[petsc-dev] thread communicator

[Falgout, Rob]

Thanks, Barry and Jeff!  I will pass the word on about MPI-4.  I was at the last FASTMath meeting and I do recall that you were at least wondering whether a shared memory model was needed, but I didn’t realize that you had ripped all of the threading code out of PETSc.  For what it’s worth, I am on board with you about the all “MPI” model.  I don’t see a compelling reason that MPI+X is needed (especially if you allow for MPI to evolve into “MPI”), but since we already support MPI+X in hypre, it’s not a huge deal for us to continue along that path with everybody else.

Thanks again.

-Rob

From: Jeff Hammond [mailto:jeff.science at gmail.com]
Sent: Tuesday, January 12, 2016 12:36 PM
To: Barry Smith
Cc: Falgout, Rob; Yang, Ulrike Meier; PETSc
Subject: Re: [petsc-dev] thread communicator

Rob:

You might be interested in the MPI-4 endpoints proposal.  It should allow MPI communicators to act as thread communicators.

Jeff

On Tue, Jan 12, 2016 at 12:33 PM, Barry Smith <bsmith at mcs.anl.gov<mailto:bsmith at mcs.anl.gov>> wrote:

  Rob,

    I guess you missed the last FASTMath meeting. We have stopped all work on using threads a long time ago because we never saw an improvement in performance and it was a pain to maintain. We even ripped the thread code out of PETSc so currently we are back to being an all "MPI" model.

   Barry

So far we haven't lost all our funding :-)



> On Jan 11, 2016, at 12:28 PM, Falgout, Rob <falgout2 at llnl.gov<mailto:falgout2 at llnl.gov>> wrote:
>
> Hi Barry,
>
> What is the latest on the thread communicator idea you guys were working on?  We are having discussions here with a variety of folks (application and library developers as well as vendors) about similar ideas, so I’d like to bring your work into the mix.  Let me know.  Thanks!
>
> -Rob
>
> Robert D. Falgout
> Center for Applied Scientific Computing
> Lawrence Livermore National Laboratory
> P.O. Box 808, L-561, Livermore, CA  94551
> Phone - (925) 422-4377, Email - rfalgout at llnl.gov<mailto:rfalgout at llnl.gov>, Web - http://people.llnl.gov/falgout2



--
Jeff Hammond
jeff.science at gmail.com<mailto:jeff.science at gmail.com>
http://jeffhammond.github.io/
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