[Mpi-22] Another MPI-2.2 attribute ambiguity?
wgropp at [hidden]
Fri Apr 17 08:40:24 CDT 2009
Yes, this is worth an ATI - the fact that we traded this much mail on
it is proof of that :)
On Apr 17, 2009, at 8:14 AM, Jeff Squyres wrote:
> Someone pointed out to me this morning that there's no restriction on
> the value of EXTRA_STATE when CREATE_KEYVAL is invoked -- it may be an
> expression, for example. I think that pretty much seals the deal that
> #2 is the correct way.
> I think that this is worth an ATI in the text; does anyone disagree?
> I volunteer to write it up/make a 3.0 ticket (hey, first ticket for
> the Misc WG! :-) ) if no one disagrees.
> On Apr 17, 2009, at 8:59 AM, Supalov, Alexander wrote:
>> Intel MPI (and most likely other MPICH2 derivatives) appears to use
>> method #2.
>> Best regards.
>> -----Original Message-----
>> From: Jeff Squyres [mailto:jsquyres_at_[hidden]]
>> Sent: Thursday, April 16, 2009 4:19 PM
>> To: MPI 2.2; Rajeev Thakur; William Gropp; Rolf Rabenseifner; Hubert
>> Ritzdorf; Terry Dontje; Dave Goodell; Darius Buntinas; Pavan Balaji;
>> Supalov, Alexander; Bronis de Supinski; David Solt; Hans Westgaard
>> Ry; Håkon Bugge
>> Subject: Another MPI-2.2 attribute ambiguity?
>> This is related to -- but different from -- MPI 2.2 ticket #55
>> ("MPI-2.1 Cross-language attribute example is wrong"). Explicitly
>> adding all the #55 CC members to this mail, plus a few others.
>> I cannot find any text in MPI-2.1 (e.g., p223-225) describing
>> behavior regarding the EXTRA_STATE arguments passed to the Fortran
>> keyval copy and delete functions (both the ADDRESS_KIND and
>> flavors). I see two choices:
>> 1. pass the user's original EXTRA_STATE argument by reference to the
>> callbacks, or
>> 2. copy the user's original EXTRA_STATE into internal MPI storage and
>> pass *that* value by reference to the callbacks
>> ==> Open MPI currently does #1. What do other implementations do?
>> I raise this issue because the text does not indicate which way is
>> right. And I just ran across an old Sun test that assumed #2. But
>> our internal copy of the Intel MPI tests assume #1 (to be fair: I
>> no idea if the Intel tests originally assumed #2 and we changed them
>> to #1 over time). Indeed, #2 is actually in-line with the philosophy
>> of storing attribute values in internal MPI storage. E.g.:
>> INTEGER foo = 4
>> INTEGER bar
>> CALL MPI_COMM_SET_ATTR(comm, keyval, foo, ierr)
>> foo = 5
>> CALL MPI_COMM_GET_ATTR(comm, keyval, bar, flag, ierr)
>> bar should equal 4, not 5 (right?).
>> So what does that mean (or imply) about the EXTRA_STATE value passed
>> to the Fortran callbacks?
>> Jeff Squyres
>> Cisco Systems
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> Jeff Squyres
> Cisco Systems
Deputy Director for Research
Institute for Advanced Computing Applications and Technologies
Paul and Cynthia Saylor Professor of Computer Science
University of Illinois Urbana-Champaign
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