Do you know for sure that MKL is only using one thread or do you merely see that the performance is consistent with it using one thread?
If MPI does process pinning, it is possible for all OpenMP threads to run on one core, which means one will observe no speedup from threads (and potentially a slowdown due to oversubscription). I do not know the option to disable this with Open-MPI, but I assume either you can find it in the docs or one of the Open-MPI experts will provide it. I have observed this issue with MVAPICH2 and Pthread applications in the past (it has been fixed both in MVAPICH2 and the relevant applications), but not in Open-MPI with OpenMP, although I am not a heavy user of Open-MPI. Best, Jeff On Wed, Jun 22, 2016 at 9:17 AM, remi marchal <remi.marc...@univ-rennes1.fr> wrote: > Dear openmpi users, > > Today, I faced a strange problem. > > I am compiling a quantum chemistry software (CASTEP-16) using intel16, mkl > threaded libraries and openmpi-18.1. > > The compilation works fine. > > When I ask for MKL_NUM_THREAD=4 and call the program in serial mode > (without mpirun), it works perfectly and use 4 threads. > > However, when I start the program with mpirun, even with 1 mpi process, > the program ran but only with 1 thread. > > I never add such kind of trouble. > > Does anyone have an explanation. > > Regards, > > Rémi > > > > > > _______________________________________________ > users mailing list > us...@open-mpi.org > Subscription: https://www.open-mpi.org/mailman/listinfo.cgi/users > Link to this post: > http://www.open-mpi.org/community/lists/users/2016/06/29495.php > -- Jeff Hammond jeff.scie...@gmail.com http://jeffhammond.github.io/
