Jeff,
Thanks for looking at this. I know it isn't specific to Open-MPI, but
it is a frustrating issue vis-a-vis MPI and Fortran. There are many
very large MPI applications around the world written in Fortran that
could benefit greatly from this MPI-3 capability. My own background is
in numerical weather prediction, and I know it would be welcome in that
community. Someone knowledgeable in both C and Fortran should be able
to get to bottom of it.
T. Rosmond
On 10/25/2016 03:05 PM, Jeff Hammond wrote:
I can reproduce this with Intel 17 and MPICH on Mac OSX so it's not an
Open-MPI issue. I added VOLATILE to the shared memory objects to
prevent Fortran compiler optimizations as well as a bunch of
MPI_Win_sync calls (after replacing fence with lock_all/unlock_all),
but neither changed the outcome.
While I claim a modest understanding of MPI-3 RMA and Fortran 2008,
unfortunately, I have never figured out how to use MPI-3 shared memory
from Fortran, which is especially unfortunate since it seems to be a
fantastic source of frustration to both real users such as yourself
and MPI+Fortran standard experts (Rolf).
Sorry for the unsatisfying response, but my suspicion is that this is
a program correctness issue. I can't point to any error, but I've
ruled out the obvious alternatives.
Jeff
On Tue, Oct 25, 2016 at 11:29 AM, Tom Rosmond <rosm...@reachone.com
<mailto:rosm...@reachone.com>> wrote:
All:
I am trying to understand the use of the shared memory features of
MPI-3 that allow direct sharing of the memory space of on-node
processes. Attached are 2 small test programs, one written in C
(testmpi3.c), the other F95 (testmpi3.f90) . They are solving the
identical 'halo' exchange problem. 'testmpi3.c' is a simplified
version of an example program from a presentation by Mark Lubin of
Intel. I wrote 'testmpi3.f90' to mimic the C version.
Also attached are 2 text files of the compile, execution, and
output of the respective programs:
CC_testmpi3.txt
F95_testmpi3.txt
Note: All 4 files are contained in the attached 'testmpi3.tar.gz'.
Comparing the outputs of each version, it is clear that the shared
memory copies in 'testmpi3.c' are working correctly, but not in
'testmpi3.f90'. As far as I can tell, the 2 programs are
equivalent up to line 134 of 'testmpi3.c' and lines 97-101 of
'testmpi3.f90'. I thought the calls to 'c_f_pointer' would produce
Fortran pointers that would access the correct shared memory
addresses as the C-pointers do in 'testmpi3.c', but clearly that
isn't happening. Can anyone explain why not, and what is needed to
make this happen. Any suggestions are welcome.
My environment:
Scientific Linux 6.8
INTEL FORTRAN and ICC version 15.0.2.164
OPEN-MPI 2.0.1
T. Rosmond
_______________________________________________
users mailing list
users@lists.open-mpi.org <mailto:users@lists.open-mpi.org>
https://rfd.newmexicoconsortium.org/mailman/listinfo/users
<https://rfd.newmexicoconsortium.org/mailman/listinfo/users>
--
Jeff Hammond
jeff.scie...@gmail.com <mailto:jeff.scie...@gmail.com>
http://jeffhammond.github.io/
_______________________________________________
users mailing list
users@lists.open-mpi.org
https://rfd.newmexicoconsortium.org/mailman/listinfo/users
_______________________________________________
users mailing list
users@lists.open-mpi.org
https://rfd.newmexicoconsortium.org/mailman/listinfo/users
