[Mpi3-subsetting] MPI subsetting: charting the way forward at atelecon next week?

[Supalov, Alexander]

Correction: Martin Schulz (LLNL) rather than Mark. Sorry.

________________________________

From: Supalov, Alexander 
Sent: Thursday, June 19, 2008 7:10 PM
To: 'MPI 3.0 Sub-setting working group'
Subject: RE: [Mpi3-subsetting] MPI subsetting: charting the way forward
at atelecon next week?

Hi everybody,
 
Thank you for your time today. Here's what we discussed:
 
Present: Mark Schulz (LLNL), Reiner Keller (HLRS), Alexander Supalov
(Intel)
 
- Opens
  - Alexander is not going to be in Menlo Park, will work with Rich to
find an adequate solution
 
- Subsetting: way forward
  - Subsetting in its extreme form (all of the standard is composed of
subsets that have user defined hierarchies, attach to opaque objects,
etc.) does not seem to be terribly practicable. However, architectural
influence, performance, and memory footprint aspects of subsetting
warrant further research and discussion in this area.
 
  - During the discussion so far we've considered several proposals that
apparently go in the subsetting direction, or at least overlap in some
parts with the subsetting idea, in that they allow control of the
essential aspects related to performance and memory footprint. The WG
feels compelled to express their opinion about some of these ideas as
follows:
 
  - Runtime
    - The subsetting WG supports Dick Treumann's MPI_Init time int based
assertion proposal as expressed in a series of emails, and encourages
creation of a full proposal, with the following notes:
      - The set of standard assertions should be settled and accepted by
all implementors
      - The question of allowing or disallowing implementation specific
assertions should be resolved
      - The distinction between assertions and hints should be
formulated in a way understandable to a first time user
      - The matter of underlying libraries and tools in their relation
to assertions should be clarified
        - It looks that tools that intercept the MPI_Init_* call family
will be able to deal with assertions they cannot support by basically
ignoring them
        - Layered underlying libraries are unlikely to be allowed to
change assertions already in effect, or adding their own assertions on
top of them. These libraries should either adapt themselves to the
defined assertions, or bail out
 
    - The subsetting WG would like to see more details of Jeff Squyres'
proposal on Info based data passing in and out of MPI library before it
expresses its opinion, with the following notes:
      - The effect of setting certain internal thresholds, like eager
threshold, should be considered as a collective action on all processes
 
    - Generally, the WG does not see a compelling need for
assertions/hints/subsets to be attached to the communicator/window/file
or other MPI entities, as this does not seem to be directly usable for
performance increase or memory footprint reduction
 
  - Link time
    - The WG does not see the need to either specify or prohibit
specific link time arrangements like various library names, versions,
combinations, dynamic loading thereof, etc. The details should be left
to the implementation, with the ABI and compatibility aspects in mind.
 
  - Compile time
    - The WG encourages Reiner Keller to produce a full proposal,
minding the ABI and application/MPI compatibility aspects
 
- Actions
  - Please provide feedback to these minutes by end of week
  - Alexander will change the proposal in the Wiki accordingly by the
time of the MPI Forum meeting
 
Best regards.
 
Alexander

________________________________

From: Supalov, Alexander 
Sent: Monday, June 16, 2008 2:43 PM
To: 'MPI 3.0 Sub-setting working group'
Subject: RE: [Mpi3-subsetting] MPI subsetting: charting the way forward
at atelecon next week?

Hi everybody,
 
Basing on the overwhelming silence, I propose that we meet on
 
Thursday, June 19, 2008, 9:00 am PDT/noon EDT/18:00 CEST
Outside Intel: +1-916-356-2663, Inside Intel: 8-356-2663, Bridge: 4,
Passcode: 1459440

 
- Opens
- Subsetting: way forward 
 
Best regards.
 
Alexander

________________________________

From: Supalov, Alexander 
Sent: Friday, June 06, 2008 6:55 PM
To: 'MPI 3.0 Sub-setting working group'
Subject: RE: [Mpi3-subsetting] MPI subsetting: charting the way forward
at atelecon next week?

Hi everybody,
 
>From the few replies I've got (thanks!), we're not going to have a
quorum next week. Let's shoot for the week after that:
 
Monday, June 16, 2008, 9:00 am PDT/noon EDT/18:00 CEST    yes/no/plan B 
Tuesday, June 17, 2008, 9:00 am PDT/noon EDT/18:00 CEST    yes/no/plan B

Thursday, June 19, 2008, 9:00 am PDT/noon EDT/18:00 CEST    yes/no/plan
B
 
Best regards.
 
Alexander

________________________________

From: mpi3-subsetting-bounces_at_[hidden]
[mailto:mpi3-subsetting-bounces_at_[hidden]] On Behalf Of
Supalov, Alexander
Sent: Tuesday, June 03, 2008 6:29 PM
To: mpi3-subsetting_at_[hidden]
Subject: [Mpi3-subsetting] MPI subsetting: charting the way forward at
atelecon next week?

Hi everybody,
 
It looks to me that we're on subsetting crossroads at the moment. There
was a lot of good analysis so far, but I'm afraid we're slow on moving
towards comparably sized synthesis.
 
On one hand, we have a rather well defined and strictly aimed proposal
from Dick that might fit into MPI-2.2 framework and is somewhat related
to subsetting. We also have a wider proposal from Jeff, which also has
interesting repercussions in the client/MPI data exchange area,
potentially usable well outside of the subsetting per se.
 
On the other hand we have a lot of things coming into the standard in
MPI-3, and still no clear way to manage this complexity and cater for
special purpose MPI configurations that may be necessary for MPI to
expand to new areas. Moreover, the meeting in Chicago showed that not
everybody agrees that introducing flexibility or going beyond the
traditional HPC is a good idea at all.
 
On this backdrop, I'd suggest we should meet on the phone before the
Forum gathering in Menlo Park, and try to develop a workable proposition
how subsetting can find its way into the standard.
 
I happen to have time for such a meeting on the following days next
week:
 
Tuesday, May 10, 2008, 8:00 am PDT/11:00 am EDT/17:00 CDT    yes/no/plan
B
Wednesday, May 11, 2008, 8:00 am PDT/11:00 am EDT/17:00 CDT
yes/no/plan B
Thursday, May 12, 2008, 8:00 am PDT/11:00 am EDT/17:00 CDT
yes/no/plan B
 
Please reply as usual to me whether you can make any of these slots.
 
Best regards.
 
Alexander
 
PS. This time I took special care to have a subsetting slot at the F2F
meeting. :)
 

--
Dr Alexander Supalov
Intel GmbH
Hermuelheimer Strasse 8a
50321 Bruehl, Germany
Phone:          +49 2232 209034
Mobile:          +49 173 511 8735
Fax:              +49 2232 209029
 
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Dornacher Strasse 1
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Sitz der Gesellschaft: Feldkirchen bei Muenchen
Geschaeftsfuehrer: Douglas Lusk, Peter Gleissner, Hannes Schwaderer
Registergericht: Muenchen HRB 47456 Ust.-IdNr.
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