[Mpi-22] Another MPI-2.2 attribute ambiguity?
jsquyres at [hidden]
Thu Apr 16 09:19:05 CDT 2009
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
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
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?
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