[Mpi3-ft] WG call on tuesday aug. 9, 3pm est

Jim Dinan james.dinan at gmail.com
Wed Jul 10 09:07:22 CDT 2013

Hi George,

Re: comm_create and friends -- I'd be interested in hearing the result of
> the F2F discussion.  I've been the person complaining about this, so if it
> would be helpful for me to join you guys over the phone next Friday, let me
> know.
> I did not have the opportunity to hear your complaint about this. Can you
> please summarize it here on the mailing list to make sure 1) that we are
> all at the same level of understanding; 2) the complaint reach all the
> interested audience and 3) we have the opportunity to address it as
> accurately as possible.

I'm concerned that the current spec is missing a few features that are
needed for the usage model where users continue to use a communicator with
"holes" in it.  In order for this model to work well, users must be able to
query which processes are known to have failed in a given communicator.
 Given the current interface, users are not able to query the set of failed
processes without creating a new communicator and translating ranks, via
 MPI_Comm_shrink.  This requires the user to first revoke the parent
communicator, which is something we want to avoid.

Along these same lines, we should also ensure that MPI_Comm_create_group
will work as expected when a communicator with holes is used, provided the
output group excludes failed processes (i.e., the operation is not
collective over any failed processes).  This might not require any text
changes, unless we want to allow this operation on revoked communicators.

Re: Roadmap -- Before a reading, it might be helpful to give a brief
> presentation to the Forum again giving the high level ideas and
> justifications for each new addition to the FT proposal.  I think it's been
> long enough that people have forgotten the details and this might help them
> feel more comfortable that the proposal is complete and self-consistent.
> There was at least one [more or less] "brief" presentation of the FT
> proposal at every meeting for the last two years. I would even emphasize
> the fact that over the last year no major modification of the proposal has
> been put forward, fact that might indicate a certain level of completeness
> and self-consistency.

I'm just trying to convey the temperature in the room, as I felt it.  I
think a 15 minute, very high level warm-up immediately before the reading
on the usage models, big ideas, and conventions would go a long way toward
prepping the audience.

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