[Mpi-forum] MPI Forum Next Week

[Jeff Hammond]

I will provide an update on the MPI ABI discussions, including:

1. Why we need MPI_<handle>_{to,from}int instead of f2c/c2f in the C API in
order to support Fortran in a non-stupid way.  This is completely
noncontroversial and makes the C API better since apparently even C++ users
are using f2c/c2f to "(de)serialize" handles.
2. Why we need new callbacks to support third-party language bindings
(including Fortran in an implementation-agnostic way).  This is useful both
for Vapaa and mpi4py.  There's one unsolved issue to discuss.
3. Why we need some sort of sentinel registration.  This addresses the
hackish way the C implementation knows what MPI_IN_PLACE, .e.g, is in
Fortran.
4. Why we need Fortran datatype registration.  Basically, the Fortran API
tells the C API the mapping from Fortran to C types so the C implementation
doesn't need to know how the Fortran compiler works.  There might need to
be an init hook here since it is legal to initialize MPI from C and then
use Fortran features.

https://urldefense.us/v3/__https://github.com/pmodels/mpich/pull/6953__;!!G_uCfscf7eWS!Y8Y9PGp1laFaFd6qvWI1K8pndpap_TWzRDxDxf-wGPepSQVf0HiRTLBSU7CJAYfoky666z29rCt1lli3VB5voxiVAsN0zBE$  and
https://urldefense.us/v3/__https://github.com/pmodels/mpich/pull/6965__;!!G_uCfscf7eWS!Y8Y9PGp1laFaFd6qvWI1K8pndpap_TWzRDxDxf-wGPepSQVf0HiRTLBSU7CJAYfoky666z29rCt1lli3VB5voxiVKTAwxdg$  have some discussion.  You don't
have to read these or the thousands of Slack messages if you don't want, as
the purpose of this plenary is to summarize the situation and get guidance
on the text changes I should make.

Jeff

On Wed, Jun 12, 2024 at 1:59 AM Martin Schulz via mpi-forum <
mpi-forum at lists.mpi-forum.org> wrote:

> Hi all, We have our next MPI Forum meeting scheduled for next week, at the
> usual times for virtual meetings from 9am to 1pm CT on Monday, Tuesday and
> Thursday (as Wednesday is a US holiday that we seemed to have missed when
> scheduling this).
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> Hi all,
>
>
>
> We have our next MPI Forum meeting scheduled for next week, at the usual
> times for virtual meetings from 9am to 1pm CT on Monday, Tuesday and
> Thursday (as Wednesday is a US holiday that we seemed to have missed when
> scheduling this).
>
>
>
> My apologies, though, for not sending a reminder for this – I have to
> admit, this sneaked up on me a bit quicker than I thought and I did not see
> this in time to catch it at the 2 week mark. Unfortunately, no-one else
> happened to catch this either, which now leaves us with only ballot item,
> the change of rules we discussed last time. Wes and I thought about whether
> we could mitigate this with a “creative” use of no/no votes, but we both
> quickly came to the conclusion that would not be in the spirit of the forum
> and the rules and, hence, would like to refrain from this.
>
>
>
> Nevertheless, we can and should still use this meeting to make progress on
> some the larger points, in particular the ABI text. With the timeline for
> (what we commonly expect to be) MPI 4.2 not set, this should actually not
> set us back in time.
>
>
>
> Therefore, if you have any particular items, you would like to have on the
> agenda, please let Wes and me know, and we will add this to the agenda
> asap. Also, if there are WGs who would like to use larger blocks for
> dedicated discussion time, this would be a good opportunity as well.
>
>
>
> Wes has already created a registration link, so please register asap if
> you plan to attend, so we can the needed data for eligibility and quorums.
>
>
>
> https://urldefense.us/v3/__https://www.mpi-forum.org/meetings/2024/06/logistics__;!!G_uCfscf7eWS!Y8Y9PGp1laFaFd6qvWI1K8pndpap_TWzRDxDxf-wGPepSQVf0HiRTLBSU7CJAYfoky666z29rCt1lli3VB5voxiVhm8svz0$ 
> <https://urldefense.us/v3/__https://www.mpi-forum.org/meetings/2024/06/logistics__;!!G_uCfscf7eWS!ZtG5TuHfs6Iw087XbvCRBEMyWwUkXvBW3xig7J6D8aLe27j4hi85o7Ah143Hfqv9xPUt_YYQRAGP0dfGYKcY6PS_XRIa$>
>
>
>
> Thanks and my apologies again for the missing reminder – let’s still make
> the best out of it!
>
>
>
> Martin
>
>
>
>
>
> --
>
> Prof. Dr. Martin Schulz, Chair of Computer Architecture and Parallel
> Systems
>
> Department of Informatics, TU-Munich, Boltzmannstraße 3, D-85748 Garching
>
> Member of the Board of Directors at the Leibniz Supercomputing Centre (LRZ)
>
> Email: schulzm at in.tum.de
>
>
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>


-- 
Jeff Hammond
jeff.science at gmail.com
https://urldefense.us/v3/__http://jeffhammond.github.io/__;!!G_uCfscf7eWS!Y8Y9PGp1laFaFd6qvWI1K8pndpap_TWzRDxDxf-wGPepSQVf0HiRTLBSU7CJAYfoky666z29rCt1lli3VB5voxiV4rWvqXE$ 
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