
242 >pdd
243 >sss>bound_process_init_
244 >udd (directory)
245 >udd>MED (directory)
246 >udd>MED>Sibert (directory)
247 [pd]>!BBBMjzKmkcngb.area.linker
250 >sss (directory)
251 >unb (directory)
252 >sl1 (directory)
253 >tools (directory)
254 >am (directory)
255 >sl1>bound_sss_active_
256 >sl1>operator_pointers_
257 >sl1>bound_sss_wired_
260 >sl1>bound_process_env_
261 >sl1>hcs_
262 [pd]>pit
263 >sl1>bound_error_handlers_
264 >sl1>bound_ipc_
265 >sss>bound_as_requests_
266 >sss>bound_info_rtns_
Not To Be Reproduced 4-30 MDD-003
_T_Y_P_I_C_A_L__A_D_D_R_E_S_S__S_P_A_C_E
267 >sc1 (directory)
270 >sc1>whotab
271 >sc1installation_parms
272 >sl1>sys_info
273 >sss>bound_command_loop_
274 >sc1>command_usage_counts
275 >sc1>command_usage_counts>command_usage_list_
276 >sc1>command_usage_counts>command_usage_totals_
277 >sss>bound_exec_com_
300 >sl1>error_table_
Not To Be Reproduced 4-31 MDD-003
_N_A_M_E_/_A_D_D_R_E_S_S__S_P_A_C_E__M_E_T_E_R_S
_s_y_s_t_e_m__l_i_n_k__m_e_t_e_r_s
ox SYSTEM_LINK_METERS - RECORDS CPU TIME AND PAGING INFORMATION USED BY THE
DYNAMIC LINKER IN ALL PROCESSES
Linkage Meters:
CPU Metering time 4:58:57
Total time in linker 0:50:53
Average time per link 6.01 msec.
Percentage of real time in linker 17.03
Percentage of CPU time in linker 4.66
Time slot (msec) <25 25-50 50-75 >75
Calls 498469 8357 414 1100
Total time in slot 0:42:03 0:04:16 0:00:24 0:04:09
Percent total time 82.63 8.40 0.81 8.16
Percent total calls 98.06 1.64 0.08 0.22
Average time 5.06 30.68 59.63 226.59
Average page faults 0.18 2.29 6.34 5.65
Segment Search
Average time 2.58 25.13 53.15 8.70
Average page faults 0.04 0.95 3.53 0.22
Percent time in slot 57.06 82.58 86.46 3.80
Get Linkage
Average time 0.84 4.08 7.16 219.16
Average page faults 0.06 0.62 0.93 5.33
Percent time in slot 18.54 13.41 11.64 95.71
Definition Search
Average time 0.24 0.24 0.23 0.20
Average page faults 0.02 0.11 0.24 0.00
Percent time in slot 5.26 0.80 0.37 0.09
Not To Be Reproduced 4-32 MDD-003
_N_A_M_E_/_A_D_D_R_E_S_S__S_P_A_C_E__M_E_T_E_R_S
_l_i_n_k__m_e_t_e_r_s
ox LINK_METERS - RECORDS CPU TIME AND PAGING INFORMATION USED BY THE
DYNAMIC LINKER IN THE PROCESS RUNNING IT
Linkage Meters:
slot calls avg time avg pf tot time % time
<25 1245 4.689 0.3 5.838 76.1
25-50 34 30.201 2.9 1.027 13.4
50-75 6 62.226 6.2 0.373 4.9
>75 2 216.545 6.0 0.433 5.6
----- -------- ----- -------
Total 1287 5.961 0.4 7.671
Not To Be Reproduced 4-33 MDD-003
_N_A_M_E_/_A_D_D_R_E_S_S__S_P_A_C_E__C_O_M_M_A_N_D_S
_d_i_s_p_l_a_y__k_s_t__e_n_t_r_y
ox DISPLAY_KST_ENTRY - DISPLAYS INFORMATION FROM A KST
! display_kst_entry >udd>Multics>Sibert
segno: 246 at 162|270
usage: 7, 0, 0, 0, 0, 0, 0, 0
entryp: 245|20750
uid: 102401170050
dtbm: 446556324757
mode: 7 (0, 0, 0)
ex mode: 70000000000 (7, 7, 7)
infcount: 3
hdr: 4
flags: dirsw write tms
TOPIC V
Directory Control
Page
Directory Control Overview. . . . . . . . . . 5-1
Directory Control Terminology . . . . . . . . 5-3
Directory Control Data Bases. . . . . . . . . 5-6
Directory Segments. . . . . . . . . . . . 5-6
Directory Header. . . . . . . . . . . . . 5-9
Directory Entries . . . . . . . . . . . . 5-12
Directory Control Commands. . . . . . . . . . 5-16
display_branch. . . . . . . . . . . . . . 5-16
5-i MDD-003
.
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L__O_V_E_R_V_I_E_W
ox FUNCTION
[] DIRECTORY CONTROL IS A SET OF HARDCORE MODULES RESPONSIBLE FOR
THE MAINTENANCE OF THE MULTICS DIRECTORY STRUCTURE -- IE: THE
HIERARCHY
[] ITS TASKS INCLUDE CREATING, MANIPULATING AND INTERPRETING THE
CONTENTS OF DIRECTORY SEGMENTS, TO INCLUDE:
[] ACCESS CONTROL LISTS (ACL'S), NAMES, AND VTOCE POINTERS OF
ENTRIES DESCRIBED THEREIN
[] ONLY DIRECTORY CONTROL IS ALLOWED TO ALTER THE CONTENTS OF
DIRECTORY SEGMENTS
[] DIRECTORY CONTROL IMPLICITLY RELIES UPON THE SERVICES OF OTHER
SUBSYSTEMS SUCH AS SEGMENT CONTROL AND PAGE CONTROL, AND ALSO
INVOKES THEM DIRECTLY BY SUBROUTINE CALL
[] DIRECTORIES ARE SIMPLY SEGMENTS TO THESE SUBSYSTEMS
[] DIRECTORY CONTROL IS INVOKED ONLY BY SUBROUTINE CALLS
ox PRINCIPAL USER INTERFACES
Not To Be Reproduced 5-1 MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L__O_V_E_R_V_I_E_W
[] COMMAND LEVEL
[] create, create_dir, link, set_acl, delete_acl, status, list,
add_name, rename
[] SUBROUTINE LEVEL
[] hcs_$append_branch, hcs_$add_acl_entries, hcs_$append_link,
hcs_$delete_acl_entries, hcs_$status_, hcs_$chname_file
ox MAJOR DATA BASES
[] DIRECTORY SEGMENTS
[] CONTAIN THE ATTRIBUTES AND OTHER INFORMATION ABOUT THEIR
SEGMENTS (NEEDED TO FIND SEGMENTS, RETURN STATUS INFORMATION,
AND BUILD VTOCE'S AT SEGMENT CREATION)
[] THE DIRLOCKT_SEG
[] SEGMENT WHERE DIRECTORY LOCKING IS MANAGED
Not To Be Reproduced 5-2 MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L__T_E_R_M_I_N_O_L_O_G_Y
=============================
INSERT Directory DIAGRAM HERE
=============================
Not To Be Reproduced 5-3 MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L__T_E_R_M_I_N_O_L_O_G_Y
UNIQUE ID (UID):
A 36-BIT ID (SERIAL NUMBER) ASSIGNED TO EVERY SEGMENT
WHEN CREATED
SON: OF A DIRECTORY. AN IMMEDIATELY INFERIOR (SUBORDINATE)
SEGMENT
SON'S LVID: OF A DIRECTORY. THE ID OF THE LOGICAL VOLUME ON WHICH
THE DIRECTORY'S SONS RESIDE (AND WILL RESIDE)
GRANDSON: OF A DIRECTORY. A SEGMENT INFERIOR BY MORE THAN ONE
HIERARCHICAL LEVEL
PARENT: OF A SEGMENT. THE "CONTAINING" DIRECTORY SEGMENT
ANCESTOR: OF A SEGMENT. THE PARENT, OR GRANDPARENT, OR GREAT
GRANDPARENT, ETC.
Not To Be Reproduced 5-4 MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L__T_E_R_M_I_N_O_L_O_G_Y
BROTHER: OF A SEGMENT. ANOTHER SEGMENT HAVING THE SAME PARENT
BRANCH (1): _I_N A DIRECTORY. A DATA STRUCTURE, CONTAINED IN A
DIRECTORY SEGMENT, THAT DESCRIBES AN IMMEDIATELY
INFERIOR SEGMENT OR DIRECTORY (BUT NOT A LINK)
BRANCH (2): _O_F A DIRECTORY. REFERS TO THE ACTUAL SEGMENT OR
DIRECTORY IMMEDIATELY INFERIOR TO THE DIRECTORY
ENTRY (1): _I_N A DIRECTORY. SAME AS BRANCH (1) BUT INCLUDES LINKS
ENTRY (2): _O_F A DIRECTORY. SAME AS BRANCH (2) BUT INCLUDES LINKS
==============================================
INSERT Storage System Terminology DIAGRAM HERE
==============================================
Not To Be Reproduced 5-5 MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_D_I_R_E_C_T_O_R_Y__S_E_G_M_E_N_T_S
=======================================
INSERT Directory Structure DIAGRAM HERE
=======================================
Not To Be Reproduced 5-6 MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_D_I_R_E_C_T_O_R_Y__S_E_G_M_E_N_T_S
ox DIRECTORY SEGMENTS ARE DISK RESIDENT (RLV) DATA BASES MAINTAINED BY
DIRECTORY CONTROL
[] ONE DIRECTORY SEGMENT PER DIRECTORY IN THE HIERARCHY
ox DIRECTORY SEGMENTS CONTAIN A CATALOG OF STORAGE SYSTEM INFORMATION
ABOUT OTHER SEGMENTS, DIRECTORIES AND LINKS
ox ALL DIRECTORY SEGMENTS, BY CONVENTION, RESIDE ON THE ROOT LOGICAL
VOLUME (RLV)
ox DIRECTORY SEGMENTS ARE CREATED BY append MUCH LIKE NORMAL SEGMENTS
ARE CREATED
ox DIRECTORY SEGMENTS CONTAIN MANY INTER-RELATED COMPLEX DATA
STRUCTURES TO INCLUDE THE FOLLOWING (NOT NECESSARILY CONTIGUOUS)
REGIONS:
[] DIRECTORY HEADER
[] CONTAINS SELF DESCRIPTIVE INFORMATION LIKE UID, AIM
CLASSIFICATION, ETC; AND POINTERS TO OTHER REGIONS
Not To Be Reproduced 5-7 MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_D_I_R_E_C_T_O_R_Y__S_E_G_M_E_N_T_S
[] HASH TABLE
[] USED TO QUICKLY LOCATE AN ENTRY, GIVEN ITS NAME
[] ENTRY LIST
[] CONTAINS ONE DESCRIPTIVE DATA STRUCTURE (AN ENTRY) FOR EACH
SEGMENT, DIRECTORY, OR LINK IMMEDIATELY INFERIOR TO THE
DIRECTORY (I.E. ALL ENTRIES)
[] PERSON_ID AND PROJECT_ID NAME LISTS
[] CONTAINS ALL PERSON_ID'S/PROJECT_ID'S REQUIRED TO DESCRIBE
THE ACL, THE AUTHOR, ETC. OF ALL SEGMENTS AND DIRECTORIES
IMMEDIATELY INFERIOR TO THE DIRECTORY (I.E. ALL BRANCHES)
[] NAME LIST (ONE PER ENTRY)
[] CONTAINS ALL NAMES CURRENTLY ASSIGNED TO THE ENTRY
[] PRIMARY NAME IS ACTUALLY CONTAINED IN ENTRY STRUCTURE
ITSELF
[] ACCESS CONTROL LIST (ONE PER ENTRY)
[] CONTAINS ALL ACL ENTRIES CURRENTLY ASSOCIATED WITH THE ENTRY
Not To Be Reproduced 5-8 MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_D_I_R_E_C_T_O_R_Y__H_E_A_D_E_R
====================================
INSERT Directory Header DIAGRAM HERE
====================================
Not To Be Reproduced 5-9 MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_D_I_R_E_C_T_O_R_Y__H_E_A_D_E_R
ox THE DIRECTORY HEADER IS A DISK RESIDENT DATA BASE CONTAINED AT THE
BEGINNING OF A DIRECTORY SEGMENT
[] ONE DIRECTORY HEADER PER DIRECTORY SEGMENT
ox THE DIRECTORY HEADER CONTAINS SELF DESCRIPTIVE INFORMATION SUCH AS:
[] THE PROCESS ID OF THE LAST PROCESS TO MODIFY THE DIRECTORY
SEGMENT'S CONTENTS
[] THE DIRECTORY'S UID, LVID, PVID, VTOC INDEX, AND AIM
CLASSIFICATION
[] RELATIVE POINTERS TO THE BEGINNING AND END OF THE ENTRY LIST,
PERSON_ID LIST, PROJECT_ID LIST, AND THE HASH TABLE
[] HIERARCHY DEPTH OF THE DIRECTORY SEGMENT
[] UID OF THE MASTER DIRECTORY AND THE PARENT DIRECTORY
[] SON'S LVID - THE ID OF THE LV ON WHICH INFERIOR NON-DIRECTORY
SEGMENTS RESIDE (AND WILL RESIDE)
Not To Be Reproduced 5-10 MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_D_I_R_E_C_T_O_R_Y__H_E_A_D_E_R
ox THE DIRECTORY HEADER IS ACCESSED AT THE BEGINNING OF DIRECTORY
QUERY AND UPDATE OPERATIONS
Not To Be Reproduced 5-11 MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_D_I_R_E_C_T_O_R_Y__E_N_T_R_I_E_S
================================
INSERT Branch Entry DIAGRAM HERE
================================
Not To Be Reproduced 5-12 MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_D_I_R_E_C_T_O_R_Y__E_N_T_R_I_E_S
==============================
INSERT Link Entry DIAGRAM HERE
==============================
Not To Be Reproduced 5-13 MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_D_I_R_E_C_T_O_R_Y__E_N_T_R_I_E_S
ox THE DIRECTORY ENTRY IS A DISK RESIDENT (RLV) DATA BASE CONTAINED
WITHIN A DIRECTORY SEGMENT
[] ONE DIRECTORY ENTRY (IN THE DIRECTORY SEGMENT) FOR EACH
IMMEDIATELY INFERIOR ENTRY IN THE HIERARCHY
ox EACH DIRECTORY ENTRY IS A DATA STRUCTURE DESCRIBING THE ATTRIBUTES
OF A SEGMENT, DIRECTORY OR LINK
ox DIRECTORY ENTRIES COME IN TWO FLAVORS:
[] LINK ENTRY, (38 OR 72 WORDS) CONTAINING:
[] DATE TIME MODIFIED AND DUMPED (BY THE HIERARCHY DUMPER, NOT
VOLUME DUMPER)
[] RELATIVE POINTERS TO THE ENTRY'S NAME LIST AND AUTHOR'S USER
ID
[] ABSOLUTE PATHNAME OF THE LINK'S TARGET
[] UID OF PARENT DIRECTORY
Not To Be Reproduced 5-14 MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_D_I_R_E_C_T_O_R_Y__E_N_T_R_I_E_S
[] BRANCH ENTRY, (38 WORDS) CONTAINING:
[] DATE TIME MODIFIED AND DUMPED (BY THE HIERARCHY DUMPER, NOT
VOLUME DUMPER)
[] RELATIVE POINTERS TO THE ENTRY'S NAME LIST AND AUTHOR'S USER
ID
[] BRANCH'S UID, PVID, AND VTOC INDEX
[] AIM CLASSIFICATION, ENTRY POINT BOUND, RING BRACKETS, AND
RELATIVE POINTERS TO THE ACL
[] BRANCH'S BIT COUNT AND BIT COUNT AUTHOR
[] SON'S LVID (IF A DIRECTORY) AND PARENT'S UID
[] FLAGS DESCRIBING VARIOUS STATES AND PROPERTIES OF THE ENTRY
SUCH AS: DIRECTORY, MASTER DIRECTORY, SECURITY OUT OF
SERVICE, COPY AND SAFETY SWITCH, ETC
Not To Be Reproduced 5-15 MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L__C_O_M_M_A_N_D_S
_d_i_s_p_l_a_y__b_r_a_n_c_h
ox DISPLAY_BRANCH - DISPLAYS BRANCHES IN THE DIRECTORY HIERARCHY
[] OFTEN USEFUL ON CONJUNCTION WITH DUMP_VTOCE
! display_branch >udd>Multics>Sibert
Branch for Sibert in >udd>Multics at 245|20742
UID 102401170050, is vtocx 63 on root4 (of log vol. root)
Sibert is a directory.
Ring brackets (0 0 0)
Entry modified 02/23/83 1912.1 est Wed
Dumped 03/20/83 0955.6 est Sun
9 names.
ox DISPLAY IS NOT COMPLETE, SO A RING_ZERO_DUMP OF THE SAME DATA IS
INCLUDED
! ring_zero_dump >udd>Multics 20742 46 -ch
020742 021310020604 000004000046 102401170050 446556324757 .......&B.x(....
020746 400000000011 020752021152 001720000532 172000000000 .......j....z...
020752 021010000000 000006000016 020742000233 000000000000 ................
020756 123151142145 162164040040 040040040040 040040040040 Sibert
020762 040040040040 040040040040 040040040040 040040040040
020766 000000000000 102401170050 446752147026 000000000000 ....B.x(..g.....
020772 135240026001 000063000000 400000000000 000000000000 ]....3..........
020776 000000000000 000770000012 021170021300 001720000532 .........x......
021002 172000000000 225072707470 000000000000 000000000000 z....:..........
021006 033023254650 000000000000 ........
6-i MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L__C_O_M_M_A_N_D_S
_d_i_s_p_l_a_y__b_r_a_n_c_h
TOPIC VI
Volume Management
Page
Volume Management Overview. . . . . . . . . . 6-1
The New Storage System. . . . . . . . . . . . 6-4
Volume Management Terminology . . . . . . . . 6-13
Volume Management Data Bases. . . . . . . . . 6-16
Volume Label. . . . . . . . . . . . . . . 6-16
Volume Map. . . . . . . . . . . . . . . . 6-19
Dumper Bit Map. . . . . . . . . . . . . . 6-23
VTOC Map. . . . . . . . . . . . . . . . . 6-25
Physical Volume Table (PVT) . . . . . . . 6-26
Logical Volume Table (LVT). . . . . . . . 6-29
Physical Volume Hold Table. . . . . . . . 6-32
Volume Management Operations. . . . . . . . . 6-34
Acceptance of Physical Volumes. . . . . . 6-35
Demounting of Physical Volumes. . . . . . 6-37
Logical Volume Management . . . . . . . . 6-39
Volume Management Commands. . . . . . . . . . 6-40
print_configuration_deck. . . . . . . . . 6-40
list_vols . . . . . . . . . . . . . . . . 6-42
display_label . . . . . . . . . . . . . . 6-44
display_pvte. . . . . . . . . . . . . . . 6-46
Volume Management Meters. . . . . . . . . . . 6-48
disk_meters . . . . . . . . . . . . . . . 6-48
device_meters . . . . . . . . . . . . . . 6-49
disk_queue. . . . . . . . . . . . . . . . 6-50
6-i MDD-003
_D_I_R_E_C_T_O_R_Y__C_O_N_T_R_O_L__C_O_M_M_A_N_D_S
_d_i_s_p_l_a_y__b_r_a_n_c_h
ox FUNCTION
[] VOLUME MANAGEMENT IS RESPONSIBLE FOR THE MANAGEMENT OF PHYSICAL
AND LOGICAL VOLUMES
[] ITS TASKS INCLUDE:
[] ACCEPTANCE AND DEMOUNTING OF PHYSICAL VOLUMES
[] MAINTAINING THE ASSOCIATION BETWEEN PHYSICAL VOLUMES, LOGICAL
VOLUMES, AND DISK DRIVES
[] ENSURING THE INTEGRITY OF VOLUME CONTENTS
[] MAKING VOLUME CONTENTS ACCESSABLE TO PAGE CONTROL (PAGES) AND
SEGMENT CONTROL (VTOC ENTRIES)
[]
Not To Be Reproduced 6-0 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__O_V_E_R_V_I_E_W
VOLUME MANAGEMENT IS INVOKED ONLY BY SUBROUTINE CALLS
ox MAJOR DATA BASES
[] PHYSICAL VOLUME TABLE (PVT) - ONE PER SYSTEM
[] PHYSICAL VOLUME TABLE ENTRY (PVTE) - ONE PER DISK DRIVE KNOWN
TO THE SYSTEM
[] EACH PVTE IDENTIFIES A DRIVE'S DEVICE NUMBER, SUBSYSTEM NAME,
DEVICE TYPE, AND INFORMATION ABOUT THE PHYSICAL VOLUME
CURRENTLY MOUNTED
[] USED TO MAP REFERENCES TO PAGES OF SEGMENTS INTO AN I/O
REQUEST TO THE CORRECT DISK DRIVE
[] LOGICAL VOLUME TABLE (LVT) - ONE PER SYSTEM
[] LOGICAL VOLUME TABLE ENTRY (LVTE) - ONE PER MOUNTED LOGICAL
VOLUME
[] EACH LVTE CONTAINS THE LOGICAL VOLUME ID, POINTERS TO MEMBER
PVTE'S, AIM CLASS LIMITS, ETC.
[] USED TO DETERMINE A USER'S ACCESS TO A LOGICAL VOLUME
(PRIVATE OR PUBLIC) AND TO LOCATE MEMBER PHYSICAL VOLUMES
[] VOLUME HEADER - ONE PER PACK
[] VOLUME LABEL (REGISTRATION AND ACCEPTANCE INFORMATION)
Not To Be Reproduced 6-1 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__O_V_E_R_V_I_E_W
[] VOLUME MAP (OCCUPIED/VACANT INFORMATION FOR VOLUME CONTENTS)
[] RECORD STOCKS - ONE PER MOUNTED VOLUME
[] ONLINE CACHE OF INFORMATION ABOUT USED / UNUSED RECORDS ON
THE VOLUME
[] THIS INFORMATION IS DERIVED FROM THE VOLUME MAP, BUT KEPT
ONLINE TO AVOID THE NECESSITY OF REFERRING TO THE VOLUME MAP
ON DISK EVERY TIME A RECORD IS ALLOCATED OR FREED
[] WHEN THE CACHE BECOMES COMPLETELY EMPTY OR COMPLETELY FULL,
IT MUST BE UPDATED FROM/TO DISK - A PROTOCOL ENSURES THAT THE
COPY ON DISK IS ALWAYS CONSISTENT
[] PROVIDED BY VOLUME MANAGEMENT, BUT USED BY PAGE CONTROL
[] VTOCE STOCKS - ONE PER VOLUME
[] SIMILAR TO RECORD STOCKS, BUT MAINTAINS INFORMATION ABOUT
USED / UNUSED VTOC ENTRIES ON THE VOLUME
[] PROVIDED BY VOLUME MANAGEMENT, BUT USED BY SEGMENT CONTROL
[] PHYSICAL VOLUME HOLD TABLE (PVHT) - ONE PER SYSTEM
[] RECORDS THE COMMENCEMENT OF COMPOUND I/O OPERATIONS UPON A
PHYSICAL VOLUME
[] THIS INFORMATION PREVENTS A VOLUME FROM BEING DEMOUNTED WHILE
SUCH AN OPERATION IS IN PROGRESS
Not To Be Reproduced 6-2 MDD-003
_T_H_E__N_E_W__S_T_O_R_A_G_E__S_Y_S_T_E_M
=======================
INSERT NSS DIAGRAM HERE
=======================
Not To Be Reproduced 6-3 MDD-003
_T_H_E__N_E_W__S_T_O_R_A_G_E__S_Y_S_T_E_M
ox SINCE RELEASE 4.0, THE MULTICS STORAGE SYSTEM HAS BEEN ORGANIZED
INTO PHYSICAL AND LOGICAL VOLUMES HAVING THE FOLLOWING PROPERTIES
[] A PHYSICAL VOLUME (PV) IS A DISK PACK (MOUNTED OR NOT)
CONTAINING:
[] A LABEL IDENTIFYING ITSELF - INCLUDING A PHYSICAL VOLUME ID
(PVID)
[] A VOLUME MAP DESCRIBING WHICH PAGES and VTOCES ARE IN USE AND
WHICH ARE FREE.
[] A VOLUME TABLE OF CONTENTS (VTOC) DESCRIBING WHICH SEGMENTS
ARE RESIDENT THEREIN - AND THE EXACT LOCATION OF EACH OF
THEIR PAGES
[] THE PAGES OF RESIDENT SEGMENTS (ASSIGNED TO RECORDS OF 1024
WORDS IN SIZE)
[] AND OPTIONALLY: CONTIGUOUS REGIONS CALLED PARTITIONS, SET
ASIDE FOR SPECIAL USE (FDUMP IMAGES, HARDCORE PAGING, ETC)
[] ALL PAGES OF A SEGMENT RESIDE ON A GIVEN PHYSICAL VOLUME
[] THAT IS: EACH NON-ZERO PAGE OF A SEGMENT IS ASSIGNED TO A
RECORD OF THE PHYSICAL VOLUME
[] THE PAIR OF PHYSICAL VOLUME ID (PVID) AND VTOC INDEX UNIQUELY
IDENTIFIES ANY SEGMENT IN THE STORAGE SYSTEM HIERARCHY
Not To Be Reproduced 6-4 MDD-003
_T_H_E__N_E_W__S_T_O_R_A_G_E__S_Y_S_T_E_M
[] A LOGICAL VOLUME (LV) CONSISTS OF ONE OR MORE PHYSICAL VOLUMES,
WHICH ARE:
[] GIVEN ONE LOGICAL VOLUME ID (LVID)
[] ALWAYS MOUNTED AS A SET
[] OFFSPRING (SONS, GRANDSONS, ETC) OF A DIRECTORY (NORMALLY)
RESIDE WITHIN A GIVEN LOGICAL VOLUME
[] IN OTHER WORDS, A SUB-TREE (NORMALLY) SPANS NO MORE THAN ONE
LOGICAL VOLUME
[] DIRECTORY SEGMENTS ARE AN EXCEPTION TO THE ABOVE AS ALL
DIRECTORY SEGMENTS ARE ASSIGNED TO A LOGICAL VOLUME OF THEIR OWN
CALLED THE "ROOT LOGICAL VOLUME" (RLV)
[] THE PHYSICAL VOLUME CONTAINING THE ROOT DIRECTORY IS CALLED
"THE ROOT PHYSICAL VOLUME" (RPV)
[] THE RLV IS SPECIAL BECAUSE IT MUST ALWAYS BE MOUNTED, AND IT
CONTAINS ALL DIRECTORY SEGMENTS, BUT IT ALSO CONTAINS OTHER
SEGMENTS
[] SHOULD THE GROWING OF A SEGMENT CAUSE A PHYSICAL VOLUME TO
BECOME FULL, A "SEGMENT MOVE" IS AUTOMATICALLY INITIATED
[] THIS IS ONE OF THE MOST COMPLEX AND EXPENSIVE SERVICES
PERFORMED BY THE SYSTEM - BUT HAPPENS VERY INFREQUENTLY
Not To Be Reproduced 6-5 MDD-003
_T_H_E__N_E_W__S_T_O_R_A_G_E__S_Y_S_T_E_M
[] SHOULD A LOGICAL VOLUME BECOME FULL:
[] USER AND SYSTEM ERROR MESSAGES ARE GENERATED
[] SPACE MUST BE OBTAINED ON THE LOGICAL VOLUME BY ADDING MORE
PHYSICAL VOLUMES OR BY DELETING OR MOVING SEGMENTS FROM THE
LOGICAL VOLUME
[] BECAUSE IT CONTAINS ALL DIRECTORY SEGMENTS, SPACE ON THE RLV
IS CRITICAL: IF IT IS USED UP, THE SYSTEM MAY NOT BE ABLE TO
CONTINUE OPERATION.
[] THE CHOICE OF WHICH PHYSICAL VOLUME TO USE WHEN CREATING A
SEGMENT IS MADE IN SUCH A WAY AS TO TRY TO BALANCE THE ALLOCATED
SPACE ON ALL THE PHYSICAL VOLUMES OF A LOGICAL VOLUME
Not To Be Reproduced 6-6 MDD-003
_T_H_E__N_E_W__S_T_O_R_A_G_E__S_Y_S_T_E_M
=============================
INSERT PV Format DIAGRAM HERE
=============================
Not To Be Reproduced 6-7 MDD-003
_T_H_E__N_E_W__S_T_O_R_A_G_E__S_Y_S_T_E_M
==========================================
INSERT Hierarchy to SS Maping DIAGRAM HERE
==========================================
Not To Be Reproduced 6-8 MDD-003
_T_H_E__N_E_W__S_T_O_R_A_G_E__S_Y_S_T_E_M
ox IF ONE KNOWS WHERE THE ROOT DIRECTORY IS, ALL SEGMENTS IN THE
MULTICS HIERARCHY CAN BE FOUND (ASSUMING THE AVAILABILITY OF ALL
REQUIRED PHYSICAL VOLUMES)
ox MAJOR DESIGN POINT
[] MANY DISK RESIDENT DATA BASES (TO INCLUDE THE PAGES OF SEGMENTS)
ARE COPIED INTO MAIN MEMORY AND WRITTEN BACK TO DISK AT SUCH
TIMES AS:
[] SYSTEM START-UP/SHUT-DOWN
[] PHYSICAL VOLUME MOUNTING/DEMOUNTING
[] SEGMENT ACTIVATION/DEACTIVATION
[] PAGE FAULTS
[] WHILE IN MAIN MEMORY, THE MEMORY RESIDENT COPY IS CONSIDERED TO
BE _T_H_E COPY
[] WHILE IN MAIN MEMORY, THE DISK RESIDENT COPY IS CONSIDERED TO BE
(AND OFTEN IS) WHOLLY INVALID
Not To Be Reproduced 6-9 MDD-003
_T_H_E__N_E_W__S_T_O_R_A_G_E__S_Y_S_T_E_M
===================================
INSERT Disk Statistics DIAGRAM HERE
===================================
Not To Be Reproduced 6-10 MDD-003
_T_H_E__N_E_W__S_T_O_R_A_G_E__S_Y_S_T_E_M
======================================
INSERT LV/MD Relationship DIAGRAM HERE
======================================
Not To Be Reproduced 6-11 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__T_E_R_M_I_N_O_L_O_G_Y
MOUNT: TO PHYSICALLY PLACE A DISK PACK ON A DRIVE AND CYCLE UP
THE DRIVE. (PERFORMED BY THE OPERATOR, NOT BY
SOFTWARE)
ACCEPT: AFTER MOUNTING, TO ESTABLISH IN THE SUPERVISOR THE
BINDING BETWEEN THE DRIVE AND THE PHYSICAL VOLUME
MOUNTED
PUBLIC: A LOGICAL VOLUME ATTRIBUTE INDICATING THAT THE VOLUME
IS ATTACHED TO ALL PROCESSES (BY DEFAULT) WHEN ACCEPTED
PRIVATE: A LOGICAL VOLUME ATTRIBUTE INDICATING THAT THE VOLUME
IS ATTACHED ONLY TO REQUESTING PROCESSES (SUBJECT TO
ACCESS CONTROLS)
PARTITION: A REGION WITHIN A PHYSICAL VOLUME SET ASIDE FOR SPECIAL
USE
RECORD: A LOGICAL UNIT OF DISK SPACE, 1024 CONTIGUOUS WORDS IN
SIZE. (NUMBERED/ADDRESSED FROM ZERO)
SECTOR: A LOGICAL UNIT OF DISK SPACE, 64 CONTIGUOUS WORDS IN
Not To Be Reproduced 6-12 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__T_E_R_M_I_N_O_L_O_G_Y
SIZE. THE SMALLEST ADDRESSABLE UNIT OF DISK SPACE. A
RECORD CONTAINS 16 SECTORS
Not To Be Reproduced 6-13 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__T_E_R_M_I_N_O_L_O_G_Y
PAGE: A 1024 WORD EXTENT OF DATA STARTING AT A 1024 WORD
BOUNDARY OF A SEGMENT. SEGMENTS MUST BE AN INTEGER
NUMBER OF PAGES IN SIZE. A PAGE CAN RESIDE IN ONE OR
MORE OF THE FOLLOWING LOCATIONS:
MAIN MEMORY FRAME
DISK RECORD
Not To Be Reproduced 6-14 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__D_A_T_A__B_A_S_E_S
_V_O_L_U_M_E__L_A_B_E_L
==================================
INSERT Volume Label 1 DIAGRAM HERE
==================================
Not To Be Reproduced 6-15 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__D_A_T_A__B_A_S_E_S
_V_O_L_U_M_E__L_A_B_E_L
==================================
INSERT Volume Label 2 DIAGRAM HERE
==================================
Not To Be Reproduced 6-16 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__D_A_T_A__B_A_S_E_S
_V_O_L_U_M_E__L_A_B_E_L
ox THE VOLUME LABEL IS A DISK RESIDENT DATA BASE OCCUPYING THE FIRST
MULTICS RECORD OF EACH STORAGE SYSTEM PHYSICAL VOLUME
[] ONE VOLUME LABEL PER PHYSICAL VOLUME
ox THE LABEL IS GENERATED BY init_disk_pack (init_empty_root IF RPV
LABEL) AND CONTAINS REGISTRATION AND STATUS INFORMATION
ox THE LABEL IS INSPECTED WHEN THE VOLUME IS ACCEPTED AND UPDATED WHEN
DEMOUNTED
ox THE LABEL IS DIVIDED INTO SIX SECTORS
[] GCOS REGION (SECTORS 0 TO 4)
[] SKIPPED OVER BY MULTICS TO AVOID ACCIDENTAL OVERWRITING OF
GCOS PACKS AND ALLOW FOR FUTURE COMPATABILITY
[] PERMANENT REGION (SECTOR 5)
[] CONTAINS PERMANENT PER-PV INFORMATION (EG: MANUFACTURERS
SERIAL NUMBER)
Not To Be Reproduced 6-17 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__D_A_T_A__B_A_S_E_S
_V_O_L_U_M_E__L_A_B_E_L
[] DYNAMIC INFORMATION REGION (SECTOR 6)
[] CONTAINS INFORMATION RELATING TO THE MOST RECENT MOUNTING OF
THE PV (EG: LAST MOUNT TIME)
[] ALLOWS THE STORAGE SYSTEM TO ENSURE THE INTEGRITY OF THE PV
[] ROOT INFORMATION REGION (SECTOR 7)
[] DEFINED ONLY FOR THE ROOT PHYSICAL VOLUME
[] CONTAINS DYNAMIC INFORMATION ABOUT THE ENTIRE STORAGE SYSTEM
(EG: SHUT DOWN STATE, PAGING DEVICE STATE, ETC)
[] PARTITION MAP (SECTOR 8)
[] IDENTIFIES THE LOCATION AND LENGTH OF ANY RESIDENT PARTITIONS
[] UNUSED (SECTORS 9 TO 13)
Not To Be Reproduced 6-18 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__D_A_T_A__B_A_S_E_S
_V_O_L_U_M_E__M_A_P
==============================
INSERT Volume Map DIAGRAM HERE
==============================
Not To Be Reproduced 6-19 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__D_A_T_A__B_A_S_E_S
_V_O_L_U_M_E__M_A_P
ox THE VOLUME MAP IS A DISK RESIDENT DATA BASE
[] OCCUPIES RECORDS 1, 2, AND 3, IMMEDIATELY FOLLOWING THE VOLUME
LABEL
[] ONE VOLUME MAP PER PHYSICAL VOLUME
ox THE VOLUME MAP IDENTIFIES THE EXTENT OF THE PAGING REGION, THE
NUMBER OF VACANT RECORDS, AND THE STATE (VACANT/OCCUPIED) OF EVERY
RECORD IN THE VOLUME'S PAGING REGION
[] THIS INFORMATION IS ALSO DERIVABLE FROM AN ANALYSIS OF THE VTOC
(AT CONSIDERABLE EXPENSE) - THIS IS DONE WHEN THE VOLUME IS
SCAVENGED OR SALVAGED.
ox RECORDS ARE TAKEN FROM THE VOLUME MAP DURING OPERATION AND PLACED
IN THE RECORD STOCK
[] RECORDS ARE ALLOCATED BY PAGE CONTROL FROM THE RECORD STOCK
[] VOLUME MAP ON DISK IS ALWAYS CONSISTENT
[] RECORDS MARKED FREE ON DISK ARE GUARANTEED TO BE FREE, AND
SAFE TO RE-USE
Not To Be Reproduced 6-20 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__D_A_T_A__B_A_S_E_S
_V_O_L_U_M_E__M_A_P
[] RECORDS MARKED AS ALLOCATED MAY NOT ACTUALLY BE IN-USE, IF A
CRASH OCCURRED AND DESTROYED THE STOCK CONTENTS
[] THIS SITUATION IS BENIGN, AND CORRECTED BY A SCAVENGE OR
SALVAGE AT SOME CONVENIENT TIME
[] RECORDS FREED ARE PLACED BACK IN THE STOCK
[] IF STOCK FILLS, IT IS WRITTEN BACK TO THE VOLUME MAP
[] CONSISTENCY IS ENSURED BY COMPLEX PROTOCOL IN PAGE CONTROL
[] RECORD STOCK MECHANISM REPLACES FSMAP SEGMENTS IN PRE-MR10.0
SYSTEMS
Not To Be Reproduced 6-21 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__D_A_T_A__B_A_S_E_S
_D_U_M_P_E_R__B_I_T__M_A_P
==================================
INSERT Dumper Bit Map DIAGRAM HERE
==================================
Not To Be Reproduced 6-22 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__D_A_T_A__B_A_S_E_S
_D_U_M_P_E_R__B_I_T__M_A_P
ox THE DUMPER BIT MAP DESCRIBES WHICH VTOCES ON THE VOLUME HAVE BEEN
VOLUME DUMPED
[] ONE PER PHYSICAL VOLUME
[] OCCUPIES RECORDS 4 AND 5, IMMEDIATELY FOLLOWING VOLUME MAP
[] SEPARATE BIT MAPS FOR INCREMENTAL AND CONSOLIDATED VOLUME DUMPS
Not To Be Reproduced 6-23 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__D_A_T_A__B_A_S_E_S
_V_T_O_C__M_A_P
ox THE VTOC MAP DESCRIBES THE LOCATION AND SIZE OF THE VTOC, AND
CONTAINS A BIT MAP OF VTOC ALLOCATIONS
[] OCCUPIES RECORD 6, IMMEDIATELY FOLLOWING THE DUMPER BIT MAP
[] VTOC FOLLOWS, STARTING AT RECORD 8
[] RECORD 7 IS UNUSED
ox VTOCES ARE TAKEN FROM THE VTOCE MAP AND PLACED IN AN ONLINE STOCK
[] VTOCE STOCK IS LIKE RECORD STOCK, BUT LESS CRITICAL
[] VTOCES ARE SELF-IDENTIFYING AS TO WHETHER THEY ARE IN USE OR
NOT, SO IT IS NOT NECESSARY TO MAINTAIN PERFECT CONSISTENCY
IF A CRASH OCCURS
[] VTOCE MAP IS ALSO REBUILT BY SCAVENGE OR SALVAGE OPERATIONS
[] VTOCE MAP REPLACES VTOCE FREE LIST IN PRE-MR10.0 SYSTEMS
Not To Be Reproduced 6-24 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__D_A_T_A__B_A_S_E_S
_P_H_Y_S_I_C_A_L__V_O_L_U_M_E__T_A_B_L_E__(_P_V_T_)
=======================
INSERT PVT DIAGRAM HERE
=======================
Not To Be Reproduced 6-25 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__D_A_T_A__B_A_S_E_S
_P_H_Y_S_I_C_A_L__V_O_L_U_M_E__T_A_B_L_E__(_P_V_T_)
ox THE PHYSICAL VOLUME TABLE (PVT) IS A HARDCORE, WIRED, PAGED DATA
BASE MAINTAINED BY VOLUME MANAGEMENT
[] ONE PVT PER SYSTEM
ox THE PVT IS THE MOST IMPORTANT DATA BASE OF VOLUME MANAGEMENT, AND
CONTAINS AN ARRAY OF PHYSICAL VOLUME TABLE ENTRIES (PVTE'S)
[] ONE PVTE PER DISK DRIVE KNOWN TO THE SYSTEM
ox EACH PVTE DESCRIBES:
[] A DISK DRIVE CONFIGURED TO THE SYSTEM
[] INCLUDING THE DEVICE NUMBER, DEVICE TYPE, SUBSYSTEM NAME AND
OTHER INFORMATION NEEDED BY THE DISK DIM
[] THE PHYSICAL VOLUME CURRENTLY MOUNTED ON THE DISK DRIVE
[] INCLUDING THE PVID, LVID, AND OTHER INFORMATION TAKEN FROM
THE VOLUME HEADER, VOLUME MAP AND VTOC MAP, NEEDED BY PAGE
AND SEGMENT CONTROL (THE PV & LV NAMES ARE _N_O_T RECORDED HERE)
Not To Be Reproduced 6-26 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__D_A_T_A__B_A_S_E_S
_P_H_Y_S_I_C_A_L__V_O_L_U_M_E__T_A_B_L_E__(_P_V_T_)
[] RECORD AND VTOCE STOCKS ARE LOCATED FROM THE PVT, BUT KEPT IN
THE stock_seg
Not To Be Reproduced 6-27 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__D_A_T_A__B_A_S_E_S
_L_O_G_I_C_A_L__V_O_L_U_M_E__T_A_B_L_E__(_L_V_T_)
=======================
INSERT LVT DIAGRAM HERE
=======================
Not To Be Reproduced 6-28 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__D_A_T_A__B_A_S_E_S
_L_O_G_I_C_A_L__V_O_L_U_M_E__T_A_B_L_E__(_L_V_T_)
ox THE LOGICAL VOLUME TABLE (LVT) IS A HARDCORE, PAGED DATA BASE
MAINTAINED BY VOLUME CONTROL
[] ONE LVT PER SYSTEM
ox THE LVT CONTAINS AN ARRAY OF LOGICAL VOLUME TABLE ENTRIES (LVTE'S)
[] ONE LVTE FOR EACH MOUNTED LOGICAL VOLUME
ox EACH LVTE DESCRIBES THE LOGICAL VOLUME TO INCLUDE:
[] LVID AND AIM CLASSIFICATION
[] RELATIVE POINTER TO THE THREAD OF PVTE'S OF ACCEPTED PHYSICAL
VOLUMES THAT ARE MEMBERS OF THE LOGICAL VOLUME
Not To Be Reproduced 6-29 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__D_A_T_A__B_A_S_E_S
_L_O_G_I_C_A_L__V_O_L_U_M_E__T_A_B_L_E__(_L_V_T_)
ox THE LVT IS REQUIRED AT THE FOLLOWING TIMES:
[] SEGMENT CREATION
[] SEGMENT MOVING TIME
[] VOLUME MOUNTING AND DEMOUNTING
[] INITIATION AND SEGMENT FAULT TIME (FOR PUBLIC/PRIVATE CHECK)
Not To Be Reproduced 6-30 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__D_A_T_A__B_A_S_E_S
_P_H_Y_S_I_C_A_L__V_O_L_U_M_E__H_O_L_D__T_A_B_L_E
==================================
INSERT PVT Hold Table DIAGRAM HERE
==================================
ox THE PHYSICAL VOLUME HOLD TABLE (PVHT) IS A HARDCORE DATA BASE
MAINTAINED BY VOLUME MANAGEMENT
[] ONE PVHT PER SYSTEM
ox THE PVHT IDENTIFIES THE PHYSICAL VOLUME AND THE PROCESS ID OF
PROCESS THAT HAS STARTED (AND HAS NOT YET COMPLETED) COMPOUND
OPERATIONS UPON THE PHYSICAL VOLUME
ox THIS INFORMATION PREVENTS A VOLUME FROM BEING DEMOUNTED WHILE SUCH
AN OPERATION IS IN PROGRESS
Not To Be Reproduced 6-31 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__D_A_T_A__B_A_S_E_S
_P_H_Y_S_I_C_A_L__V_O_L_U_M_E__H_O_L_D__T_A_B_L_E
ox INTERRUPTION OF A COMPOUND OPERATION CAUSES THE VOLUME TO BE MARKED
AS CONTAINING AN INCONSISTENCY
ox FOR CRASH ANALYSIS, sst.pvthp CONTAINS A POINTER TO THIS TABLE
Not To Be Reproduced 6-32 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__O_P_E_R_A_T_I_O_N_S
_A_C_C_E_P_T_A_N_C_E__O_F__P_H_Y_S_I_C_A_L__V_O_L_U_M_E_S
ox THE ACCEPTANCE OF PHYSICAL VOLUMES IS THE MOST IMPORTANT AND
FUNDAMENTAL OPERATION OF VOLUME MANAGEMENT
ox PHYSICAL VOLUME ACCEPTANCE IS ACCOMPLISHED BY CALLING
initializer_gate_$accept_fs_disk
ox THE ROOT PHYSICAL VOLUME (RPV) IS ACCEPTED IN A SPECIAL FASHION
DURING COLLECTION 2 OF BOOTLOAD
[] THE RPV IS THE ONLY PV REQUIRED TO BOOTLOAD THE SYSTEM (MORE OF
THE RLV WILL BE ACCEPTED BY RING ZERO DURING BOOTLOAD IF POINTED
TO BY THE "ROOT" CONFIGURATION CARD)
ox ACCEPTANCE INCLUDES:
[] VALIDATE THAT THE DISK PACK MOUNTED IS THE PACK REQUESTED BY THE
OPERATOR OR REQUESTING PROCESS VIA label.pvid
[] DETERMINE THAT THE DISK PACK MOUNTED IS IN FACT A MEMBER OF _T_H_I_S
HIERARCHY VIA label.root_pvid
Not To Be Reproduced 6-33 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__O_P_E_R_A_T_I_O_N_S
_A_C_C_E_P_T_A_N_C_E__O_F__P_H_Y_S_I_C_A_L__V_O_L_U_M_E_S
[] INITIALIZING THE APPROPRIATE PVTE WITH DATA FROM THE LABEL,
VOLUME MAP, AND VTOC MAP
[] INITIALIZING THE INITIAL CONTENTS OF THE RECORD STOCK AND VTOCE
STOCKS
[] DETERMINING IF ANY VOLUME INCONSISTENCIES ARE PRESENT, AND
LOGGING THIS INFORMATION
[] VOLUME INCONSISTENCIES ARE CAUSED BY EVENTS WHICH MAY MEAN
THAT THE DISK RESIDENT COPY OF THE VOLUME MAP OR VTOC MAP IS
INCONSISTENT:
[] A CRASH WITHOUT ESD - INDICATED BY label.time_map_updated
and label.time_unmounted BEING UNEQUAL, DETECTED AT
ACCEPTANCE TIME
[] AN INCONSISTENCY DETECTED ONLINE, SUCH AS AN INVALID VTOC
BIT MAP OR A REUSED ADDRESS
[] AN I/O ERROR WHEN WRITING THE VOLUME MAP OR VTOC MAP
DURING NORMAL OPERATION
[] A COUNT IS KEPT IN THE LABEL, AND UPDATED AS NECESSARY
[] NORMALLY, INCONSISTENCIES ARE MERELY LOGGED, AND LEFT FOR THE
SITE TO TAKE CARE OF AT SOME CONVENIENT TIME
[] IF AN RLV VOLUME CLAIMS ONLY A VERY SMALL NUMBER OF FREE
PAGES, A VOLUME SALVAGE IS DONE AUTOMATICALLY TO TRY TO
RECOVER ANY LOST DUE TO THE INCONSISTENCY, SINCE A FULL
RLV WILL CAUSE SYSTEM CRASHES
Not To Be Reproduced 6-34 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__O_P_E_R_A_T_I_O_N_S
_A_C_C_E_P_T_A_N_C_E__O_F__P_H_Y_S_I_C_A_L__V_O_L_U_M_E_S
[] WRITING OUT THE LABEL TO UPDATE label.time_map_updated.
[] NOTE: label.time_map_updated AND label.time_unmounted ARE
NOW UNEQUAL
[] THIS INEQUALITY IMPLIES THAT THE VOLUME HAS _N_O_T BEEN PROPERLY
SHUT DOWN, AND WILL BE MARKED INCONSISTENT IF ACCEPTED AGAIN
IN THIS STATE
[] MARKING THE PVTE AS "IN USE" (LAST STEP)
Not To Be Reproduced 6-35 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__O_P_E_R_A_T_I_O_N_S
_D_E_M_O_U_N_T_I_N_G__O_F__P_H_Y_S_I_C_A_L__V_O_L_U_M_E_S
ox THE DEMOUNTING OF PHYSICAL VOLUMES INVOLVES REVERSING ALL OF THE
STEPS TAKEN AT ACCEPTANCE TIME
ox DEMOUNTING IS COMPLICATED BY THE FACT THAT THE PV MAY BE IN USE AT
THE TIME
ox DEMOUNTING IS ACCOMPLISHED BY CALLING demount_pv ("THE DEMOUNTER")
ox ALL VOLUMES ARE DEMOUNTED AT SHUTDOWN TIME
ox DEMOUNTING INCLUDES:
[] TURNING ON pvte.being_demounted AND WAITING FOR ALL COMPOUND
OPERATIONS TO TERMINATE
[] DEACTIVATING ALL SEGMENTS FROM THE PV WHICH ARE ACTIVE. THIS
INCLUDES:
[] FLUSHING MAIN MEMORY AND PAGING DEVICE (IF PRESENT) OF ALL
RELEVANT PAGES
Not To Be Reproduced 6-36 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__O_P_E_R_A_T_I_O_N_S
_D_E_M_O_U_N_T_I_N_G__O_F__P_H_Y_S_I_C_A_L__V_O_L_U_M_E_S
[] UPDATING THE VTOCE'S FROM THE ASTE'S AND PAGE TABLES
[] FLUSHING THE VTOC MANAGER'S BUFFER SEGMENT OF ALL RELEVANT
VTOCE-PARTS
[] EMPTYING THE RECORD AND VTOCE STOCKS BACK INTO THE VOLUME MAP
AND VTOC MAP
[] UPDATING THE VOLUME LABEL FROM THE PVTE, PARTICULARLY
[] label.time_unmounted, label.time_map_updated, AND
label.inconsistency_count
[] PHYSICALLY CYCLING DOWN THE DISK DRIVE
[] NOT DONE AT SYSTEM SHUTDOWN, HOWEVER
ox ONLY ONE PV MAY BE DEMOUNTED AT A TIME
Not To Be Reproduced 6-37 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__O_P_E_R_A_T_I_O_N_S
_L_O_G_I_C_A_L__V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T
ox LOGICAL VOLUME MANAGEMENT INCLUDES:
[] MAINTAINING THE LOGICAL VOLUME TABLE (LVT) TO REFLECT THE STATE
OF THE LOGICAL VOLUMES
[] MAINTAINING, IN THE KNOWN SEGMENT TABLE (KST) OF EACH PROCESS, A
TABLE OF PRIVATE LOGICAL VOLUMES MOUNTED TO THE PROCESS
[] ANSWERING THE QUESTION OF WHETHER OR NOT A GIVEN LOGICAL VOLUME
IS MOUNTED TO THE CALLING PROCESS
[] OR, IF A PUBLIC LV, MOUNTED AT ALL (TO THE SYSTEM)
[] PROVIDING THE HEAD OF THE PVT CHAIN FOR A GIVEN LV, FOR THE
SEGMENT CREATION FUNCTION
Not To Be Reproduced 6-38 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__C_O_M_M_A_N_D_S
_p_r_i_n_t__c_o_n_f_i_g_u_r_a_t_i_o_n__d_e_c_k
ox PRINT_CONFIGURATION_DECK - DISPLAYS >sl1>config_deck, WHICH
CONTAINS INFORMATION ABOUT DISK LOCATIONS, THE RLV, AND PARTITIONS
[] ONLY THE PART OF THE CONFIG DECK RELEVANT TO VOLUME MANAGEMENT
AND DISK CONFIGURATION IS SHOWN HERE
root dska 16. dskb 25. dskb 23. dskb 24. dska 8.
part bos dska 16.
part dump dska 16.
part log dska 16.
prph dska a 20. 2 451. 16.
chnl dska a 26. 2 b 24. 2 b 22. 2
prph dskb b 20. 2 0 16. 451. 16.
chnl dskb b 26. 2 a 24. 2 a 22. 2
prph dskc a 28. 2 501. 32.
chnl dskc a 30. 2 b 30. 2 b 28. 2
prph dske b 32. 2 451. 8.
chnl dske b 34. 2
prph dskf a 32. 2 501. 16.
chnl dskf a 34. 2
mpc mspa 451. a 20. 4 a 24. 4
mpc mspb 451. b 20. 4 b 24. 4
mpc mspc 607. a 28. 4
mpc mspd 607. b 28. 4
mpc mspe 451. b 32. 4
mpc mspf 607. a 32. 4
Not To Be Reproduced 6-39 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__C_O_M_M_A_N_D_S
_p_r_i_n_t__c_o_n_f_i_g_u_r_a_t_i_o_n__d_e_c_k
ox DISK CONFIGURATION CONFIG CARDS
[] ROOT
[] IDENTIFIES THOSE VOLUMES IN THE ROOT LOGICAL VOLUME WHICH
HAVE HC PARTITIONS, USED BY THE SUPERVISOR FOR PAGING OF
SUPERVISOR SEGMETNS
[] PART
[] IDENTIFIES THE LOCATIONS OF CERTAIN IMPORTANT PARTITIONS
[] ONLY PARTITIONS NECESSARY FOR MULTICS OPERATIONS ARE
IDENTIFIED, NOT ALT PARTITIONS
[] HC PARTITIONS ARE LOCATED BY THE ROOT CARD
[] PRPH DSK_n, CHNL
[] IDENTIFY PHYSICAL I/O CHANNEL PATHS FOR ACCESSING DISK DRIVES
[] MPC
[] IDENTIFY PHYSICAL CONNECTIONS TO MICROPROGRAMMED DISK
CONTROLLERS
Not To Be Reproduced 6-40 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__C_O_M_M_A_N_D_S
_l_i_s_t__v_o_l_s
ox LIST_VOLS - DISPLAYS A TABLE OF ONLINE VOLUMES, THEIR LOCATION, AND
SPACE UTILIZATION
Drive Records Left % VTOCEs Left % Avg PV PB/PD LV Name
Size Name
dskc_17 64504 54730 85 13440 11356 84 4 alpha01 pb pd Alpha
dskc_18 64504 55389 86 13440 11352 84 4 alpha02 pb pd Alpha
dska_05 36428 5305 15 8400 2662 32 5 mul03 pb pd Multics_Pubs
dska_06 36428 4323 12 8400 2365 28 5 mul01 pb pd Multics_Pubs
dskb_19 36428 4632 13 8400 2813 33 5 mul02 pb pd Multics_Pubs
dskb_26 36429 13690 38 8400 4326 52 5 mul05 pb pd Multics_Pubs
dskb_27 36429 4672 13 8400 2333 28 5 mul04 pb pd Multics_Pubs
dska_01 36308 4680 13 9000 450 5 3 pub01 pb pd Public
dska_03 36268 3588 10 9200 1017 11 3 pub07 pb pd Public
dska_04 36268 4500 12 9200 884 10 3 pub04 pb pd Public
dska_09 36268 4816 13 9200 864 9 3 pub02 pb pd Public
dskb_17 36269 4281 12 9200 1002 11 3 pub05 pb pd Public
dskb_18 36268 3840 11 9200 539 6 3 pub08 pb pd Public
dskc_13 64504 294 0 13440 5539 41 8 rel01 Release
dskc_14 64504 269 0 13440 5214 39 7 rel02 Release
dskc_01 64503 43631 68 13440 10032 75 6 xpub01 pb Xpublic
dskc_02 64503 45502 71 13440 9838 73 5 xpub02 pb Xpublic
dskc_03 64503 42374 66 13440 9839 73 6 xpub03 pb Xpublic
dskc_04 64503 43591 68 13440 9785 73 5 xpub04 pb Xpublic
dskc_09 64504 58010 90 13440 12394 92 6 xpub05 pb Xpublic
dskc_10 64504 56786 88 13440 12407 92 7 xpub06 pb Xpublic
dskc_21 64503 23947 37 13440 6446 48 5 ypub01 pb Ypublic
dskc_22 64503 23744 37 13440 6194 46 5 ypub02 pb Ypublic
dskc_29 64503 23794 37 13440 6185 46 5 ypub05 pb Ypublic
dskc_30 64503 24111 37 13440 6481 48 5 ypub06 pb Ypublic
dskc_07 64503 11723 18 13440 6149 46 7 zpub01 pb pd Zpublic
dskc_08 64503 11665 18 13440 6429 48 7 zpub02 pb pd Zpublic
dskc_23 64504 9777 15 13440 6094 45 7 zpub03 pb pd Zpublic
dskc_24 64504 11805 18 13440 6141 46 7 zpub04 pb pd Zpublic
dskc_25 64504 11514 18 13440 7407 55 8 zpub05 pb pd Zpublic
dskc_26 64504 12958 20 13440 7149 53 8 zpub06 pb pd Zpublic
dske_06 37089 8053 22 5100 3797 74 22 list01 pb pd list_1
dska_12 37562 6046 16 2735 957 35 17 list02 pb list_2
dska_07 37309 6825 18 4000 2107 53 16 list03 pb list_3
dska_08 36209 3827 11 7000 491 7 4 root5 pb root
dska_11 36209 8597 24 7000 4181 60 9 root6 pb root
Not To Be Reproduced 6-41 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__C_O_M_M_A_N_D_S
_l_i_s_t__v_o_l_s
dska_16 31283 2892 9 9000 3476 39 5 rpv pb root
dskb_23 36208 4888 13 7000 455 7 4 root3 pb root
dskb_24 36209 3097 9 7000 238 3 4 root4 pb root
dskb_25 36350 4483 12 7000 223 3 4 root2 pb root
Not To Be Reproduced 6-42 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__C_O_M_M_A_N_D_S
_d_i_s_p_l_a_y__l_a_b_e_l
ox DISPLAY_LABEL - DISPLAYS THE LABEL OF A STORAGE SYSTEM VOLUME BY
READING IT FROM DISK
[] USED / FREE INFORMATION IS COPY ON DISK, AND THEREFORE OUT OF
DATE WITH RESPECT TO THE PVTE
Label for Multics Storage System Volume rpv on dska_01 d451
PVID 220531524345
Serial rpv
Logical Volume root
LVID 220531524466
Registered 01/28/81 1249.5
Dismounted 03/15/83 0741.9
Map Updated 03/15/83 0744.6
Salvaged 10/01/82 0300.3
Bootload 03/15/83 0743.5
Reloaded 01/28/81 1510.1
Dumped
Incremental 03/17/83 2153.0
Consolidated 03/16/83 2359.3
Complete 03/15/83 2353.0
Inconsistencies 0
Minimum AIM 0:000000
Maximum AIM 7:777777
Volume contains Root (>) at vtocx 0
disk_table_ at vtocx 100 (uid 033022210261)
Volume Map from Label
First Rec (Octal) Size
0 0 8 Label Region
8 10 2000 VTOC Region
2008 3730 2008 hc Partition
4016 7660 33901 Paging Region
37917 112035 200 bos Partition
Not To Be Reproduced 6-43 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__C_O_M_M_A_N_D_S
_d_i_s_p_l_a_y__l_a_b_e_l
38117 112345 141 alt Partition
38258 Total Size
Not To Be Reproduced 6-44 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__C_O_M_M_A_N_D_S
_d_i_s_p_l_a_y__p_v_t_e
ox DISPLAY_PVTE - DISPLAYS THE PVT ENTRY OF A STORAGE SYSTEM VOLUME
[] PARTITION INFORMATION IS NOT DETAILED IN THE PVTE, BUT USED/FREE
INFORMATION IS COMPLETELY UP TO DATE
PVTE for Multics Storage System Volume rpv on dska_01 d451 at pvt|50
PVID 220531524345
LVID 220531524466
VTOCEs
Number 10000
Left 3323
Records
Number 33901
Left 3796
Inconsistencies 0
Volume Map
volmap_seg ASTE 15|4420
record stock 76|100
Page 0 - Base 7660
Free 3364
Page 1 - Base 103660
Free 3740
Page 2 - Base 203660
Free 0
vtoce stock 76|2400
ON: storage_system permanent hc_part_used
OFF: being_mounted being_demounted being_demounted2
scav_check_address device_inoperative vacating
dmpr_in_use(incr) dmpr_in_use(cons) dmpr_in_use(comp)
Volume Map from PVTE
First Rec (Octal) Size
0 0 8 Label Region
8 10 2000 VTOC Region
Not To Be Reproduced 6-45 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__C_O_M_M_A_N_D_S
_d_i_s_p_l_a_y__p_v_t_e
2008 3740 2008 Partitions
4016 7660 33901 Paging Region
37917 112035 199 Partitions
38258 Total Size
Not To Be Reproduced 6-46 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__M_E_T_E_R_S
_d_i_s_k__m_e_t_e_r_s
ox DISK_METERS - DISPLAYS I/O ACTIVITY TO DISK DRIVES
[] ONLY ONE SUBSYSTEM SHOWN HERE TO CONSERVE SPACE
Total metering time 0:20:12
Subsystem dska Count Waits %Waits Avg. Wait(ms.)
call locks 26005 217 0.83 0.259
run locks 112 0 0.00 0.000
interrupt locks 25998 239 0.92 0.208
allocations 26001 0 0.00 0.000
Drive Reads Writes Seek ATB ATB ATB
Distance Reads Writes I/O
1 269 67 214 4508 18102 3609
3 362 243 109 3350 4991 2004
4 309 131 184 3925 9258 2756
5 547 165 180 2217 7350 1703
6 631 165 161 1922 7350 1523
7 0 0 0 0 0 0
8 5843 2187 122 207 554 151
9 366 116 153 3313 10455 2516
11 3501 1431 200 346 847 245
12 0 0 0 0 0 0
16 7158 2508 135 169 483 125
Not To Be Reproduced 6-47 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__M_E_T_E_R_S
_d_e_v_i_c_e__m_e_t_e_r_s
ox DEVICE_METERS - DISPLAYS SUMMARY OF I/O ACTIVITY FOR ALL DISK
SUBSYSTEMS
Total metering time 0:20:13
dska dskb dskc dskd
Prior Page I/O 18571 17743 462 1273
ATB 65.334 68.383 2626.240 953.121
Other Page I/O 6525 5135 16 696
ATB 185.949 236.284 75832.692 1743.280
ATB Page I/O 48.347 53.034 2538.332 616.212
Prior VTOCE I/O 934 895 38 304
ATB 1299.061 1355.668 31929.554 3991.194
ATB I/O 46.612 51.037 2351.401 533.798
% Busy 76 74 0 4
Avg. Page Wait 47.289 46.197 20.341 24.666
Avg. Page ^Wait 176.082 101.023 36.996 61.704
Avg VTOCE Wait 41.138 37.610 38.595 29.090
Avg. Page I/O T 35.619 38.314 20.050 22.482
Avg. VTOCE I/O T 31.139 32.277 37.060 26.606
EDAC Corr. Errs 0 0 0 0
Errors 0 0 0 1
Fatal Errors 0 0 0 0
Not To Be Reproduced 6-48 MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__M_E_T_E_R_S
_d_i_s_k__q_u_e_u_e
ox DISK_QUEUE - DISPLAYS I/O QUEUE FOR A DISK SUBSYSTEM
[] ONLY ONE SUBSYSTEM SHOWN HERE TO CONSERVE SPACE
Connects = 2604781, 1359725, 677321, 309367,
123430, 40159, 10227, 1969.
P RW VP DV SECTOR MEM
0 W P 24 1350330 27304000
0 W P 9 1020150 4432000
0 W P 16 1204130 36246000
0 W P 16 314370 27306000
0 W P 16 314430 34166000
TOPIC VII
Page
Segment Control Overview. . . . . . . . . . . 7-1
Segment Control Terminology . . . . . . . . . 7-4
Segment Control Data Bases. . . . . . . . . . 7-5
Volume Table of Contents (VTOC) . . . . . 7-5
Active Segment Table (AST). . . . . . . . 7-11
Services of Segment Control . . . . . . . . . 7-25
Creating Segments . . . . . . . . . . . . 7-25
Segment Fault . . . . . . . . . . . . . . 7-28
Segment Activation. . . . . . . . . . . . 7-29
Segment Trailers. . . . . . . . . . . . . 7-30
Boundsfault Handling. . . . . . . . . . . 7-32
Segment Deactivation. . . . . . . . . . . 7-35
Summary of Major Services . . . . . . . . 7-37
Encacheability. . . . . . . . . . . . . . 7-38
Truncating Segments . . . . . . . . . . . 7-38
Deleting Segments . . . . . . . . . . . . 7-40
Other Services. . . . . . . . . . . . . . 7-42
Segment Control Meters. . . . . . . . . . . . 7-44
7-i MDD-003
_V_O_L_U_M_E__M_A_N_A_G_E_M_E_N_T__M_E_T_E_R_S
_d_i_s_k__q_u_e_u_e
file_system_meters. . . . . . . . . . . . 7-44
vtoc_buffer_meters. . . . . . . . . . . . 7-46
Segment Control Commands. . . . . . . . . . . 7-47
print_aste_ptp. . . . . . . . . . . . . . 7-47
dump_vtoce. . . . . . . . . . . . . . . . 7-48
7-i MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__O_V_E_R_V_I_E_W
ox FUNCTION
[] SEGMENT CONTROL IS RESPONSIBLE FOR THE MANAGEMENT OF _L_O_G_I_C_A_L
_M_E_M_O_R_Y
[] ITS TASKS INCLUDE:
[] MAINTAINING THE DISK RESIDENT MAPS OF SEGMENTS (IE: THEIR
VTOCE'S)
[] SEGMENT CREATION, TRUNCATION AND DELETION
[] SEGMENT ACTIVATION AND DEACTIVATION (ASTE MULTIPLEXING)
[] SEGMENT CONTROL CAN BE INVOKED EITHER BY SUBROUTINE CALLS OR BY
SEGMENT FAULTS
ox BASIC PHILOSOPHY OF ACTIVATION/DEACTIVATION
[] OF ALL SEGMENTS RESIDENT WITHIN THE SYSTEM'S MOUNTED PHYSICAL
VOLUMES, ONLY A SMALL SUBSET WILL REQUIRE ACCESSING AT ANY ONE
TIME. SUCH SEGMENTS WILL BE CALLED "ACTIVE SEGMENTS"
[] A PART OF MAIN MEMORY, CALLED THE "ACTIVE SEGMENT TABLE" (AST),
WILL BE RESERVED TO HOLD MANAGEMENT INFORMATION FOR THESE ACTIVE
SEGMENTS (IDENTITY, PVT INDEX, LOCATION OF PAGES, ETC.)
Not To Be Reproduced 7-1 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__O_V_E_R_V_I_E_W
[] AS SEGMENTS FALL INTO DISUSE, THEIR "MANAGEMENT INFORMATION" IN
THE AST WILL BE REPLACED WITH INFORMATION OF OTHER SEGMENTS
REQUIRING ACTIVATION
ox USER INTERFACE
[] COMMAND LEVEL
[] create, delete, truncate, etc.
[] SUBROUTINE LEVEL
[] hcs_$append_branch, hcs_$append_branchx, hcs_$delentry_seg,
hcs_$delentry_file, hcs_$truncate_seg, hcs_$truncate_file,
hcs_$force_write, etc
ox MAJOR DATA BASES
[] SYSTEM SEGMENT TABLE (SST) - ONE PER SYSTEM, SHARED WITH PAGE
CONTROL. ONE MAJOR COMPONENT IS "OWNED" BY SEGMENT CONTROL:
[] ACTIVE SEGMENT TABLE (AST) - ONE PER SYSTEM
[] THE AST IS A LIST OF ACTIVE (CURRENTLY BEING USED) SEGMENTS
[] ACTIVE SEGMENT TABLE ENTRY (ASTE) - ONE PER ACTIVE SEGMENT
[] ASTES CONTAIN PHYSICAL VOLUME ID'S (PVID'S) AND VTOC
Not To Be Reproduced 7-2 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__O_V_E_R_V_I_E_W
INDEX'S (VTOCX'S) OF SEGMENTS. NEEDED BY SEGMENT CONTROL
TO FIND THE SEGMENT ON DISK (HARDWARE)
[] AST HASH TABLE
[] ALLOWS EFFICIENT SEARCHING OF ASTE'S
[] LOGICALLY PART OF THE AST, BUT ELSEWHERE FOR HISTORICAL
REASONS
[] DIRECTORY SEGMENTS
[] CONTAIN LOCATIONS AND ATTRIBUTES OF SEGMENTS. LOCATION
INFORMATION FROM DIRECTORY SEGMENTS IS PROVIDED TO SEGMENT
CONTROL BY DIRECTORY CONTROL
[] VOLUME TABLE OF CONTENTS (VTOC) - ONE PER PHYSICAL VOLUME
[] VOLUME TABLE OF CONTENTS ENTRY (VTOCE) - ONE PER
DISK-RESIDENT SEGMENT
[] EACH VTOCE CONTAINS THE SEGMENT'S UNIQUE ID, CURRENT LENGTH,
FILE MAP, ETC (NEED TO BUILD ASTE'S AND PT'S)
[] VTOCES ARE READ AND WRITTEN ONLY BY SEGMENT CONTROL
[] VTOCE STOCKS - FROM VOLUME MANAGEMENT
[] USED WHEN CREATING AND DELETING VTOCES FOR SEGMENTS
Not To Be Reproduced 7-3 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__T_E_R_M_I_N_O_L_O_G_Y
MULTIPLEXING: CONTROLLED SHARING OF A REUSABLE RESOURCE
VTOC: VOLUME TABLE OF CONTENTS (ONE PER PV). AN ARRAY OF
VTOCE'S IDENTIFYING ALL SEGMENTS RESIDENT ON THE
PHYSICAL VOLUME
VTOCE: VOLUME TABLE OF CONTENTS ENTRY (ONE PER RESIDENT
SEGMENT). CONTAINS IDENTIFICATION AND LOCATOR
INFORMATION ABOUT A SEGMENT RESIDENT WITHIN THE
PHYSICAL VOLUME
SEGMENT: A COLLECTION OF INFORMATION (PROCEDURE OR DATA) GROUPED
TOGETHER UNDER THE SAME ACCESS CONTROL CONSTRAINTS.
EACH SEGMENT IS GIVEN ONE OR MORE NAMES AND A
COLLECTION OF ATTRIBUTES INCLUDING LENGTH, ACCESS
PERMISSIONS, ETC
SEMI-PERMANENT ACTIVATION:
ACTIVATING A SEGMENT AND TURNING ON ITS ENTRY HOLD
SWITCH (aste.ehs) PREVENTING NORMAL (ASTE CONTENTION)
DEACTIVATION
Not To Be Reproduced 7-4 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_V_O_L_U_M_E__T_A_B_L_E__O_F__C_O_N_T_E_N_T_S__(_V_T_O_C_)
=============================
INSERT VTOCE (1) DIAGRAM HERE
=============================
Not To Be Reproduced 7-5 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_V_O_L_U_M_E__T_A_B_L_E__O_F__C_O_N_T_E_N_T_S__(_V_T_O_C_)
=============================
INSERT VTOCE (2) DIAGRAM HERE
=============================
Not To Be Reproduced 7-6 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_V_O_L_U_M_E__T_A_B_L_E__O_F__C_O_N_T_E_N_T_S__(_V_T_O_C_)
ox THE "VOLUME TABLE OF CONTENTS" (VTOC) IS A DISK RESIDENT DATA BASE
CONTAINING (OF INTEREST HERE) AN ARRAY OF ENTRIES KNOWN AS "VOLUME
TABLE OF CONTENTS ENTRIES" (VTOCE'S)
[] ONE VTOC PER PHYSICAL VOLUME
[] ONE VTOCE PER SEGMENT
ox EACH VTOCE CONTAINS RESIDENCY INFORMATION (AND SOME ATTRIBUTE
INFORMATION) OF A PARTICULAR SEGMENT
ox EACH VTOCE IS ADDRESSED BY INDEXING INTO THE ARRAY OF VTOCE'S
[] CONSEQUENTLY, THE PAIR OF PVID AND VTOC INDEX UNIQUELY
IDENTIFIES ANY SEGMENT IN THE STORAGE SYSTEM HIERARCHY
ox EACH VTOCE IS 192 WORDS LONG AND IS DIVIDED INTO THREE LOGICAL
PARTS:
[] ACTIVATION INFORMATION (16 WORDS)
Not To Be Reproduced 7-7 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_V_O_L_U_M_E__T_A_B_L_E__O_F__C_O_N_T_E_N_T_S__(_V_T_O_C_)
[] CONTAINS ALL INFORMATION (EXCLUDING THE FILE MAP) NEEDED TO
_U_S_E THE SEGMENT, OR MORE TECHNICALLY, TO ACTIVATE THE SEGMENT
[] INCLUDES: UID, CURRENT LENGTH, RECORDS USED, MAXIMUM
LENGTH, RECORDS USED, ETC
[] ALL INFORMATION LIKELY TO CHANGE BECAUSE OF THE ACTIVATION
[] INCLUDES: DATE TIME MODIFIED AND USED, QUOTA CELLS (IF A
DIRECTORY), ETC
[] FILE MAP (128 WORDS)
[] AN ARRAY OF 256 RECORD ADDRESS OR NULL ADDRESS DETAILING
WHERE EACH PAGE OF THE SEGMENT RESIDES
[] A _N_U_L_L ADDRESS (NOT TO BE CONFUSED WITH A _N_U_L_L_E_D ADDRESS --
DISCUSSED LATER) INDICATES THAT NO RECORD OF THE VOLUME IS
ASSIGNED TO THAT PAGE OF THE SEGMENT
[] A RECORD ADDRESS IS THE ADDRESS OF THE RECORD ASSIGNED TO
THAT PAGE OF THE SEGMENT (I.E., THE DISK RESIDENT HOME OF THE
PAGE)
[] NOTE: PAGE CONTROL _E_N_S_U_R_E_S THAT NO RECORD ADDRESS _E_V_E_R
APPEARS (OR REMAINS) IN THE FILE MAP _U_N_L_E_S_S THE PAGE _A_C_T_U_A_L_L_Y
APPEARS ON THE VOLUME
[] PERMANENT INFORMATION (48 WORDS)
[] CONTAINS ATTRIBUTES WHICH RARELY (IF EVER) CHANGE SUCH AS:
[] UID'S OF SUPERIOR DIRECTORIES, AIM CLASSIFICATION, DATE
TIME DUMPED (BY PHYSICAL VOLUME DUMPER)
Not To Be Reproduced 7-8 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_V_O_L_U_M_E__T_A_B_L_E__O_F__C_O_N_T_E_N_T_S__(_V_T_O_C_)
ox EACH VTOCE IS ALSO DIVIDED INTO THREE PHYSICAL PARTS:
[] FIRST SECTOR (WORDS 0-63):
[] CONTAINS ALL "ACTIVATION INFORMATION" AND THE FIRST PORTION
OF THE FILE MAP
[] SECOND SECTOR (WORDS 64-127):
[] CONTAINS THE BULK OF THE FILE MAP
[] THIRD SECTOR (WORDS 128-191):
[] CONTAINS THE END OF THE FILE MAP AND ALL "PERMANENT
INFORMATION"
Not To Be Reproduced 7-9 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_V_O_L_U_M_E__T_A_B_L_E__O_F__C_O_N_T_E_N_T_S__(_V_T_O_C_)
ox VTOCE I/O
[] USING RECORD I/O (IN UNITS OF 1024 WORDS) TO ACCESS A VTOCE (192
WORDS) WOULD HAVE EXCESSIVE OVERHEAD FOR BUFFERS
[] FURTHERMORE, BECAUSE MOST SEGMENTS ARE SMALL, MOST VTOCE
ACCESSING IS ONLY CONCERNED WITH ACTIVATION INFORMATION AND THE
FIRST PORTION OF THE FILE MAP, I.E., THE FIRST SECTOR (64 WORDS)
[] TO TAKE ADVANTAGE OF THESE FACTS, VTOCE'S ARE ACCESSED VIA
SECTOR I/O, NOT RECORD I/O
[] A LARGE MECHANISM KNOWN AS THE VTOC MANAGER (vtoc_man) EXIST TO
EFFICIENTLY MANAGE THIS SECTOR I/O AND ITS BUFFERING
[] VTOCE I/O IS THE ONLY NON-PAGE I/O DONE TO DISK
[] VTOCE I/O IS DONE IN PARTS (SECTORS)
[] FOR A SEGMENT, OR A DIRECTORY WITHOUT TERMINAL QUOTA, PARTS
ONE AND TWO CAN BE WRITTEN ENTIRELY FROM INFORMATION DERIVED
FROM THE ASTE, AND NEED NOT BE READ IN FIRST
[] PART THREE MUST ALWAYS BE READ BEFORE BEING WRITTEN, AS MUST
PART ONE FOR A DIRECTORY WITH QUOTA
[] ALL THREE PARTS OF A VTOCE ARE ALWAYS READ WHENEVER ANY PART
IS REQUESTED, IN CASE THE OTHERS ARE NEEDED SOON AFTERWARDS
Not To Be Reproduced 7-10 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_A_C_T_I_V_E__S_E_G_M_E_N_T__T_A_B_L_E__(_A_S_T_)
===========================
INSERT ASTE/PT DIAGRAM HERE
===========================
Not To Be Reproduced 7-11 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_A_C_T_I_V_E__S_E_G_M_E_N_T__T_A_B_L_E__(_A_S_T_)
ox THE ACTIVE SEGMENT TABLE (AST) IS A HARDCORE, WIRED, UNPAGED, DATA
BASE LOCATED WITHIN THE _SYSTEM _SEGMENT _TABLE (SST), AND CONSISTS OF
AN ARRAY OF PAIRED ENTRIES KNOWN AS ACTIVE SEGMENT TABLE ENTRIES
(ASTE'S) AND PAGE TABLES (PT'S)
[] ONE AST PER SYSTEM
[] ONE ASTE/PT PAIR PER ACTIVE SEGMENT
ox IN ORDER FOR A SEGMENT TO BE ACCESSED VIA THE HARDWARE, VTOCE
INFORMATION MUST BE BROUGHT INTO MAIN MEMORY
ox THE 12 WORD ASTE (AND ITS ASSOCIATED PAGE TABLE) CAN BE THOUGHT OF
AS THE MAIN MEMORY RESIDENT IMAGE OF THE VTOCE
[] SPECIFICALLY, THE ASTE CONTAINS:
[] THE VTOCE'S "ACTIVATION INFORMATION" SUCH AS THE SEGMENTS
UID, CURRENT LENGTH, MAX LENGTH, DTU, DTM, QUOTA DATA
[] AND NON-VTOCE INFORMATION SUCH AS: PVT INDEX, VTOC INDEX,
VARIOUS FLAGS AND POINTERS
Not To Be Reproduced 7-12 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_A_C_T_I_V_E__S_E_G_M_E_N_T__T_A_B_L_E__(_A_S_T_)
[] THE PAGE TABLE CONTAINS THE RECORD ADDRESS (TAKEN FROM THE
VTOCE'S "FILE MAP") OF EACH NONZERO PAGE OF THE SEGMENT
ox A SEGMENT HAVING AN ASTE AND A PAGE TABLE IS SAID TO BE ACTIVE
[] "ACTIVATING" A SEGMENT IS THE PROCESS OF ALLOCATING (AND FILLING
IN) AN ASTE AND A PAGE TABLE FOR THE SEGMENT
[] CONVERSELY, "DEACTIVATING" A SEGMENT INVOLVES FREEING ITS ASTE
AND PAGE TABLE FOR FURTHER USE
[] BEING ACTIVE DOES NOT IMPLY THAT THE SEGMENT IS ACTUALLY IN USE
BY ANY PROCESS
ox SINCE THE AST IS A PART OF A SINGLE SEGMENT (HAVING FINITE SIZE),
THE NUMBER OF ASTE/PT PAIRS IS FINITE, IMPLYING:
[] ONLY A FINITE NUMBER OF SEGMENTS MAY BE ACTIVE AT ONE TIME
[] WHEN A NON-ACTIVE SEGMENT IS REFERENCED, AND THERE ARE NO FREE
ASTE'S AVAILABLE, SOME SEGMENT MUST BE DEACTIVATED
[] THIS ASTE/PT MULTIPLEXING IS THE PRIME RESPONSIBILITY OF
SEGMENT CONTROL
Not To Be Reproduced 7-13 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_A_C_T_I_V_E__S_E_G_M_E_N_T__T_A_B_L_E__(_A_S_T_)
[] BEING A FINITE (AND A CRITICAL) SYSTEM RESOURCE, THE NUMBER OF
ASTE/PT PAIRS CAN DRAMATICALLY AFFECT THE COMPETITION FOR
ASTE'S, AND CONSEQUENTLY SYSTEM PERFORMANCE
[] TOO FEW ASTE/PT PAIRS WILL CAUSE "SEGMENT THRASHING"
[] TOO MANY ASTE/PT PAIRS WILL OCCUPY MAIN MEMORY FRAMES THAT
MIGHT BETTER BE UTILIZED FOR NORMAL PAGING TRAFFIC, PERHAPS
LEADING TO "PAGE THRASHING"
[] CONSEQUENTLY, THE NUMBER OF ASTE/PT PAIRS IS A CRITICAL
SYSTEM PARAMETER (SET ON THE SST CONFIG CARD)
[] OF THE TWO POSSIBILITIES, TOO MANY OR TOO FEW, TOO FEW IS
BY FAR THE WORSE
Not To Be Reproduced 7-14 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_A_C_T_I_V_E__S_E_G_M_E_N_T__T_A_B_L_E__(_A_S_T_)
=======================================
INSERT Connecting Segments DIAGRAM HERE
=======================================
Not To Be Reproduced 7-15 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_A_C_T_I_V_E__S_E_G_M_E_N_T__T_A_B_L_E__(_A_S_T_)
ox IN ORDER TO MAXIMIZE THE NUMBER OF ASTE/PT PAIRS WITHIN AN AST OF A
GIVEN SIZE, ASTE/PT PAIRS COME IN FOUR FIXED SIZES:
[] ASTE + A 4 WORD PAGE TABLE (16 WORDS TOTAL)
[] FOR 0-4K SEGMENTS
[] ASTE + A 16 WORD PAGE TABLE (28 WORDS TOTAL)
[] FOR 5-16K SEGMENTS
[] ASTE + A 64 WORD PAGE TABLE (76 WORDS TOTAL)
[] FOR 17-64K SEGMENTS
[] ASTE + A 256 WORD PAGE TABLE (268 WORDS TOTAL)
[] FOR 65-256K SEGMENTS
Not To Be Reproduced 7-16 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_A_C_T_I_V_E__S_E_G_M_E_N_T__T_A_B_L_E__(_A_S_T_)
============================
INSERT AST Pool DIAGRAM HERE
============================
Not To Be Reproduced 7-17 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_A_C_T_I_V_E__S_E_G_M_E_N_T__T_A_B_L_E__(_A_S_T_)
ox THE SIZE OF EACH OF THE FOUR ASTE POOLS IS DETERMINED AT SYSTEM
INITIALIZATION BY THE SST CONFIG CARD AND IS A CRITICAL SYSTEM
TUNING PARAMETER
ox SINCE THE FREQUENCY OF SMALL SEGMENTS IS HIGHER THAN THE FREQUENCY
OF LARGE SEGMENTS, THE DISTRIBUTION OF ASTE'S IS NORMALLY AS
FOLLOWS:
[] 4K > 16K > 64K > 256K
[] ON SYSTEM-M, IN PHOENIX, A 6 CPU, 8MW MEMORY, 200 USER SYSTEM,
THE ASTE DISTRIBUTION IS NORMALLY:
3500 1500 750 250
ON MIT-MULTICS, A 3 CPU, 3.5MW MEMORY, 110 USER SYSTEM, THE ASTE
DISTRIBUTION IS NORMALLY:
1700 600 220 75
ox A SEGMENT NORMALLY REMAINS ACTIVE (FOR >200 SECONDS) UNTIL FORCED
TO GIVE UP ITS ASTE/PT PAIR TO ANOTHER SEGMENT (DEACTIVATION)
Not To Be Reproduced 7-18 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_A_C_T_I_V_E__S_E_G_M_E_N_T__T_A_B_L_E__(_A_S_T_)
ox THIS DEACTIVATION CONSISTS OF:
[] MAKING THE SEGMENT INACCESSIBLE TO USER PROCESSES
[] DONE BY "CUTTING TRAILERS", IN THE PROGRAM setfaults.pl1
[] A LIST OF ALL SEGMENTS CONNECTED TO (USING) THE SEGMENT IS
KEPT FOR THIS PURPOSE
[] EVICTING ALL PAGES OF THE SEGMENT FROM MAIN MEMORY
[] ONLY MODIFIED PAGES MUST BE WRITTEN BACK TO DISK. UNMODIFIED
PAGES ARE SIMPLY OVERWRITTEN
[] UPDATING THE VTOCE BY WRITING THE (POSSIBLY MODIFIED) ACTIVATION
INFORMATION BACK TO THE VTOCE
[] FREEING THE ASTE/PT PAIR
ox SINCE ACTIVATING/DEACTIVATING SEGMENTS IS EXPENSIVE, THE CHOICE OF
A SEGMENT FOR DEACTIVATION IS IMPORTANT, AND BELONGS TO THE SEGMENT
REQUIRING ACTIVATION FURTHEST IN THE FUTURE
Not To Be Reproduced 7-19 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_A_C_T_I_V_E__S_E_G_M_E_N_T__T_A_B_L_E__(_A_S_T_)
ox THE ALGORITHM WHICH CHOOSES A "BEST" SEGMENT FOR DEACTIVATION IS
IMPLEMENTED IN THE PROGRAM get_aste, AND CONSIDERS SUCH FACTORS AS:
[] THE PRESENCE OF ACTIVE INFERIORS (IF A DIRECTORY)
[] THE NUMBER OF PAGES CURRENTLY IN MAIN MEMORY (SINCE WORK IS
REQUIRED TO EVICT THE MODIFIED FRACTION OF SUCH PAGES AND
BECAUSE THIS INDICATES "USED RECENTLY" IN SOME SENSE)
[] IT LOOKS FIRST FOR A SEGMENT WITH NO INFERIORS, AND NO PAGES IN
MEMORY, AND ALMOST ALWAYS SUCCEEDS - BUT IF IT FAILS, IT TRIES
TO MAKE A "GOOD CHOICE", AND DEACTIVATES INFERIORS, AND/OR
FLUSHES PAGES TO DISK IF NECESSARY
Not To Be Reproduced 7-20 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_A_C_T_I_V_E__S_E_G_M_E_N_T__T_A_B_L_E__(_A_S_T_)
=====================================
INSERT Typical Used List DIAGRAM HERE
=====================================
Not To Be Reproduced 7-21 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_A_C_T_I_V_E__S_E_G_M_E_N_T__T_A_B_L_E__(_A_S_T_)
ox NOTE: WHILE INSPECTING THE ASTE'S, OPPORTUNITY IS TAKEN TO NOTICE
ASTE'S WHOSE FILE MAPS HAVE CHANGED AND TO UPDATE THEIR VTOCE'S
[] KNOWN AS "AST TRICKLE"
[] THIS IS DONE TOTALLY AS A HEDGE AGAINST A FATAL CRASH, AS A
SUCCESSFUL SHUTDOWN UPDATES ALL VTOCE'S OF ACTIVE SEGMENTS
[] THIS IS NOT DONE FOR PROCESS DIRECTORY SEGMENTS, SINCE THEIR
CONTENTS ARE OF LITTLE USE AFTER A CRASH
[] THE "AST TRICKLE" IS ALSO FORCED TO OCCUR EVERY FIFTEEN MINUTES
WHEN THE SYSTEM IS LIGHTLY LOADED, BECAUSE OTHERWISE VTOCES
MIGHT REMAIN UNUPDATED FOR HOURS
Not To Be Reproduced 7-22 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_A_C_T_I_V_E__S_E_G_M_E_N_T__T_A_B_L_E__(_A_S_T_)
ox AST HIERARCHY
[] MIRRORS A SUBSET OF THE STORAGE SYSTEM HIERARCHY
[] THE ROOT DIRECTORY (>) CANNOT BE DEACTIVATED
[] NO SEGMENT (EXCEPT THE ROOT) MAY BE ACTIVE UNLESS ITS PARENT IS
ACTIVE. THE REASONS FOR THIS ARE:
[] PARENT MUST BE ACTIVATED IN ORDER TO FIND THE SON
[] ACTIVATION OF OTHER SONS IS EASIER IF THE PARENT REMAINS
ACTIVE
[] THE QUOTA ACCOUNT AGAINST WHICH AN ACTIVE SEGMENT'S "RECORDS
USED" IS TALLIED SHOULD BE IMMEDIATELY AVAILABLE WHEN A
SEGMENT CHANGES SIZE. THE QUOTA ACCOUNT IS FOUND IN ONE OF
THE ANCESTORS' ASTES
[] DATE TIME MODIFIED (DTM) FOR A DIRECTORY _I_S THE DTM OF THE
LAST MODIFIED SEGMENT IN THE SUBTREE. DTM OF ALL ANCESTOR'S
SHOULD BE IMMEDIATELY AVAILABLE WHEN A SEGMENT IS MODIFIED.
DTM IS FOUND IN THE ASTE OF THE ANCESTORS. (USED BY THE
HIERARCHY DUMPER)
[] SUCH UPDATES TO THE ASTE'S OF PARENTS ARE PERFORMED BY PAGE
CONTROL
[] EACH ASTE HAS A POINTER TO ITS PARENT'S ASTE FOR THE ABOVE
Not To Be Reproduced 7-23 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_A_C_T_I_V_E__S_E_G_M_E_N_T__T_A_B_L_E__(_A_S_T_)
REASONS. (THIS POINTER IMPLEMENTS THE AST HIERARCHY)
ox ASTE'S MAY BE THREADED ONTO ONE OF SIX LISTS VIA THE RELATIVE
POINTERS aste.fp and aste.bp
[] FOUR USED LISTS: THREADS ALL FREE AND REPLACEABLE ASTE'S OF
EACH POOL SIZE (sst.level.ausedp POINTS TO THE FIRST FREE ASTE
IN THE LIST)
[] INIT AND TEMP LISTS: USED AT SYSTEM INITIALIZATION TO RECEIVE
(AND DELETE) INITIALIZATION AND TEMPORARY SEGMENTS
ox THERE ALSO EXIST SEVERAL AUXILIARY LISTS SUCH AS THE HASH THREAD
AND FATHER-SON, AND BROTHERS LISTS
ox ALL ACTIVE SEGMENTS IN THE HIERARCHY ARE IN THE FOUR USED LISTS -
EXCEPT FOR SEGMENTS IN THE HARDCORE PARTITION (THE PAGED
SUPERVISOR), AND A SMALL CLASS OF SEGMENTS WHICH MAY NOT BE
DEACTIVATED
[] SEGMENTS ARE SOMETIMES UNTHREADED FROM THEIR USED LIST
TEMPORARILY IN ORDER TO KEEP THEM OUT OF REACH WHILE SOME
COMPLEX OPERATION IS PERFORMED
Not To Be Reproduced 7-24 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_C_R_E_A_T_I_N_G__S_E_G_M_E_N_T_S
ox SEGMENT CREATION IS PERFORMED BY THE PROCEDURE create_vtoce
[] INPUT: A POINTER TO THE BRANCH ENTRY IN A DIRECTORY SEGMENT
[] OUTPUT: PVID AND VTOC INDEX OF THE CREATED SEGMENT
ox create_vtoce MAY BE CALLED BY append (NORMAL SEGMENT CREATION) OR
segment_mover (DUE TO PACK OVERFLOW)
ox PRINCIPAL STEPS OF create_vtoce:
[] CREATE A LOCAL IMAGE OF THE VTOCE TO BE CREATED
[] FILL IN MOST ACTIVATION AND PERMANENT INFORMATION FROM THE
BRANCH ENTRY
[] CREATE A NULL FILE MAP
[] DETERMINE THE UID PATH (UID'S OF SUPERIOR DIRECTORIES)
Not To Be Reproduced 7-25 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_C_R_E_A_T_I_N_G__S_E_G_M_E_N_T_S
[] SELECT AN APPROPRIATE PV WITHIN THE LV SPECIFIED BY THE
sons_lvid OF THE DIRECTORY IN WHICH THE BRANCH ENTRY APPEARS
[] SELECTION GOAL IS TO EVENLY DISTRIBUTE SEGMENTS OVER ALL PV'S
OF THE LV, THEREBY REDUCING DISK CONTENTION
[] SELECTION ALGORITHM WALKS THE CHAIN (THROUGH
pvte.brother_pvtx) OF PV'S IN THE LV AND SELECTS THE PV
HAVING THE HIGHEST _P_E_R_C_E_N_T_A_G_E OF UNUSED RECORDS IN ITS PAGING
REGION
[] NO PV IS ACCEPTED IF pvte.vacating IS ON, SIGNIFYING THAT
sweep_pv IS TRYING TO VACATE, OR INHIBIT CREATION UPON, THE
PV
[] AN EXCEPTION IS MADE FOR PER PROCESS SEGMENTS
(entry.per_process IS ON)
[] SINCE SUCH SEGMENTS ARE ALL HEAVILY USED, A ROUND ROBIN
ALGORITHM EVENLY DISTRIBUTES THESE SEGMENTS ACROSS ALL
PV'S IN THE LV
[] INVOKE THE VTOC MANAGER (vtoc_man$alloc_and_put_vtoce) TO
ALLOCATE AND WRITE THE VTOCE IMAGE ON THE SELECTED PV
[] VTOC_MAN ATTEMPTS TO ALLOCATE A VTOCE FROM THE VTOCE STOCK
FOR THE VOLUME
[] IF THE STOCK IS EMPTY, IT REFILLS IT FROM THE VTOCE MAP ON
DISK (SEE vtoce_stock_man.pl1)
[] BECAUSE IT IS PERMISSIBLE TO TAKE PAGE FAULTS IN THE
VTOC_MAN ENVIRONMENT, THE VTOCE STOCK IS ACCESSED WITHOUT
ANY SPECIAL PAGE CONTROL PROTOCOLS
[] RETURNS THE VTOC INDEX OF THE ALLOCATED VTOCE
Not To Be Reproduced 7-26 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_C_R_E_A_T_I_N_G__S_E_G_M_E_N_T_S
[] RETURN THE PVID AND VTOC INDEX OF THE NEW SEGMENT TO THE CALLER
(WHO RECORDS SAME IN entry.pvid AND entry.vtocx)
Not To Be Reproduced 7-27 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_S_E_G_M_E_N_T__A_C_T_I_V_A_T_I_O_N
ox SEGMENT ACTIVATION IS PERFORMED BY THE PROCEDURE "activate"
[] INPUT: A POINTER TO THE BRANCH ENTRY IN A DIRECTORY SEGMENT
[] OUTPUT: AN ASTE POINTER
ox activate IS PRINCIPALLY CALLED BY seg_fault (OF ADDRESS/NAME SPACE
MANAGEMENT) WHO HAS LOCATED THE SEGMENT'S BRANCH ENTRY, VALIDATED
THE USER'S ACCESS, AND CHECKED THE PRESENCE OF THE LV
ox PRINCIPAL STEPS OF activate:
[] LOCK THE AST LOCK AND CHECK IF THE SEGMENT IS ALREADY ACTIVE.
IF SO, UNLOCK THE AST AND RETURN ITS ASTE POINTER
[] IF THE SEGMENT IS NOT ACTIVE, UNLOCK THE AST AND READ IN ALL
REQUIRED PARTS OF THE VTOCE AND COMPARE UID'S FOR CONNECTION
FAILURE (IN WHICH CASE, DO NOT ACTIVATE AND RETURN AN ERROR)
[] ENSURE THAT THE SEGMENT'S PARENT IS ACTIVE
[] THIS IS DONE BY REFERENCING THE PARENT DIRECTORY (PERHAPS
CAUSING A RECURSIVE SEGMENT FAULT AND ACTIVATION) AND SETTING
THE aste.ehs BIT FOR IT TEMPORARILY WHILE ACTIVATION IS
TAKING PLACE
Not To Be Reproduced 7-28 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_S_E_G_M_E_N_T__A_C_T_I_V_A_T_I_O_N
[] NOTE THAT THE _O_N_L_Y EXPLICIT ACTION TAKEN TO ACTIVATE THE
PARENT IS TO REFERENCE IT; THE POSSIBLE RECURSIVE SEGMENT
FAULT TAKES CARE OF EVERYTHING AND ALLOWS THAT REFERENCE TO
PROCEED
[] OBTAIN AN ASTE FOR THE SEGMENT BY CALLING get_aste. THIS MAY
INVOLVE DEACTIVATING SOME OTHER SEGMENT - BUT HOPEFULLY NOT THE
PARENT! (ENSURED BY THE aste.ehs BEING ON)
[] THREAD THE ASTE INTO THE INFERIOR LIST OF THE PARENT'S ASTE
(THIS WILL KEEP HIM ACTIVE), AND RESET THE PARENT'S aste.ehs
[] FILL IN THE ASTE WITH THE VTOCE'S ACTIVATION INFORMATION AND
INITIAL FLAG VALUES
[] CALL pc$fill_page_table (PASSING THE VTOCE'S FILE MAP) TO
INITIALIZE THE PAGE TABLE AND OTHER PAGE CONTROL INFORMATION
[] PLACE THE UID IN THE ASTE AND HASH IT INTO THE AST HASH TABLE
[] AFTER A SYSTEM FAILURE, ESD USES A ZERO UID AS A CUE THAT THE
ASTE IS INVALID, AND DOES NOT INVOKE A VTOCE UPDATE FOR THE
ASTE
Not To Be Reproduced 7-29 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_S_E_G_M_E_N_T__T_R_A_I_L_E_R_S
ox WHEN A PROCESS IS USING A SEGMENT, AND IT HAS A VALID SDW FOR THAT
SEGMENT, A RECORD MUST BE KEPT IN CASE IT IS NECESSARY TO REVOKE
THAT SDW (WHEN THE SEGMENT IS DELETED, WHEN THE ASTE IS RE-USED,
ETC)
[] THIS IS DONE BY THE SEGMENT TRAILER MECHANISM
[] EACH PROCESS WHICH HAS A VALID SDW FOR A SEGMENT HAS A
"TRAILER ENTRY" WHICH RECORDS ITS PROCESS IDENTIFICATION AND
THE SEGMENT NUMBER IT IS USING FOR THE SEGMENT
[] TRAILER ENTRIES ARE KEPT IN THE str_seg, A PAGED SUPERVISOR
SEGMENT
[] THERE IS A LINKED LIST OF TRAILER ENTRIES FOR EACH SEGMENT;
THE HEAD IS POINTED TO BY aste.strp
[] TRAILERS ARE ONLY KEPT FOR SEGMENTS WHICH MAY BE DEACTIVATED:
ORDINARY SEGMENTS AND DIRECTORIES, BUT NOT SUPERVISOR SEGMENTS
[] A TRAILER IS ATTACHED FOR A SEGMENT BY seg_fault.pl1 BEFORE IT
PLACES THE SDW INTO THE DSEG FOR THE PROCESS
[] TRAILERS ARE USED LATER BY setfaults.pl1 FOR:
[] DEACTIVATION - THE SDW IS ENTIRELY REVOKED (ZEROED)
[] ACCESS CHANGES, DELETION - THE SDW IS MADE INVALID, BUT ITS
PAGE TABLE ADDRESS IS LEFT UNCHANGED, INDICATING TO
seg_fault.pl1 THAT ALL IT MUST DO IS RECALCULATE THE ACCESS
Not To Be Reproduced 7-30 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_S_E_G_M_E_N_T__T_R_A_I_L_E_R_S
[] PROCESS TERMINATION - ALL SDWS A PROCESS HAD ARE REVOKED AT
TERMINATION
[] CACHE CONTROL - WHEN THE ENCACHABILITY OF A SEGMENT CHANGES,
THE SDWS WHICH REFER TO IT MUST HAVE THEIR CACHE CONTROL BITS
UPDATED
[] TRAILERS ARE ONLY REMOVED WHEN THE ASSOCIATED SDW IS REVOKED
COMPLETELY
Not To Be Reproduced 7-31 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_B_O_U_N_D_S_F_A_U_L_T__H_A_N_D_L_I_N_G
================================
INSERT Bounds Fault DIAGRAM HERE
================================
Not To Be Reproduced 7-32 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_B_O_U_N_D_S_F_A_U_L_T__H_A_N_D_L_I_N_G
ox THE BOUNDSFAULT HANDLER IS THE PROCEDURE "boundsfault", INVOKED BY
THE FAULT INTERCEPTER MODULE, FIM, WHEN THE BOUNDSFAULT IS DETECTED
BY THE APPENDING UNIT HARDWARE
ox BASIC STEPS OF BOUNDSFAULT
[] USING THE SEGMENT NUMBER IN THE (SAVED) MACHINE CONDITIONS, FIND
AND LOCK THE PARENT DIRECTORY, AND FIND THE BRANCH ENTRY
[] LOCK THE AST AND FIND THE SEGMENT'S ASTE VIA
get_ptrs_$given_segno. IF ATTEMPTED REFERENCE IS BEYOND THE
MAXIMUM LENGTH (aste.msl) THEN CAUSE "out_of_bounds" TO BE
SIGNALLED
[] MAKE THE SEGMENT INACCESSIBLE TO USERS BY "CUTTING TRAILERS"
[] TURN ON THE PARENT'S aste.ehs BIT AND CALL get_aste TO OBTAIN A
LARGER ASTE
[] CALL PAGE CONTROL'S pc$move_page_table TO MOVE ALL ASTE/PT
INFORMATION TO THE NEW ASTE
[] RETHREAD ALL INFERIOR LIST AND PARENT POINTERS AFFECTED AND TURN
OFF THE PARENT'S aste.ehs BIT
Not To Be Reproduced 7-33 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_B_O_U_N_D_S_F_A_U_L_T__H_A_N_D_L_I_N_G
[] NOTE: IF THE SEGMENT IS A DIRECTORY, ALL FATHER POINTERS OF
INFERIOR SEGMENTS MUST BE UPDATED
[] THIS IS THE ONLY REASON FOR THE EXISTENCE OF INFERIOR LIST IN
THE AST
[] REMOVE THE OLD ASTE FROM THE AST HASH TABLE AND HASH IN THE NEW
[] CALL put_aste TO FREE THE OLD ASTE
[] UNLOCK THE AST AND RETURN A ZERO STATUS CODE TO THE FIM
Not To Be Reproduced 7-34 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_S_E_G_M_E_N_T__D_E_A_C_T_I_V_A_T_I_O_N
ox SEGMENT DEACTIVATION IS PERFORMED BY THE PROCEDURE "deactivate"
[] INPUT: POINTER TO AN ASTE
ox deactivate MAY BE CALLED BY:
[] get_aste WHEN AN ASTE MUST BE FREED TO MAKE ROOM FOR A NEW
SEGMENT
[] delete_vtoce AS PART OF SEGMENT DELETING
[] demount_pv IN ORDER TO UPDATE THE VTOCE'S (AND SEGMENTS) OF A
DISK BEING DEMOUNTED
ox PRINCIPAL STEPS OF deactivate:
[] MAKE THE SEGMENT INACCESSIBLE TO USERS BY "CUTTING TRAILERS"
[] CALL pc$cleanup TO REMOVE ALL PAGES OF THE SEGMENT FROM BULK
STORE AND MAIN MEMORY, WRITING ALL MODIFIED PAGES TO DISK
Not To Be Reproduced 7-35 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_S_E_G_M_E_N_T__D_E_A_C_T_I_V_A_T_I_O_N
[] UPDATE THE VTOCE FROM THE NOW QUIESCENT ASTE
[] THREAD THE ASTE OUT OF PARENT'S INFERIOR LIST, AND OUT OF THE
AST HASH TABLE
[] CALL put_aste TO CLEAR AND INITIALIZE THE ASTE/PT PAIR, AND
THREAD THE ASTE AT THE HEAD OF THE APPROPRIATE USED LIST
Not To Be Reproduced 7-36 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_S_U_M_M_A_R_Y__O_F__M_A_J_O_R__S_E_R_V_I_C_E_S
==============================
INSERT Life Cycle DIAGRAM HERE
==============================
Not To Be Reproduced 7-37 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_T_R_U_N_C_A_T_I_N_G__S_E_G_M_E_N_T_S
ox SEGMENT TRUNCATION (IE: PAGE REMOVAL) IS PERFORMED BY THE
PROCEDURE truncate_vtoce
[] INPUT: A POINTER TO THE BRANCH ENTRY IN A DIRECTORY SEGMENT,
AND A PAGE NUMBER FROM WHICH TO START TRUNCATING
ox truncate_vtoce IS CALLED BY:
[] truncate (DIRECTORY CONTROL) WHO HAS LOCATED THE SEGMENTS BRANCH
ENTRY AND VALIDATED THE USER'S ACCESS
[] delete_vtoce (SEGMENT CONTROL) WHO REQUIRES TRUNCATION (FROM
PAGE #0) PRIOR TO VTOCE DELETION
ox PRINCIPAL STEPS OF truncate_vtoce:
[] IF SEGMENT IS ACTIVE, CALL pc$truncate WHO MARKS THE DEVICE
ADDRESS OF ALL PAGES ABOVE THE PAGE NUMBER SPECIFIED AS "NULLED"
ADDRESSES (DISCUSSED IN "PAGE CONTROL" TOPIC)
[] IF SEGMENT IS NOT ACTIVE:
[] READ IN ALL REQUIRED PARTS OF THE VTOCE AND COMPARE UID'S FOR
CONNECTION FAILURE (RETURN AN ERROR IF SO)
Not To Be Reproduced 7-38 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_T_R_U_N_C_A_T_I_N_G__S_E_G_M_E_N_T_S
[] CALL get_pvtx$hold_pvtx TO PREVENT A DEMOUNT (IF CALLED BY
truncate)
[] COPY ALL ADDRESSES OF PAGES TO BE TRUNCATED FROM THE FILE MAP
AND REPLACE THEM WITH "NULL" ADDRESSES
[] FABRICATE A NEW VTOCE AND WRITE THE VTOCE BACK BY CALLING
vtoc_man$put_vtoce
[] IF ANY REAL ADDRESSES WERE COPIED FROM THE FILE MAP, AWAIT
THE SUCCESSFUL COMPLETION OF THE VTOCE WRITE BY CALLING
vtoc_man$await_vtoce
[] CALL pc$deposit_list TO DEPOSIT (FREE) THESE REAL RECORD
ADDRESSES
[] CALL get_pvtx$release_pvtx TO AGAIN PERMIT DEMOUNTING (IF
CALLED BY truncate). THIS CREATES AN ENTRY IN THE PV HOLD
TABLE (SEE TOPIC 6, VOLUME MANAGEMENT)
Not To Be Reproduced 7-39 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_D_E_L_E_T_I_N_G__S_E_G_M_E_N_T_S
ox SEGMENT DELETION IS PERFORMED BY THE PROCEDURE delete_vtoce
[] INPUT: A POINTER TO THE BRANCH ENTRY IN A DIRECTORY SEGMENT
ox delete_vtoce IS CALLED BY delentry (OF DIRECTORY CONTROL FAME) WHO
HAS LOCATED THE SEGMENT'S BRANCH ENTRY AND VALIDATED THE USER'S
ACCESS
ox PRINCIPAL STEPS OF delete_vtoce:
[] CALL get_pvtx$hold_pvtx TO PREVENT A VOLUME DEMOUNT IN THE
MIDDLE OF THE DELETION
[] IF ACTIVE, MAKE THE SEGMENT INACCESSIBLE TO USERS (SEE "ADDRESS
AND NAME SPACE MANAGEMENT", TOPIC 5)
[] TRUNCATE THE SEGMENT TO ZERO LENGTH (SEE "TRUNCATING SEGMENTS"
IN THIS TOPIC), FREEING ALL DISK, BULK STORE, AND MAIN MEMORY
PAGES OCCUPIED BY THE SEGMENT
[] IF THE SEGMENT IS A DIRECTORY SEGMENT HAVING A QUOTA ACCOUNT,
CALL THE QUOTA MOVE PRIMITIVE (quotaw$mq) TO RELINQUISH THE
QUOTA TO ITS SUPERIOR
Not To Be Reproduced 7-40 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_D_E_L_E_T_I_N_G__S_E_G_M_E_N_T_S
[] NOTE: DIRECTORY CONTROL IS RESPONSIBLE FOR DELETING ALL
INFERIOR SEGMENTS BEFORE REQUESTING DELETION OF THE DIRECTORY
- ENSURING A CONSISTENT HIERARCHY AND RECOVERY OF ALL
INFERIOR QUOTA ACCOUNTS
[] IF THE SEGMENT IS ACTIVE, DEACTIVATE IT, RELEASING ITS ASTE
[] FREE THE VTOCE WITH A CALL TO vtoc_man$free_vtoce
[] CALL get_pvtx$release_pvtx TO AGAIN PERMIT VOLUME DEMOUNTING
Not To Be Reproduced 7-41 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_O_T_H_E_R__S_E_R_V_I_C_E_S
ox OTHER SERVICES PERFORMED BY SEGMENT CONTROL INCLUDE:
[] SEGMENT MOVING
[] REQUIRED WHEN AN ATTEMPT IS MADE TO GROW A SEGMENT AND THERE
IS NO MORE ROOM ON THE PHYSICAL VOLUME
[] THE ENTIRE SEGMENT MUST BE MOVED TO ANOTHER PV WITHIN THE
SAME LV --- TRANSPARENT TO THE USER AND DIRECTORY CONTROL
[] THIS IS THE SINGLE MOST INVOLVED AND ESOTERIC SERVICE OF
SEGMENT CONTROL
[] SEMI-PERMANENT ACTIVATION
[] ACTIVATING A SEGMENT INTO AN ASTE OF A GIVEN SIZE AND TURNING
ON ITS aste.ehs (DONE BY grab_aste)
[] SERVICES FOR sweep_pv
[] LISTING THE VTOC OF A PACK (IE: REPORTING THE PATHNAMES OF
ALL SEGMENTS OWNING VTOCE'S)
[] THE LOCATING AND DELETING OF ORPHAN VTOCE'S (VTOCE'S NOT
DESCRIBED IN ANY BRANCH)
[] REBALANCING OR VACATING PACKS VIA DEMAND SEGMENT MOVING
Not To Be Reproduced 7-42 MDD-003
_S_E_R_V_I_C_E_S__O_F__S_E_G_M_E_N_T__C_O_N_T_R_O_L
_O_T_H_E_R__S_E_R_V_I_C_E_S
[] SERVICES AT DEMOUNT/SHUTDOWN TIME
[] DEACTIVATION OF ALL SEGMENTS ON THE VOLUME BEING DEMOUNTED
AND WRITING OUT THE LABEL, ETC
[] SERVICES FOR ADDRESS/NAME SPACE MANAGEMENT (SEE TOPIC 4)
[] _DESCRIPTOR _S_E_GMENT (DSEG), _PROCESS _DATA _SEGMENT (PDS) AND
_KNOWN _SEGMENT _TABLE (KST) MANAGEMENT
[] SEGMENT FAULT HANDLING (seg_fault), CREATION, ENTRY HOLDING
Not To Be Reproduced 7-43 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__M_E_T_E_R_S
_f_i_l_e__s_y_s_t_e_m__m_e_t_e_r_s
ox FILE_SYSTEM_METERS - DISPLAYS MISCELLANEOUS METERING INFORMATION
FOR THE FILE SYSTEM
[] ONLY PARTS RELEVANT TO SEGMENT CONTROL INCLUDED HERE; SEE TOPIC
8 (PAGE CONTROL) FOR THE REST
Total metering time 0:20:02
# ATB
Activations 1043 1.153 sec.
segfault 969 1.241 sec. 92.905% of all
makeknown 74 16.251 sec. 7.095% of all
directories 96 12.527 sec. 9.204% of all
Deactivations 1056 1.139 sec.
Demand deactivate
attempts 3 400.857 sec.
Seg Faults 5080 0.237 sec.
fault 4311 0.279 sec. 84.862% of Seg Faults
call 769 1.564 sec. 15.138% of Seg Faults
activations 969 1.241 sec. 19.075% of Seg Faults
Bound Faults 220 5.466 sec.
Setfaults 4484 268.191 msec.
access 42 28.633 sec. 0.937% of setfaults
ASTE Trickle 139 8.652 sec.
Steps 4279 281.040 msec.
Skips 3016 0.399 sec. 70.484% of Steps
ehs 271 4.438 sec. 8.985% of Skips
mem 1083 1.110 sec. 35.909% of Skips
init 1662 0.724 sec. 55.106% of Skips
Searches 0 0.000 sec.
Cleanups 1056 1.139 sec. 0.1 % of real time
Force writes 3 400.857 sec.
pages written 3 400.857 sec.
Lock AST 18422 0.065 sec.
Not To Be Reproduced 7-44 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__M_E_T_E_R_S
_f_i_l_e__s_y_s_t_e_m__m_e_t_e_r_s
AVE/lock %
AST locked 4.833 msec. 7.4
AST lock waiting 1.601 msec. 2.5
AST Sizes 4 16 64 256
Number 1701 601 221 74
Need 819 202 208 34
Steps 2341 645 1139 154
Ave Steps 2.9 3.2 5.5 4.5
Lap Time(sec) 873.8 1120.5 233.3 577.9
Not To Be Reproduced 7-45 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__M_E_T_E_R_S
_v_t_o_c__b_u_f_f_e_r__m_e_t_e_r_s
ox VTOC_BUFFER_METERS - DISPLAYS VTOC BUFFER MANAGER ACTIVITY
Total metering time: 65:21:12
Routine # calls ATB(sec)
get_vtoce 1346752 0.17
put_vtoce 0 0.00
alloc_and_put_vtoce 77378 3.04
free_vtoce 75664 3.11
await_vtoce 93370 2.52
GET_BUFFERS 2732265 0.09 1656952 Hits ( 60.6% of calls)
WAIT 946437 0.25 946435 TC Waits (100.0% of calls)
Buffer Allocation
# ATB(sec)
Steps 1354279 0.17
Skips 278866 0.84 20.6% of steps
os 240348 0.98 86.2% of skips
hot 0 0.00 0.0% of skips
wait 38518 6.11 13.8% of skips
Disk I/Os
# ATB(sec)
Reads 836941 0.28
Writes 548573 0.43
Not To Be Reproduced 7-46 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__C_O_M_M_A_N_D_S
_p_r_i_n_t__a_s_t_e__p_t_p
ox PRINT_ASTE_PTP - DISPLAYS INFORMATION FROM AN ASTE
ASTE for >udd>Multics>Sibert at 115244 in sst_seg
077550100664 041540056140 165706076310 102401170050
315015000063 640000044000 446736250032 446736250272
003720000000 003164000110 006200006000 073770000102
uid = 102401170050, vtocx = 63 on pvtx 15 (root4 = dskd_13)
max len 205, 6 recs used, 0 in core, cur len 6 (decimal)
Used 03/18/83 0116.0 est Fri
Modified 03/18/83 0116.2 est Fri
Par astep = 76310, Son = 56140, brother = 41540
Trailer thread = 165706
Aste for a directory.
Quota (S D) = (2000 0)
QUsed (S D) = (1652 72)
Flags: usedf init seg-tqsw fms
PAGE PT DEVADD
0 063540200041 63540
1 063546200041 63546
2 063547200041 63547
3 063550200041 63550
4 063567200041 63567
5 063571200041 63571
6 377020000001 null
====
17 377020000001 null
Not To Be Reproduced 7-47 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__C_O_M_M_A_N_D_S
_d_u_m_p__v_t_o_c_e
ox DUMP_VTOCE - READS A VTOCE FROM DISK AND DISPLAYS ITS CONTENTS
vtoce Sibert (Directory), vtocx 63 on pvtx 15 (root4)-03/18/83 0116.7 est Fri
Uid = 102401170050, msl/csl/rec = 205 6 6
Quota (S D) = (2000 0)
Quota used (S D) = (1423 44)
Quota received (S D) = (2000 0)
Created 08/16/81 1204.0 est Sun
Dumped 03/18/83 0106.7 est Fri
Used 03/17/83 1737.8 est Thu
Modified 03/15/83 2138.3 est Tue
Switches: fm_checksum_valid
Activation information:
0 000000000000 102401170050 315006006000 446734564570
4 446723404647 001000400000 063560063567 003720000000
10 002617000054 003720000000 000000000000 015364402005
14 000000000000 000652154327 446734634556 445673737671
File map:
20 063540063546 063547063550 063567063571 777020777020
24 777020777020 777020777020 777020777020 777020777020
30 777776777776 777776777776 777776777776 777776777776
======
214 777776777776 777776777776 777776777776 777776777776
Permanent information:
220 000000000000 000000000000 000000000000 000000000000
======
230 000000000000 000000000000 000000000000 446736227316
234 126104000547 126104000525 126104000764 000000000000
240 777777777777 033022237767 033023254650 000000000000
244 000000000000 000000000000 000000000000 000000000000
======
260 123151142145 162164040040 040040040040 040040040040
264 040040040040 040040040040 040040040040 040040040040
Not To Be Reproduced 7-48 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__C_O_M_M_A_N_D_S
_d_u_m_p__v_t_o_c_e
270 441200557477 135240026001 004370027106 000000000000
274 000000000000 000000000000 000000000000 000000000000
TOPIC VIII
Page Control
Page
Page Control Overview . . . . . . . . . . . . 8-1
Page Control Terminology. . . . . . . . . . . 8-5
Page Control Data Bases . . . . . . . . . . . 8-6
Page Tables . . . . . . . . . . . . . . . 8-6
Core Map. . . . . . . . . . . . . . . . . 8-9
System Segment Table (SST) Header . . . . 8-11
Other Data Bases. . . . . . . . . . . . . 8-13
Services of Page Control. . . . . . . . . . . 8-15
Page Fault Handling . . . . . . . . . . . 8-15
Post Purging. . . . . . . . . . . . . . . 8-27
Page Control Meters . . . . . . . . . . . . . 8-28
file_system_meters. . . . . . . . . . . . 8-28
8-1 MDD-003
_S_E_G_M_E_N_T__C_O_N_T_R_O_L__C_O_M_M_A_N_D_S
_d_u_m_p__v_t_o_c_e
ox FUNCTION
[] PAGE CONTROL IS RESPONSIBLE FOR THE MANAGEMENT OF _P_H_Y_S_I_C_A_L
_M_E_M_O_R_Y TO INCLUDE THE MULTIPLEXING OF MAIN MEMORY FRAMES, AND
THE MANAGEMENT OF DISK STORAGE
[] ITS TASKS INCLUDE:
[] TRANSFERRING THE PAGES OF SEGMENTS BETWEEN THE MEMORY
DEVICES, AND RECORDING THE LOCATION OF "THE" COPY OF THESE
PAGES
[] REPORTING THE STATUS AND FILE MAPS OF SEGMENTS TO SEGMENT
CONTROL
[] PAGE CONTROL IS LARGELY CODED IN MULTICS ASSEMBLER LANGUAGE
(ALM)
[] PAGE CONTROL CAN BE INVOKED EITHER BY SUBROUTINE CALLS OR BY
PAGE FAULTS
[]
Not To Be Reproduced 8-0 MDD-003
_P_A_G_E__C_O_N_T_R_O_L__O_V_E_R_V_I_E_W
THERE ARE NO EXPLICIT USER INTERFACES TO PAGE CONTROL
ox BASIC PHILOSOPHY
[] OF ALL THE SEGMENTS ACTIVE AT A GIVEN TIME, ONLY A SMALL SUBSET
OF THEIR TOTAL PAGES WILL BE REQUIRED FOR ACCESSING
[] PAGES WILL BE READ INTO MAIN MEMORY AS THEY ARE REQUIRED
[] THE READING OF A PAGE INTO MAIN MEMORY WILL (PROBABLY) REQUIRE
THE EVICTION OF A PREVIOUSLY REQUIRED PAGE
[] THE CHOICE OF A PAGE FOR EVICTION WILL BE BASED ESSENTIALLY UPON
A "LEAST RECENTLY USED" CRITERIA
[] AN EVICTED PAGE NEED BE WRITTEN BACK TO DISK _O_N_L_Y IF IT WAS
MODIFIED DURING ITS RESIDENCY IN MAIN MEMORY
ox MAJOR DATA BASES
[] PHYSICAL VOLUME TABLE (PVT) - ONE PER SYSTEM. PROVIDED BY
VOLUME MANAGEMENT
[] PHYSICAL VOLUME TABLE ENTRY (PVTE) - ONE PER DISK DRIVE
CONFIGURED
[] EACH PVTE CONTAINS:
Not To Be Reproduced 8-1 MDD-003
_P_A_G_E__C_O_N_T_R_O_L__O_V_E_R_V_I_E_W
[] THE DEVICE ID (DISK DRIVE ID) AND THE ID OF THE PHYSICAL
VOLUME (DISK PACK) CURRENTLY MOUNTED
[] THE NUMBER OF RECORDS LEFT UNALLOCATED ON THE PHYSICAL
VOLUME, POINTER TO THE RECORD STOCK, ETC
[] RECORD STOCKS - ONE PER MOUNTED PHYSICAL VOLUME, PROVIDED BY
VOLUME MANAGEMENT
[] CONTAINS AN IN-MEMORY CACHE OF THE IN-USE STATUS OF RECORDS
ON THE VOLUME, FROM THE VOLUME MAP, USED WHEN ALLOCATING OR
FREEING PAGES
[] ACCESSED BY A COMPLEX MECHANISM WHICH USES NORMAL PAGE I/O
BUT HAS A PROTOCOL TO ENSURE SYNCHRONIZATION OF DISK CONTENTS
AND RECORD STOCK CONTENTS
[] SYSTEM SEGMENT TABLE (SST) - ONE PER SYSTEM. SHARED WITH
SEGMENT CONTROL. CONTAINS THE FOLLOWING FIVE DATA BASES USED BY
PAGE CONTROL:
[] SYSTEM SEGMENT TABLE (SST) HEADER - ONE PER SYSTEM
[] CONTAINS A LARGE NUMBER OF COUNTERS AND POINTERS VITAL TO
THE MAINTENANCE AND METERING OF THE STORAGE SYSTEM
[] CONTAINS LOCKWORDS USED TO SYNCHRONIZE PAGE CONTROL AND
SEGMENT CONTROL OPERATIONS
[] CORE MAP - THE core_map SEGMENT - ONE PER SYSTEM
[] CORE MAP ENTRY (CME) - ONE PER FRAME (1024 WORDS) OF
CONFIGURED MAIN MEMORY
[] EACH CME REPRESENTS A FRAME OF MAIN MEMORY AND IDENTIFIES
THE CURRENT OCCUPANT OF THAT FRAME
[]
Not To Be Reproduced 8-2 MDD-003
_P_A_G_E__C_O_N_T_R_O_L__O_V_E_R_V_I_E_W
NOT PART OF THE SST SEGMENT ANY MORE, BUT LOGICALLY PART
OF THE SST
[] ACTIVE SEGMENT TABLE (AST) - ONE PER SYSTEM
[] ACTIVE SEGMENT TABLE ENTRY (ASTE) - ONE PER ACTIVE SEGMENT
[] LIST OF ACTIVE (CURRENTLY BEING USED) SEGMENTS
[] PAGE TABLES (PT) - ONE PER ACTIVE SEGMENT, THE OTHER HALF OF
EACH ASTE
[] PAGE TABLE WORD (PAGE PTW) - EITHER 4, 16, 64, OR 256 PER
PAGE TABLE
[] EACH PTW DEFINES THE CURRENT LOCATION OF A PAGE OF THE
SEGMENT: DISK, MAIN MEMORY ADDRESS, OR NULL
Not To Be Reproduced 8-3 MDD-003
_P_A_G_E__C_O_N_T_R_O_L__T_E_R_M_I_N_O_L_O_G_Y
PAGING: THE PROCESS OF TRANSFERRING PAGES OF DATA BETWEEN DISK
STORAGE AND MAIN MEMORY (CORE) TO ACHIEVE THE EFFECT OF
ALL DATA BEING IN MEMORY ALL THE TIME
CORE: AN OBSOLETE TERM USED FREQUENTLY TO REFER TO MAIN
MEMORY (WHICH IS MOS TECHNOLOGY, NOT CORE TECHNOLOGY)
PAGE FAULT: AN EXCEPTION CONDITION DETECTED BY THE PROCESSOR
HARDWARE (IN THE APPENDING UNIT) WHEN AN ATTEMPT IS
MADE TO USE A PTW SPECIFYING THAT ITS PAGE IS NOT IN
MAIN MEMORY
Not To Be Reproduced 8-4 MDD-003
_P_A_G_E__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_P_A_G_E__T_A_B_L_E_S
==============================
INSERT Page Table DIAGRAM HERE
==============================
ox THE PAGE TABLES (PT'S) ARE HARDCORE (SST), UNPAGED, DATA BASES EACH
CONSISTING OF AN ARRAY OF PAGE TABLE WORDS (PTW'S)
[] ONE PAGE TABLE PER ACTIVE SEGMENT
[] 4, 16, 64, OR 256 PTW PER PAGE TABLE
Not To Be Reproduced 8-5 MDD-003
_P_A_G_E__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_P_A_G_E__T_A_B_L_E_S
ox ALL PAGE TABLES ARE ASSOCIATED WITH, AND IMMEDIATELY FOLLOW AN ASTE
IN THE AST REGION OF THE SST
ox EACH PTW DESCRIBES THE STATUS OF ONE PAGE OF THE SEGMENT CURRENTLY
IN POSSESSION OF THE ASSOCIATED ASTE, INCLUDING:
[] THE DEVICE ADDRESS OF _T_H_E COPY OF THE PAGE
[] PTW VALID INDICATOR AND FAULT NUMBER (FAULT #1)
[] FLAGS INDICATING VARIOUS STATES AND PROPERTIES OF THE PAGE SUCH
AS I/O IN PROGRESS, WIRED, USED, MODIFIED
ox THE ADDRESS PORTION OF EACH PTW IS INITIALIZED FROM THE SEGMENT'S
VTOCE FILE MAP AT SEGMENT ACTIVATION TIME
Not To Be Reproduced 8-6 MDD-003
_P_A_G_E__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_P_A_G_E__T_A_B_L_E_S
==========================================
INSERT Page Table Device ADDR DIAGRAM HERE
==========================================
Not To Be Reproduced 8-7 MDD-003
_P_A_G_E__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_C_O_R_E__M_A_P
==================================
INSERT Core Map Entry DIAGRAM HERE
==================================
ox THE CORE MAP IS A PERMANENTLY WIRED, UNPAGED, SEGMENT CONTAINING AN
ARRAY OF CORE MAP ENTRIES (CME'S)
[] ONE CORE MAP PER SYSTEM
[] ONE CME PER ADDRESSABLE MAIN MEMORY FRAME
[] IF THE CONFIGURATION HAS HOLES IN THE MEMORY ADDRESS
ASSIGNMENTS, OR MEMORIES WHICH ARE TURNED OFF, THOSE CMES ARE
PRESENT ANYWAY (BUT UNUSED) (0 TO HIGHEST FRAME ADDRESS)
Not To Be Reproduced 8-8 MDD-003
_P_A_G_E__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_C_O_R_E__M_A_P
ox EACH CME DESCRIBES THE STATUS OF ONE PAGE FRAME IN MAIN MEMORY
INCLUDING:
[] THE DISK ADDRESS OF THE PAGE CURRENTLY OCCUPYING THE FRAME
[] ADDRESS OF THE ASTE AND PTW OF THE OCCUPANT
[] FLAGS INDICATING VARIOUS STATES AND PROPERTIES OF THE FRAME AND
ITS OCCUPANT SUCH AS I/O IN PROGRESS, NOTIFICATION REQUESTED,
AND PIN WEIGHT
ox THE CME'S ARE KEPT IN A DOUBLE-THREADED CIRCULAR LIST POINTED TO BY
sst.usedp
[] CME'S FOR FRAMES UNDERGOING I/O ARE TEMPORARILY THREADED OUT OF
THE LIST
[] CME'S FOR FRAMES CONFIGURED BUT NOT PHYSICALLY PRESENT ARE ALSO
THREADED OUT BUT WITH THREAD WORD "777777777777" OCTAL
[] THE REMAINING CME'S REPRESENT MAIN MEMORY FRAMES ACTIVELY IN USE
- _A_N_D SUBJECT TO EVICTION BY THE PAGE REPLACEMENT ALGORITHM
Not To Be Reproduced 8-9 MDD-003
_P_A_G_E__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_S_Y_S_T_E_M__S_E_G_M_E_N_T__T_A_B_L_E__(_S_S_T_)__H_E_A_D_E_R
ox THE FIRST 512 WORDS OF THE SST IS CALLED THE SST HEADER AND
CONTAINS:
[] A LARGE NUMBER OF GLOBAL VARIABLES VITAL TO THE OPERATION OF THE
STORAGE SYSTEM AND ITS SUBSYSTEMS
[] NUMEROUS CELLS USED TO METER THE STORAGE SYSTEM
ox AMONG THOSE OF INTEREST TO PAGE CONTROL ARE THE FOLLOWING:
[] GLOBAL VARIABLES:
[] PAGE TABLE LOCK (sst.ptl)
[] NUMBER OF MAIN MEMORY FRAMES AVAILABLE FOR PAGING ACTIVITIES
(sst.nused) AND NUMBER WIRED (sst.wired)
[] POINTERS TO THE BASE OF THE CME ARRAY AND TO THE CME OF THE
"BEST" CANDIDATE PAGE FOR REPLACEMENT
[] PVT INDEX OF THE RPV (USED DURING INITIALIZATION)
[] METERS
[] THRASHING, POST-PURGE-TIME, PAGE FAULTS ON DIRECTORIES, RING
0 PAGE FAULTS, LOOP LOCK TIME, SEGMENT MOVES
Not To Be Reproduced 8-10 MDD-003
_P_A_G_E__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_S_Y_S_T_E_M__S_E_G_M_E_N_T__T_A_B_L_E__(_S_S_T_)__H_E_A_D_E_R
[] PAGING METERS REPORTED BY file_system_meters SUCH AS STEPS,
NEEDS, CEILING, SKIPS
Not To Be Reproduced 8-11 MDD-003
_P_A_G_E__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_O_T_H_E_R__D_A_T_A__B_A_S_E_S
ox ALTHOUGH BASICALLY DATA BASES OF VOLUME MANAGEMENT, THE FOLLOWING
CONTAIN INFORMATION REQUIRED BY PAGE CONTROL (AS INDICATED)
ox PHYSICAL VOLUME TABLE (PVT) - ONE PER SYSTEM
[] INFORMATION REQUIRED BY THE DISK DIM FOR I/O
[] INFORMATION USED BY THE DISK RECORD ALLOCATOR/DEALLOCATOR
(free_store) SUCH AS:
[] THE NUMBER OF UNALLOCATED RECORDS LEFT ON THE VOLUME
[] THE LOCATION OF THE RECORD STOCK FOR THE VOLUME
ox RECORD STOCKS
[] RECORD STOCKS ARE KEPT IN A WIRED SEGMENT: stock_seg
[] THE RECORD STOCK FOR A VOLUME IS A LIST OF SOME OF THE RECORDS
WHICH ARE FREE ON THE VOLUME
[] WHEN THERE ARE NO MORE ENTRIES AVAILABLE IN THE STOCK, IT IS
UPDATED FROM THE VOLUME MAP
Not To Be Reproduced 8-12 MDD-003
_P_A_G_E__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_O_T_H_E_R__D_A_T_A__B_A_S_E_S
[] IF THE STOCK BECOMES FULL, SOME OF ITS ENTRIES ARE UPDATED TO
THE VOLUME MAP AND REMOVED FROM THE STOCK
[] A COMPLEX MECHANISM (SEE volmap.alm, volmap_page.alm) MAKES
IT POSSIBLE TO REFERENCE THE VOLUME MAP PAGES WHILE
SATISFYING A PAGE FAULT
Not To Be Reproduced 8-13 MDD-003
_S_E_R_V_I_C_E_S__O_F__P_A_G_E__C_O_N_T_R_O_L
_P_A_G_E__F_A_U_L_T__H_A_N_D_L_I_N_G
ox WITHIN ANY DEMAND PAGING ENVIRONMENT THE CHOICE OF WHICH PAGE TO
EVICT IS CRUCIAL TO SYSTEM PERFORMANCE
ox ONE OF THE BETTER CHOICES FOR EVICTION IS THE "LEAST RECENTLY USED"
PAGE....OR (BECAUSE OF EFFICIENCY), THE "LEAST RECENTLY _N_O_T_I_C_E_D AS
BEING USED" PAGE.
ox THE MULTICS PAGE REPLACEMENT ALGORITHM (PRA), KNOWN IN THE
LITERATURE AS THE "CLOCK" ALGORITHM WAS ONE OF THE FIRST EVER TO BE
IMPLEMENTED
ox THE VERSION AS IT EXISTS TODAY IS A DIRECT DESCENDANT OF Corbato's
ORIGINAL ALGORITHM (SEE SECTION 5 OF THE "MULTICS STORAGE SYSTEM
PLM", AN61, FOR A BIBLIOGRAPHY)
ox PAGES ARE KEPT IN A CIRCULAR LIST, THE CORE USED LIST, IMPLEMENTED
BY THE DOUBLY THREADED CME'S
ox A POINTER, MAINTAINED IN THE SST, (sst.usedp) POINTS TO THE LOGICAL
HEAD OF THIS LIST AS FOLLOWS:
Not To Be Reproduced 8-14 MDD-003
_S_E_R_V_I_C_E_S__O_F__P_A_G_E__C_O_N_T_R_O_L
_P_A_G_E__F_A_U_L_T__H_A_N_D_L_I_N_G
===================================
INSERT Clock Algorithm DIAGRAM HERE
===================================
Not To Be Reproduced 8-15 MDD-003
_S_E_R_V_I_C_E_S__O_F__P_A_G_E__C_O_N_T_R_O_L
_P_A_G_E__F_A_U_L_T__H_A_N_D_L_I_N_G
ox PAGE FAULT HANDING IS THE MOST VISIBLE AND CRUCIAL SERVICE OF PAGE
CONTROL
ox A PAGE FAULT OCCURS WHEN A USER REFERENCES A PAGE OF SOME SEGMENT
THAT IS NOT IN MAIN MEMORY
[] OR MORE SPECIFICALLY: HARDWARE ATTEMPTS TO USE A PTW THAT
INDICATES ITS PAGE IS NOT IN THE MAIN MEMORY
ox PAGE FAULT HANDLING IS IMPLEMENTED IN THE ALM PROGRAM page_fault
WHICH IS INVOKED _D_I_R_E_C_T_L_Y BY THE FAULT VECTOR CODE (page_fault _I_S
THE FAULT INTERCEPTOR FOR PAGE FAULTS)
ox THE PRINCIPAL STEPS OF page_fault ARE:
[] SAVE ALL MACHINE CONDITIONS, MASK AGAINST INTERRUPTS, AND
ESTABLISH A STACK FRAME ON THE BASE OF THE _P_ROCESSOR _DATA
_SEGMENT (PRDS), WHICH IS USED AS THE STACK FOR INTERRUPTS AND
PAGE FAULTS
[] CHECK FOR ILLEGAL CONDITIONS AND CRASH IF SO
Not To Be Reproduced 8-16 MDD-003
_S_E_R_V_I_C_E_S__O_F__P_A_G_E__C_O_N_T_R_O_L
_P_A_G_E__F_A_U_L_T__H_A_N_D_L_I_N_G
[] ATTEMPT TO LOCK THE PAGE TABLE LOCK (sst.ptl) AND WAIT IF
UNSUCCESSFUL
[] LOCATE THE RESPONSIBLE PTW AND ITS ASTE. THIS IS OFTEN THE MOST
DIFFICULT TASK
[] IT IS DIFFICULT BECAUSE IT REQUIRES FETCHING THE SDW FROM THE
DSEG, WHICH IS, ITSELF, PAGED, AND NOT GUARANTEED TO BE IN
MEMORY
[] CHECK FOR TWO WINDOW SITUATIONS INVOLVING SOME OTHER PROCESS
HANDLING A PAGE FAULT FOR THE SAME PAGE:
[] IF PAGE IS NOW IN, THEN UNLOCK THE LOCK AND RESTART THE
MACHINE CONDITIONS
[] IF PAGE IS BEING READ IN NOW, DEVELOP THE WAIT EVENT FOR THE
PTW AND SKIP THE NEXT THREE STEPS
[] INVOKE read_page TO FIND THE LEAST RECENTLY (NOTICED AS BEING)
USED MAIN MEMORY FRAME, _B_E_G_I_N THE PAGE-READING FUNCTION, AND
DEVELOP THE WAIT EVENT
[] EXECUTE THE REPLACEMENT ALGORITHM'S WRITE-BEHIND (PURIFIER)
FUNCTION, CAUSING PASSED OVER WRITE REQUESTS TO BE QUEUED
[] METER THE PAGE FAULT TO INCLUDE: TIME SPENT; MAIN MEMORY USAGE
OF THIS PROCESS; RING ZERO, DIRECTORY, AND PER-PROCESS FAULTS
Not To Be Reproduced 8-17 MDD-003
_S_E_R_V_I_C_E_S__O_F__P_A_G_E__C_O_N_T_R_O_L
_P_A_G_E__F_A_U_L_T__H_A_N_D_L_I_N_G
[] TRANSFER TO THE TRAFFIC CONTROLLER, WHO PLACES THE PROCESS IN
THE WAIT STATE, UNLOCKS THE PAGE TABLE LOCK, AND ABANDONS THE
ENVIRONMENT (SEE "TRAFFIC CONTROL", TOPIC 10)
ox WHEN THE PAGE READING I/O IS COMPLETE, THE EVENT WILL BE POSTED.
THE WAITING PROCESS WILL BE GIVEN THE PROCESSOR AGAIN AND TRAFFIC
CONTROLLER WILL TRANSFER THE FAULTING PROCESS TO
page_fault$wait_return TO RESTART THE MACHINE CONDITIONS
Not To Be Reproduced 8-18 MDD-003
_S_E_R_V_I_C_E_S__O_F__P_A_G_E__C_O_N_T_R_O_L
_P_A_G_E__F_A_U_L_T__H_A_N_D_L_I_N_G
===============================================
INSERT Page Fault Scenario Scene 1 DIAGRAM HERE
===============================================
Not To Be Reproduced 8-19 MDD-003
_S_E_R_V_I_C_E_S__O_F__P_A_G_E__C_O_N_T_R_O_L
_P_A_G_E__F_A_U_L_T__H_A_N_D_L_I_N_G
===============================================
INSERT Page Fault Scenario Scene 2 DIAGRAM HERE
===============================================
Not To Be Reproduced 8-20 MDD-003
_S_E_R_V_I_C_E_S__O_F__P_A_G_E__C_O_N_T_R_O_L
_P_A_G_E__F_A_U_L_T__H_A_N_D_L_I_N_G
===============================================
INSERT Page Fault Scenario Scene 3 DIAGRAM HERE
===============================================
Not To Be Reproduced 8-21 MDD-003
_S_E_R_V_I_C_E_S__O_F__P_A_G_E__C_O_N_T_R_O_L
_P_A_G_E__F_A_U_L_T__H_A_N_D_L_I_N_G
================================================
INSERT Page Fault Scenario Scene 4A DIAGRAM HERE
================================================
Not To Be Reproduced 8-22 MDD-003
_S_E_R_V_I_C_E_S__O_F__P_A_G_E__C_O_N_T_R_O_L
_P_A_G_E__F_A_U_L_T__H_A_N_D_L_I_N_G
================================================
INSERT Page Fault Scenario Scene 5A DIAGRAM HERE
================================================
Not To Be Reproduced 8-23 MDD-003
_S_E_R_V_I_C_E_S__O_F__P_A_G_E__C_O_N_T_R_O_L
_P_A_G_E__F_A_U_L_T__H_A_N_D_L_I_N_G
================================================
INSERT Page Fault Scenario Scene 4B DIAGRAM HERE
================================================
Not To Be Reproduced 8-24 MDD-003
_S_E_R_V_I_C_E_S__O_F__P_A_G_E__C_O_N_T_R_O_L
_P_A_G_E__F_A_U_L_T__H_A_N_D_L_I_N_G
================================================
INSERT Page Fault Scenario Scene 5B DIAGRAM HERE
================================================
Not To Be Reproduced 8-25 MDD-003
_S_E_R_V_I_C_E_S__O_F__P_A_G_E__C_O_N_T_R_O_L
_P_O_S_T__P_U_R_G_I_N_G
ox POST PURGING IS PERFORMED BY THE PROCEDURE post_purge
ox POST PURGING IS AN OPTIONAL SERVICE USED TO OPTIMIZE THE PAGE
REPLACEMENT ALGORITHM
ox POST PURGING:
[] _F_A_V_O_R_S THE REPLACING OF PAGES USED BY A PROCESS WHICH HAS JUST
LOST ELIGIBILITY (SEE "TRAFFIC CONTROL", TOPIC 9)
[] IS A WORK CLASS SETTABLE ATTRIBUTE
ox POST PURGING IS LARGELY USELESS TODAY, BECAUSE MAIN MEMORY SIZE IS
SO MUCH GREATER
Not To Be Reproduced 8-26 MDD-003
_P_A_G_E__C_O_N_T_R_O_L__M_E_T_E_R_S
_f_i_l_e__s_y_s_t_e_m__m_e_t_e_r_s
ox FILE_SYSTEM_METERS - DISPLAYS MISCELLANEOUS METERING INFORMATION
FOR THE FILE SYSTEM
[] ONLY PARTS RELEVANT TO PAGE CONTROL INCLUDED HERE; SEE TOPIC 7
(SEGMENT CONTROL) FOR THE REST
Total metering time 0:20:02
# ATB
Needc 62654 19.194 msec.
Ring 0 faults 16.639 %
PDIR faults 50.607 %
Level 2 faults 21.556 %
DIR faults 7.645 %
New Pages 14.661 %
Volmap_seg 0 0.000 msec.
Zero pages 770 1561.779 msec.
Laps 105 11.453 sec.
Steps 361483 3.327 msec.
Skip 322555 3.728 msec. 89.231% of Steps
wired 11057 108.761 msec. 3.428% of Skip
used 109719 10.960 msec. 34.016% of Skip
mod 140336 8.569 msec. 43.508% of Skip
fc pin 37717 31.884 msec. 11.693% of Skip
cl pin 23726 50.686 msec. 7.356% of Skip
3419 pages, 139 wired.
Average steps 5.770
TOPIC IX
Tarffic Control
Page
Traffic Control Overview. . . . . . . . . . . 9-1
Traffic Control Terminology . . . . . . . . . 9-3
9-i MDD-003
_P_A_G_E__C_O_N_T_R_O_L__M_E_T_E_R_S
_f_i_l_e__s_y_s_t_e_m__m_e_t_e_r_s
Traffic Control Data Bases. . . . . . . . . . 9-5
tc_data . . . . . . . . . . . . . . . . . 9-5
Services of Traffic Control . . . . . . . . . 9-8
Wait Locks. . . . . . . . . . . . . . . . 9-8
Processor Multiplexing. . . . . . . . . . 9-9
Traffic Control Meters. . . . . . . . . . . . 9-18
total_time_meters . . . . . . . . . . . . 9-18
traffic_control_meters. . . . . . . . . . 9-19
traffic_control_queue . . . . . . . . . . 9-21
work_class_meters . . . . . . . . . . . . 9-23
respons_meters. . . . . . . . . . . . . . 9-24
post_purge_meters . . . . . . . . . . . . 9-26
Traffic Control Commands. . . . . . . . . . . 9-27
print_tuning_parameters . . . . . . . . . 9-27
print_apt_entry . . . . . . . . . . . . . 9-28
9-i MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__O_V_E_R_V_I_E_W
ox FUNCTION
[] TRAFFIC CONTROL (OR THE "TRAFFIC CONTROLLER") IS RESPONSIBLE FOR
MANAGING THE ASSIGNMENT OF PHYSICAL PROCESSORS TO MULTICS
PROCESSES AND IMPLEMENTING THE SYSTEM'S WAIT/NOTIFY AND
INTERPROCESS COMMUNICATION PRIMITIVES
[] THE FUNCTIONS ASSUMED BY THE TRAFFIC CONTROLLER ARE KNOWN AS
MULTIPROGRAMMING, MULTIPROCESSING, SCHEDULING, DISPATCHING,
PROCESSOR MANAGEMENT, AND INTERPROCESS COMMUNICATION.
[] ITS MAJOR FUNCTION IS ALLOWING PROCESSES TO AWAIT THE COMPLETION
OF FILE SYSTEM OPERATIONS, SUCH AS PAGE I/O
[] TRAFFIC CONTROL CAN BE INVOKED BY SUBROUTINE CALLS AND
INTERRUPTS
[] THERE ARE NO IMPORTANT USER SUBROUTINE INTERFACES, BUT THERE ARE
PRIVILEGED SUBROUTINE INTERFACES FOR PROCESS CREATION,
ADJUSTMENT OF SCHEDULING PARAMETERS, ETC.
ox MAJOR DATA BASES
[] TC_DATA SEGMENT - ONE PER SYSTEM. CONTAINS THE FOLLOWING FOUR
DATA BASES:
[] TC_DATA HEADER - ONE PER SYSTEM
Not To Be Reproduced 9-1 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__O_V_E_R_V_I_E_W
[] CONTAINS VARIOUS METERS, COUNTERS AND POINTERS USED BY THE
TRAFFIC CONTROLLER
[] ACTIVE PROCESS TABLE (APT) - ONE PER SYSTEM
[] ACTIVE PROCESS TABLE ENTRY (APTE) - ONE OCCUPIED PER
ACTIVE PROCESS (TOTAL NUMBER IS DETERMINED BY CONFIG DECK)
[] EACH APTE CONTAINS VARIOUS ATTRIBUTES OF AN ACTIVE PROCESS
INCLUDING THE PROCESS ID, STATE, THE VALUE OF ITS
DESCRIPTOR BASE REGISTER (DBR), SCHEDULING PARAMETERS, AND
A POINTER TO THE PROCESS'S ITT ENTRIES
[] THE APTE CONTAINS ALL INFORMATION THE SUPERVISOR NEEDS TO
KNOW ABOUT A PROCESS WHEN THE PROCESS IS NOT RUNNING
[] INTERPROCESS TRANSMISSION TABLE (ITT) - ONE PER SYSTEM
[] ITT ENTRY - ONE OCCUPIED PER OUTSTANDING IPC WAKEUP
[] A QUEUE FOR TEMPORARILY STORING IPC WAKEUP INFORMATION
(CHANNEL NAME, RANDOM DATA, PROCESS ID, ETC)
[] WORK CLASS TABLE (WCT) - ONE PER SYSTEM
[] WORK CLASS TABLE ENTRY (WCTE) - ONE PER WORKCLASS
[] EACH WCTE CONTAINS ADMINISTRATOR DEFINED PARAMETERS OF THE
WORKCLASS, VARIOUS METERS AND POINTERS
Not To Be Reproduced 9-2 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__T_E_R_M_I_N_O_L_O_G_Y
PROCESS:
AN ADDRESS SPACE AND AN EXECUTION POINT WITHIN THAT
ADDRESS SPACE
MULTIPROGRAMMING:
PERTAINING TO THE _C_O_N_C_U_R_R_E_N_T EXECUTION OF TWO OR MORE
PROGRAMS BY INTERLEAVING THEIR EXECUTION
MULTIPROCESSING:
PERTAINING TO THE _S_I_M_U_L_T_A_N_E_O_U_S EXECUTION OF TWO OR MORE
PROGRAMS BY A MULTIPROCESSOR SYSTEM (PARALLEL
PROCESSING)
ELIGIBLE:
AN ADJECTIVE DESCRIBING THOSE PROCESSES ACTIVELY
COMPETING FOR A PROCESSOR. ALL PROCESSES ARE EITHER
ELIGIBLE OR INELIGIBLE
SCHEDULING:
PERTAINS TO THE ACT OF CHOSING AND PROMOTING AN
"INELIGIBLE" PROCESS TO "ELIGIBLE" STATUS
Not To Be Reproduced 9-3 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__T_E_R_M_I_N_O_L_O_G_Y
DISPATCHING:
PERTAINS TO THE ACT OF CHOSING AND PLACING AN ELIGIBLE
PROCESS IN THE "RUNNING" STATE (IE: EXECUTING
INSTRUCTIONS ON A PROCESSOR)
WORK CLASS: A WELL DEFINED SET OF USERS (USUALLY CONSISTING
OF ONE OR MORE PROJECTS) HAVING COMMON PERFORMANCE
PARAMETERS. THE USER COMMUNITY MAY BE DIVIDED INTO NO
MORE THAN 16 WORK CLASSES
WORKING SET:
THE SET OF PAGES A PROCESS TOUCHES DURING A GIVEN
INTERVAL. THE SIZE OF A CURRENT WORKING SET IS
PREDICTIVE OF FUTURE MEMORY REQUIREMENTS
Not To Be Reproduced 9-4 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_T_C__D_A_T_A
===========================
INSERT tc_data DIAGRAM HERE
===========================
Not To Be Reproduced 9-5 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_T_C__D_A_T_A
===========================
INSERT APTE #1 DIAGRAM HERE
===========================
Not To Be Reproduced 9-6 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__D_A_T_A__B_A_S_E_S
_T_C__D_A_T_A
===========================
INSERT APTE #2 DIAGRAM HERE
===========================
Not To Be Reproduced 9-7 MDD-003
_S_E_R_V_I_C_E_S__O_F__T_R_A_F_F_I_C__C_O_N_T_R_O_L
_W_A_I_T__L_O_C_K_S
==============================
INSERT wait locks DIAGRAM HERE
==============================
Not To Be Reproduced 9-8 MDD-003
_S_E_R_V_I_C_E_S__O_F__T_R_A_F_F_I_C__C_O_N_T_R_O_L
_P_R_O_C_E_S_S_O_R__M_U_L_T_I_P_L_E_X_I_N_G
ox SINCE THE NUMBER OF ACTIVE PROCESSES GENERALLY EXCEEDS THE NUMBER
OF PROCESSORS (OFTEN 50:1) THE PROCESSORS MUST BE MULTIPLEXED
ox PROCESSOR MULTIPLEXING IS THE PRIMARY RESPONSIBILITY OF THE TRAFFIC
CONTROLLER
ox THE MULTICS ARCHITECTURE DICTATES THE FOLLOWING AXIOMS:
[] ALL PROCESSORS ARE SYMMETRICAL
[] AN INTERRUPT IS SEEN BY ALL PROCESSORS AND IS SERVICED BY THE
PROCESSOR THAT CLAIMS IT FIRST
[] NOT ACTUALLY TRUE, DUE TO HARDWARE CONNECTION LIMITATIONS
[] THERE ARE NO MASTER OR SLAVE PROCESSORS. ONLY A PROCESSOR
DESIGNATED TO PERFORM BOOTLOAD AND SHUTDOWN (THE "BOOTLOAD
PROCESSOR")
[] BOOTLOAD PROCESSOR CAN BE CHANGED AT ANY TIME BY DYNAMIC
RECONFIGURATION
[] A PROCESSOR MAY BE "IN" AT MOST ONE PROCESS AT A TIME
[] A PROCESS MAY EXECUTE ON ONE AND ONLY ONE PROCESSOR AT A TIME.
THE PROCESS MAY, HOWEVER, "RANDOMLY" MIGRATE FROM ONE PROCESSOR
TO ANOTHER
Not To Be Reproduced 9-9 MDD-003
_S_E_R_V_I_C_E_S__O_F__T_R_A_F_F_I_C__C_O_N_T_R_O_L
_P_R_O_C_E_S_S_O_R__M_U_L_T_I_P_L_E_X_I_N_G
[] A PROCESSOR WILL, AT ALL TIMES, BE "IN" A PROCESS
ox PROCESSES MAY EXIST IN ONE OF SIX STATES - ONE OF WHICH IS
"RUNNING" (IE: EXECUTING ON A PROCESSOR)
ox THE TRAFFIC CONTROLLER CODE PERFORMS ALL STATE CHANGES. THE STATE
CHANGES FALL INTO TWO CATEGORIES: SELF IMPOSED AND EXTERNALLY
IMPOSED.
[] SELF IMPOSED STATE CHANGES (THE PROCESS MUST HAVE A PROCESSOR)
[] RUNNING -> READY (#1 -> #2)
[] THE PROCESS WAS TOLD (BY EITHER A CONNECT FAULT FROM
ANOTHER PROCESSOR OR A TIMER RUNOUT) TO GIVE UP ITS
PROCESSOR
[] THE PROCESS IS NOW WAITING FOR NO OTHER RESOURCE THAN A
PROCESSOR
[] RUNNING -> WAITING (#1 -> #3)
[] THE PROCESS ISSUED A REQUEST FOR A "SYSTEM EVENT" (EG: A
PAGE FAULT OR A WAIT LOCK)
[] "SYSTEM EVENTS" OCCUR AFTER A PREDICTABLY SHORT PERIOD OF
TIME AND ARE HANDLED BY THE WAIT/NOTIFY MECHANISM
[] THE PROCESS IS NOW WAITING FOR A NOTIFY INDICATING THE
COMPLETION OF THE EVENT (EG: THE ARRIVAL OF THE PAGE IN
MAIN MEMORY)
Not To Be Reproduced 9-10 MDD-003
_S_E_R_V_I_C_E_S__O_F__T_R_A_F_F_I_C__C_O_N_T_R_O_L
_P_R_O_C_E_S_S_O_R__M_U_L_T_I_P_L_E_X_I_N_G
[] RUNNING -> PAGE TABLE LOCK WAITING (#1 -> #6)
[] THE PROCESS ATTEMPTED TO LOCK THE PAGE-TABLE LOCK AND
FOUND IT ALREADY LOCKED
[] THE PROCESS IS NOW WAITING FOR A NOTIFY INDICATING THE
UNLOCKING (A SYSTEM EVENT)
[] RUNNING -> BLOCKED (#1 -> #4)
[] THE PROCESS ISSUED A REQUEST FOR A "USER EVENT" (EG: A
READ FROM THE TERMINAL)
[] "USER EVENTS" OCCUR AFTER A PREDICTABLY LONG PERIOD OF
TIME AND ARE HANDLED BY THE BLOCK/WAKEUP MECHANISM
[] THE PROCESS IS NOW WAITING FOR A WAKE_UP INDICATING THE
COMPLETION OF THE EVENT (EG: A LINE_FEED GENERATES A
WAKE_UP) ARE HANDLED BY THE BLOCK/WAKE_UP MECHANISM
[] A PROCESS GOING BLOCKED GIVES UP ITS RING ZERO STACK
[] RUNNING -> STOPPED (#1 -> #5)
[] THE PROCESS EXECUTED THE logout OR new_proc COMMAND,
EVENTUALLY CALLING hcs_$stop_process
[] THE PROCESS IS PROHIBITED FROM RUNNING AGAIN AND WILL
QUICKLY BE DESTROYED BY THE INITIALIZER
Not To Be Reproduced 9-11 MDD-003
_S_E_R_V_I_C_E_S__O_F__T_R_A_F_F_I_C__C_O_N_T_R_O_L
_P_R_O_C_E_S_S_O_R__M_U_L_T_I_P_L_E_X_I_N_G
[] EXTERNALLY IMPOSED STATE CHANGES (THE STATE IS CHANGED BY
ANOTHER PROCESS)
[] READY -> RUNNING (#2 -> #1)
[] THE PROCESS (WHICH WAS WAITING FOR NO OTHER RESOURCE THAN
A PROCESSOR) WAS CHOSEN AS SUCCESSOR BY A PROCESS
RELINQUISHING A PROCESSOR
[] THE PROCESS IS NOW EXECUTING
[] BLOCKED -> READY (#4 -> #2)
[] SOME OTHER PROCESS SENT A WAKEUP INDICATING THE COMPLETION
OF THE EVENT THIS PROCESS WAS WAITING ON, AND CHANGE THE
STATE OF THIS PROCESS
[] THE PROCESS IS NOW WAITING FOR NO OTHER RESOURCE THAN A
PROCESSOR
[] WAITING -> READY (#6 -> #2)
PTL-WAITING -> READY (#3 -> #2)
[] SOME OTHER PROCESS SENT A NOTIFY INDICATING THE COMPLETION
OF THE EVENT THIS PROCESS WAS WAITING ON, AND CHANGED THE
STATE OF THIS PROCESS
[] THE PROCESS IS NOW WAITING FOR NO OTHER RESOURCE THAN A
PROCESSOR
Not To Be Reproduced 9-12 MDD-003
_S_E_R_V_I_C_E_S__O_F__T_R_A_F_F_I_C__C_O_N_T_R_O_L
_P_R_O_C_E_S_S_O_R__M_U_L_T_I_P_L_E_X_I_N_G
==========================================
INSERT Traffic Control States DIAGRAM HERE
==========================================
Not To Be Reproduced 9-13 MDD-003
_S_E_R_V_I_C_E_S__O_F__T_R_A_F_F_I_C__C_O_N_T_R_O_L
_P_R_O_C_E_S_S_O_R__M_U_L_T_I_P_L_E_X_I_N_G
==================================
INSERT TC Scenario #1 DIAGRAM HERE
==================================
Not To Be Reproduced 9-14 MDD-003
_S_E_R_V_I_C_E_S__O_F__T_R_A_F_F_I_C__C_O_N_T_R_O_L
_P_R_O_C_E_S_S_O_R__M_U_L_T_I_P_L_E_X_I_N_G
==================================
INSERT TC Scenario #2 DIAGRAM HERE
==================================
Not To Be Reproduced 9-15 MDD-003
_S_E_R_V_I_C_E_S__O_F__T_R_A_F_F_I_C__C_O_N_T_R_O_L
_P_R_O_C_E_S_S_O_R__M_U_L_T_I_P_L_E_X_I_N_G
=============================================
INSERT Working Sets and Trashing DIAGRAM HERE
=============================================
Not To Be Reproduced 9-16 MDD-003
_S_E_R_V_I_C_E_S__O_F__T_R_A_F_F_I_C__C_O_N_T_R_O_L
_P_R_O_C_E_S_S_O_R__M_U_L_T_I_P_L_E_X_I_N_G
===================================
INSERT Idle Categories DIAGRAM HERE
===================================
Not To Be Reproduced 9-17 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__M_E_T_E_R_S
_t_o_t_a_l__t_i_m_e__m_e_t_e_r_s
ox TOTAL_TIME_METERS - OVERVIEW OF HOW THE SYSTEM IS USING ITS
RESOURCES, ALSO MEASURED AGAINST NON-IDLE TIME
Total metering time 0:20:36
% %NI AVE
Page Faults 6.55 7.19 2130.424
PC Loop Locks 0.39 0.43 1993.209
PC Queue 0.86 0.94 348.946
Seg Faults 1.74 1.90 9579.170
Bound Faults 0.15 0.16 17426.208
Interrupts 9.02 9.89 1713.504
Other Fault 8.45 9.27
Getwork 4.54 4.98 660.550
TC Loop Locks 0.20 0.22 247.788
Post Purging 0.36 0.39 1407.132
MP Idle 0.70 0.77
Work Class Idle 0.98 1.08
Loading Idle 0.16 0.17
NMP Idle 8.84
Zero Idle 0.00
Other Overhead 0.03 0.04
Virtual CPU Time 62.53 68.59
Not To Be Reproduced 9-18 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__M_E_T_E_R_S
_t_r_a_f_f_i_c__c_o_n_t_r_o_l__m_e_t_e_r_s
ox TRAFFIC_CONTROL_METERS - DISPLAY THE STATE OF THE SCHEDULER
[] OUTPUT COMES IN THREE PARTS, SHOWN OUT OF ORDER HERE:
[] QUEUE LENGTHS AND RESPONSE TIME - THESE ARE WEIGHTED AVERAGES
OVER THE LAST FIFTEEN SECONDS.
[] ACTIVITIES VERSUS DEPTH - HOW DEEP THE TRAFFIC CONTROLLER HAD
TO SEARCH TO FIND A SCHEDULABLE PROCESS
[] MISCELLANEOUS COUNTERS AND FREQUENCIES OF VARIOUS EVENTS
Total metering time 0:20:34
Ave queue length 16.52
Ave eligible 13.31
Response time 0.264 sec
DEPTH %PF TBPF %GTW TBS %CPU
1 12.0 22.8 10.8 11.6 8.1
2 11.8 21.0 9.2 12.2 7.4
3 10.8 24.9 8.7 14.1 8.0
4 10.2 27.9 8.5 15.2 8.4
5 9.5 29.8 8.3 15.5 8.4
6 8.4 33.5 7.8 16.5 8.4
7 7.4 36.3 7.3 16.8 8.0
Not To Be Reproduced 9-19 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__M_E_T_E_R_S
_t_r_a_f_f_i_c__c_o_n_t_r_o_l__m_e_t_e_r_s
COUNTER TOTAL ATB #/INT
Interactions 7977 0.155 sec
Loadings 12161 0.102 sec 1.525
Blocks 14082 0.088 sec
Wakeups 36078 0.034 sec
Schedulings 12591 0.098 sec 1.578
Lost priority 1 1234.756 sec
Priority boosts 0 0.000 sec
I/O boosts 578 2.136 sec
Wait Page 127040 9.719 msec 15.926
Wait PTL 75691 16.313 msec 9.489
Wait Other 31912 38.693 msec 4.001
Total Waits 234643 5.262 msec 29.415
Notify Page 128954 9.575 msec
Notify PTL 75691 16.313 msec
Notify Other 25330 48.747 msec
Total Notifies 229975 5.369 msec
Get Processor 245856 5.022 msec
Pre-empts 94235 13.103 msec 11.813
Getwork 338802 3.644 msec
Retry getwork 4988 0.248 sec
Extra notifies 2949 0.419 sec
Last EN event 000000000071
Last NTO event 033022237767
ox ALARM_CLOCK_METERS - DISPLAYS INFORMATION ABOUT THE USER ALARM
TIMER FACILITY (HARDCORE INTERFACE FOR timer_manager_)
Total metering time 0:20:31
No. alarm clock sims. 2171
Simulation lag 5.245 msecs.
Max. lag 1.7340314e4 msecs.
Not To Be Reproduced 9-20 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__M_E_T_E_R_S
_t_r_a_f_f_i_c__c_o_n_t_r_o_l__q_u_e_u_e
ox TRAFFIC_CONTROL_QUEUE - DISPLAYS THE CURRENT CONTENTS OF THE
SCHEDULER QUEUES, USEFUL FOR GETTING AN IDEA OF WHAT THE USER
PROCESSES ARE DOING
[] FIRST PART OF OUTPUT IS ELIGIBLE QUEUE:
avq = 13, elapsed time = 1247 sec, 64 active last 15 sec.
flags dtu dpf temax te ts ti tssc event d ws wc process
rWLE(d) 148 6946 2097 37 0 0 -0.001 0 0 6 0 Initializer
xLED(c) 15 1111 1000 910 2012 1897 0.001 0 0 11 6 Sibert
rLE(d) 14 1370 500 89 0 0 -0.009 0 0 0 4 Diaz
rLE(d) 15 823 500 13 0 0 -0.009 0 0 64 8 JCrow
wLE(d) 13 634 500 422 0 0 0.018 316537 0 3 3 Gintell
xWLED(a) 6 108 1000 495 2054 2004 0.010 0 0 13 6 Brunelle
wLE(d) 16 864 1000 85 0 510 0.016 504031 0 46 6 WPeck
wWLE(b) 468 2734 1000 315 3010 8000 0.013 224641 0 4 3 Spratt
wLE(d) 17 686 500 60 0 0 0.007 165111 0 3 4 RTowle
wLE(b) 12 520 500 50 0 0 0.005 71 0 3 3 Kress
wLE(d) 69 1895 500 21 0 0 0.001 177022 0 0 2 OPCTL
xLED(b) 12 872 500 85 0 0 0.005 0 0 0 3 Pandolf
rLE(d) 67 3279 500 0 0 0 -0.006 0 0 0 3 Lackey
Not To Be Reproduced 9-21 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__M_E_T_E_R_S
_t_r_a_f_f_i_c__c_o_n_t_r_o_l__q_u_e_u_e
[] SECOND PART IS REALTIME, INTERACTIVE, AND ALL WORKCLASS QUEUES:
REALTIME QUEUE:
INTERACTIVE QUEUE:
WORKCLASS 2 QUEUE: credits = 576 ms.
WORKCLASS 3 QUEUE: credits = 242 ms.
r 289 5326 1000 0 0 503 0.218 0 0 22 3 Dupuis
r 131 2513 1000 0 4010 8000 0.128 0 0 0 3 Falksenj
WORKCLASS 4 QUEUE: credits = 2601 ms.
WORKCLASS 5 QUEUE: credits = 4000 ms.
WORKCLASS 6 QUEUE: credits = -563 ms.
WORKCLASS 7 QUEUE: credits = 3962 ms.
rW 5 166 500 0 0 0 0.192 0 0 2 7 Saccuci
WORKCLASS 8 QUEUE: credits = 3934 ms.
WORKCLASS 9 QUEUE: credits = 2216 ms.
WORKCLASS 10 QUEUE: credits = 4000 ms.
WORKCLASS 11 QUEUE: credits = 4000 ms.
Not To Be Reproduced 9-22 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__M_E_T_E_R_S
_w_o_r_k__c_l_a_s_s__m_e_t_e_r_s
ox WORK_CLASS_METERS - DISPLAY THE VARIOUS WORKCLASS PARAMETERS, AND
SHOW WHAT RESOURCES EACH WORKCLASS IS CONSUMING.
Total metering time 0:20:38
WC %GUAR %MAX %TCP V/ELIG PW IRESP IQUANT RESP QUANT P M R I LCG
0 3. 0.12 3 0.26 2.10 0.26 2.10 P 0 R I Init
1 3. 0.09 1 0.25 0.75 0.50 1.00 P 0 R I RTime
2 7. 15. 0.44 1 P 0 I System SysAdm OPR FED
3 32. 44. 0.49 1 P 0 I SysProg SysDev
4 9. 14. 4. 0.26 1 P 0 SEngr
5 20. 2. 0.46 1 P 0 I HEngr
6 12. 16. 8. 0.25 1 P 0 MktUS MktFor MktEd
7 3. 7. 4. 0.36 1 P 0 DS-CC
8 6. 0. 0.18 1 P 0 I OffAuto
9 4. 8. 2. 0.62 1 P 0 Misc Mfg
10 3. 0. 0.55 1 P 0 I Other
11 4. 2. 0.16 1 P 0 I Special
TCPU percents (%GUAR) control non-realtime work_classes.
Not To Be Reproduced 9-23 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__M_E_T_E_R_S
_r_e_s_p_o_n_s__m_e_t_e_r_s
ox RESPONSE_METERS - DISPLAYS RESPONSE TIME, BASED ON TERMINAL
INTERACTIONS, ON A PER-WORKCLASS BASIS
Total metering time 0:20:36
WC ---Thinks/-- ----Response Times by VCPU Range---- Load Control Group
---Queues--- -VCPU Range- # Avg Avg Resp
# Avg From To Int VCPU RT Fact
0 86 2.70 0.00 0.50 113 0.04 0.42 9.34 Init
92 0.15 0.50 1.00 3 0.55 5.51 10.00
1.00 10.00 3 2.43 14.96 6.15
----- ----- 119 0.12 0.91 7.76
1 35 11.78 0.00 0.50 34 0.11 0.96 8.74 RTime
39 0.21 0.50 1.00 2 0.83 4.06 4.87
----- ----- 36 0.15 1.13 7.55
2 593 14.90 0.00 0.50 620 0.05 0.49 10.50 System SysAdm OPR FED
612 0.15 0.50 1.00 28 0.71 3.61 5.10
1.00 10.00 39 1.77 8.39 4.74
----- ----- 687 0.17 1.07 6.22
3 2496 6.38 0.00 0.50 2993 0.08 0.66 7.96 SysProg SysDev
2622 0.17 0.50 1.00 117 0.68 4.22 6.16
1.00 10.00 66 2.46 13.47 5.49
10.00 99.99 10 56.85 99.99 3.33
----- ----- 3186 0.33 1.65 4.96
4 581 15.82 0.00 0.50 663 0.05 0.71 12.94 SEngr
590 0.26 0.50 1.00 13 0.64 4.64 7.30
1.00 10.00 8 3.47 32.07 9.24
----- ----- 684 0.11 1.15 10.88
5 133 29.51 0.00 0.50 148 0.06 0.83 12.95 HEngr
141 0.17 0.50 1.00 3 0.69 4.64 6.70
1.00 10.00 5 3.15 10.24 3.25
10.00 99.99 2 26.69 48.84 1.83
----- ----- 158 0.51 1.81 3.55
Not To Be Reproduced 9-24 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__M_E_T_E_R_S
_r_e_s_p_o_n_s__m_e_t_e_r_s
6 1180 11.65 0.00 0.50 977 0.05 1.13 20.91 MktUS MktFor MktEd
1211 0.58 0.50 1.00 24 0.64 4.95 7.74
1.00 10.00 16 1.89 11.88 6.29
----- ----- 1017 0.10 1.39 14.38
7 259 14.65 0.00 0.50 292 0.08 1.53 20.17 DS-CC
287 0.98 0.50 1.00 9 0.71 9.03 12.66
1.00 10.00 17 2.04 14.76 7.24
10.00 99.99 1 12.22 99.99 9.45
----- ----- 319 0.24 2.81 11.86
8 73 2.69 0.00 0.50 79 0.06 0.31 5.45 OffAuto
74 0.05 0.50 1.00 2 0.60 6.40 10.62
1.00 10.00 1 3.20 6.73 2.10
----- ----- 82 0.11 0.54 4.94
9 94 41.91 0.00 0.50 80 0.11 1.23 11.07 Misc Mfg
96 0.30 0.50 1.00 11 0.69 4.74 6.91
1.00 10.00 13 2.99 12.82 4.30
----- ----- 104 0.53 3.05 5.74
10 7 99.99 0.00 0.50 10 0.11 1.45 13.82 Other
8 0.21 1.00 10.00 1 3.88 39.11 10.09
----- ----- 11 0.45 4.88 10.89
11 417 12.71 0.00 0.50 445 0.03 0.50 15.32 Special
420 0.16 0.50 1.00 5 0.57 3.61 6.29
1.00 10.00 4 1.65 11.40 6.90
----- ----- 454 0.05 0.63 11.93
All 5954 11.13 0.00 0.50 6454 0.07 0.77 11.40
6192 0.29 0.50 1.00 217 0.68 4.54 6.70
1.00 10.00 173 2.31 13.11 5.68
10.00 99.99 13 48.77 99.99 3.32
----- ----- 6857 0.24 1.51 6.39
86797 calls to meter_response_time 283 invalid transitions.
Overhead = 0.09% ( 0.052 ms./call)
Not To Be Reproduced 9-25 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__M_E_T_E_R_S
_p_o_s_t__p_u_r_g_e__m_e_t_e_r_s
ox POST_PURGE_METERS - DISPLAY THE STATE OF POST-PURGE ACTIVITY.
[] CONSIDERABLY MORE DETAILED METERS ARE KEPT BY RING ZERO, BUT NOT
REPORTED AND NOT PARTICULARLY INTERESTING.
Total metering time 0:20:29
Post purge time 1.41 msec. (0.36% of system)
Ave list size 17.76 entries
Ave working set 5.59 pages
Working set factor 0.50
Working set addend 0
Thrashing percentage 1.34 %
Ave post in core 10.65 (59.94 %)
Not To Be Reproduced 9-26 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__C_O_M_M_A_N_D_S
_p_r_i_n_t__t_u_n_i_n_g__p_a_r_a_m_e_t_e_r_s
ox PRINT_TUNING_PARAMETERS - PRINT VALUES FOR SYSTEM CONTROL
PARAMETERS. MOST CONTROL THE SCHEDULER
Current system tuning parameters:
tefirst 0.5 seconds
telast 1. seconds
timax 8. seconds
priority_sched_inc 80. seconds
min_eligible 2.
max_eligible 20.
max_batch_elig 0
working_set_factor 0.5
working_set_addend 0
deadline_mode off
int_q_enabled on
post_purge on
pre_empt_sample_time 0.04 seconds
gp_at_notify off
gp_at_ptlnotify off
process_initial_quantum 2. seconds
quit_priority 0.
gv_integration 4. seconds
realtime_io_priority on
realtime_io_deadline 0. seconds
realtime_io_quantum 0.005 seconds
notify_timeout_interval 30. seconds
notify_timeout_severity 0
write_limit 724
[] THESE ARE "INTERNAL", NORMALLY NEVER CHANGED, AND ONLY PRINTED
IF THE -all CONTROL ARGUMENT IS GIVEN
stack_truncation on
stack_truncation_always off
stk_trunc_block_avg_factor 0.25
trap_invalid_masked off
meter_ast_locking off
checksum_filemap on
Not To Be Reproduced 9-27 MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__C_O_M_M_A_N_D_S
_p_r_i_n_t__a_p_t__e_n_t_r_y
ox PRINT_APT_ENTRY - INTERPRETS AND DUMPS AN APT ENTRY
! print_apt_entry Sibert -dump
Sibert.Multics.a b.h126 at 10300 in tc_data, >pdd>!BblCpbBbBBBBBB
PID:010300356001 TRM:000447007410 407777000460
Running for 0.067825 (since 01:28:53).
Usage: cpu 8:40.8; vcpu 6:04.6; pf 23622.
te/s/i/x: 0.411 0.000 0.647 32.000.
Flags: loaded,eligible,mbz11,dbr_loaded.
Alarm in 31.244 (at 01:29:24).
0 005400003000 014225000001 000000056106 010300356001
4 000001443141 000000000000 000002356631 000172044000
10 000000000000 000000000000 005200013740 000000002076
14 003000777777 115641364232 000000000000 003702747134
20 000000000000 001360000002 000000111567 457572337662
24 000000000000 000000000000 011700111567 457761705103
30 000447007410 407777000460 000000000000 000001720440
34 000000111567 457736532472 003322000000 000000000000
40 000000000000 000004325430 000000000000 000000000000
44 035117540004 001775100023 000000000000 002556711030
50 000000000000 000000000000 000000000004 000000004441
54 000000111567 457572506651 000000000000 014274070015
60 000000000000 002557051053 000001720440 776000000000
64 000000000000 000000000000 000000000000 000000000000
70 000000000000 000000000000 000000000000 000000000000
74 000000000000 000000000000 000000000000 000000000000
TOPIC X
Fault and Interrupt Handling
Page
Fault and Interrupt Handling Overview . . . . 10-1
Fault and Interrupt Data Bases. . . . . . . . 10-4
10-i MDD-003
_T_R_A_F_F_I_C__C_O_N_T_R_O_L__C_O_M_M_A_N_D_S
_p_r_i_n_t__a_p_t__e_n_t_r_y
Fault and Interrupt Vectors . . . . . . . 10-4
Fault Data Save Areas . . . . . . . . . . 10-6
Important Types of Faults . . . . . . . . 10-8
Fault/Interrupt Meters. . . . . . . . . . . . 10-13
fim_meters. . . . . . . . . . . . . . . . 10-13
interrupt_meters. . . . . . . . . . . . . 10-14
10-i MDD-003
.
_F_A_U_L_T__A_N_D__I_N_T_E_R_R_U_P_T__H_A_N_D_L_I_N_G__O_V_E_R_V_I_E_W
ox FUNCTION
[] RESPONSIBLE FOR HANDLING ALL EXCEPTIONS IN A CPU WHETHER
INTERNAL TO THE PROCESSOR (REFERRED TO AS _F_A_U_L_T_S) OR EXTERNAL
(REFERRED TO AS _I_N_T_E_R_R_U_P_T_S)
[] ESTABLISHES THE SUPERVISOR ENVIRONMENT AT FAULT AND INTERRUPT
TIME. SAVES THE MACHINE CONDITIONS AND TRANSFERS TO THE
APPROPRIATE HANDLER
[] MAJOR COMPONENTS: THE FAULT INTERCEPT MODULE (fim), WIRED-FAULT
INTERCEPT MODULE (wired_fim), I/O INTERRUPT HANDLER
(io_interrupt), sys_trouble, page_fault
ox MAJOR DATA BASES
[] INTERRUPT VECTORS - ONE SET PER SYSTEM (WIRED)
[] INTERRUPT PAIR (2 INSTRUCTIONS) - ONE PAIR PER DEFINED
INTERRUPT TYPE
[] LOCATED AT ABSOLUTE ADDRESS 0. A HARDWARE RECOGNIZED DATA
BASE
[] DESCRIBE WHERE TO SAVE THE CONTEXT, AND WHERE TO TRANSFER TO
TO PROCESS THE INTERRUPT (ALWAYS io_interrupt)
Not To Be Reproduced 10-1 MDD-003
_F_A_U_L_T__A_N_D__I_N_T_E_R_R_U_P_T__H_A_N_D_L_I_N_G__O_V_E_R_V_I_E_W
[] FAULT VECTORS - ONE SET PER SYSTEM (WIRED)
[] VECTOR PAIR (2 INSTRUCTIONS) - ONE PAIR PER DEFINED FAULT
TYPE
[] LOCATED AT ABSOLUTE ADDRESS 100 (OCTAL) IMMEDIATELY ABOVE THE
INTERRUPT VECTORS. A HARDWARE RECOGNIZED DATA BASE
[] DESCRIBE WHERE TO SAVE THE CONTEXT, AND WHERE TO TRANSFER TO
TO PROCESS THE FAULT (fim, wired_fim, page_fault)
[] _P_R_O_C_E_S_S DATA SEGMENT (PDS) - ONE PER PROCESS (WIRED WHEN
ELIGIBLE)
[] CONTAINS PROCESS RELEVANT INFO SUCH AS PROCESS ID, USER ID,
HOME/WORKING/PROCESS DIRECTORIES, AIM CLASSIFICATION, INITIAL
RING, ETC
[] CONTAINS ALL INFORMATION ABOUT THE PROCESS NEEDED BY THE
SUPERVISOR CODE WHEN THE PROCESS IS RUNNING
[] CONTAINS SAVE AREAS FOR CONTEXT INFORMATION ABOUT FAULTS
WHICH CAN RESULT IN GIVING UP THE PROCESSOR: PAGE FAULTS,
SEGMENT FAULTS, AND ALL FAULTS NOT HANDLED BY THE SUPERVISOR
[] _P_R_O_C_E_S_S_O_R DATA SEGMENT (PRDS) - ONE PER CONFIGURED CPU (WIRED)
[] SERVES AS RING-ZERO STACK FOR PAGE CONTROL AND TRAFFIC
CONTROL
[] ALSO CONTAINS SAVE AREAS FOR CONTEXT INFORMATION ABOUT FAULTS
WHICH USUALLY DO NOT MEAN GIVING UP THE PROCESSOR: CONNECT
FAULTS AND INTERRUPTS.
Not To Be Reproduced 10-2 MDD-003
_F_A_U_L_T__A_N_D__I_N_T_E_R_R_U_P_T__H_A_N_D_L_I_N_G__O_V_E_R_V_I_E_W
[] FIM_TABLE
[] A TABLE IN THE FIM PROGRAM WHICH DESCRIBES THE ACTION TO BE
TAKEN FOR VARIOUS TYPES OF FAULTS
Not To Be Reproduced 10-3 MDD-003
_F_A_U_L_T__A_N_D__I_N_T_E_R_R_U_P_T__D_A_T_A__B_A_S_E_S
_F_A_U_L_T__A_N_D__I_N_T_E_R_R_U_P_T__V_E_C_T_O_R_S
ox ALL FAULTS AND INTERRUPTS ARE HANDLED IN A CENTRALIZED FASHION
[] FOR EACH FAULT OR INTERRUPT, THERE ARE TWO INSTRUCTIONS:
[] AN scu INSTRUCTION, TO STORE THE ABSOLUTELY ESSENTIAL DATA
NEEDED TO RESTART FROM THE FAULT
[] A tra INSTRUCTION, TO TRANSFER TO TO THE APPROPRIATE FAULT
HANDLER
[] ASSOCIATED WITH EACH OF THESE INSTRUCTIONS, THERE IS A POINTER
[] AN SCU DATA POINTER, POINTING TO ONE OF SIX REGIONS WHERE
FAULT DATA GOES
[] A FAULT HANDLER POINTER, INDICATING ONE OF THE PROCEDURES
USED TO HANDLE FAULTS
[] THESE INSTRUCTIONS AND POINTERS ARE STORED IN THE fault_vector
[] THE DATA STORED BY scu IS ONLY THE "CONTROL UNIT DATA" - EACH
HANDLER MUST IMMEDIATELY SAVE THE PROGRAM VISIBLE REGISTERS, THE
EIS POINTER & LENGTH DATA, AND SO FORTH. THIS DATA IS ALWAYS
STORED IN THE SAME FORMAT, THE MACHINE CONDITIONS STRUCTURE
(mc.incl.pl1)
Not To Be Reproduced 10-4 MDD-003
_F_A_U_L_T__A_N_D__I_N_T_E_R_R_U_P_T__D_A_T_A__B_A_S_E_S
_F_A_U_L_T__A_N_D__I_N_T_E_R_R_U_P_T__V_E_C_T_O_R_S
===============================================
INSERT Fault and Interrupt Vectors DIAGRAM HERE
===============================================
Not To Be Reproduced 10-5 MDD-003
_F_A_U_L_T__A_N_D__I_N_T_E_R_R_U_P_T__D_A_T_A__B_A_S_E_S
_F_A_U_L_T__D_A_T_A__S_A_V_E__A_R_E_A_S
ox THERE ARE SIX REGIONS WHERE MACHINE CONDITIONS ARE STORED.
[] THEY ARE SELECTED TO MINIMIZE THE NUMBER OF TIMES WHEN FAULT
DATA MUST BE MOVED. USUALLY, ONCE FAULT DATA HAS BEEN STORED IN
A PARTICULAR PLACE, IT CAN BE RESTORED DIRECTLY FROM THERE, BUT
SOMETIMES IT MUST BE MOVED TO ANOTHER PLACE
[] prds$interrupt_data - USED FOR INTERRUPTS, ONLY
[] prds$fim_data - USED FOR FAULTS SUCH AS CONNECT FAULTS, WHICH
WILL BE HANDLED ENTIRELY USING THE WIRED RING ZERO STACK
(PRDS)
[] prds$sys_trouble_data - USED FOR THE FAULT THAT CRASHED THE
SYSTEM. NO MACHINE CONDITIONS ARE EVER STORED HERE DIRECTLY,
ONLY MOVED HERE.
[] pds$fim_data - USED FOR FAULTS WHICH WILL BE HANDLED IN RING
ZERO, USING THE RING ZERO STACK, WHERE PAGE FAULTS MIGHT BE
TAKEN WHILE THE OTHER FAULT IS BEING HANDLED
[] pds$page_fault_data - USED FOR PAGE FAULTS AND TIMER RUNOUTS
(WHICH INDICATE THE END OF A QUANTUM) - BOTH ARE EVENTS WHICH
ALMOST ALWAYS RESULT IN GIVING UP THE PROCESSOR, BUT WHICH
ARE HANDLED ON THE WIRED RING ZERO STACK (PRDS)
[] pds$signal_data - USED FOR FAULTS WHICH WILL BE SIGNALLED OUT
FOR THE USER RING TO HANDLE. IF AN ERROR OCCURS PROCESSING
SOME FAULT IN RING ZERO, ITS FAULT DATA IS MOVED HERE BEFORE
SIGNALLING
Not To Be Reproduced 10-6 MDD-003
_F_A_U_L_T__A_N_D__I_N_T_E_R_R_U_P_T__D_A_T_A__B_A_S_E_S
_F_A_U_L_T__D_A_T_A__S_A_V_E__A_R_E_A_S
[] THERE ARE ALSO SPECIAL STACK FRAMES CREATED BY THE FIM USED FOR
FAULT SIGNALLING, AND THE MACHINE CONDITIONS ARE COPIED THERE.
Not To Be Reproduced 10-7 MDD-003
_F_A_U_L_T__A_N_D__I_N_T_E_R_R_U_P_T__D_A_T_A__B_A_S_E_S
_I_M_P_O_R_T_A_N_T__T_Y_P_E_S__O_F__F_A_U_L_T_S
ox CERTAIN FAULTS DESERVE SPECIAL DISCUSSION, AS THEY ARE USED TO
IMPLEMENT IMPORTANT SUPERVISOR SERVICES
[] LINKAGE FAULT
[] OCCUR WHEN A POINTER CONTAINING 46 OCTAL IN THE LOW SIX BITS
OF THE FIRST WORD IS USED
[] USED TO IMPLEMENT DYNAMIC LINKING (SEE NAME/ADDRESS SPACE
MANAGEMENT, TOPIC 4)
[] USES pds$fim_data, IS HANDLED BY fim.alm, WHICH INVOKES
link_man.pl1, HANDLED ENTIRELY ON THE stack_0
[] SEGMENT FAULT
[] OCCURS WHEN AN NON-ACTIVE SEGMENT IS REFERENCED (SEE SEGMENT
CONTROL, TOPIC 7)
[] USES pds$fim_data, IS HANDLED BY fim.alm, WHICH INVOKES
seg_fault.pl1, HANDLED ENTIRELY ON THE stack_0
[] A SEGMENT FAULT MAY OCCUR WHILE ANOTHER IS BEING HANDLED, AND
IT WILL BE HANDLED RECURSIVELY
[] PAGE FAULT
[] OCCURS WHEN A PAGE NOT IN MEMORY IS REFERENCED (SEE PAGE
CONTROL, TOPIC 8)
Not To Be Reproduced 10-8 MDD-003
_F_A_U_L_T__A_N_D__I_N_T_E_R_R_U_P_T__D_A_T_A__B_A_S_E_S
_I_M_P_O_R_T_A_N_T__T_Y_P_E_S__O_F__F_A_U_L_T_S
[] USES pds$page_fault_data, IS HANDLED DIRECTLY BY
page_fault.alm, AND IS HANDLED ENTIRELY ON THE PRDS.
[] TIMER RUNOUT
[] OCCURS WHEN THE TIMER REGISTER IS DECREMENTED THROUGH ZERO,
INDICATING THAT THE RUNNING PROCESS HAS NOW OVERSTAYED ITS
WELCOME, AND SHOULD LOSE ELIGIBILITY
[] TIMER RUNOUT FAULTS ARE ALSO USED INTERNAL TO TRAFFIC
CONTROL TO IMPLEMENT "PRE-EMPT" SAMPLING; IN THIS MODE,
NOW THE DEFAULT, THE TIMER GOES OFF EVERY FEW MILLISECONDS
AND THE PROCESS CHECKS TO SEE WHETHER A HIGHER PRIORITY
PROCESS WANTS THE PROCESSOR; THIS DOES NOT MAKE THE
RUNNING PROCESS INELIGIBLE, HOWEVER, UNLESS ITS QUANTUM
HAS ALSO RUN OUT
[] A PROCESS RUNNING IN RING ZERO NEED NEVER GIVE UP
ELIGIBILITY - WHEN A TIMER RUNOUT HAPPENS, IT REMEMBERS,
AND SETS THE RING ALARM REGISTER, WHICH WILL CAUSE A RING
ALARM FAULT LATER ON WHEN IT LEAVES RING ZERO
[] USES pds$page_fault_data, IS HANDLED DIRECTLY BY pxss.alm,
AND IS HANDLED ENTIRELY ON THE PRDS.
[] RING ALARM FAULT
[] OCCURS WHEN A PROCESS RETURNS TO AN OUTER RING FROM AN INNER
RING, AND THE RING ALARM REGISTER HAS BEEN SET
[] (1) USED TO DEFER ACTION ON TIMER RUNOUTS AND CONNECT FAULTS
(SEE BELOW) UNTIL A PROCESS LEAVES RING ZERO
[] (2) USED TO ENSURE THAT THE SOFTWARE VALIDATION LEVEL (SET
WITH cu_$level_set) IS NEVER LOWER THAN THE RING OF EXECUTION
- SETTING THE VALIDATION LEVEL ALSO SETS THE RING ALARM
REGISTER, AND THE RING ALARM FAULT CAUSES THE VALIDATION
LEVEL TO BE RESET
Not To Be Reproduced 10-9 MDD-003
_F_A_U_L_T__A_N_D__I_N_T_E_R_R_U_P_T__D_A_T_A__B_A_S_E_S
_I_M_P_O_R_T_A_N_T__T_Y_P_E_S__O_F__F_A_U_L_T_S
[] USES pds$page_fault_data, IS HANDLED DIRECTLY BY
ring_alarm.alm AND IS HANDLED ENTIRELY ON THE PRDS.
[] IS ACTUALLY A SUBTYPE OF ACCESS VIOLATION
[] CONNECT FAULT
[] OCCURS WHEN ONE PROCESSOR SENDS A "connect" TO ANOTHER, USING
A cioc INSTRUCTION
[] RESEMBLES A SOFTWARE SENDABLE INTERRUPT; ALTHOUGH
PROCESSORS CAN SEND INTERRUPTS TO EACH OTHER, LIMITATIONS
OF THE HARDWARE MAKE CONNECT FAULTS EASIER TO USE
[] USED FOR ALL INTERPROCESSOR SIGNALLING -
[] (1) TO CAUSE ANOTHER PROCESSOR TO SELECTIVELY CLEAR ITS
CACHE OR ASSOCIATIVE MEMORY
[] (2) TO PRE-EMPT A PROCESS RUNNING ON ANOTHER CPU (WHEN
PRE-EMPT SAMPLING IS _N_O_T IN USE)
[] (3) TO INFORM ANOTHER PROCESSOR THAT THE SYSTEM IS
CRASHING
[] (4) TO INFORM ANOTHER PROCESSOR THAT IT IS BEING REMOVED
FROM THE CONFIGURATION
[] USES prds$fim_data, IS SOMETIMES HANDLED BY wired_fim.alm,
AND IS HANDLED ENTIRELY ON THE PRDS.
[] FOR TYPE 1 CONNECTS (CACHE CLEAR), THE FAULT IS HANDLED
VERY SPECIALLY BY CODE WHICH IS ACTUALLY EXECUTED FROM
WITHIN THE PRDS (SEE fast_connect_init.alm), AND RUNS
SOMEWHAT FASTER. THE COMPLICATED CASES ARE LEFT TO
WIRED_FIM
[] CELLS IN THE scs ARE USED TO DISTINGUISH BETWEEN THE
DIFFERENT TYPES OF CONNECT FAULTS; A PROCESSOR SETS THE
APPROPRIATE CELLS BEFORE SENDING THE CONNECT.
Not To Be Reproduced 10-10 MDD-003
_F_A_U_L_T__A_N_D__I_N_T_E_R_R_U_P_T__D_A_T_A__B_A_S_E_S
_I_M_P_O_R_T_A_N_T__T_Y_P_E_S__O_F__F_A_U_L_T_S
[] OTHER FAULTS
[] PARITY - RUN AUTOMATIC PARITY ERROR LOGGING AND DIAGNOSIS (TO
CHIP LEVEL, FOR CACHE) ROUTINES
[] OP_NOT_COMPLETE, COMMAND, SHUTDOWN, STARTUP, STORE, TROUBLE -
RUN HARDWARE ERROR LOGGING ROUTINES
[] OVERFLOW, UNDERFLOW - CAN BE SET UP TO AUTOMATICALLY SET A
SPECIFIED (VERY LARGE OR VERY SMALL) VALUE AND RESTART
WITHOUT INTERRUPTING THE RUNNING PROGRAM
[] DERAIL - USED WHEN CRASHING THE SYSTEM OR VOLUNTARILY
RETURNING TO BOS TO BEGIN EXECUTION IN BOS. AN ORDINARY
SIGNALLABLE FAULT AT ALL OTHER TIMES (AND USED THAT WAY BY
THE gtss EMULATOR)
[] EXECUTE - USED TO FORCE A SYSTEM CRASH
[] ACCESS VIOLATION - CAN AUTOMATICALLY LOG ACCESS VIOLATIONS
FOR SECURITY AUDITS
[] OTHERS - HANDLED BY fim.alm, WHICH MAPS THE HARDWARE FAULTS
ONTO THE MULTICS ENVIRONMENT CONDITION NAMES
[] CONSIDERABLE INTERPRETATION IS SOMETIMES REQUIRED; FOR
INSTANCE, A NULL POINTER IS ACTUALLY SIGNALLED BY THE
HARDWARE AS AN ACCESS VIOLATION, OUT OF BOUNDS ON DSEG,
FAULT
[] INTERRUPT
[] INTERRUPTS ARE USED TO ANNOUNCE THE COMPLETION OF ALL I/O
OPERATIONS, AND ALSO (RARELY) USED DURING DYNAMIC
RECONFIGURATION TO START PROCESSORS
Not To Be Reproduced 10-11 MDD-003
_F_A_U_L_T__A_N_D__I_N_T_E_R_R_U_P_T__D_A_T_A__B_A_S_E_S
_I_M_P_O_R_T_A_N_T__T_Y_P_E_S__O_F__F_A_U_L_T_S
[] USES prds$interrupt_data, IS HANDLED DIRECTLY BY
iom_interrupt.alm OR init_processor.alm, AND IS HANDLED
ENTIRELY ON THE PRDS.
Not To Be Reproduced 10-12 MDD-003
_F_A_U_L_T_/_I_N_T_E_R_R_U_P_T__M_E_T_E_R_S
_f_i_m__m_e_t_e_r_s
ox FIM_METERS - COUNTS FOR ALL FAULT PROCESSING
Total metering time: 0:20:28
fault type count
shutdown 0
store 0
mme1 0
fault_tag_1 2
timer_runout 12907
command 5
derail 0
lockup 0
connect 742501
parity 0
illegal_procedure 0
op_not_complete 0
startup 0
overflow 0
divide_check 0
execute 0
segment_fault 6697
page_fault 151772
directed_fault_2 0
directed_fault_3 0
access_violation 21120
mme2 0
mme3 0
mme4 0
linkage_fault 21058
fault_tag_3 0
trouble 0
Not To Be Reproduced 10-13 MDD-003
_F_A_U_L_T_/_I_N_T_E_R_R_U_P_T__M_E_T_E_R_S
_i_n_t_e_r_r_u_p_t__m_e_t_e_r_s
ox INTERRUPT_METERS - COUNTS & TIMING FOR ALL I/O INTERRUPTS
Total metering time 0:20:28
IOM Ch Int Avg Time % CPU Name
A 6. 11 2.043 0.00 IOM A special
A 10. 379 1.553 0.01 prtb
A 13. 9253 3.436 0.65 fnp c
A 14. 19 0.788 0.00 opc
A 16. 26248 1.347 0.72 tapa
A 17. 128 1.328 0.00 tapa
A 18. 13097 5.383 1.43 fnp b
A 20. 21041 0.860 0.37 dska
A 21. 2881 0.860 0.05 dska
A 22. 8486 0.877 0.15 dskb
A 23. 257 0.964 0.01 dskb
A 24. 17896 0.895 0.33 dskb
A 25. 2573 0.943 0.05 dskb
A 26. 10486 0.857 0.18 dska
A 27. 255 0.899 0.00 dska
A 28. 24717 0.845 0.43 dskc
A 29. 2319 0.849 0.04 dskc
A 30. 9915 0.845 0.17 dskc
A 31. 215 0.767 0.00 dskc
B 14. 236 0.877 0.00 fnp d
B 15. 6917 3.351 0.47 fnp f
B 18. 3547 3.543 0.26 fnp a
B 19. 13667 3.435 0.96 fnp e
B 20. 22013 0.881 0.39 dskb
B 21. 4745 0.863 0.08 dskb
B 22. 6054 0.861 0.11 dska
B 23. 60 0.925 0.00 dska
B 24. 15946 0.867 0.28 dska
B 25. 989 0.841 0.02 dska
B 26. 12757 0.863 0.22 dskb
B 27. 1020 0.903 0.02 dskb
B 28. 5178 0.838 0.09 dskc
B 29. 30 0.653 0.00 dskc
B 30. 16582 0.823 0.28 dskc
B 31. 825 0.841 0.01 dskc
B 32. 1764 0.825 0.03 dske
Not To Be Reproduced 10-14 MDD-003
_F_A_U_L_T_/_I_N_T_E_R_R_U_P_T__M_E_T_E_R_S
_i_n_t_e_r_r_u_p_t__m_e_t_e_r_s
Chan 262506 1.464 7.82
Ovhd 258932 0.230 1.21
Total 258932 1.713 9.03
TOPIC XI
System Initialization/Shutdown
Page
System Initialization Overview. . . . . . . . 11-1
System Initialization Terminology . . . . . . 11-4
Initialization Data Bases . . . . . . . . . . 11-7
Environment Passed to Initialization. . . . . 11-10
Collection 0. . . . . . . . . . . . . . . . . 11-11
Collection 1. . . . . . . . . . . . . . . . . 11-12
Collection 2. . . . . . . . . . . . . . . . . 11-14
Collection 3. . . . . . . . . . . . . . . . . 11-16
Normal Shutdown . . . . . . . . . . . . . . . 11-17
File System Shutdown. . . . . . . . . . . . . 11-18
Emergency Shutdown. . . . . . . . . . . . . . 11-20
11-i MDD-003
_F_A_U_L_T_/_I_N_T_E_R_R_U_P_T__M_E_T_E_R_S
_i_n_t_e_r_r_u_p_t__m_e_t_e_r_s
ox FUNCTION
[] PREPARE THE SYSTEM TO OPERATE, STARTING FROM A COMPLETELY EMPTY
MACHINE
[] READS IN SUPERVISOR PROGRAMS FROM SYSTEM TAPE, SNAPS LINKS
BETWEEN SUPERVISOR COMPONENTS, VERIFIES AND INITIALIZES HARDWARE
CONFIGURATION, SETS UP SYSTEM DATABASES, ACCEPTS STORAGE SYSTEM
DISKS AND PREPARES THEM FOR USE BY THE FILE SYSTEM
[] MOST PROGRAMS IN SYSTEM INITIALIZATION ARE DELETED AFTER
INITIALIZATION IS COMPLETE.
[] SUPERVISOR PROGRAMS ARE LOADED IN THREE "COLLECTIONS", EACH OF
WHICH DEPENDS ON THE MECHANISMS SET UP BY THE PREVIOUS ONE
ox MAJOR DATA BASES
[] THESE DATA BASES ARE ALL BUILT DURING THE PROCESS OF
INITIALIZATION (EXCEPT FOR THE CONFIG DECK) AND KEPT AFTER
INITIALIZATION IS FINISHED
[] SEGMENT LOADING TABLE (>sl1>slt)
[] CONTAINS AN ENTRY DESCRIBING THE ATTRIBUTES OF EACH SEGMENT
IN THE SUPERVISOR
Not To Be Reproduced 11-0 MDD-003
_S_Y_S_T_E_M__I_N_I_T_I_A_L_I_Z_A_T_I_O_N__O_V_E_R_V_I_E_W
[] NAME TABLE (>sl1>name_table)
[] CONTAINS A LIST OF NAMES FOR EACH OF THE SEGMENTS IN THE
SUPERVISOR
[] DEFINITIONS SEGMENT (>sl1>definitions_)
[] CONTAINS THE DEFINITIONS SECTIONS FOR ALL THE SEGMENTS IN THE
SUPERVISOR, WHICH ARE USED IN ORDER TO SNAP LINKS BETWEEN THE
SUPERVISOR MODULES
[] CONFIG DECK (>sl1>config_deck)
[] CONTAINS A DESCRIPTION OF THE HARDWARE CONFIGURATION AND
CERTAIN SOFTWARE PARAMETERS
[] PROVIDED TO SYSTEM INITIALIZATION BY BOS
ox SHUTDOWN -- TERMINATES THE ACTIVITIES OF THE SYSTEM IN AN ORDERLY
FASHION
[] TWO TYPES OF SHUTDOWN:
[] NORMAL -- REQUESTED BY THE INITIALIZER, RUNS IN THE USUAL
SUPERVISOR ENVIRONMENT
[] EMERGENCY -- USED AFTER A CRASH, MUST MAKE THE SUPERVISOR
ENVIRONMENT OPERABLE BEFORE PROCEEDING
Not To Be Reproduced 11-1 MDD-003
_S_Y_S_T_E_M__I_N_I_T_I_A_L_I_Z_A_T_I_O_N__O_V_E_R_V_I_E_W
[] BOTH TYPES EXIST PRIMARILY TO SHUT DOWN THE FILE SYSTEM -- THAT
IS, TO WRITE ALL DATA IN MEMORY INTO ITS PROPER HOME ON DISK
[] INCLUDES PAGES OF SEGMENTS, VTOCES, VOLUME AND VTOC MAPS
[] SHUTDOWN ESSENTIALLY RUNS THE STEPS OF INITIALIZATION BACKWARDS,
BUT WITH A LOT OF SHORTCUTS
Not To Be Reproduced 11-2 MDD-003
_S_Y_S_T_E_M__I_N_I_T_I_A_L_I_Z_A_T_I_O_N__T_E_R_M_I_N_O_L_O_G_Y
CONFIG DECK: A SET OF CARDS OR CARD IMAGES USED TO INFORM THE
SOFTWARE ABOUT THE OPERATIONAL READINESS OF THE
HARDWARE PRESENT, SWITCH SETTINGS AND SPECIFICATIONS OF
SOME SOFTWARE DATA BASES (SIZE, LOCATION, ETC)
BOS: THE _BOOTLOAD _OPERATING _SYSTEM. A SIMPLE OPERATING
SYSTEM (A ONE CPU, UNPAGED ENVIRONMENT) OF 8 SEGMENTS
OCCUPYING THE FIRST 16K OF MAIN MEMORY. BOS RESIDES IN
THE BOS PARTITION WHEN "MULTICS" IS RUNNING
MST: THE _MULTICS _SYSTEM _TAPE CONTAINS PRECISELY ENOUGH
INFORMATION (PROCEDURES AND DATA BASES) TO BRING A BARE
HARDWARE SYSTEM TO MULTICS COMMAND LEVEL (ACTUALLY,
ONLY ENOUGH OF COMMAND LEVEL TO PERFORM A RELOAD)
BOOT: THE OPERATIONAL PROCEDURE OF READING THE SEGMENTS FROM
THE MST AND EXECUTING THE PROCEDURE/SEGMENTS THEREIN
WARM/COLD BOOT:
BOOTING THE SYSTEM WITH/WITHOUT A HIERARCHY PRESENT
HARDCORE PARTITION:
A RLV PARTITION FOR PAGING HARDCORE SEGMENTS CREATED
DURING BOOTLOAD
Not To Be Reproduced 11-3 MDD-003
_S_Y_S_T_E_M__I_N_I_T_I_A_L_I_Z_A_T_I_O_N__T_E_R_M_I_N_O_L_O_G_Y
DECIDUOUS SEGMENT:
A SEGMENT READ IN AS PART OF THE BOOTLOAD TAPE AND
PLACED INTO THE HIERARCHY. DECIDUOUS SEGMENTS ARE PART
OF THE INITIALIZER'S HARDCORE ADDRESS SPACE AND RESIDE
ENTIRELY IN THE HARDCORE PARTITION. THEY ARE PUT INTO
THE HIERARCHY (>sl1) IN ORDER TO BE ACCESSIBLE FROM THE
USER RINGS
NON DECIDUOUS HARDCORE SEGMENT:
A PAGED HARDCORE SEGMENT NOT IN THE HIERARCHY (AND THUS
HAS NO PATHNAME)
Not To Be Reproduced 11-4 MDD-003
_S_Y_S_T_E_M__I_N_I_T_I_A_L_I_Z_A_T_I_O_N__T_E_R_M_I_N_O_L_O_G_Y
==========================================
INSERT Segment Classification DIAGRAM HERE
==========================================
Not To Be Reproduced 11-5 MDD-003
_I_N_I_T_I_A_L_I_Z_A_T_I_O_N__D_A_T_A__B_A_S_E_S
ox THE TERM INITIALIZATION REFERS TO THE ACTIONS REQUIRED TO CREATE
THE MULTICS ENVIRONMENT GIVEN THE EXISTENCE OF A CONFIGURATION
DECK, AND HARDWARE CONTAINING NO OTHER DATA THAN FIRMWARE AND BOS
ox INITIALIZATION IS ACCOMPLISHED BY AN ORDERLY LOADING AND PROCESSING
OF THE SEGMENTS RESIDING ON THE MULTICS SYSTEM TAPE (MST)
ox THE SEGMENTS OF THE MST MAY BE DIVIDED INTO THREE CATEGORIES:
[] INITIALIZATION SEGMENTS
[] PROCEDURES USED ONLY FOR INITIALIZATION AND SUBSEQUENTLY
DISCARDED
[] SUPERVISOR SEGMENTS
[] DATA BASES USED DURING INITIALIZATION THAT ULTIMATELY BECOME
DATA BASES OF Initializer.SysDaemon.z
[] PROCEDURES AND DATA BASES THAT CONSTITUTE MULTICS HARDCORE
SUPERVISOR IN ITS ENTIRETY
[] NON-SUPERVISOR SEGMENTS
[] THE SEGMENTS OF COLLECTION THREE ARE PRECISELY THE
NON-SUPERVISOR SEGMENTS OF THE MST. THESE SEGMENTS ARE
LOADED DIRECTLY INTO >system_library_1, AND ARE NOT PART OF
THE RING ZERO SUPERVISOR
Not To Be Reproduced 11-6 MDD-003
_I_N_I_T_I_A_L_I_Z_A_T_I_O_N__D_A_T_A__B_A_S_E_S
ox BOOTLOAD PROCESSOR
[] ONE PROCESSOR (THE BOOTLOAD CPU) PERFORMS ALL OF INITIALIZATION
RUNNING EXCLUSIVELY IN RING ZERO
[] IN THE MOST OF INITIALIZATION (COLLECTION ONE AND MOST OF
COLLECTION TWO), THERE ARE NO PROCESSES, AS SUCH. THE
ENVIRONMENT WHICH RUNS THERE EVENTUALLY BECOMES THE
Initializer.SysDaemon PROCESS
[] NOTE: SINCE THE Initializer.SysDaemon DOES NOT LOGIN LIKE OTHER
USERS, IT DOES NOT APPEAR IN THE NORMAL USER TABLE, CONSEQUENTLY
IS NOT VISIBLE TO THE who COMMAND
ox STRATEGY OF INITIALIZATION: BOOTSTRAPPING
[] THE FIRST PROCEDURES RUN IN AN ENVIRONMENT DEVOID OF ALL
SOFTWARE ASSISTANCE
[] EACH NEW MECHANISM (SEGMENTATION, STACKS, SYMBOLIC LINKING,
PAGING, ETC) IS MADE OPERATIVE AS SOON AS POSSIBLE TO ENRICH THE
ENVIRONMENT IN WHICH FURTHER MECHANISMS ARE MADE OPERATIVE
[] MANY MECHANISMS HAVE SUBSYSTEMS THAT CONTROL THEM AND THESE
SUBSYSTEMS ARE NORMALLY INITIALIZED BY CALLING A SPECIAL ENTRY
POINT IN THE SUBSYSTEM WHICH PERFORM SUCH TASKS AS:
Not To Be Reproduced 11-7 MDD-003
_I_N_I_T_I_A_L_I_Z_A_T_I_O_N__D_A_T_A__B_A_S_E_S
[] CREATING TABLES WHOSE SIZES ARE DETERMINED BY DATA SPECIFIED
IN THE "CONFIG" DECK
[] THREADING OF RELEVANT LISTS
[] SEGMENTS ON THE MST ARE ARRANGED IN SUCH AN ORDER THAT THE
EARLIER SEGMENTS ALLOW AS MANY MECHANISMS AS POSSIBLE TO BE USED
IN LOADING AND PROCESSING OF THE LATER SEGMENTS
[] FOR THIS PURPOSE (AND BECAUSE THE SIZE OF THE MST IS POTENTIALLY
LARGER THAN MAIN MEMORY), THE MST IS DIVIDED INTO FOUR PARTS
KNOWN AS COLLECTION ZERO, ONE, TWO AND THREE
[] INITIALIZATION CAN BE VIEWED AS THE LOADING AND PROCESSING OF
COLLECTION ONE, COLLECTION TWO, AND COLLECTION THREE, IN TURN
ox THE ADDRESS SPACE OF INITIALIZATION (MINUS THE INITIALIZATION
SEGMENTS) BECOMES THE GLOBAL SUPERVISOR ADDRESS SPACE OF MULTICS
[] THIS ADDRESS SPACE IS "CLONED" TO BECOME THE INITIAL ADDRESS
SPACE OF NEWLY CREATED PROCESSES BY DUPLICATING THE DSEG
Not To Be Reproduced 11-8 MDD-003
_E_N_V_I_R_O_N_M_E_N_T__P_A_S_S_E_D__T_O__I_N_I_T_I_A_L_I_Z_A_T_I_O_N
ox THE FIRST SEGMENT OF COLLECTION ONE IS THE BOUND SEGMENT
bound_bootload_1
ox AT THE TIME CONTROL IS TRANSFERRED TO bound_bootload_1, IT IS
REQUIRED THAT BOS HAS INITIALIZED MAIN MEMORY AS FOLLOWS:
[] THE IOM MAILBOX MUST BE AT LOCATION 1400 AND CONTAIN THE CHANNEL
AND DEVICE NUMBER OF THE TAPE DRIVE ON WHICH THE MST IS MOUNTED
[] THE CONFIG DECK (AS PRODUCED BY BOS) MUST RESIDE AT LOCATION
14000 THRU 15777
[] THE BOS TOEHOLD AND FLAGBOX MUST BE AT LOCATION 10000 THRU 11777
[] THIS ONE PAGE CONSTITUTES ALL KNOWLEDGE THAT MULTICS HAS OF
BOS
[] TRANSFERRING CONTROL TO THE START OF THE BOS TOEHOLD WILL
CAUSE:
[] FIRST 64K OF MAIN MEMORY TO BE FLUSHED OUT TO THE BOS
PARTITION
[] THE BOS OPERATING SYSTEM TO BE READ INTO THE FIRST 64K OF
MAIN MEMORY
[] CONTROL GIVEN TO BOS
[] THE REMAINDER OF MAIN MEMORY MUST CONTAIN ZEROES
Not To Be Reproduced 11-9 MDD-003
_C_O_L_L_E_C_T_I_O_N__0
ox THIS CONSISTS OF THE SEGMENTS WHICH ARE DEFINED TO BE PRESENT IN
THE INITIAL ADDRESS SPACE
[] THESE SEGMENTS ARE EMPTY, AND OVERLAY SPECIFIC REGIONS OF MAIN
MEMORY. THEY ARE DEFINED SO THAT bound_bootload_1 CAN KNOW WHAT
SEGMENT NUMBERS TO USE FOR WHAT DATA
[] THE COLLECTION ZERO SEGMENTS ARE dseg, fault_vector,
iom_mailbox, config_deck, dn355_mailbox, bos_toehold, flagbox,
slt, and name_table
[] SEE SECTION 5, NAME / ADDRESS SPACE MANAGEMENT, FOR THEIR
DESCRIPTIONS
Not To Be Reproduced 11-10 MDD-003
_C_O_L_L_E_C_T_I_O_N__1
ox COLLECTION 1 CONTAINS ALL OF THE PROCEDURES AND DATA BASES
NECESSARY TO MAKE PAGING OPERATIVE
ox BASIC STEPS OF COLLECTION 1 LOADING AND INITIALIZATION:
[] bound_bootload_1 GAINS CONTROL FROM BOS, IN ABSOLUTE MODE, AND
PERFORMS THE FOLLOWING:
[] LOADS THE REMAINDER OF ITSELF INTO MAIN MEMORY
[] ESTABLISHES INTERIM FAULT AND INTERRUPT VECTORS
[] INITIALIZES THE INITIALIZATION DSEG, AND ENTERS APPENDING
MODE
[] READS THE REMAINDER OF COLLECTION 1 INTO MAIN MEMORY
(INCLUDING A SEGMENT NAMED bootstrap2)
[] bound_bootload_1 TRANSFERS TO bootstrap2
[] bootstrap2 PERFORMS THE FOLLOWING:
[] CREATES A STACK FRAME IN THE SEGMENT "inzr_stk0"
[] CALL THE APPROPRIATE PROCEDURES TO PRELINK THE SEGMENTS OF
COLLECTION 1
[] SETS UP THE PL/I ENVIRONMENT AND CALLS THE FIRST PL/I
PROCEDURE "initializer"
Not To Be Reproduced 11-11 MDD-003
_C_O_L_L_E_C_T_I_O_N__1
[] initializer (A SUPERVISOR SEGMENT), ACTUALLY CALLS
real_initializer TO DO THE REAL WORK. ALL THE REST OF
INITIALIZATION TAKES PLACE VIA CALLS IN real_initializer
[] FOR DEBUGGING PURPOSES, THERE IS A MECHANISM IN
real_initializer WHICH CAN BE USED TO STOP AT ANY OF THOSE
CALLS BY SETTING A VALUE IN THE PROCESSOR SWITCHES
[] THE MAJOR INITIALIZATIONS PERFORMED IN THE REST OF COLLECTION
ONE ARE:
[] INITIALIZE THE SCU, CLOCK, AND CPU CONTROL MECHANISMS,
CHECKING THE SWITCHES AND THE ADDRESSABILITY OF MEMORY
[] INITIALIZE FAULT AND INTERRUPT PROCESSING. INITIALIZE THE
CONSOLE AND SYSERR MECHANISMS
[] INITIALIZE PRIMITIVE TRAFFIC CONTROL (WAIT FOR SINGLE
EVENTS). INITIALIZE THE SST
[] INITIALIZE AND CHECK THE DISK CONFIGURATION. AT THIS POINT,
IT BECOMES POSSIBLE TO TAKE PAGE FAULTS, AND ALL FURTHER DISK
I/O IS DONE BY PAGING
[] CHECK THE ROOT VOLUMES SPECIFIED ON THE ROOT CARD, AND
INITIALIZE THE HARDCORE PARTITION MECHANISM. THIS ALSO
INCLUDES CREATING THE PARTITIONS AND VTOC IN A COLD BOOT
[] MAKE SEGMENTS PAGED -- AT THIS POINT, ALL PAGED SUPERVISOR
SEGMENTS ARE COPIED INTO THE HARDCORE PARTITION, AND ACCESSED
BY THE NORMAL PAGE FAULT MECHANISM. COLLECTION ONE ENDS HERE
Not To Be Reproduced 11-12 MDD-003
_C_O_L_L_E_C_T_I_O_N__2
ox COLLECTION TWO - THE REST OF SUPERVISOR INITIALIZATION
[] READ IN THE REST OF THE SUPERVISOR SEGMENTS FROM TAPE AND
INITIALIZE THE REST OF THE SUPERVISOR DATABASES
[] WHEN COLLECTION TWO IS FINISHED, THE INITIALIZATION ENVIRONMENT
HAS _B_E_C_O_M_E Initializer PROCESS, AND IT CALLS OUT TO RING ONE TO
START UP THE ANSWERING SERVICE
[] THE FOLLOWING MAJOR STAGES TAKE PLACE IN COLLECTION TWO:
[] COLLECTION TWO IS READ FROM TAPE (STILL USING A SPECIAL
PROCEDURE, tape_reader, WHICH DOUBLE-BUFFERS)
[] THE AND CONDITION SIGNALLING AND HIGHER LEVEL FAULT
MECHANISMS ARE INITIALIZED
[] HIGH LEVEL FILE SYSTEM MECHANISMS ARE INITIALIZED: THE VTOC
MANAGER, VOLUME DUMPER BIT MAP, SCAVENGER, SEGMENT TRAILERS,
LOGICAL VOLUME MANAGEMENT, DIRECTORY LOCKING
[] TRAFFIC CONTROL IS FURTHER INITIALIZED, AND AN IDLE PROCESS
IS CREATED FOR THE RUNNING CPU
[] SYSERR LOGGING (TO THE SYSERR PARTITION) IS INITIALIZED. ALL
SYSERR MESSAGES GENERATED AFTER THIS POINT WILL GO IN THE LOG
[] THE FILE SYSTEM ON THE RPV IS "ACCEPTED", AND THE ROOT
DIRECTORY INSPECTED (OR CREATED, IF THIS IS A COLD BOOT)
[] AFTER THIS POINT, THE CONTENTS OF THE HARDCORE PARTITIONS
ARE FIXED, AND ALL FURTHER RECORD ALLOCATION AND FREEING
IS DONE FROM THE PAGING REGIONS OF THE FILE SYSTEM VOLUMES
Not To Be Reproduced 11-13 MDD-003
_C_O_L_L_E_C_T_I_O_N__2
[] DECIDUOUS SEGMENTS ARE SPLICED INTO THE HIERARCHY
[] STACK SHARING IS INITIALIZED
[] THE REST OF THE SEGMENTS, COMPRISING COLLECTION THREE, ARE
READ, DIRECTLY INTO THEIR PLACES IN THE HIERARCHY (>sl1)
[] THE USER VISIBLE SUPERVISOR I/O MECHANISM (ioi) IS
INITIALIZED, AND THE SPECIAL SUPERVISOR TAPE READER IS SHUT
DOWN
[] TRAFFIC CONTROL IS FULLY INITIALIZED BY CREATING IDLE
PROCESSES FOR THE OTHER CPUS AND STARTING THEM
[] ALL INITIALIZATION SEGMENTS ARE NOW DISCARDED, AND WHAT HAS
BECOME THE Initializer.SysDaemon PROCESS CALLS init_proc AND
BEGINS EXECUTION IN RING ONE
[] AT THIS POINT, SUPERVISOR INITIALIZATION IS FINISHED
Not To Be Reproduced 11-14 MDD-003
_C_O_L_L_E_C_T_I_O_N__3
ox COLLECTION THREE IS NOT PROPERLY A "COLLECTION" AT ALL, BUT JUST A
TERM USED TO DESCRIBE THE BEGINNING OF Initializer AND ANSWERING
SERVICE INITIALIZATION
[] MANY THINGS HAPPEN BETWEEN FIRST LEAVING RING ZERO AND LOGGING
IN THE FIRST USER. MOST HAVE NOTHING TO DO WITH THE FILE
SYSTEM. THE FEW MOST INTERESTING ONES ARE:
[] VOLUME ACCEPTANCE - THE NON-ROOT VOLUMES ARE INSPECTED AND
ACCEPTED INTO THE HIERARCHY. THEIR CONFIGURATION CAN BE
CHANGED BY USE OF OPERATOR COMMANDS
[] delete_old_pdds - THE PROCESS DIRECTORY AND DECIDUOUS
SEGMENTS LEFT OVER FROM THE PREVIOUS BOOTLOAD(S) ARE DELETED
[] THIS MUST BE DONE AFTER THE HIERARCHY IS FULLY AVAILABLE,
SINCE NON-RLV VOLUMES MAY HAVE BEEN USED FOR PROCESS DIRS
[] VOLUME SCAVENGER AND QUOTA SALVAGER PROCESSES MAY BE STARTED
AT THIS TIME, IF THERE ARE INCONSISTENCIES IN THE HIERARCHY
CAUSED BY PREVIOUS CRASHES
Not To Be Reproduced 11-15 MDD-003
_N_O_R_M_A_L__S_H_U_T_D_O_W_N
ox WHEN THE SYSTEM IS SHUT DOWN, IT MUST BE DONE IN AN ORDERLY MANNER
[] THIS IS ACCOMPLISHED, MORE OR LESS, BY RUNNING THE STEPS IN
INITIALIZATION BACKWARDS:
[] CRAWLOUTS ARE DISABLED. ONCE SHUTDOWN BEGINS, IT CAN'T BE
STOPPED
[] THE Initializer SWITCHES TO RUNNING ON THE BOOTLOAD CPU,
TRAFFIC CONTROL IS DISABLED, AND THE OTHER CPUS ARE STOPPED
AND DELETED.
[] LOCKING IS DISABLED AT THIS POINT, SINCE THERE IS NOW ONLY
ONE PROCESS AND ONE PROCESSOR RUNNING
[] ALL THE DISK DRIVES ARE EXERCISED, TO DETERMINE IF ANY ARE
BROKEN AND CANNOT BE SHUT DOWN
[] ANY VOLUME SCAVENGES IN PROGRESS ARE STOPPED AND ABANDONED
[] AT THIS POINT, NORMAL SHUTDOWN IS READY TO SHUT DOWN THE FILE
SYSTEM, AND ALL THE NORMAL MECHANISMS ARE ASSUMED TO BE
OPERATING.
[] THE Initializer SWITCHES TO inzr_stk0 (WHERE IT ALL STARTED) AND
CALLS shutdown_file_system
Not To Be Reproduced 11-16 MDD-003
_F_I_L_E__S_Y_S_T_E_M__S_H_U_T_D_O_W_N
ox FILE SYSTEM SHUTDOWN CONSISTS OF FORCING ALL DATA OUT OF MEMORY TO
ITS HOME ON DISK:
[] ALL PAGES ARE WRITTEN
[] SEGMENTS ARE DEACTIVATED, AND THEIR VTOCES UPDATED
[] VOLUMES ARE DEMOUNTED, AND THEIR LABELS UPDATED
[] FILE SYSTEM SHUTDOWN TAKES THE FOLLOWING STEPS:
[] ALL MODFIED PAGES ARE WRITTEN TO DISK. THIS IS DONE SEVERAL
TIMES DURING THE COURSE OF SHUTDOWN
[] STACK_0 SEGMENTS ARE DEACTIVATED AND DISCARDED
[] THE deactivate_for_demount PROCEDURE IS CALLED TO DEACTIVATE
ALL OTHER SEGMENTS AND UPDATE THEIR VTOCES
[] THIS IS DONE BY WALKING THE AST HIERARCHY FROM THE BOTTOM
UP, DEACTIVATING A SEGMENT, ITS SIBLINGS, AND ITS PARENTS,
ETC.
[] THIS IS DONE TO ENSURE CONSISTENT QUOTA VALUES IN VTOCES
AFTER SHUTDOWN, BECAUSE QUOTA MUST BE UPDATED FROM THE
BOTTOM UP
[] ALL VOLUMES ARE DEMOUNTED, THEIR VOUME AND VTOC MAPS UPDATED,
AND LABELS CHANGED TO INDICATE SUCCESSFUL DEMOUNT
[] THE ORDER IS NOT IMPORTANT, EXCEPT THAT THE RPV GOES LAST
Not To Be Reproduced 11-17 MDD-003
_F_I_L_E__S_Y_S_T_E_M__S_H_U_T_D_O_W_N
[] MEMORY IS FLUSHED AGAIN
[] IF ANY DRIVES WERE INOPERATIVE, THIS IS ANNOUNCED, AND THE
RPV IS _N_O_T DEMOUNTED
[] THIS MAKES IT POSSIBLE TO FIX THE BROKEN DRIVE AND DO AN
EMERGENCY SHUTDOWN TO FINISH SHUTDOWN
[] IF THERE WERE NO PROBLEMS, THE RPV IS DEMOUNTED AND MEMORY IS
FLUSHED ONE LAST TIME. ALL RELEVANT INFORMATION IS NOT ON
DISK
[] AT THE END OF FILE SYSTEM SHUTDOWN, ALL CONSOLE MESSAGES ARE
ALLOWED TO COMPLETE, AND THE SYSTEM RETURNS TO BOS
Not To Be Reproduced 11-18 MDD-003
_E_M_E_R_G_E_N_C_Y__S_H_U_T_D_O_W_N
ox EMERGENCY SHUTDOWN IS DONE AFTER A CRASH OR SHUTDOWN FAILURE
[] LIKE NORMAL SHUTDOWN, THE MISSION OF ESD IS TO SHUT DOWN THE
FILE SYSTEM, AND IT DOES THIS BY MAKING THE SYSTEM WORK WELL
ENOUGH TO CALL shutdown_file_system
[] UNLIKE NORMAL SHUTDOWN, IT CANNOT ASSUME THAT NORMAL MECHANISMS
ARE OPERATIONAL, AND MUST MAKE THEM WORK FIRST
[] AFTER THE SUPERVISOR IS MADE OPERATIONAL, EMERGENCY SHUTDOWN
TRANSFERS TO THE NORMAL FILE SYSTEM SHUTDOWN
[] THE FOLLOWING STEPS ARE TAKEN TO REANIMATE THE SUPERVISOR:
[] EMERGENCY SHUTDOWN STARTS OUT RUNNING IN ABSOLUTE MODE
[] IT ENTERS APPENDING MODE, FINDS THE PRDS FOR THE PROCESSOR IT
IS RUNNING ON, SETS IT UP AS ITS STACK
[] ALL CRITICAL LOCKS (PAGE TABLE, APT) ARE FORCIBLY UNLOCKED.
TRAFFIC CONTROL IS DISABLED. THE PROCESSOR RUNNING IS NOW
THE ONLY ONE, AND LOCKS ARE UNNECESSARY
[] THE CONSOLE AND SYSERR MECHANISMS ARE RESET
[] SUPERVISOR I/O SUPPORT, IN PARTICULAR THE DISK DIM, IS
REINITIALIZED
[] THE STATE OF PAGE TABLES AND THE CORE MAP IS MADE CONSISTENT
[] THIS IS DONE BY pc_recover_sst AND CAN BE DONE ONLY
Not To Be Reproduced 11-19 MDD-003
_E_M_E_R_G_E_N_C_Y__S_H_U_T_D_O_W_N
BECAUSE ALL OF PAGE CONTROL IS CODED TO FOLLOW PROTOCOLS
ABOUT THE ORDER IN WHICH TO UPDATE RELATED DATA
[] BECAUSE OF THIS, IF PAGE CONTROL IS INTERRUPTED AT ANY
POINT, IT IS POSSIBLE TO DETERMINE WHAT IT WAS DOING AND
COMPLETE THE OPERATION
[] THIS STEP IS CRUCIAL TO BEING ABLE TO TAKE PAGE FAULTS
LATER IN SHUTDOWN
[] BECAUSE THERE IS NO GUARANTEE THAT THE PROCESS WHICH CRASHED
THE SYSTEM (AND THUS, THE ADDRESS SPACE WHERE ESD IS RUNNING)
IS NOT DEFECTIVE, ESD REBUILDS ITS PDS FROM THE template_pds
[] ESD SWITCHES TO THE inzr_stk0 AND CALLS wired_shutdown
[] ALL THE ABOVE STEPS WERE DONE IN ALM. wired_shutdown IS A
PL/I PROCEDURE
[] THE VTOC BUFFER IS CHECKED TO SEE WHETHER ANY OPERATIONS WERE
IN PROGRESS. IF SO, THOSE VOLUMES ARE MARKED (IN THE PVT) TO
INDICATE THAT THEY MAY HAVE INCONSISTENCIES
[] MEMORY IS FLUSHED
[] THE VTOC MANAGER IS REINITIALIZED
[] AT THIS POINT, THE SUPERVISOR SHOULD BE WORKING WELL ENOUGH
TO RUN shutdown_file_system. FROM NOW ON, EMERGENCY SHUTDOWN
FOLLOWS THE SAME PATH AS NORMAL SHUTDOWN
[] IF EMERGENCY SHUTDOWN FAILS, FOR TAKING A FAULT OR SOME OTHER
REASON, IT CAN BE RETRIED INDEFINITELY
[] SHUTDOWN IS MARKED COMPLETE IN VOLUME LABELS, AND THESE ARE NOT
UPDATED UNTIL THE VERY END. THUS, NO HARM CAN COME FROM
RETRYING ARBITRARILY
Not To Be Reproduced 11-20 MDD-003
_E_M_E_R_G_E_N_C_Y__S_H_U_T_D_O_W_N
[] ESD TRIES TO CORRECT ALL THE PROBLEMS THAT MIGHT ARISE.
BECAUSE OF THE COMPLEXITY OF THE SUPERVISOR, IT DOES NOT
ALWAYS GET ALL OF THEM
TOPIC XII
File System Salvagers
Page
Overview of Salvagers . . . . . . . . . . . . 12-1
Directory Salvager. . . . . . . . . . . . . . 12-4
Quota Salvaging . . . . . . . . . . . . . . . 12-7
Physical Volume Scavenger . . . . . . . . . . 12-9
Physical Volume Salvager. . . . . . . . . . . 12-11
sweep_pv. . . . . . . . . . . . . . . . . . . 12-12
12-i MDD-003
_E_M_E_R_G_E_N_C_Y__S_H_U_T_D_O_W_N
ox FUNCTION
[] ENSURE THE CONSISTENCY OF THE FILE SYSTEM DATABASES AND PERFORM
PERIODIC PREVENTIVE MAINTENANCE OPERATIONS
[] THERE ARE SEVERAL SALVAGERS, EACH WITH A DIFFERENT FUNCTION
[] BECAUSE OF THE COMPLICATED INTERACTIONS THEY HAVE WITH THE REST
OF THE FILE SYSTEM, THE SALVAGERS ARE PERHAPS THE MOST
COMPLICATED SINGLE PROGRAMS IN THE SUPERVISOR
[] SOME SALVAGING IS DONE AUTOMATICALLY, WHEN THE SYSTEM DETECTS AN
INCONSISTENCY. OTHER SALVAGE OPERATIONS ARE EXPLICITLY
REQUESTED, BY PRIVILEGED USERS.
[] EXCEPT FOR SUPERVISOR BUGS, THE ONLY TIME DAMAGE OCCURS THAT
REQUIRES SALVAGING TO FIX IS AFTER A CRASH WHERE EMERGENCY
SHUTDOWN FAILS
ox THE SALVAGERS:
[] DIRECTORY SALVAGER
[] CORRECTS INCONSISTENCIES IN DIRECTORY SEGMENTS BY REBUILDING
THEM
Not To Be Reproduced 12-0 MDD-003
_O_V_E_R_V_I_E_W__O_F__S_A_L_V_A_G_E_R_S
[] THIS IS THE ONLY SALVAGER INVOKED AUTOMATICALLY IN USER
PROCESSES: ANY ATTEMPT TO LEAVE RING ZERO WITH A DIRECTORY
LOCKED FOR WRITING WILL CAUSE IT TO BE SALVAGED
[] DIRECTORY SALVAGING ALSO RECLAIMS WASTED SPACE IN THE
DIRECTORY, AND IS RUN PERIODICALLY TO COMPACT DIRECTORIES
[] QUOTA SALVAGER
[] CORRECTS INCONSISTENCIES IN THE QUOTA SYSTEM
[] PHYSICAL VOLUME SCAVENGER
[] RECONSTRUCTS RECORD AND VTOCE STOCK INFORMATION FROM THE
VTOCES ON A VOLUME, THEREBY RECLAIMING ANY RECORDS OR VTOCES
WHICH MIGHT HAVE BEEN LOST
[] RUNS ENTIRELY ONLINE WHILE THE SYSTEM IS UP FOR USERS (NEW IN
MR10.1)
[] THIS TYPE OF DAMAGE IS USUALLY BENIGN, SO RUNNING THE
SCAVENGER CAN BE DELAYED.
[] PHYSICAL VOLUME SALVAGER
[] RECONSTRUCTS RECORD AND VTOCE STOCK INFORMATION
[] RUNS ONLY DURING INITIALIZATION, AND THEREFORE DELAYS CRASH
RECOVERY
[] NOW USED ONLY FOR RARE CASES WHERE THERE IS NOT ENOUGH FREE
SPACE LEFT FOR THE SCAVENGER TO RUN. IN THESE RARE CASES, IT
IS INVOKED AUTOMATICALLY BY SYSTEM INITIALIZATION.
Not To Be Reproduced 12-1 MDD-003
_O_V_E_R_V_I_E_W__O_F__S_A_L_V_A_G_E_R_S
[] SWEEP_PV
[] DELETES UNUSED VTOC ENTRIES WHICH HAVE NO DIRECTORY ENTRY
POINTING TO THEM
[] RUNS ENTIRELY IN USER RING, EXCEPT FOR ACTUALLY READING VTOC
ENTRIES AND DIRECTORY ENTRIES
[] PURELY A HOUSEKEEPING FUNCTION, AND RUN ONLY RARELY.
Not To Be Reproduced 12-2 MDD-003
_D_I_R_E_C_T_O_R_Y__S_A_L_V_A_G_E_R
ox THE DIRECTORY SALVAGER IS USED FOR TWO MAIN PURPOSES: DAMAGE
CORRECTION AND STORAGE RECLAIMATION
ox DIRECTORY DAMAGE
[] DAMAGE CAN OCCUR IN A DIRECTORY FOR SEVERAL REASONS:
[] DISK I/O ERROR WRITING BAD DATA TO A DIRECTORY SEGMENT
[] SUPERVISOR BUG
[] CRASH WITHOUT ESD, WHERE THE DIRECTORY WAS UPDATED, BUT NOT
FULLY WRITTEN TO DISK
[] ACTUAL DAMAGE TO DIRECTORIES IS COMPARATIVELY RARE, BUT:
[] IF A FAULT OCCURS FOR ANY REASON WHILE A USER HAS A DIRECTORY
LOCKED, THE SYSTEM ASSUMES THE DIRECTORY COULD BE AT FAULT,
AND SALVAGES
[] THIS SORT OF SALVAGING IS DONE BY THE online_salvager
PROGRAM, WHICH IS INVOKED DYNAMICALLY BY verify_lock IF A
PROCESS ATTEMPTS TO LEAVE RING ZERO ("CRAWL OUT") WITH A
DIRECTORY LOCKED
[] ORDINARILY, THERE IS NOTHING WRONG, AND THE SALVAGER JUST
CHECKS OVER THE DIRECTORY
[] IF THE DIRECTORY IS DAMAGED, IT IS "REPAIRED" AS WELL AS
POSSIBLE
Not To Be Reproduced 12-3 MDD-003
_D_I_R_E_C_T_O_R_Y__S_A_L_V_A_G_E_R
[] UNFORTUNATELY, THE MOST COMMON FORMS OF DAMAGE DESTROY THE
DIRECTORY HEADER SO THAT NO REPAIR IS POSSIBLE, AND THE
DIRECTORY MUST BE REINITIALIZED AS EMPTY
ox STORAGE RECLAIMATION
[] DIRECTORY SPACE CANNOT ALWAYS BE EFFICIENTLY RE-USED, AND
UNUSABLE SPACE ACCUMULATES AS ENTRIES ARE CREATED AND DELETED
[] IT IS NOT PRACTICAL FOR THE SYSTEM TO COMPACT DIRECTORIES
WHEN THIS HAPPENS, SINCE THIS COULD CAUSE MAJOR RESOURCE
CONSUMPTION, AND CAUSE EXPENSE FOR RANDOM PROCESSES
[] INSTEAD, THE DIRECTORY SALVAGER IS PERIODICALLY RUN IN
Salvager.SysDaemon PROCESSES TO REBUILD ALL THE DIRECTORIES
IN THE HIERARCHY, COLLECTING ALL FREE SPACE
[] THIS IS DONE BY CALLS TO hphcs_$salv_directory
[] IF THE Salvager PROCESSES DETECT DAMAGE, IT IS CORRECTED AS
WELL
[] DEMAND DIRECTORY SALVAGING IS USUALLY ALSO INSTRUCTED TO LOOK
FOR AND CORRECT "CONNECTION FAILURES"
[] A CONNECTION FAILURE IS A DIRECTORY BRANCH WHICH INDICATES
A FREE VTOCE, OR A VTOCE WITH A DIFFERENT UID THAN THE
BRANCH. THIS MEANS THAT THE DIRECTORY AND VTOC ARE
INCONSISTENT
[] CONNECTION FAILURES ARE USUALLY DELETED BY DEMAND
SALVAGING (THIS IS AN OPTION)
[] ONLINE SALVAGING DOES NOT DELETE CONNECTION FAILURES
BECAUSE IT IS NOT ALWAYS POSSIBLE TO IDENTIFY THEM
PROPERLY DURING AN ONLINE SALVAGE
Not To Be Reproduced 12-4 MDD-003
_D_I_R_E_C_T_O_R_Y__S_A_L_V_A_G_E_R
[] DEMAND DIRECTORY SALVAGING CAN ALSO BE USED BY SYSTEM
MAINTENANCE PERSONNEL WHEN THERE APPEAR TO BE DIRECTORY PROBLEMS
Not To Be Reproduced 12-5 MDD-003
_Q_U_O_T_A__S_A_L_V_A_G_I_N_G
ox QUOTA SALVAGING CORRECTS INCONSISTENCIES IN THE HIERARCHY OF
QUOTA-USED VALUES
[] THESE INCONSISTENCIES ARISE AFTER A CRASH WHERE ESD FAILS:
[] A SEGMENT (>udd>a>b) IS DELETED, FREEING PAGES, AND THE ASTES
OF ITS PARENT (>udd>a) AND ITS PARENT'S PARENT (>udd) ARE
UPDATED TO REFLECT THIS DECREASE IN QUOTA USED
[] THE VTOCE FOR >udd>a IS WRITTEN TO DISK DURING NORMAL
OPERATION. THE VTOCE FOR >udd IS NOT
[] THE SYSTEM CRASHES, AND NO ESD IS PERFORMED
[] WHEN THE SYSTEM COMES BACK UP, THE VTOCE FOR >udd IS
INACCURATE: IT CLAIMS THAT RECORDS ARE STILL IN USE, WHEN IN
FACT THEY WERE FREED
[] IF A NEW SEGMENT (>udd>a>c) IS NOW CREATED, IT MAY SPURIOUSLY
CAUSE A RECORD QUOTA OVERFLOW ON >udd.
[] QUOTA SALVAGING IS PERFORMED ENTIRELY ONLINE, WHILE THE SYSTEM
IS RUNNING, USUALLY IN A Salvager.SysDaemon PROCESS
[] THE FUNDAMENTAL PRINCIPLE BEHIND THE QUOTA SALVAGER IS THAT
QUOTA INCONSISTENCIES CANNOT ARISE DURING NORMAL OPERATION:
IF QUOTA IS CONSISTENT, OR INCONSISTENT BY _n RECORDS, IT WILL
STAY THAT WAY UNLESS EXPLICITLY CORRECTED
[] THE QUOTA SALVAGER PROCESS WALKS THE HIERARCHY FROM THE
BOTTOM UP, USING do_subtree, CORRECTING INCONSISTENCIES IN A
DIRECTORY AND ALL ITS SIBLINGS, THEN IN THEIR PARENT, AND SO
ON UP
Not To Be Reproduced 12-6 MDD-003
_Q_U_O_T_A__S_A_L_V_A_G_I_N_G
[] AN hphcs_ ENTRY IS CALLED TO CORRECT EACH DIRECTORY, ON THE
ASSUMPTION THAT ALL ITS CHILDREN ARE CONSISTENT
[] THE ACTUAL CORRECTION MECHANISM INVOLVES COMPLICATED
MANIPULATION OF VARIOUS LOCKS. REFER TO THE Multics
Storage System PLM (AN61) FOR A DESCRIPTION
Not To Be Reproduced 12-7 MDD-003
_P_H_Y_S_I_C_A_L__V_O_L_U_M_E__S_C_A_V_E_N_G_E_R
ox THIS IS ALSO PRIMARILY USEFUL AFTER A CRASH WITHOUT ESD
[] IT REBUILDS THE VOLUME MAP AND VTOC MAP FOR A VOLUME BY
EXAMINING ALL THE VTOCES AND ASTES FOR SEGMENTS ON THE VOLUME
[] IT RUNS WHILE THE VOLUME IS IN USE BY USERS, AND NO INTERRUPTION
OF SERVICE OCCURS
[] DAMAGE TO THE MAPS OCCURS AFTER A CRASH WHEN THE STOCKS, IN
MEMORY, DO NOT GET PROPERLY UPDATED TO THE MAPS ON DISK
[] BECAUSE OF THE STOCK MANAGEMENT POLICIES, THIS IS ALWAYS
BENIGN: RECORDS MAY BE MARKED IN-USE THAT ARE NOT, BUT IT IS
NOT POSSIBLE FOR THE MAP TO INDICATE A RECORD AS FREE
(REUSABLE) WHEN IT BELONGS TO A SEGMENT ON THE VOLUME
[] FOR RECONSTRUCTING THE VOLUME MAP, THE SCAVENGER WORKS BY AN
INTERACTION WITH THE PAGE CONTROL RECORD ALLOCATION MECHANISM
[] IT BUILDS A MAP, IN scavenger_data, THAT SAYS WHAT VTOCE OWNS
EACH RECORD ON THE VOLUME, AND THEN RESOLVES THE
INCONSISTENCIES BETWEEN THAT AND THE MAP ON DISK
[] THE DATABASE IS WIRED FOR THE DURATION OF THE SCAVENGE,
AND CAN BE QUITE LARGE (64K FOR AN MSU0501)
[] WHILE A SCAVENGER IS RUNNING, PAGE CONTROL KEEPS THE
DATABASE UP TO DATE AS IT ALLOCATES AND FREES RECORDS
[] FOR VTOCES, THE PROBLEM IS MUCH SIMPLER: THE VTOC IS SIMPLY
SCANNED, AND ALL IN-USE VTOCES ARE RECORDED
Not To Be Reproduced 12-8 MDD-003
_P_H_Y_S_I_C_A_L__V_O_L_U_M_E__S_C_A_V_E_N_G_E_R
[] vtoc_man ALSO KEEPS THE TABLE UP TO DATE AS IT FREES AND
ALLOCATES VTOCES ON THE VOLUME
[] A VTOCE THAT APPEARS IN-USE MAY NOT NECESSARILY BE PART OF
THE HIERARCHY -- sweep_pv IS RUN TO TAKE CARE OF THAT
[] AFTER THE NEW MAPS ARE CONSTRUCTED, THEY ARE WRITTEN TO DISK
[] THE SCAVENGE RUNS ENTIRELY IN RING ZERO, BUT IT CAN BE SAFELY
INTERRUPTED AND RESTARTED FROM THE BEGINNING AT ANY TIME
[] THE SCAVENGER ACCESSES THE VTOC USING vtoc_man
[] THE SCAVENGER TAKES ABOUT FIFTEEN MINUTES PER VOLUME, BUT THE
SYSTEM IS UP WHILE IT DOES SO
Not To Be Reproduced 12-9 MDD-003
_P_H_Y_S_I_C_A_L__V_O_L_U_M_E__S_A_L_V_A_G_E_R
ox THIS DOES THE SAME JOB AS THE SCAVENGER, BUT CAN RUN ONLY WHEN THE
VOLUME IS UNAVAILABLE TO USERS
[] BECAUSE IT HAS THE VOLUME ALL TO ITSELF, IT IS MUCH SIMPLER:
[] IT SCANS THE VTOC, BUILDING THE SAME SORT OF DATABASES AS THE
SCAVENGER
[] WHEN FINISHED, IT RESOLVES INCONSISTENCIES, AND WRITES THE
MAPS BACK TO DISK
[] THE VOLUME SALVAGER ACCESSES THE VTOC USING
salv_abs_seg_NN
[] THE VOLUME SALVAGER TAKES ABOUT A MINUTE AND A HALF PER VOLUME,
BUT ALL VOLUMES MUST BE SALVAGED BEFORE THE SYSTEM CAN RUN AGAIN
[] AFTER A CRASH WITHOUT ESD, _A_L_L VOLUMES MOUNTED AT THE TIME OF
THE CRASH ARE PRESUMED TO BE INCONSISTENT
[] THE VOLUME SALVAGER IS LARGELY OBSOLETE TODAY. IT IS RETAINED
TO DEAL WITH RARE SITUATIONS WHICH MAKE IT IMPOSSIBLE TO BRING
THE SYSTEM UP FAR ENOUGH TO RUN THE SCAVENGER WITHOUT FIRST
REBUILDING THE FILE MAP TO FREE UNUSED SPACE
Not To Be Reproduced 12-10 MDD-003
_S_W_E_E_P__P_V
ox sweep_pv ELIMINATES ORPHAN VTOCES
[] AN ORPHAN VTOCE IS ONE WHICH APPEARS TO DESCRIBE A VALID
SEGMENT, BUT DOES NOT APPEAR IN ANY DIRECTORIES
[] ORPHANS ARE USUALLY CREATED BY CRASHES OR DIRECTORY DAMAGE
WHERE THE DIRECTORY COULD NOT BE REPAIRED
[] ORPHANS ARE ALSO SOMETIMES CALLED "REVERSE CONNECTION
FAILURES"
[] sweep_pv WORKS BY INSPECTING EVERY VTOCE ON A VOLUME, AND
ATTEMPTING TO FIND ITS PARENT
[] THERE IS A "UID PATHNAME" IN PART 3 OF ALL VTOCES WHICH
CONTAINS THE UIDS OF ALL ITS PARENT DIRECTORIES
[] BY STARTING FROM THE ROOT, AND SEARCHING EACH DIRECTORY IN
THE PATH FOR THE UID OF THE NEXT ONE, THE VTOCE CAN BE FOUND
[] IF IT CAN'T BE FOUND, IT IS AN ORPHAN, AND SWEEP_PV
DELETES IT
[] IT IS POSSIBLE TO "ADOPT" ORPHANS INTO A DIFFERENT PLACE IN THE
HIERARCHY IF IT IS IMPORTANT TO RECOVER THEIR CONTENTS, USING
THE adopt_seg TOOL
[] THE UID PATHNAME OF A VTOCE CAN BE INTERPRETED MANUALLY BY USING
THE vtoc_pathname TOOL
TOPIC XIII
13-i MDD-003
_S_W_E_E_P__P_V
The Initializer.SysDaemon Process
Page
Initializer Overview. . . . . . . . . . . . . 13-1
Services of Initializer . . . . . . . . . . . 13-3
13-i MDD-003
_I_N_I_T_I_A_L_I_Z_E_R__O_V_E_R_V_I_E_W
ox FUNCTION
[] THE SYSTEM'S INITIALIZATION, ADMINISTRATIVE AND CONTROL PROCESS
(Initializer.SysDaemon.z), RESPONSIBLE FOR:
[] INITIALIZING THE OPERATING SYSTEM AT BOOTLOAD, FOLLOWING
SUCCESSFUL INITIALIZATION OF THE SUPERVISOR
[] ANSWERING SERVICE (login and logout)
[] PROCESS CREATION AND DESTRUCTION
[] MESSAGE COORDINATOR (DAEMON COORDINATION)
[] SYSTEM ADMINISTRATION FUNCTIONS
[] SYSTEM ACCOUNTING FUNCTIONS
ox MAJOR DATA BASES, ALL KEPT IN >sc1
[] ANSWER_TABLE
[] ABSENTEE_USER_TABLE
[] DAEMON_USER_TABLE
Not To Be Reproduced 13-1 MDD-003
_I_N_I_T_I_A_L_I_Z_E_R__O_V_E_R_V_I_E_W
[] MASTER GROUP TABLE (MGT)
[] CHANNEL DEFINITION TABLE (CDT)
[] SYSTEM ADMINISTRATION TABLE (SAT)
[] PERSON NAME TABLE (PNT)
[] PROJECT DEFINITION TABLES (PDT'S)
Not To Be Reproduced 13-2 MDD-003
_S_E_R_V_I_C_E_S__O_F__I_N_I_T_I_A_L_I_Z_E_R
ox THE Initializer.SysDaemon PROCESS PERFORMS VARIOUS SERVICES
NECESSARY FOR THE SUPERVISOR. MANY OF THEM ARE PERFORMED BY THE
INITIALIZER PRIMARILY FOR CONVENIENCE, SINCE IT IS EASIER TO
CONTROL RESOURCES IN A CONTROLLED ENVIRONMENT SUCH AS A SINGLE
PROCESS THAN TO CREATE A MECHANISM WHICH CAN BE RUN IN ALL
PROCESSES
[] SYSTEM INITIALIZATION AND SHUTDOWN
[] THE Initializer PROCESS IS CREATED FROM THE ENVIRONMENT THAT
INITIALIZES THE SUPERVISOR
[] WHEN THE SYSTEM IS SHUT DOWN, THE Initializer COORDINATES THE
ORDERLY CESSATION OF SYSTEM ACTIVITY AND CALLS
hphcs_$shutdown TO SHUT DOWN THE SUPERVISOR
[] LOGICAL VOLUME MANAGEMENT
[] THE Initializer PROCESS HANDLES ALL REQUESTS FROM USER
PROCESSES TO MOUNT AND UNMOUNT PRIVATE LOGICAL VOLUMES
[] IT ALSO MAKES THE NECESSARY CHECKS TO ACCEPT A VOLUME INTO
THE HIERARCHY OR REMOVE IT FOR DEMOUNTING
[] RESOURCE CONTROL
[] THE Initializer DOES ALL THE CONTROL, ASSIGNMENT, AND ACCESS
CHECKING OF RESOURCES (SUCH AS I/O DEVICES) CONTROLLED BY RCP
[] PROCESS CREATION AND DESTRUCTION
Not To Be Reproduced 13-3 MDD-003
_S_E_R_V_I_C_E_S__O_F__I_N_I_T_I_A_L_I_Z_E_R
[] THE Initializer CREATES AND DESTROYS ALL PROCESSES, SCHEDULES
ABSENTEE PROCESSES, AND HANDLES "CONSOLE" I/O FROM DAEMON
PROCESSES
[] AN IMPORTANT SERVICE OF PROCESS MANAGEMENT IS PROCESS DIR
VOLUME MANAGEMENT, IN WHICH THE Initializer PICKS THE LOGICAL
VOLUMES USED FOR PROCESS DIRECTORIES
[] THE Initializer ALSO HANDLES ALL PROCESS ACCOUNTING AND LOAD
CONTROL
[] COMMUNICATIONS
[] THE Initializer MANAGES LOADING / DUMPING OF FNPs AND
SOFTWARE COMMUNICATIONS MULTIPLEXERS
[] IT ALSO HANDLES ALLOCATION OF COMMUNICATION CHANNELS, BOTH
FOR PROCESSES LOGGING IN AND REQUESTS MADE THROUGH
dial_manager_
[] DYNAMIC RECONFIGURATION
[] THE Initializer RUNS THE DYNAMIC RECONFIGURATION SOFTWARE,
AND UPDATES THE SYSTEM LOAD LIMITS WHEN THE CONFIGURATION
CHANGES
[] ACTUALLY, ANY PROCESS WITH hphcs_ ACCESS CAN USE THE
RECONFIGURATION COMMANDS, BUT ONLY THE Initializer CAN KEEP
ALL THE ACCOUNTING DATABASES UP TO DATE
TOPIC XIV
Metering and Tuning
Page
14-i MDD-003
_S_E_R_V_I_C_E_S__O_F__I_N_I_T_I_A_L_I_Z_E_R
Meter and Tuning Overview . . . . . . . . . . 14-1
Analyzing Performance Problems. . . . . . . . 14-3
Detailed Problem Analysis . . . . . . . . . . 14-6
Output From Metering Commands . . . . . . . . 14-8
total_time_meters . . . . . . . . . . . . 14-8
interrupt_meters. . . . . . . . . . . . . 14-9
file_system_meters. . . . . . . . . . . . 14-10
file_system_meters. . . . . . . . . . . . 14-12
device_meters . . . . . . . . . . . . . . 14-14
disk_meters . . . . . . . . . . . . . . . 14-15
disk_queue. . . . . . . . . . . . . . . . 14-16
print_configuration_deck. . . . . . . . . 14-17
list_vols . . . . . . . . . . . . . . . . 14-19
traffic_control_queue . . . . . . . . . . 14-21
traffic_control_meters. . . . . . . . . . 14-23
print_tuning_parameters . . . . . . . . . 14-25
work_class_meters . . . . . . . . . . . . 14-26
respons_meters. . . . . . . . . . . . . . 14-27
system_performance_graph. . . . . . . . . 14-29
meter_gate. . . . . . . . . . . . . . . . 14-31
14-i MDD-003
.
_M_E_T_E_R__A_N_D__T_U_N_I_N_G__O_V_E_R_V_I_E_W
ox WHILE NOT A SUBSYSTEM ITSELF, METERING AND TUNING IS A POLICY AND
CAPABILITY COMMON TO ALL OF THE SUPERVISOR'S SUBSYSTEMS
ox FUNCTION
[] METERING (CONSISTS OF THREE ACTIVITIES)
[] ACCUMULATING DATA: THIS IS PERFORMED THROUGHOUT THE
SUPERVISOR BY CODE WHICH
[] RECORDS THE NUMBER OF TIMES AN EVENT HAPPENS OR A
PARTICULAR PIECE OF CODE IS EXECUTED; AND/OR
[] RECORDS THE TIME REQUIRED TO PERFORM A TASK
[] SUCH DATA IS STORED IN AREAS REFERRED TO AS "METERING
CELLS"
[] EXTRACTING DATA: THIS IS PERFORMED BY NUMEROUS METERING
COMMANDS WHICH (WHEN INVOKED)
[] READ AND STORE THE CURRENT VALUES OF RELEVANT METERING
CELLS
[] REPORTING THE DATA: THIS IS PERFORMED BY THE METER COMMANDS
WHICH (WHEN INVOKED)
[] COMPARE CURRENT METERING CELL VALUES WITH PREVIOUSLY READ
VALUES
[] PERFORM THE APPROPRIATE ARITHMETIC COMPUTATIONS UPON THE
DATA IN ORDER TO ARRIVE AT THE DESIRED STATISTIC
[] ARRANGE THE DATA IN A USEFUL FORMAT (A REPORT OR DIAGRAM)
AND PRINT IT
Not To Be Reproduced 14-1 MDD-003
_M_E_T_E_R__A_N_D__T_U_N_I_N_G__O_V_E_R_V_I_E_W
[] TUNING
[] CHANGING THE SYSTEM'S OPERATING PARAMETERS AND/OR
CONFIGURATION BASED UPON THE DATA AND INSIGHTS FROM THE
SYSTEM'S METERS
ox MAJOR DATA BASES
[] SST HEADER, TC_DATA HEADER, ETC.
Not To Be Reproduced 14-2 MDD-003
_A_N_A_L_Y_Z_I_N_G__P_E_R_F_O_R_M_A_N_C_E__P_R_O_B_L_E_M_S
ox MULTICS IS VERY HEAVILY INSTRUMENTED WITH MANY METERING COMMANDS
[] MOST SOLVABLE PERFORMANCE PROBLEMS SHOW UP QUITE DIRECTLY IN THE
METERS
[] IF THE SYSTEM IS TOO SLOW, THERE ARE GOOD RULES OF THUMB TO
FOLLOW TO LOOK FOR WHEN PROBLEM
[] NO TWO SYSTEMS ARE IDENTICAL - THE MOST IMPORTANT INFORMATION
YOU HAVE IS HOW THE METERS ARE _D_I_F_F_E_R_E_N_T FROM THE WAY THEY WERE
WHEN THE SYSTEM WAS WORKING BETTER
[] NOT ALL TUNING PROBLEMS CAN BE RESOLVED WITH SOFTWARE. OFTEN IT
SIMPLY INDICATES THAT THERE IS NOT ENOUGH MEMORY, OR NOT ENOUGH
DISK CAPACITY. IT IS OFTEN DIFFICULT TO DETERMINE WHAT HARDWARE
CHANGES WOULD BE MOST COST-EFFECTIVE
ox total_time_meters - THE FIRST STEP
[] total_time_meters MAY INDICATE EXCESSIVE TIME SPENT IN SEVERAL
AREAS:
[] PAGE FAULTS - TOO MANY PAGE FAULTS MEAN NOT ENOUGH MEMORY,
TOO MANY ELIGIBLE PROCESSES (max_eligible), WHICH CAUSE
THRASHING, INSUFFICIENT DISK CAPACITY, OR INEFFICIENT
APPLICATIONS
[] LOOK TO file_system_meters, device_meters, AND disk_meters
FOR MORE HELP
Not To Be Reproduced 14-3 MDD-003
_A_N_A_L_Y_Z_I_N_G__P_E_R_F_O_R_M_A_N_C_E__P_R_O_B_L_E_M_S
[] SEGMENT FAULTS - TOO MANY ALMOST ALWAYS MEAN THAT THE AST
POOLS (sst CONFIG CARD) ARE TOO SMALL
[] LOOK TO file_system_meters (AST Pool grace time) FOR MORE
HELP
[] INTERRUPT - USUALLY MEANS EXCESSIVE INTERRUPT ACTIVITY EITHER
FOR FNPS OR BECAUSE OF EXCESSIVE PAGING, BUT MAY INDICATE
HARDWARE PROBLEMS
[] LOOK TO interrupt_meters TO LOCALIZE IT, THEN TO
file_system_meters and system_comm_meters
[] OTHER FAULT - GENERALLY INDICATES TOO MANY CONNECT OR TIMER
RUNOUTS FAULTS, INDICATING EXCESSIVE TRAFFIC CONTROL ACTIVITY
[] LOOK TO THE TUNING PARAMETERS (ptp) AND
traffic_control_meters FOR MORE HELP
[] MP IDLE - INDICATES TOO MUCH TRAFFIC CONTROL ACTIVITY,
USUALLY BECAUSE THERE ARE TOO MANY ELIGIBLE PROCESSES
(max_eligible) AND/OR NOT ENOUGH MEMORY
[] LOOK TO THE TUNING PARAMETERS (ptp), file_system_meters,
device_meters, disk_meters, AND traffic_control_meters FOR
MORE HELP
[] WORK CLASS IDLE - THIS IS CPU TIME WASTED BECAUSE GOVERNED
WORKCLASSES WERE NOT PERMITTED TO USE IT, AND NO OTHER TAKERS
WANTED IT
[] FREQUENTLY NOT A PROBLEM, BUT MAY INDICATE A NEED TO
READJUST WORKCLASSES (work_class_meters)
[] NMP IDLE, ZERO IDLE - INDICATE THAT CPU TIME HAS GONE TO
WASTE BECAUSE NO PROCESSES WANTED IT. NMP IDLE MEANS THAT
THERE ARE MORE PROCESSORS THAN PROCESSES THAT WANT CPU TIME,
Not To Be Reproduced 14-4 MDD-003
_A_N_A_L_Y_Z_I_N_G__P_E_R_F_O_R_M_A_N_C_E__P_R_O_B_L_E_M_S
AND ZERO IDLE MEANS THERE ARE NO PROCESSES AT ALL
[] NORMALLY INSIGNIFICANT QUANTITIES - THE FOLLOWING NUMBERS
SHOULD ALWAYS BE VERY SMALL; LARGE VALUES PROBABLY INDICATE A
HARDWARE OR SOFTWARE PROBLEM
PC LOOP LOCKS
BOUND FAULTS
TC LOOP LOCKS
POST PURGING
LOADING IDLE
OTHER OVERHEAD
Not To Be Reproduced 14-5 MDD-003
_D_E_T_A_I_L_E_D__P_R_O_B_L_E_M__A_N_A_L_Y_S_I_S
ox THE MORE DETAILED METERING COMMANDS CAN BE USED TO PIN DOWN A
PROBLEM
[] DETAILED DESCRIPTIONS CAN BE FOUND IN THE Multics Metering
Manual (AN52)
[] THE DETAILED METERS SHOULD ALSO BE CHECKED IF THERE IS NO
OBVIOUS PROBLEM SHOWN BY total_time_meters
[] AGAIN, THE REALLY IMPORTANT THING IS TO BE ABLE TO COMPARE
AGAINST PREVIOUS DATA FOR YOUR SITE
ox SOME GOOD PLACES TO LOOK ARE:
[] interrupt_meters
[] UNUSUALLY LONG DISK INTERRUPTS MAY INDICATE LOCKING PROBLEMS
- SEE disk_meters
[] TOO MUCH TOTAL TIME SPENT WITH DISK INTERRUPTS USUALLY MEANS
TOO MANY PAGE FAULTS, WHICH WILL BE SHOWN IN MORE DETAIL BY
file_system_meters
[] FNP INTERRUPTS ARE TYPICALLY MUCH LONGER THAN OTHERS. TOO
MUCH FNP INTERRUPT TIME _M_A_Y INDICATE A BAD FRONT END CHANNEL,
BUT THIS IS RARE
Not To Be Reproduced 14-6 MDD-003
_D_E_T_A_I_L_E_D__P_R_O_B_L_E_M__A_N_A_L_Y_S_I_S
[] file_system_meters
[] A SHORT PAGE LAP TIME MEANS THAT PAGES ARE NOT STAYING IN
MEMORY LONG ENOUGH; THAT IS, THERE IS NOT ENOUGH MEMORY
[] FREQUENT PAGE CLAIM RUNS INDICATE THAT THE WRITE LIMIT IS TOO
LOW
[] IF THE AVERAGE PAGE FAULT DURATION IS HIGH, IT CAN MEAN THAT
THE WRITE LIMIT IS TOO HIGH, AND THAT DISK ALLOCATION LOCKS
ARE A LIMITATION; SEE disk_meters TO CHECK
[] SHORT AST POOL GRACE TIMES MEANS THAT THE POOL SIZES SHOULD
BE INCREASED. THIS IS USUALLY ALSO INDICATED BY TOO HIGH A
FREQUENCY OF SEGMENT FAULTS
[] disk_meters
[] WHEN THE ATB I/O FOR A DRIVE IS TOO LOW, THE DRIVE IS A
SERIOUS BOTTLENECK.
[] THIS OFTEN HAPPENS FOR RLV DRIVES, BECAUSE OF DIRECTORIES
[] IF PARM DIRW IS ON, IT SHOULD BE TURNED OFF
[] TOO HIGH A PERCENTAGE OF ALLOCATION LOCKS INDICATE THAT TOO
MANY WRITES ARE BEING QUEUED SIMULTANEOUSLY, AND MAKING IT
IMPOSSIBLE TO GET A QUEUE ENTRY FOR READING
[] THIS USUALLY MEANS THAT WRITE_LIMIT IS TOO HIGH
[] device_meters
[] IF THE SUBSYSTEM BUSY PERCENTAGE IS TOO CLOSE TO THE DISK
CHANNEL CAPACITY, IT USUALLY MEANS THAT THERE ARE TOO FEW
PHYSICAL DISK CHANNELS
Not To Be Reproduced 14-7 MDD-003
_O_U_T_P_U_T__F_R_O_M__M_E_T_E_R_I_N_G__C_O_M_M_A_N_D_S
_t_o_t_a_l__t_i_m_e__m_e_t_e_r_s
ox TOTAL_TIME_METERS - OVERVIEW OF HOW THE SYSTEM IS USING ITS
RESOURCES, ALSO MEASURED AGAINST NON-IDLE TIME
Total metering time 0:20:36
% %NI AVE
Page Faults 6.55 7.19 2130.424
PC Loop Locks 0.39 0.43 1993.209
PC Queue 0.86 0.94 348.946
Seg Faults 1.74 1.90 9579.170
Bound Faults 0.15 0.16 17426.208
Interrupts 9.02 9.89 1713.504
Other Fault 8.45 9.27
Getwork 4.54 4.98 660.550
TC Loop Locks 0.20 0.22 247.788
Post Purging 0.36 0.39 1407.132
MP Idle 0.70 0.77
Work Class Idle 0.98 1.08
Loading Idle 0.16 0.17
NMP Idle 8.84
Zero Idle 0.00
Other Overhead 0.03 0.04
Virtual CPU Time 62.53 68.59
Not To Be Reproduced 14-8 MDD-003
_O_U_T_P_U_T__F_R_O_M__M_E_T_E_R_I_N_G__C_O_M_M_A_N_D_S
_i_n_t_e_r_r_u_p_t__m_e_t_e_r_s
ox INTERRUPT_METERS - COUNTS & TIMING FOR ALL I/O INTERRUPTS
Total metering time 0:20:28
IOM Ch Int Avg Time % CPU Name
A 6. 11 2.043 0.00 IOM A special
A 10. 379 1.553 0.01 prtb
A 13. 9253 3.436 0.65 fnp c
A 14. 19 0.788 0.00 opc
A 16. 26248 1.347 0.72 tapa
A 17. 128 1.328 0.00 tapa
A 18. 13097 5.383 1.43 fnp b
A 20. 21041 0.860 0.37 dska
A 21. 2881 0.860 0.05 dska
A 22. 8486 0.877 0.15 dskb
A 23. 257 0.964 0.01 dskb
A 24. 17896 0.895 0.33 dskb
A 25. 2573 0.943 0.05 dskb
A 26. 10486 0.857 0.18 dska
A 27. 255 0.899 0.00 dska
A 28. 24717 0.845 0.43 dskc
A 29. 2319 0.849 0.04 dskc
A 30. 9915 0.845 0.17 dskc
A 31. 215 0.767 0.00 dskc
B 14. 236 0.877 0.00 fnp d
B 15. 6917 3.351 0.47 fnp f
B 18. 3547 3.543 0.26 fnp a
B 19. 13667 3.435 0.96 fnp e
B 20. 22013 0.881 0.39 dskb
B 21. 4745 0.863 0.08 dskb
B 22. 6054 0.861 0.11 dska
B 23. 60 0.925 0.00 dska
B 24. 15946 0.867 0.28 dska
B 25. 989 0.841 0.02 dska
B 26. 12757 0.863 0.22 dskb
B 27. 1020 0.903 0.02 dskb
B 28. 5178 0.838 0.09 dskc
B 29. 30 0.653 0.00 dskc
B 30. 16582 0.823 0.28 dskc
B 31. 825 0.841 0.01 dskc
B 32. 1764 0.825 0.03 dske
Not To Be Reproduced 14-9 MDD-003
_O_U_T_P_U_T__F_R_O_M__M_E_T_E_R_I_N_G__C_O_M_M_A_N_D_S
_i_n_t_e_r_r_u_p_t__m_e_t_e_r_s
Chan 262506 1.464 7.82
Ovhd 258932 0.230 1.21
Total 258932 1.713 9.03
Not To Be Reproduced 14-10 MDD-003
_O_U_T_P_U_T__F_R_O_M__M_E_T_E_R_I_N_G__C_O_M_M_A_N_D_S
_f_i_l_e__s_y_s_t_e_m__m_e_t_e_r_s
ox FILE_SYSTEM_METERS - DISPLAYS MISCELLANEOUS METERING INFORMATION
FOR THE FILE SYSTEM
[] ONLY PARTS RELEVANT TO SEGMENT CONTROL INCLUDED HERE; SEE TOPIC
8 (PAGE CONTROL) FOR THE REST
Total metering time 0:20:02
# ATB
Activations 1043 1.153 sec.
segfault 969 1.241 sec. 92.905% of all
makeknown 74 16.251 sec. 7.095% of all
directories 96 12.527 sec. 9.204% of all
Deactivations 1056 1.139 sec.
Demand deactivate
attempts 3 400.857 sec.
Seg Faults 5080 0.237 sec.
fault 4311 0.279 sec. 84.862% of Seg Faults
call 769 1.564 sec. 15.138% of Seg Faults
activations 969 1.241 sec. 19.075% of Seg Faults
Bound Faults 220 5.466 sec.
Setfaults 4484 268.191 msec.
access 42 28.633 sec. 0.937% of setfaults
ASTE Trickle 139 8.652 sec.
Steps 4279 281.040 msec.
Skips 3016 0.399 sec. 70.484% of Steps
ehs 271 4.438 sec. 8.985% of Skips
mem 1083 1.110 sec. 35.909% of Skips
init 1662 0.724 sec. 55.106% of Skips
Searches 0 0.000 sec.
Cleanups 1056 1.139 sec. 0.1 % of real time
Force writes 3 400.857 sec.
pages written 3 400.857 sec.
Lock AST 18422 0.065 sec.
Not To Be Reproduced 14-11 MDD-003
_O_U_T_P_U_T__F_R_O_M__M_E_T_E_R_I_N_G__C_O_M_M_A_N_D_S
_f_i_l_e__s_y_s_t_e_m__m_e_t_e_r_s
AVE/lock %
AST locked 4.833 msec. 7.4
AST lock waiting 1.601 msec. 2.5
AST Sizes 4 16 64 256
Number 1701 601 221 74
Need 819 202 208 34
Steps 2341 645 1139 154
Ave Steps 2.9 3.2 5.5 4.5
Lap Time(sec) 873.8 1120.5 233.3 577.9
Not To Be Reproduced 14-12 MDD-003
_O_U_T_P_U_T__F_R_O_M__M_E_T_E_R_I_N_G__C_O_M_M_A_N_D_S
_f_i_l_e__s_y_s_t_e_m__m_e_t_e_r_s
ox FILE_SYSTEM_METERS - DISPLAYS MISCELLANEOUS METERING INFORMATION
FOR THE FILE SYSTEM
[] ONLY PARTS RELEVANT TO PAGE CONTROL INCLUDED HERE; SEE TOPIC 7
(SEGMENT CONTROL) FOR THE REST
Total metering time 0:20:02
# ATB
Needc 62654 19.194 msec.
Ring 0 faults 16.639 %
PDIR faults 50.607 %
Level 2 faults 21.556 %
DIR faults 7.645 %
New Pages 14.661 %
Volmap_seg 0 0.000 msec.
Zero pages 770 1561.779 msec.
Laps 105 11.453 sec.
Steps 361483 3.327 msec.
Skip 322555 3.728 msec. 89.231% of Steps
wired 11057 108.761 msec. 3.428% of Skip
used 109719 10.960 msec. 34.016% of Skip
mod 140336 8.569 msec. 43.508% of Skip
fc pin 37717 31.884 msec. 11.693% of Skip
cl pin 23726 50.686 msec. 7.356% of Skip
3419 pages, 139 wired.
Average steps 5.770
Not To Be Reproduced 14-13 MDD-003
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ox DEVICE_METERS - DISPLAYS SUMMARY OF I/O ACTIVITY FOR ALL DISK
SUBSYSTEMS
Total metering time 0:20:13
dska dskb dskc dskd
Prior Page I/O 18571 17743 462 1273
ATB 65.334 68.383 2626.240 953.121
Other Page I/O 6525 5135 16 696
ATB 185.949 236.284 75832.692 1743.280
ATB Page I/O 48.347 53.034 2538.332 616.212
Prior VTOCE I/O 934 895 38 304
ATB 1299.061 1355.668 31929.554 3991.194
ATB I/O 46.612 51.037 2351.401 533.798
% Busy 76 74 0 4
Avg. Page Wait 47.289 46.197 20.341 24.666
Avg. Page ^Wait 176.082 101.023 36.996 61.704
Avg VTOCE Wait 41.138 37.610 38.595 29.090
Avg. Page I/O T 35.619 38.314 20.050 22.482
Avg. VTOCE I/O T 31.139 32.277 37.060 26.606
EDAC Corr. Errs 0 0 0 0
Errors 0 0 0 1
Fatal Errors 0 0 0 0
Not To Be Reproduced 14-14 MDD-003
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ox DISK_METERS - DISPLAYS I/O ACTIVITY TO DISK DRIVES
[] ONLY ONE SUBSYSTEM SHOWN HERE TO CONSERVE SPACE
Total metering time 0:20:12
Subsystem dska Count Waits %Waits Avg. Wait(ms.)
call locks 26005 217 0.83 0.259
run locks 112 0 0.00 0.000
interrupt locks 25998 239 0.92 0.208
allocations 26001 0 0.00 0.000
Drive Reads Writes Seek ATB ATB ATB
Distance Reads Writes I/O
1 269 67 214 4508 18102 3609
3 362 243 109 3350 4991 2004
4 309 131 184 3925 9258 2756
5 547 165 180 2217 7350 1703
6 631 165 161 1922 7350 1523
7 0 0 0 0 0 0
8 5843 2187 122 207 554 151
9 366 116 153 3313 10455 2516
11 3501 1431 200 346 847 245
12 0 0 0 0 0 0
16 7158 2508 135 169 483 125
Not To Be Reproduced 14-15 MDD-003
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ox DISK_QUEUE - DISPLAYS I/O QUEUE FOR A DISK SUBSYSTEM
[] ONLY ONE SUBSYSTEM SHOWN HERE TO CONSERVE SPACE
Connects = 2604781, 1359725, 677321, 309367,
123430, 40159, 10227, 1969.
P RW VP DV SECTOR MEM
0 W P 24 1350330 27304000
0 W P 9 1020150 4432000
0 W P 16 1204130 36246000
0 W P 16 314370 27306000
0 W P 16 314430 34166000
Not To Be Reproduced 14-16 MDD-003
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ox PRINT_CONFIGURATION_DECK - DISPLAYS >sl1>config_deck, WHICH
CONTAINS INFORMATION ABOUT DISK LOCATIONS, THE RLV, AND PARTITIONS
[] ONLY THE PART OF THE CONFIG DECK RELEVANT TO VOLUME MANAGEMENT
AND DISK CONFIGURATION IS SHOWN HERE
root dska 16. dskb 25. dskb 23. dskb 24. dska 8.
part bos dska 16.
part dump dska 16.
part log dska 16.
prph dska a 20. 2 451. 16.
chnl dska a 26. 2 b 24. 2 b 22. 2
prph dskb b 20. 2 0 16. 451. 16.
chnl dskb b 26. 2 a 24. 2 a 22. 2
prph dskc a 28. 2 501. 32.
chnl dskc a 30. 2 b 30. 2 b 28. 2
prph dske b 32. 2 451. 8.
chnl dske b 34. 2
prph dskf a 32. 2 501. 16.
chnl dskf a 34. 2
mpc mspa 451. a 20. 4 a 24. 4
mpc mspb 451. b 20. 4 b 24. 4
mpc mspc 607. a 28. 4
mpc mspd 607. b 28. 4
mpc mspe 451. b 32. 4
mpc mspf 607. a 32. 4
Not To Be Reproduced 14-17 MDD-003
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ox DISK CONFIGURATION CONFIG CARDS
[] ROOT
[] IDENTIFIES THOSE VOLUMES IN THE ROOT LOGICAL VOLUME WHICH
HAVE HC PARTITIONS, USED BY THE SUPERVISOR FOR PAGING OF
SUPERVISOR SEGMETNS
[] PART
[] IDENTIFIES THE LOCATIONS OF CERTAIN IMPORTANT PARTITIONS
[] ONLY PARTITIONS NECESSARY FOR MULTICS OPERATIONS ARE
IDENTIFIED, NOT ALT PARTITIONS
[] HC PARTITIONS ARE LOCATED BY THE ROOT CARD
[] PRPH DSK_n, CHNL
[] IDENTIFY PHYSICAL I/O CHANNEL PATHS FOR ACCESSING DISK DRIVES
[] MPC
[] IDENTIFY PHYSICAL CONNECTIONS TO MICROPROGRAMMED DISK
CONTROLLERS
Not To Be Reproduced 14-18 MDD-003
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ox LIST_VOLS - DISPLAYS A TABLE OF ONLINE VOLUMES, THEIR LOCATION, AND
SPACE UTILIZATION
Drive Records Left % VTOCEs Left % Avg PV PB/PD LV Name
Size Name
dskc_17 64504 54730 85 13440 11356 84 4 alpha01 pb pd Alpha
dskc_18 64504 55389 86 13440 11352 84 4 alpha02 pb pd Alpha
dska_05 36428 5305 15 8400 2662 32 5 mul03 pb pd Multics_Pubs
dska_06 36428 4323 12 8400 2365 28 5 mul01 pb pd Multics_Pubs
dskb_19 36428 4632 13 8400 2813 33 5 mul02 pb pd Multics_Pubs
dskb_26 36429 13690 38 8400 4326 52 5 mul05 pb pd Multics_Pubs
dskb_27 36429 4672 13 8400 2333 28 5 mul04 pb pd Multics_Pubs
dska_01 36308 4680 13 9000 450 5 3 pub01 pb pd Public
dska_03 36268 3588 10 9200 1017 11 3 pub07 pb pd Public
dska_04 36268 4500 12 9200 884 10 3 pub04 pb pd Public
dska_09 36268 4816 13 9200 864 9 3 pub02 pb pd Public
dskb_17 36269 4281 12 9200 1002 11 3 pub05 pb pd Public
dskb_18 36268 3840 11 9200 539 6 3 pub08 pb pd Public
dskc_13 64504 294 0 13440 5539 41 8 rel01 Release
dskc_14 64504 269 0 13440 5214 39 7 rel02 Release
dskc_01 64503 43631 68 13440 10032 75 6 xpub01 pb Xpublic
dskc_02 64503 45502 71 13440 9838 73 5 xpub02 pb Xpublic
dskc_03 64503 42374 66 13440 9839 73 6 xpub03 pb Xpublic
dskc_04 64503 43591 68 13440 9785 73 5 xpub04 pb Xpublic
dskc_09 64504 58010 90 13440 12394 92 6 xpub05 pb Xpublic
dskc_10 64504 56786 88 13440 12407 92 7 xpub06 pb Xpublic
dskc_21 64503 23947 37 13440 6446 48 5 ypub01 pb Ypublic
dskc_22 64503 23744 37 13440 6194 46 5 ypub02 pb Ypublic
dskc_29 64503 23794 37 13440 6185 46 5 ypub05 pb Ypublic
dskc_30 64503 24111 37 13440 6481 48 5 ypub06 pb Ypublic
dskc_07 64503 11723 18 13440 6149 46 7 zpub01 pb pd Zpublic
dskc_08 64503 11665 18 13440 6429 48 7 zpub02 pb pd Zpublic
dskc_23 64504 9777 15 13440 6094 45 7 zpub03 pb pd Zpublic
dskc_24 64504 11805 18 13440 6141 46 7 zpub04 pb pd Zpublic
dskc_25 64504 11514 18 13440 7407 55 8 zpub05 pb pd Zpublic
dskc_26 64504 12958 20 13440 7149 53 8 zpub06 pb pd Zpublic
dske_06 37089 8053 22 5100 3797 74 22 list01 pb pd list_1
dska_12 37562 6046 16 2735 957 35 17 list02 pb list_2
dska_07 37309 6825 18 4000 2107 53 16 list03 pb list_3
dska_08 36209 3827 11 7000 491 7 4 root5 pb root
dska_11 36209 8597 24 7000 4181 60 9 root6 pb root
Not To Be Reproduced 14-19 MDD-003
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dska_16 31283 2892 9 9000 3476 39 5 rpv pb root
dskb_23 36208 4888 13 7000 455 7 4 root3 pb root
dskb_24 36209 3097 9 7000 238 3 4 root4 pb root
dskb_25 36350 4483 12 7000 223 3 4 root2 pb root
Not To Be Reproduced 14-20 MDD-003
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_t_r_a_f_f_i_c__c_o_n_t_r_o_l__q_u_e_u_e
ox TRAFFIC_CONTROL_QUEUE - DISPLAYS THE CURRENT CONTENTS OF THE
SCHEDULER QUEUES, USEFUL FOR GETTING AN IDEA OF WHAT THE USER
PROCESSES ARE DOING
[] FIRST PART OF OUTPUT IS ELIGIBLE QUEUE:
avq = 13, elapsed time = 1247 sec, 64 active last 15 sec.
flags dtu dpf temax te ts ti tssc event d ws wc process
rWLE(d) 148 6946 2097 37 0 0 -0.001 0 0 6 0 Initializer
xLED(c) 15 1111 1000 910 2012 1897 0.001 0 0 11 6 Sibert
rLE(d) 14 1370 500 89 0 0 -0.009 0 0 0 4 Diaz
rLE(d) 15 823 500 13 0 0 -0.009 0 0 64 8 JCrow
wLE(d) 13 634 500 422 0 0 0.018 316537 0 3 3 Gintell
xWLED(a) 6 108 1000 495 2054 2004 0.010 0 0 13 6 Brunelle
wLE(d) 16 864 1000 85 0 510 0.016 504031 0 46 6 WPeck
wWLE(b) 468 2734 1000 315 3010 8000 0.013 224641 0 4 3 Spratt
wLE(d) 17 686 500 60 0 0 0.007 165111 0 3 4 RTowle
wLE(b) 12 520 500 50 0 0 0.005 71 0 3 3 Kress
wLE(d) 69 1895 500 21 0 0 0.001 177022 0 0 2 OPCTL
xLED(b) 12 872 500 85 0 0 0.005 0 0 0 3 Pandolf
rLE(d) 67 3279 500 0 0 0 -0.006 0 0 0 3 Lackey
Not To Be Reproduced 14-21 MDD-003
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[] SECOND PART IS REALTIME, INTERACTIVE, AND ALL WORKCLASS QUEUES:
REALTIME QUEUE:
INTERACTIVE QUEUE:
WORKCLASS 2 QUEUE: credits = 576 ms.
WORKCLASS 3 QUEUE: credits = 242 ms.
r 289 5326 1000 0 0 503 0.218 0 0 22 3 Dupuis
r 131 2513 1000 0 4010 8000 0.128 0 0 0 3 Falksenj
WORKCLASS 4 QUEUE: credits = 2601 ms.
WORKCLASS 5 QUEUE: credits = 4000 ms.
WORKCLASS 6 QUEUE: credits = -563 ms.
WORKCLASS 7 QUEUE: credits = 3962 ms.
rW 5 166 500 0 0 0 0.192 0 0 2 7 Saccuci
WORKCLASS 8 QUEUE: credits = 3934 ms.
WORKCLASS 9 QUEUE: credits = 2216 ms.
WORKCLASS 10 QUEUE: credits = 4000 ms.
WORKCLASS 11 QUEUE: credits = 4000 ms.
Not To Be Reproduced 14-22 MDD-003
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ox TRAFFIC_CONTROL_METERS - DISPLAY THE STATE OF THE SCHEDULER
[] OUTPUT COMES IN THREE PARTS, SHOWN OUT OF ORDER HERE:
[] QUEUE LENGTHS AND RESPONSE TIME - THESE ARE WEIGHTED AVERAGES
OVER THE LAST FIFTEEN SECONDS.
[] ACTIVITIES VERSUS DEPTH - HOW DEEP THE TRAFFIC CONTROLLER HAD
TO SEARCH TO FIND A SCHEDULABLE PROCESS
[] MISCELLANEOUS COUNTERS AND FREQUENCIES OF VARIOUS EVENTS
Total metering time 0:20:34
Ave queue length 16.52
Ave eligible 13.31
Response time 0.264 sec
DEPTH %PF TBPF %GTW TBS %CPU
1 12.0 22.8 10.8 11.6 8.1
2 11.8 21.0 9.2 12.2 7.4
3 10.8 24.9 8.7 14.1 8.0
4 10.2 27.9 8.5 15.2 8.4
5 9.5 29.8 8.3 15.5 8.4
6 8.4 33.5 7.8 16.5 8.4
7 7.4 36.3 7.3 16.8 8.0
Not To Be Reproduced 14-23 MDD-003
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_t_r_a_f_f_i_c__c_o_n_t_r_o_l__m_e_t_e_r_s
COUNTER TOTAL ATB #/INT
Interactions 7977 0.155 sec
Loadings 12161 0.102 sec 1.525
Blocks 14082 0.088 sec
Wakeups 36078 0.034 sec
Schedulings 12591 0.098 sec 1.578
Lost priority 1 1234.756 sec
Priority boosts 0 0.000 sec
I/O boosts 578 2.136 sec
Wait Page 127040 9.719 msec 15.926
Wait PTL 75691 16.313 msec 9.489
Wait Other 31912 38.693 msec 4.001
Total Waits 234643 5.262 msec 29.415
Notify Page 128954 9.575 msec
Notify PTL 75691 16.313 msec
Notify Other 25330 48.747 msec
Total Notifies 229975 5.369 msec
Get Processor 245856 5.022 msec
Pre-empts 94235 13.103 msec 11.813
Getwork 338802 3.644 msec
Retry getwork 4988 0.248 sec
Extra notifies 2949 0.419 sec
Last EN event 000000000071
Last NTO event 033022237767
ox ALARM_CLOCK_METERS - DISPLAYS INFORMATION ABOUT THE USER ALARM
TIMER FACILITY (HARDCORE INTERFACE FOR timer_manager_)
Total metering time 0:20:31
No. alarm clock sims. 2171
Simulation lag 5.245 msecs.
Max. lag 1.7340314e4 msecs.
Not To Be Reproduced 14-24 MDD-003
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ox PRINT_TUNING_PARAMETERS - PRINT VALUES FOR SYSTEM CONTROL
PARAMETERS. MOST CONTROL THE SCHEDULER
Current system tuning parameters:
tefirst 0.5 seconds
telast 1. seconds
timax 8. seconds
priority_sched_inc 80. seconds
min_eligible 2.
max_eligible 20.
max_batch_elig 0
working_set_factor 0.5
working_set_addend 0
deadline_mode off
int_q_enabled on
post_purge on
pre_empt_sample_time 0.04 seconds
gp_at_notify off
gp_at_ptlnotify off
process_initial_quantum 2. seconds
quit_priority 0.
gv_integration 4. seconds
realtime_io_priority on
realtime_io_deadline 0. seconds
realtime_io_quantum 0.005 seconds
notify_timeout_interval 30. seconds
notify_timeout_severity 0
write_limit 724
[] THESE ARE "INTERNAL", NORMALLY NEVER CHANGED, AND ONLY PRINTED
IF THE -all CONTROL ARGUMENT IS GIVEN
stack_truncation on
stack_truncation_always off
stk_trunc_block_avg_factor 0.25
trap_invalid_masked off
meter_ast_locking off
checksum_filemap on
Not To Be Reproduced 14-25 MDD-003
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ox WORK_CLASS_METERS - DISPLAY THE VARIOUS WORKCLASS PARAMETERS, AND
SHOW WHAT RESOURCES EACH WORKCLASS IS CONSUMING.
Total metering time 0:20:38
WC %GUAR %MAX %TCP V/ELIG PW IRESP IQUANT RESP QUANT P M R I LCG
0 3. 0.12 3 0.26 2.10 0.26 2.10 P 0 R I Init
1 3. 0.09 1 0.25 0.75 0.50 1.00 P 0 R I RTime
2 7. 15. 0.44 1 P 0 I System SysAdm OPR FED
3 32. 44. 0.49 1 P 0 I SysProg SysDev
4 9. 14. 4. 0.26 1 P 0 SEngr
5 20. 2. 0.46 1 P 0 I HEngr
6 12. 16. 8. 0.25 1 P 0 MktUS MktFor MktEd
7 3. 7. 4. 0.36 1 P 0 DS-CC
8 6. 0. 0.18 1 P 0 I OffAuto
9 4. 8. 2. 0.62 1 P 0 Misc Mfg
10 3. 0. 0.55 1 P 0 I Other
11 4. 2. 0.16 1 P 0 I Special
TCPU percents (%GUAR) control non-realtime work_classes.
Not To Be Reproduced 14-26 MDD-003
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ox RESPONSE_METERS - DISPLAYS RESPONSE TIME, BASED ON TERMINAL
INTERACTIONS, ON A PER-WORKCLASS BASIS
Total metering time 0:20:36
WC ---Thinks/-- ----Response Times by VCPU Range---- Load Control Group
---Queues--- -VCPU Range- # Avg Avg Resp
# Avg From To Int VCPU RT Fact
0 86 2.70 0.00 0.50 113 0.04 0.42 9.34 Init
92 0.15 0.50 1.00 3 0.55 5.51 10.00
1.00 10.00 3 2.43 14.96 6.15
----- ----- 119 0.12 0.91 7.76
1 35 11.78 0.00 0.50 34 0.11 0.96 8.74 RTime
39 0.21 0.50 1.00 2 0.83 4.06 4.87
----- ----- 36 0.15 1.13 7.55
2 593 14.90 0.00 0.50 620 0.05 0.49 10.50 System SysAdm OPR FED
612 0.15 0.50 1.00 28 0.71 3.61 5.10
1.00 10.00 39 1.77 8.39 4.74
----- ----- 687 0.17 1.07 6.22
3 2496 6.38 0.00 0.50 2993 0.08 0.66 7.96 SysProg SysDev
2622 0.17 0.50 1.00 117 0.68 4.22 6.16
1.00 10.00 66 2.46 13.47 5.49
10.00 99.99 10 56.85 99.99 3.33
----- ----- 3186 0.33 1.65 4.96
4 581 15.82 0.00 0.50 663 0.05 0.71 12.94 SEngr
590 0.26 0.50 1.00 13 0.64 4.64 7.30
1.00 10.00 8 3.47 32.07 9.24
----- ----- 684 0.11 1.15 10.88
5 133 29.51 0.00 0.50 148 0.06 0.83 12.95 HEngr
141 0.17 0.50 1.00 3 0.69 4.64 6.70
1.00 10.00 5 3.15 10.24 3.25
10.00 99.99 2 26.69 48.84 1.83
----- ----- 158 0.51 1.81 3.55
Not To Be Reproduced 14-27 MDD-003
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6 1180 11.65 0.00 0.50 977 0.05 1.13 20.91 MktUS MktFor MktEd
1211 0.58 0.50 1.00 24 0.64 4.95 7.74
1.00 10.00 16 1.89 11.88 6.29
----- ----- 1017 0.10 1.39 14.38
7 259 14.65 0.00 0.50 292 0.08 1.53 20.17 DS-CC
287 0.98 0.50 1.00 9 0.71 9.03 12.66
1.00 10.00 17 2.04 14.76 7.24
10.00 99.99 1 12.22 99.99 9.45
----- ----- 319 0.24 2.81 11.86
8 73 2.69 0.00 0.50 79 0.06 0.31 5.45 OffAuto
74 0.05 0.50 1.00 2 0.60 6.40 10.62
1.00 10.00 1 3.20 6.73 2.10
----- ----- 82 0.11 0.54 4.94
9 94 41.91 0.00 0.50 80 0.11 1.23 11.07 Misc Mfg
96 0.30 0.50 1.00 11 0.69 4.74 6.91
1.00 10.00 13 2.99 12.82 4.30
----- ----- 104 0.53 3.05 5.74
10 7 99.99 0.00 0.50 10 0.11 1.45 13.82 Other
8 0.21 1.00 10.00 1 3.88 39.11 10.09
----- ----- 11 0.45 4.88 10.89
11 417 12.71 0.00 0.50 445 0.03 0.50 15.32 Special
420 0.16 0.50 1.00 5 0.57 3.61 6.29
1.00 10.00 4 1.65 11.40 6.90
----- ----- 454 0.05 0.63 11.93
All 5954 11.13 0.00 0.50 6454 0.07 0.77 11.40
6192 0.29 0.50 1.00 217 0.68 4.54 6.70
1.00 10.00 173 2.31 13.11 5.68
10.00 99.99 13 48.77 99.99 3.32
----- ----- 6857 0.24 1.51 6.39
86797 calls to meter_response_time 283 invalid transitions.
Overhead = 0.09% ( 0.052 ms./call)
Not To Be Reproduced 14-28 MDD-003
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ox SYSTEM_PERFORMANCE_GRAPH - GIVES A ROUGH SNAPSHOT OF SYSTEM
ACTIVITY, SAMPLED PERIODICALLY
04/02/83 1114.3 est Sat
up= 04/01/83 0855.6 est, sys_hours= 26.3, cpu_hours= 78.9
cpu= 3, pages= 3419, min_e= 3, max_e= 16, wsa= 0, wsf= 0.50,
tefirst= 0.13, telast= 0.50, timax= 32.0
1115.00 Qe . | *******|**+******|******mitpS y . DV
1116.00 Qe .****|*********|**+******|**iiits |y . S DV
1117.00 Q*e*******|***iittpp| + . y| . | . D V
1118.00 Q*e*******|*******iittps+. y | . | . D V
1119.00 Qe********|*********|***+*iit |y . | . DV
1120.00 Qe********|*********|***+**it |y . | . DV
1121.01 Q*e*******|******iitpp +y | . | . D V
1122.00 Qe********|*********|****+iitp|y . | S DV
1123.00 Qe********|*********|**mi+ts y . | S DV
1124.00 Q*e*******|*********|*iii+ps |y . | . DV
1125.00 Q*e*******|**********miii+tps |y . | . D V
1126.00 Q*e*******|****iiiit|tps+. y | . | . D V
1127.00 Q*e*******|*********|*ii+tp y| . | . D V
1128.00 Q*e*******|*********|***+*iiittp y | . D V
1129.00 Qe *******|*********|***+*****|****iittp|y . D V
1130.00 Qe *******|*********|***+*****|**iiittp |y . DV
1131.00 Qe *******|*********|***+*****|****iiitt| y . DV
1132.00 Qe********|*********|***+*****|****iiit |y . DV
1133.00 rQ********|*********|**+******|*iiitts y . D V
1134.00 Qe********|*********|**+******|***iitp y . DV
1135.00 Qe . | *******|**+******|********iit y. DV
1136.00 Qe********|*********|***+******iiitts y| . D V
1137.00 rQ********|*********|***+*****|****iitts|y . D V
1138.01 Qe********|*********|***+*****iiiitp y . DV
1139.00 Qe********|*********|****+*****iitps y S DVP
1140.02 rQ********|*********|***+*****iiittpp y . D VP
Not To Be Reproduced 14-29 MDD-003
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_s_y_s_t_e_m__p_e_r_f_o_r_m_a_n_c_e__g_r_a_p_h
[] SOME CHARACTERS INDICATES PERCENTAGES OF SYSTEM TIME SPENT IN
VARIOUS ACTIVITIES. OTHERS INDICATE ACTUAL VALUES
[] PERCENTAGES
[] BLANK - USER PROCESSING. RING ZERO TIME BETWEEN "y" AND
THE RIGHT MARGIN, USER RING BETWEEN "s" and "y"
[] SYSTEM SERVICES - SEGMENT FAULTS ("s"), PAGE FAULTS ("p"),
TRAFFIC CONTROL ("t"), INTERRUPTS ("i")
[] IDLE TIME - MP IDLE ("m"), NMP IDLE ("*"), ZERO IDLE
(BLANKS ON THE LEFT)
[] OTHER VALUES (RELATIVE TO THE LEFT MARGIN)
[] TRAFFIC CONTROL QUEUE LENGTHS - READY QUEUE ("q"),
ELIGIBLE QUEUE ("e")
[] USER COUNTS - NUMBER OF USERS ("+"), LOAD UNITS ("-")
[] TRAFFIC CONTROL VALUES - RESPONSE TIME ("r"), QUITS PER
MINUTE ("Q"), SCHEDULINGS IN TEN SECONDS ("S")
[] OTHER VALUES (RELATIVE TO THE RIGHT MARGIN)
[] I/O TRAFFIC - DISK I/O PER 100 MILLISECONDS ("D"), VTOC
I/O PER 100 MILLISECONDS ("V")
Not To Be Reproduced 14-30 MDD-003
_O_U_T_P_U_T__F_R_O_M__M_E_T_E_R_I_N_G__C_O_M_M_A_N_D_S
_m_e_t_e_r__g_a_t_e
ox METER_GATE - SHOWS TIME SPENT CALLING THROUGH SUPERVISOR GATES
(HCS_, ETC.)
Metering since 04/01/83 0855.6 est Fri.
Total non-idle time at 04/02/83 1101.9 est Sat = 39 hr. 36 min. 57 sec.
Gate meters for hcs_: total calls = 6294028.
7 hr. 35 min. 54 sec. or 19.180% spent in calls through gate.
calls pcnt avg pwait entry name
902768 4.50 7.11 0.02 tty_write
13857 2.29 236.01 2.28 list_dir
442912 1.19 3.85 0.01 tty_read
435510 1.01 3.30 0.02 tty_order
165154 0.97 8.35 0.10 initiate
120204 0.83 9.84 0.76 make_ptr
20620 0.51 34.95 0.48 make_seg
60796 0.50 11.69 0.14 truncate_seg
45464 0.45 14.25 0.16 status_long
337615 0.40 1.69 0.01 set_alarm_timer
532081 0.35 0.95 0.00 read_events
4085 0.35 122.90 3.57 star_dir_list_
42080 0.33 11.17 0.02 list_acl
59354 0.32 7.76 0.01 status_for_backup
103029 0.32 4.44 0.03 tty_get_line
61851 0.32 7.33 0.03 tty_write_whole_string
48621 0.31 9.05 0.35 status_minf
31637 0.26 11.64 0.04 set_max_length_seg
150703 0.26 2.41 0.03 terminate_noname
67267 0.20 4.19 0.03 tty_read_echoed
14851 0.20 18.77 0.08 quota_get
21051 0.18 12.48 0.72 get_link_target
30337 0.18 8.25 0.40 initiate_count
6288 0.17 39.36 0.25 delentry_seg
247420 0.16 0.95 0.03 wakeup
14024 0.16 15.99 0.43 status_
476759 0.16 0.47 0.00 level_set
13601 0.13 13.69 0.00 dir_quota_read
14860 0.13 12.05 0.02 list_dir_acl
13496 0.13 13.22 0.01 get_max_length
28194 0.12 6.15 0.41 make_entry
Not To Be Reproduced 14-31 MDD-003
_O_U_T_P_U_T__F_R_O_M__M_E_T_E_R_I_N_G__C_O_M_M_A_N_D_S
_m_e_t_e_r__g_a_t_e
23725 0.11 6.65 0.09 set_bc_seg
1416 0.11 108.00 2.08 star_
13941 0.10 10.68 0.40 get_access_class
28696 0.10 5.03 0.04 status_mins
13598 0.09 9.76 0.02 list_inacl_all
102810 0.09 1.27 0.01 tty_state
12881 0.08 8.50 0.39 get_user_effmode
46180 0.08 2.33 0.01 tty_read_with_mark
206 0.07 493.77 3.79 star_list_
1109005 0.07 0.09 0.00 level_get
Not To Be Reproduced 14-32 MDD-003
_O_U_T_P_U_T__F_R_O_M__M_E_T_E_R_I_N_G__C_O_M_M_A_N_D_S
_m_e_t_e_r__g_a_t_e
[] HPHCS_ AND IOI_ ARE THE OTHER SUPERVISOR GATES THAT CONSUME
SIGNIFICANT RESOURCES
Metering since 04/01/83 0855.6 est Fri.
Total non-idle time at 04/02/83 1102.7 est Sat = 39 hr. 37 min. 59 sec.
Gate meters for hphcs_: total calls = 70604.
0 hr. 29 min. 51 sec. or 1.256% spent in calls through gate.
calls pcnt avg pwait entry name
869 0.57 928.77 5.40 destroy_process_finish
911 0.24 381.04 15.09 create_proc
5944 0.20 48.34 1.04 dir_quota_read
8326 0.05 8.47 0.04 tty_write_force
5946 0.05 11.31 0.00 quota_read
105 0.04 500.68 0.00 flush_core
246 0.04 208.83 0.17 flush_ast_pool
1753 0.02 16.94 0.76 star_
5595 0.02 4.12 0.00 set_backup_dump_time
31893 0.01 0.60 0.00 set_kst_attributes
1 0.01 14598.71 8.00 add_scu
Metering since 04/01/83 0855.6 est Fri.
Total non-idle time at 04/02/83 1103.0 est Sat = 39 hr. 38 min. 22 sec.
Gate meters for ioi_: total calls = 245985.
0 hr. 12 min. 14 sec. or 0.515% spent in calls through gate.
calls pcnt avg pwait entry name
243976 0.50 2.94 0.00 connect
248 0.01 65.91 2.09 workspace
793 0.00 0.58 0.00 get_special_status
533 0.00 0.54 0.00 set_event
322 0.00 0.59 0.14 set_status
105 0.00 0.55 0.00 timeout
3 0.00 4.38 0.00 set_channel_required
5 0.00 0.65 0.00 get_detailed_status
15-i MDD-003
_O_U_T_P_U_T__F_R_O_M__M_E_T_E_R_I_N_G__C_O_M_M_A_N_D_S
_m_e_t_e_r__g_a_t_e
TOPIC XV
Evolution of Memory Addressing/Management
Page
Conventional Memory . . . . . . . . . . . . . 15-1
Structure . . . . . . . . . . . . . . . . 15-1
Address Formation . . . . . . . . . . . . 15-1
Characteristics . . . . . . . . . . . . . 15-2
Problems. . . . . . . . . . . . . . . . . 15-4
Single Virtual Memory . . . . . . . . . . . . 15-7
Structure . . . . . . . . . . . . . . . . 15-7
Address Formation . . . . . . . . . . . . 15-7
Characteristics . . . . . . . . . . . . . 15-7
Solved Problems . . . . . . . . . . . . . 15-9
Problems. . . . . . . . . . . . . . . . . 15-11
Multiple Virtual Memories . . . . . . . . . . 15-12
Structure . . . . . . . . . . . . . . . . 15-12
Address Formation . . . . . . . . . . . . 15-12
Characteristics . . . . . . . . . . . . . 15-13
Solved Problems . . . . . . . . . . . . . 15-14
Problems. . . . . . . . . . . . . . . . . 15-15
Multics Virtual Memory. . . . . . . . . . . . 15-16
Structure . . . . . . . . . . . . . . . . 15-16
Address Formation . . . . . . . . . . . . 15-16
Characteristics . . . . . . . . . . . . . 15-17
Solved Problems . . . . . . . . . . . . . 15-18
Problems. . . . . . . . . . . . . . . . . 15-20
15-i MDD-003
.
_C_O_N_V_E_N_T_I_O_N_A_L__M_E_M_O_R_Y
_S_T_R_U_C_T_U_R_E
ox 1-DIMENSIONAL ADDRESS SPACE USED BY THE SYSTEM
Not To Be Reproduced 15-1 MDD-003
_C_O_N_V_E_N_T_I_O_N_A_L__M_E_M_O_R_Y
_C_H_A_R_A_C_T_E_R_I_S_T_I_C_S
ox SPACE DIVIDED INTO REGIONS OF VARIOUS SIZES, ONE REGION PER
PROCESS/JOB/USER
ox REGIONS ARE:
[] PROTECTED FROM ONE ANOTHER BY A BAR OR BY PROTECT KEYS
[] SUBDIVIDED INTO POOLS OF STORAGE USED FOR: PROGRAMS, I/O
BUFFERS, MEMORY ALLOCATION AREA, AUTOMATIC VARIABLES, STATIC
VARIABLES
ox 1-DIMENSIONAL ADDRESS SPACE WIRED DIRECTLY ONTO REAL MEMORY
ox PROGRAMS MUST BE LOADED INTO REAL MEMORY
[] MEMORY ALLOCATION FOR REGION
[] PROGRAMS AND BUFFERS ALLOCATED WITHIN REGION
Not To Be Reproduced 15-2 MDD-003
_C_O_N_V_E_N_T_I_O_N_A_L__M_E_M_O_R_Y
_C_H_A_R_A_C_T_E_R_I_S_T_I_C_S
[] PREPARATORY ADDRESS MODIFICATION (ADDRESSES MUST BE MODIFIED TO
REFLECT LOCATION WITHIN THE REGION)
ox LINKAGE EDITING REQUIRED
[] ALL SYMBOLIC REFERENCES MUST BE RESOLVED - IMPLYING THAT ALL
REFERENCED PROGRAMS MUST BE LOADED REGARDLESS OF WHETHER OR NOT
THEY ARE ACTUALLY NEEDED AT RUN TIME
ox EXAMPLES: GCOS, IBM OS/MFT, IBM OS/MVT
Not To Be Reproduced 15-3 MDD-003
_C_O_N_V_E_N_T_I_O_N_A_L__M_E_M_O_R_Y
_P_R_O_B_L_E_M_S
ox SYSTEM ADDRESS SPACE LIMITED TO SIZE OF REAL MEMORY
ox USER ADDRESS SPACES (REGIONS) ARE SMALL. THIS MEANS:
[] PROGRAMS MUST BE WRITTEN TO FIT INTO SMALL REGIONS
[] SMALL REGION PROGRAMS OFTEN OPERATE LESS EFFICIENTLY IN THEIR
USE OF CPU TIME THAN A SIMILAR PROGRAM DESIGNED FOR A LARGE
REGION
[] BECAUSE SMALL REGION OPERATION IS PROGRAMMED IN, SUCH PROGRAMS
CANNOT TAKE ADVANTAGE OF MORE MEMORY WHEN IT CAN BE MADE
AVAILABLE
[] PROGRAMMER MUST WASTE INGENUITY (AND SYSTEM RESOURCES) TO MAKE
PROGRAMS RUN IN A SMALL REGION:
[] WRITING OVERLAY PROGRAMS
[] DIVIDING REGION INTO OPTIONAL-SIZE POOLS
[] PROGRAMMING MECHANISMS TO EXTEND OR SWAP-OUT POOLS WHEN THEY
OVERFLOW
Not To Be Reproduced 15-4 MDD-003
_C_O_N_V_E_N_T_I_O_N_A_L__M_E_M_O_R_Y
_P_R_O_B_L_E_M_S
[] PROGRAMMER TIME WASTED WHEN PROGRAMS MUST BE CONVERTED TO TAKE
ADVANTAGE OF LARGER REGIONS WHEN CONFIGURATION IS INCREASED
ox REAL MEMORY IS USED INEFFICIENTLY
[] WITHIN A REGION, PROGRAM COMPONENTS OR DATA AREAS NOT REFERENCED
STILL OCCUPY REAL MEMORY
[] UNUSED SPACE BETWEEN REGIONS WASTES REAL MEMORY (FRAGMENTATION)
ox SCHEMES FOR USING REAL MEMORY MORE EFFICIENTLY ARE COSTLY
[] CPU COST OF MOVING REGIONS TO REDUCE FRAGMENTATION
[] CPU AND I/O COSTS TO SWAP OUT ENTIRE REGIONS TO SHARE REAL
MEMORY AMONG MORE USERS
ox NO PROTECTION OF DATA WITHIN A REGION
[] PROGRAMMING ERRORS CAN CAUSE UNWANTED WRITING INTO PROGRAM OR
DATA AREAS
Not To Be Reproduced 15-5 MDD-003
_C_O_N_V_E_N_T_I_O_N_A_L__M_E_M_O_R_Y
_P_R_O_B_L_E_M_S
ox OVERHEAD AND INCONVENIENCE OF LOADING AND LINKAGE EDITING
ox NO SHARING OF PROGRAMS AND DATA BETWEEN REGIONS
[] EACH REGION MUST CONTAIN A COPY OF SHARED DATA (INEFFICIENT USE
OF MEMORY)
[] MODIFICATIONS TO SHARED DATA CANNOT EASILY BE REFLECTED IN ALL
COPIES
ox PHYSICAL INPUT/OUTPUT OPERATIONS ON DISK FILES OFTEN BECOME THE
RESPONSIBILITY OF THE PROGRAMMER (REDUCING PRODUCTIVITY)
Not To Be Reproduced 15-6 MDD-003
_S_I_N_G_L_E__V_I_R_T_U_A_L__M_E_M_O_R_Y
_S_T_R_U_C_T_U_R_E
ox A LARGE ADDRESS SPACE USED BY THE SYSTEM (EG, 4M WORDS)
ox THE ADDRESS SPACE IS LOGICALLY DIVIDED INTO REGIONS OF VARIOUS
SIZES, AS IN CONVENTIONAL MEMORY
ox THE VIRTUAL MEMORY IS PHYSICALLY DIVIDED INTO PAGES HAVING A FIXED
SIZE
ox THE ADDRESS SPACE AND THE VIRTUAL MEMORY HAVE THE SAME SIZE
ox THE 1-DIMENSIONAL ADDRESS SPACE IS MAPPED DIRECTLY ONTO THE PAGED,
1-DIMENSIONAL VIRTUAL MEMORY
ox THE VIRTUAL MEMORY IS MAPPED BY A PAGING ALGORITHM ONTO A SMALLER
(EG, 256K WORDS) REAL MEMORY
Not To Be Reproduced 15-7 MDD-003
_S_I_N_G_L_E__V_I_R_T_U_A_L__M_E_M_O_R_Y
_C_H_A_R_A_C_T_E_R_I_S_T_I_C_S
ox PROGRAMS MUST BE LOADED INTO THE VIRTUAL MEMORY AS IN CONVENTIONAL
MEMORY SYSTEMS
ox LINKAGE EDITING REQUIRED AS IN CONVENTIONAL MEMORY SYSTEMS
ox EXAMPLES:
[] IBM OS/VS-1 OR OS/VS-2 RELEASE 1
Not To Be Reproduced 15-8 MDD-003
_S_I_N_G_L_E__V_I_R_T_U_A_L__M_E_M_O_R_Y
_S_O_L_V_E_D__P_R_O_B_L_E_M_S
ox THE SYSTEM'S ADDRESS SPACE IS MUCH LARGER THAN REAL MEMORY
[] THE SYSTEM CAN RUN MORE AND/OR LARGER USER REGIONS
ox THE USER REGIONS CAN BE LARGER
[] PROGRAMS CAN BE WRITTEN FOR A LARGE REGION TO TAKE ADVANTAGE OF
ADDITIONAL MEMORY WHEN IT IS AVAILABLE
ox PROGRAMMER PRODUCTIVITY IMPROVES
[] PROGRAMMERS WORRY LESS ABOUT OPTIMIZING MEMORY USAGE
[] CONVERTING PROGRAMS TO USE LARGER MEMORY CONFIGURATIONS OFTEN
UNNECESSARY - LESS COMPETITION
ox REAL MEMORY USED MORE EFFICIENTLY
[] FEWER UNREFERENCED AREAS OF ADDRESS SPACE OCCUPY REAL MEMORY
Not To Be Reproduced 15-9 MDD-003
_S_I_N_G_L_E__V_I_R_T_U_A_L__M_E_M_O_R_Y
_S_O_L_V_E_D__P_R_O_B_L_E_M_S
[] PAGING ALGORITHM SIMPLIFIES MEMORY MANAGEMENT SCHEMES
Not To Be Reproduced 15-10 MDD-003
_S_I_N_G_L_E__V_I_R_T_U_A_L__M_E_M_O_R_Y
_P_R_O_B_L_E_M_S
ox MEMORY SWAPPING MAY STILL BE NECESSARY TO SHARE THE ADDRESS SPACE
AMONG MANY USERS
ox USER REGIONS STILL TOO SMALL TO HANDLE EVERY APPLICATION. SOME
MEMORY MANAGEMENT STILL REQUIRED
ox NO PROTECTION OF DATA WITHIN A REGION
ox OVERHEAD AND INCONVENIENCE OF LOADING AND LINKAGE EDITING
ox NO SHARING OF DATA BETWEEN REGIONS
ox EXPLICIT DISK I/O STILL REQUIRED TO ACCESS FILES
ox THE ADVANTAGES OF SOLVING THE PROBLEMS ABOVE MAY BE OUTWEIGHED BY
COSTS IN HARDWARE AND SOFTWARE OF THE PAGING OVERHEAD
Not To Be Reproduced 15-11 MDD-003
_M_U_L_T_I_P_L_E__V_I_R_T_U_A_L__M_E_M_O_R_I_E_S
_S_T_R_U_C_T_U_R_E
ox THE SYSTEM USES MANY LARGE (4M WORD), 1-DIMENSIONAL ADDRESS SPACES,
ONE PER USER REGION
ox EACH ADDRESS SPACE CONTAINS THE SUPERVISOR PROGRAMS PLUS ONE LARGE
USER REGION (DIVIDED INTO POOLS), PLUS PROGRAMS AND DATA SHARED
AMONG ALL REGIONS
ox EACH ADDRESS SPACE IS MAPPED DIRECTLY ONTO ITS OWN, PAGED VIRTUAL
MEMORY
ox EACH VIRTUAL MEMORY IS MAPPED BY A PAGING ALGORITHM ONTO THE
SINGLE, SMALLER REAL MEMORY
ox PROGRAMS MUST BE LOADED INTO THE VIRTUAL MEMORY AS IN CONVENTIONAL
MEMORY SYSTEMS
ox LINKAGE EDITING REQUIRED AS IN CONVENTIONAL MEMORY SYSTEMS
Not To Be Reproduced 15-12 MDD-003
_M_U_L_T_I_P_L_E__V_I_R_T_U_A_L__M_E_M_O_R_I_E_S
_C_H_A_R_A_C_T_E_R_I_S_T_I_C_S
ox EXAMPLES:
[] IBM OS/VS-2 RELEASE 2 (MVS)
Not To Be Reproduced 15-13 MDD-003
_M_U_L_T_I_P_L_E__V_I_R_T_U_A_L__M_E_M_O_R_I_E_S
_S_O_L_V_E_D__P_R_O_B_L_E_M_S
ox THE LARGE USER REGIONS CAN HANDLE ALL BUT THE LARGEST PROGRAMS
WITHOUT SPECIAL MEMORY MANAGEMENT. PROGRAMMER MUST STILL DIVIDE
REGIONS INTO POOLS, HOWEVER, AND SOMETIMES PROVIDE POOL OVERFLOW
MECHANISMS
ox MEMORY SWAPPING IS NOW UNNECESSARY. PREVIOUSLY SWAPPED REGIONS NOW
OCCUPY THEIR OWN ADDRESS SPACES AND ARE PAGED IN AND OUT
ox PROGRAMS AND DATA (USUALLY READ-ONLY) CAN BE SHARED BETWEEN REGIONS
IN A LIMITED WAY BY OCCUPYING THE SAME POOL IN EVERY ADDRESS SPACE
ox NEWLY SOLVED PROBLEMS MAKE PAGING OVERHEAD MORE WORTHWHILE
Not To Be Reproduced 15-14 MDD-003
_M_U_L_T_I_P_L_E__V_I_R_T_U_A_L__M_E_M_O_R_I_E_S
_P_R_O_B_L_E_M_S
ox NO PROTECTION OF DATA WITHIN THE MAJORITY OF A USER'S ADDRESS SPACE
(REGION)
ox OVERHEAD AND INCONVENIENCE OF LOADING AND LINKAGE EDITING
ox GENERAL SHARING OF READ-WRITE DATA STILL NOT POSSIBLE
ox EXPLICIT DISK I/O STILL REQUIRED TO ACCESS FILES
Not To Be Reproduced 15-15 MDD-003
_M_U_L_T_I_C_S__V_I_R_T_U_A_L__M_E_M_O_R_Y
_S_T_R_U_C_T_U_R_E
ox THE SYSTEM USES MANY, VERY LARGE (EG, 256M WORDS), 2-DIMENSIONAL
ADDRESS SPACES, ONE PER USER PROCESS (REGION)
ox EACH ADDRESS SPACE IS DIVIDED INTO SEGMENTS WHICH PERFORM THE SAME
FUNCTION AS POOLS IN MULTIPLE VIRTUAL MEMORY SYSTEMS
ox SEGMENTS:
[] HAVE VARYING SIZES
[] ARE EXTENDABLE
[] ARE FILES IN THE MULTICS STORAGE SYSTEM
[] ARE ACCESSED AS READ-WRITE, READ-ONLY, EXECUTABLE OR CALLABLE
DATA, WITH ACCESS CONTROLLED BY AN ACL, RING BRACKETS AND AN AIM
CLASSIFICATION
[] ARE SHARED AMONG ADDRESS SPACES, WITH EACH ADDRESS SPACE HAVING
ITS OWN PERMISSION TO ACCESS THE SEGMENT
Not To Be Reproduced 15-16 MDD-003
_M_U_L_T_I_C_S__V_I_R_T_U_A_L__M_E_M_O_R_Y
_C_H_A_R_A_C_T_E_R_I_S_T_I_C_S
ox EACH ADDRESS SPACE INTERSECTS IN VARYING DEGREES WITH EVERY OTHER
ADDRESS SPACE
ox EACH ADDRESS SPACE IS MAPPED DIRECTLY ONTO ITS OWN PAGED, SEGMENTED
VIRTUAL MEMORY OF THE SAME SIZE
ox EACH VIRTUAL MEMORY IS MAPPED BY A PAGING ALGORITHM ONTO THE
SINGLE, SMALLER REAL MEMORY
ox NO LOADING IS REQUIRED SINCE ALL ADDRESSES ARE INTERPRETED AS
OFFSETS WITHIN SEGMENTS
ox NO LINKAGE EDITING IS REQUIRED SINCE ALL SYMBOLIC REFERENCES ARE
RESOLVED AT RUN TIME IF AND WHEN THEY ARE ENCOUNTERED (DYNAMIC
LINKING)
Not To Be Reproduced 15-17 MDD-003
_M_U_L_T_I_C_S__V_I_R_T_U_A_L__M_E_M_O_R_Y
_S_O_L_V_E_D__P_R_O_B_L_E_M_S
ox DATA WITHIN THE ADDRESS SPACE PROTECTED
[] READ OR READ-EXECUTE DATA STORED IN SEPARATE SEGMENTS WHICH ARE
PROTECTED FROM MODIFICATION
[] PROGRAMMING ERRORS REFERENCING OUTSIDE ARRAY BOUNDS CANNOT
REFERENCE DATA IN ANOTHER SEGMENT
ox DATA CAN BE SHARED IN A GENERAL WAY BETWEEN ADDRESS SPACES
[] EACH SEGMENT (NOT A COPY OF THE SEGMENT) CAN APPEAR IN SEVERAL
ADDRESS SPACES
[] DIFFERENT PROCESSES CAN HAVE DIFFERENT ACCESS TO THE SAME
SEGMENT IN THEIR ADDRESS SPACE
ox OVERHEAD AND INCONVENIENCE OF LOADING (SOFTWARE) REPLACED BY AN
ADDRESS FORMATION SCHEME (HARDWARE)
[] UNREFERENCED PROGRAMS (AND/OR PAGES OF PROGRAMS) DO NOT REQUIRE
MAIN MEMORY SPACE
Not To Be Reproduced 15-18 MDD-003
_M_U_L_T_I_C_S__V_I_R_T_U_A_L__M_E_M_O_R_Y
_S_O_L_V_E_D__P_R_O_B_L_E_M_S
[] PROGRAMS NEVER REQUIRE PREPARATORY ADDRESS MODIFICATION
ox EXPLICIT I/O IS NOT REQUIRED TO ACCESS FILES (SEGMENTS)
[] SEGMENTS CAN BE ACCESSED BY MAKING THEM KNOWN TO THE ADDRESS
SPACE AND REFERENCING THE SEGMENT
[] THIS IS CALLED VIRTUAL FILE I/O
ox OVERHEAD AND INCONVENIENCE OF LINKAGE EDITING REPLACED BY DYNAMIC
LINKING
[] UNREFERENCED PROGRAMS DO NOT REQUIRE LINKING
ox ADVANTAGES OF VERY LARGE ADDRESS SPACE, SHARED FILES, DATA
PROTECTION, AND VIRTUAL I/O DEFINITELY OUTWEIGH THE COSTS OF PAGING
AND SEGMENTATION OVERHEAD
Not To Be Reproduced 15-19 MDD-003
_M_U_L_T_I_C_S__V_I_R_T_U_A_L__M_E_M_O_R_Y
_P_R_O_B_L_E_M_S
ox MULTICS FILE I/O IS OFTEN LESS EFFICIENT THEN SPECIAL CASED METHODS
BASED ON KNOWN ACCESS PATTERNS
ox THE SYSTEM'S SEGMENT SIZE DOES NOT GENERALIZE UPWARD TO HANDLE VERY
LARGE DATA BASES. ALTERNATE (KLUDGY) METHODS MUST BE USED (SUCH AS
MSF'S)
ox THE OVERHEAD TO TOUCH A PAGE OF ONE HUNDRED DIFFERENT SEGMENTS IS
CONSIDERABLY MORE THAN THE OVERHEAD TO TOUCH ONE HUNDRED PAGES OF
THE SAME SEGMENT. (IE: SPARSE AND INFREQUENT ACCESSING IS
EXPENSIVE)
ox LACK OF EXPLICIT I/O CONTROL MAKES OVERALL SYSTEM RELIABILITY
SUFFER SINCE FULL RECOVERY FROM A SYSTEM CRASH REQUIRES THE
SUCCESSFUL FLUSHING OF ALL PAGES FROM MAIN MEMORY
[] hcs_$force_write MAY BE USED BY THOSE APPLICATIONS REQUIRING
SUCH RELIABILITY
-----------------------------------------------------------
Historical Background
This edition of the Multics software materials and documentation is provided and donated
to Massachusetts Institute of Technology by Group BULL including BULL HN Information Systems Inc.
as a contribution to computer science knowledge.
This donation is made also to give evidence of the common contributions of Massachusetts Institute of Technology,
Bell Laboratories, General Electric, Honeywell Information Systems Inc., Honeywell BULL Inc., Groupe BULL
and BULL HN Information Systems Inc. to the development of this operating system.
Multics development was initiated by Massachusetts Institute of Technology Project MAC (1963-1970),
renamed the MIT Laboratory for Computer Science and Artificial Intelligence in the mid 1970s, under the leadership
of Professor Fernando Jose Corbato. Users consider that Multics provided the best software architecture
for managing computer hardware properly and for executing programs. Many subsequent operating systems
incorporated Multics principles.
Multics was distributed in 1975 to 2000 by Group Bull in Europe , and in the U.S. by Bull HN Information Systems Inc.,
as successor in interest by change in name only to Honeywell Bull Inc. and Honeywell Information Systems Inc. .
-----------------------------------------------------------
Permission to use, copy, modify, and distribute these programs and their documentation for any purpose and without
fee is hereby granted,provided that the below copyright notice and historical background appear in all copies
and that both the copyright notice and historical background and this permission notice appear in supporting
documentation, and that the names of MIT, HIS, BULL or BULL HN not be used in advertising or publicity pertaining
to distribution of the programs without specific prior written permission.
Copyright 1972 by Massachusetts Institute of Technology and Honeywell Information Systems Inc.
Copyright 2006 by BULL HN Information Systems Inc.
Copyright 2006 by Bull SAS
All Rights Reserved