Jim,
I don’t fully understand your question. Is it “If all processes reach
MPI_Barrier, are they guaranteed to exit the barrier without the need for any
other MPI function to be called on any process?” I would say yes.
Rajeev
From: mpi-forum <mpi-forum-boun...@lists.mpi-forum.org> on behalf of Jim Dinan
via mpi-forum <mpi-forum@lists.mpi-forum.org>
Reply-To: Main MPI Forum mailing list <mpi-forum@lists.mpi-forum.org>
Date: Saturday, October 10, 2020 at 12:31 PM
To: Main MPI Forum mailing list <mpi-forum@lists.mpi-forum.org>
Cc: Jim Dinan <james.di...@gmail.com>
Subject: [Mpi-forum] Progress Question
Hi All,
A colleague recently asked a question that I wasn't able to answer
definitively. Is the following code guaranteed to make progress?
MPI_Barrier();
if rank == 1
create_file("test")
if rank == 0
while not_exists("test")
sleep(1);
That is, can rank 1 require rank 0 to make MPI calls after its return from the
barrier, in order for rank 1 to complete the barrier? If the code were written
as follows:
isend(..., other_rank, &req[0])
irecv(..., other_rank, &req[1])
waitall(2, req)
if rank == 1
create_file("test")
if rank == 0
while not_exists("test")
sleep(1);
I think it would clearly not guarantee progress since the send data can be
buffered. Is the same true for barrier?
Cheers,
~Jim.
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