PetscLogEventBarrierBegin

Logs the time in a barrier before an event.

e -integer associated with the event obtained from PetscLogEventRegister()

o1,o2,o3,o4 -objects associated with the event, or 0

comm -communicator the barrier takes place over

void PetscLogEventBarrierBegin(int e,PetscObject o1,PetscObject o2,PetscObject o3,
PetscObject o4,MPI_Comm comm)

     PetscLogEventBarrierBegin(VEC_NormBarrier,0,0,0,0,comm);
       MPI_Allreduce()
     PetscLogEventBarrierEnd(VEC_NormBarrier,0,0,0,0,comm);

This is for logging the amount of time spent in a barrier for an event that requires synchronization.

Synchronization events always come in pairs; for example, VEC_NormBarrier and VEC_NormComm = VEC_NormBarrier + 1

log, event, begin, barrier