Thank you. We can actually introduce what you propose, possibly with a query function to make it still easier to live with, as early as in MPI 2.2, as a subset precursor. Judging by the discussion in Chicago, subsets may not need much more than that in the end, possibly with a little more flags and semantics added in MPI-3.

The reservation against 32- (or for that matter, 64-) bit limitation is the only one I have at the moment. Not being able to attach assertions to communicators, etc. may be missed by some advanced programmers, but here we need to be pragmatic: who will ever want to go that deep?

From: mpi-22-bounces@lists.mpi-forum.org [mailto:mpi-22-bounces@lists.mpi-forum.org] On Behalf Of Richard Treumann
Sent: Monday, May 05, 2008 7:18 PM
To: MPI 2.2
Subject: Re: [Mpi-22] mpi-22 Digest, Vol 2, Issue 7

Hi Alexander

I have no objection to citing my "assertions" proposal in the subsetting discussions. I do want to keep it clear that this proposal is intended to be as simple as practical to implement, exploit and live with.

"Live with" applies to 3rd party library authors or anyone else who must write MPI code but does not know and control the structure of the entire application. That guy must "live with" the decisions made by whoever coded the MPI_INIT piece. "Live with" also applies to whoever must test or certify a specific MPI implementation.

Thanks - Dick

Dick Treumann - MPI Team/TCEM
IBM Systems & Technology Group
Dept 0lva / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601
Tele (845) 433-7846 Fax (845) 433-8363

"Supalov, Alexander" <alexander.supalov@intel.com>

"Supalov, Alexander" <alexander.supalov@intel.com>

Sent by: mpi-22-bounces@lists.mpi-forum.org

04/26/2008 04:03 AM

Please respond to
"MPI 2.2" <mpi-22@lists.mpi-forum.org>

To	"MPI 2.2" <mpi-22@lists.mpi-forum.org>
cc
Subject	Re: [Mpi-22] mpi-22 Digest, Vol 2, Issue 7

Dear Dick,

Thank you. Would you mind if I cite your proposal in the subsets discussion? Yours looks like a good alternative to the thinking of some of us that subsets might be very rich and mutable, and to Jeff's proposal on hints I've already cited there with his permission.

Best regards.

Alexander

Dick Treumann - MPI Team/TCEM
IBM Systems & Technology Group
Dept 0lva / MS P963 -- 2455 South Road -- Poughkeepsie, NY 12601
Tele (845) 433-7846 Fax (845) 433-8363

mpi-22-bounces@lists.mpi-forum.org wrote on 04/24/2008 11:33:42 AM: > Hi, > > Note that this is an argument for making the assertions optional: those > who don't care don't have to use them. Those who care should use them > correctly or else. As usual. > > Best regards. > > Alexander >
Hi Alexander
The assertions are optional in this proposal. If this is added to the MPI standard the minimal impacts (day one impacts) are:
== To application writers (none) - MPI_INIT and MPI_INIT_THREAD still work. MPI_INIT_THREAD_xxx can be passed 0 (zero) as the assertions bit vector.
To MPI Implementors (small) - subroutine MPI_INIT_THREAD_xxx can be a clone of MPI_INIT_THREAD under the covers. If the Forum decides the query function is for asking what assertions are being honored, the implementation can just return "none" to every query. If there is also a query for what assertions have been made then there are a few more lines of code the implementor must write to preserve the value so it can be returned(maybe 10 lines)
Writers of opaque libraries (small) - call the query function at library init time and if any assertions are found, issue an error message and kill the job. This is awkward for a library that wants to support every MPI whether it has implemented the new query function or not. ==
As MPI implementations begin to take advantage of assertions there is more work for the MPI implementor and the library author must begin to think about whether his customer will be upset if the library simply outlaws all assertions.
The library author will never be wrong if he simply forbids assertions forever. If they become valuable he will feel the pressure to work it out.
The MPI implementor will never be wrong if he adds the API but simply ignores assertions forever. If they become valuable he will feel the pressure to honor some at least.

--------------------------------------------------------------------- Intel GmbH Dornacher Strasse 1 85622 Feldkirchen/Muenchen Germany Sitz der Gesellschaft: Feldkirchen bei Muenchen Geschaeftsfuehrer: Douglas Lusk, Peter Gleissner, Hannes Schwaderer Registergericht: Muenchen HRB 47456 Ust.-IdNr. VAT Registration No.: DE129385895 Citibank Frankfurt (BLZ 502 109 00) 600119052 This e-mail and any attachments may contain confidential material for the sole use of the intended recipient(s). Any review or distribution by others is strictly prohibited. If you are not the intended recipient, please contact the sender and delete all copies._______________________________________________ mpi-22 mailing list mpi-22@lists.mpi-forum.orghttp://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-22