We discussed this on the OMPI call yesterday, but I am not knowledgeable of the
consequences of only supporting building Open MPI main and v5.x against PMIx
v4.x are (vs. also supporting building Open MPI main+v5.x against PMIx v3.2.x,
or even PMIx v3.x).
I think we might need to talk to the PMIx community and find out what those
consequences are. Then we can decide what we'd like to do here for Open MPI
main/v5.0.x.
--
Jeff Squyres
jsquy...@cisco.com
From: devel on behalf of Austen W Lauria via
devel
Sent: Tuesday, May 3, 2022 12:07 PM
To: Jeff Squyres (jsquyres) via devel
Cc: Austen W Lauria
Subject: [OMPI devel] What PMIx version(s) does v5.0.0 and main support?
There is a question as to what PMIx versions OMPI supports, specifically
with respect to v5.0.0 and main. This came to our attention where a user
tried to build OMPI v5 with PMIx v3.2.3, and ran into compile issues:
https://github.com/open-mpi/ompi/issues/10341
This leads to some open questions:
1. Is there a need to support v3.2.3 PMIx or lower with v5.0.0?
- If so, these compile errors need to get stamped out. Sessions in v5.0.0
would also be impacted,
and will need to be disabled in this case since it relies on PMIx v4
features not available in the v3 series.
It would also be good to either add an MTT build and/or a CI test to make
sure this does not break in the future.
2. Could/should OMPI compiled with a v4 PMIx work with SLURM compiled with a
v3.2 PMIx?
- There are some cross-version-compatibility features with PMIx, so it may
be possible.
Finally, the PMIx version(s) as well as other required OMPI dependencies need
to be documented. There is an open issue here to track that here:
https://github.com/open-mpi/ompi/issues/10345.
Thanks
