[Mpi-forum] MPI user survey

[Jeff Hammond]

Can we completely ignore the performance-richness dichotomy and ask
the following?

"Would you benefit if the MPI Forum enhances and extends the existing
one-sided operations?  That is, would you like to replace MPI
two-sided calls in your code with one-sided ones and/or use MPI
instead of another one-sided API (e.g. ARMCI)?"

As has been pointed out many times, this question is susceptible to
the criticism that it is asking "should we make MPI better?" to which
almost anyone will answer "yes", which is why it is important to query
whether or not such improvements would actually be used in code.

Jeff

On Mon, Nov 16, 2009 at 10:43 AM, Jeff Squyres (jsquyres)
<jsquyres at cisco.com> wrote:
> +1
>
> -jms
> Sent from my PDA. No type good.
>
> ________________________________
> From: mpi-forum-bounces at lists.mpi-forum.org
> <mpi-forum-bounces at lists.mpi-forum.org>
> To: Main MPI Forum mailing list <mpi-forum at lists.mpi-forum.org>
> Sent: Mon Nov 16 11:38:51 2009
> Subject: Re: [Mpi-forum] MPI user survey
>
> The important thing to discern is whether we have any user base that wants
> that second interface.
>
>
>
> Keith
>
>
>
> From: mpi-forum-bounces at lists.mpi-forum.org
> [mailto:mpi-forum-bounces at lists.mpi-forum.org] On Behalf Of Vinod tipparaju
> Sent: Monday, November 16, 2009 8:27 AM
> To: mpi-forum at lists.mpi-forum.org
> Subject: Re: [Mpi-forum] MPI user survey
>
>
>
> I am concerned with the way this question is worded.
>
>
>
> I am only concerned for a general user that is doing this survey. I think
> this question seems to suggest that MPI-3 RMA will finally be defined in
> such a way that either a) rich RMA feature set, or  b) good message rate, is
> utimately possible. I disagree with this completely. RMA for MPI-3 must
> target and deliver both, even if we have to have two interfaces for RMA
> (after Keith and Brian do their investigation and conclude that having a
> second interface is a must). I think we cannot get away with an interface
> with rich feature set that prevents high-message rate or low latency just
> because 95% of users who take the survey say they only care about rich
> feature set. Alternatively, if we don't care what users say and still are
> going to deliver an RMA specification that gives both, why are we asking
> this question?
>
>
>
> Note that I (as a participant in RMA standardization meetings) understand
> that the intention of this question may be to see what people care more
> about --latency/message-rate or rich feature set.
>
>
>
> I cannot see how this can be worded to address all the concerns with out
> including 1/2 a page of explanation. So I think we should hold-off on
> including this question in the survey for now.
>
>
>
> Thanks,
>
> Vinod.
>
>
>
> --
> Vinod Tipparaju ^ http://ft.ornl.gov/~vinod ^ 1-865-241-1802
>
>
>
>> From: jsquyres at cisco.com
>> To: mpi-forum at lists.mpi-forum.org
>> Date: Mon, 16 Nov 2009 07:39:09 -0800
>> Subject: Re: [Mpi-forum] MPI user survey
>>
>> On Nov 16, 2009, at 7:28 AM, Supalov, Alexander wrote:
>>
>> > Why don't we ask directly: do you want to have subsets in MPI-3 to
>> > trade feature richness for performance if you care?
>> >
>>
>> We didn't ask about subsets at all because the WG is "on hold". Do
>> you want to introduce a new question? If so, can you suggest the
>> specific wording?
>>
>> Note that Keith suggested an improved wording for the RMA question
>> (this was buried in my reply to Dick):
>>
>> "MPI one-sided communication performance (e.g., message rate and
>> latency) is more important to me than supporting a rich remote memory
>> access (RMA) feature set (e.g., communicators, datatypes)."
>>
>> Jeff H. replied to me off-list that he liked this better than his
>> suggestion. Does anyone else have any suggestions / comments on this
>> one?
>>
>> --
>> Jeff Squyres
>> jsquyres at cisco.com
>>
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>> mpi-forum at lists.mpi-forum.org
>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-forum
>
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>



-- 
Jeff Hammond
Argonne Leadership Computing Facility
jhammond at mcs.anl.gov / (630) 252-5381
http://www.linkedin.com/in/jeffhammond
http://home.uchicago.edu/~jhammond/