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Howard Pritchard edited this page Jun 26, 2017 · 2 revisions

June 26, 2017 Webex Meeting

Attendees

  • Dan Holmes
  • Howard Prichard
  • Aurelien Bouteiller

Review of MPI Forum activities

Dan said there was a lot of talk about Sessions in different WG discussions. There seems to be a good deal of join-the- Sessions-bandwagon to solve other problems.

A half day was devoted to the Sessions WG. (we will update with a list of active participants when we get the attendance list). In the plenary time, there was a discussion of Sessions + endpoints led by Dan, and Isaias Compres discussed a replacement for MPI_Comm_spawn - adaptation that has some connection with Sessions. A vote was taken to merge this effort in to the Sessions WG. (add link when Martin sets up links to presentations).

Howard mentioned that this join-the-Sessions-bandwagon approach also came up in the last MPI FT WG telecon in the context of how to handle failures during MPI_Init. With Sessions, one can create error handler locally with Sessions and then pass in to MPI_Session_Init. There was some discussion of what pieces of MPI need to be initialized for this to work, e.g. error handler framework, etc.

Using different MPIs within a single Process

The group discussed the problem of different MPI libraries potentially being used by different Sessions. A related discussion is going on in the tools working group around using different MPI libraries - possibly in the context of coupled applications (including debuggers, perf. monitoring tools, etc.). Dan mentioned the virtual reality cave at the last MPI Forum as an example of one use-case for this coupled application scenario (a GPU cluster + compute cluster). In the general case, Aurelien thinks we need some kind of interoperability API. Dan said this request for multiple MPI support keeps coming up. Having Sessions implemented as code that is shared by multiple MPI implementations - something like the ROMIO model. This seems like a lot of scope creep.

Next Forum

Dan will be able to attend. Howard and Aurelien expect to attend as well.

TODOS

  • Howard will come up with a Sessions cheat-sheet wiki page to avoid having to wade through the big presentation when one wants to look up some of the Sessions related routines.

  • Dan will write up a wiki that summarizes use cases for supporting multiple MPI libraries within a single application.

  • Howard will update links in these minutes once presentations are available.

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