Your gfortran command line strongly suggests your program is serial and
does not use MPI at all.
Consequently, mpirun will simply spawn 8 identical instances of the very
same program, and no speed up should be expected
(but you can expect some slow down and/or file corruption).
If you observe similar behaviour with Open MPI and IntelMPI, then this
is very unlikely an Open MPI issue,
and this mailing it not the right place to discuss a general
MPI/parallelization performance issue.
Cheers,
Gilles
On 11/28/2019 1:54 PM, Mahesh Shinde via users wrote:
Hi,
I am running a physics based boundary layer model with parallel code
which uses openmpi libraries. I installed openmpi. I am running it on
general purpose Azure machine with 8 cores, 32GB RAM. I compiled the
code with /*gfortran -O3 -fopenmp -o abc.exe abc.f*/ and then /*mpirun
-np 8 ./abc.exe*/ But i found slow speed with 4 and 8 cores. I also
tried it with trial version of intel parallel studio suite, but no
improvement in the speed.
why this is happening? is the code not properly utilize mpi? does it
need HPC machine on Azure? Does it compiled with intel ifort?
your suggestions/comments are welcome.
Thanks and regards.
Mahesh
