[Mpi-22] Another MPI-2.2 attribute ambiguity?
jsquyres at [hidden]
Fri Apr 17 08:14:40 CDT 2009
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 specific
> behavior regarding the EXTRA_STATE arguments passed to the Fortran
> keyval copy and delete functions (both the ADDRESS_KIND and deprecated
> 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 have
> 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
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