[MPI3 Fortran] Nonblocking MPI and Fortran temporary memory modifications

[Rasmussen, Craig E]

I've found the relevant paper in J3 meeting minutes (J3 document 09-235r2).  The paper is 09-231 "Answer to MPI Forum regarding MPI asynchronous operations" from J3 meeting 188.  The minutes state the following regarding this paper:

There was a straw vote taken on what syntax to use to inhibit optimizations for MPI asynchronous operations:

   Paper 09-231 "Answer to MPI Forum regarding MPI asynchronous
   operations" [Rasmussen] discussed how to prevent code-motion and
   copy-in/out:

      SV: extend ASYNCHRONOUS - invent new attribute - undefined: 8-2-3


The vote was 8 for ASYNCHRONOUS and 2 for new syntax with 3 abstentions.

There was also a report from the INTEROP subcommittee:

   /INTEROP: no further action will be taken on 09-185r1, 09-189r1,
             09-191, 09-231 - they are all input for the Interop TR
             N1761

So according to the minutes N1761 was supposed to take this vote and paper 09-231 into account.  However, to my knowledge no text was added to the TR in response to this.

This was my bad.  I should have realized that just because ASYNCHRONOUS is currently part of the Fortran standard, that this keyword can be used outside of Fortran I/O without further words to that affect in the standard.

We can discuss what to do in response to this in the telecon this evening.

-craig


On Mar 28, 2011, at 4:18 PM, Rasmussen, Craig E wrote:

I'll look for the vote in the minutes.

-craig

On Mar 28, 2011, at 4:12 PM, Rolf Rabenseifner wrote:

Craig, is there a protocol, file, ... on
http://www.nag.co.uk/sc22wg5/
where this vote is protocolled?
Rolf

----- Original Message -----
From: "Craig E Rasmussen" <rasmussn at lanl.gov<mailto:rasmussn at lanl.gov>>
To: "Rolf Rabenseifner" <rabenseifner at hlrs.de<mailto:rabenseifner at hlrs.de>>
Cc: "MPI-3 Fortran working group" <mpi3-fortran at lists.mpi-forum.org<mailto:mpi3-fortran at lists.mpi-forum.org>>, "N.M. Maclaren" <nmm1 at cam.ac.uk<mailto:nmm1 at cam.ac.uk>>, "Bill Long"
<longb at cray.com<mailto:longb at cray.com>>, "Reinhold Bader" <reinhold.bader at lrz.de<mailto:reinhold.bader at lrz.de>>
Sent: Monday, March 28, 2011 6:14:00 PM
Subject: Re: Nonblocking MPI and Fortran temporary memory modifications
We've had several discussions regarding the use of ASYNCHRONOUS for
the usage required by MPI on the J3 committee. Some members thought
that ASYNCHRONOUS shouldn't be used apart from I/O. However, a vote
was taken and a large majority voted that the ASYNCHRONOUS attribute
should be used for this purpose.

So the question is not about whether a compiler implements
ASYNCHRONOUS I/O but whether it respects the ASYNCHRONOUS semantics.
Perhaps we need an interp request to formalize this beyond a simple J3
member vote.

-craig


On Mar 27, 2011, at 3:34 AM, Rolf Rabenseifner wrote:

Dear all,

Reinhold showed me that the ASYNCHRONOUS attribute may not help
because a compiler may implement asynchronous Fortran I/O
with blocking I/O and therefore may ignore all ASYNCHRONOUS
attributes.

Please have a look at
https://svn.mpi-forum.org/trac/mpi-forum-web/attachment/ticket/229/mpi-report-F2008-2011-03-26-changeonly-majorpages.pdf

Pages 24-31 in the pdf (pages 549-556 in the original document)
show our knowledge about the nonblocking and datatype (MPI_BOTTOM)
problems
in the combination of Fortran and MPI.

Unfortunately in the taböle on page 550, we have to modify all
entries
about ASYNCHRONOUS into "NOT solved".

Do you see further solutions?

Do you see further problems with nonblocking and "MPI_BOTTOM",
that are not mentioned in this section and that should be.

Is the rest of this section correct?
If something is incorrect, it would be important to understand why.

I've reworked this section based on many discussions and on my best
knowledge - but I'm not sure whether this was enough.

Best regards
Rolf


--
Dr. Rolf Rabenseifner . . . . . . . . . .. email
rabenseifner at hlrs.de<mailto:rabenseifner at hlrs.de>
High Performance Computing Center (HLRS) . phone
++49(0)711/685-65530
University of Stuttgart . . . . . . . . .. fax ++49(0)711 /
685-65832
Head of Dpmt Parallel Computing . . .
www.hlrs.de/people/rabenseifner<http://www.hlrs.de/people/rabenseifner>
Nobelstr. 19, D-70550 Stuttgart, Germany . (Office: Allmandring 30)

--
Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner at hlrs.de<mailto:rabenseifner at hlrs.de>
High Performance Computing Center (HLRS) . phone ++49(0)711/685-65530
University of Stuttgart . . . . . . . . .. fax ++49(0)711 / 685-65832
Head of Dpmt Parallel Computing . . . www.hlrs.de/people/rabenseifner<http://www.hlrs.de/people/rabenseifner>
Nobelstr. 19, D-70550 Stuttgart, Germany . (Office: Allmandring 30)