On Wed, Oct 8, 2008 at 7:16 PM, Jeff Squyres <jsquy...@cisco.com> wrote:
> On Oct 8, 2008, at 9:10 AM, Sangamesh B wrote: > > I wanted to switch from mpich2/mvapich2 to OpenMPI, as OpenMPI >> supports both ethernet and infiniband. Before doing that I tested an >> application 'GROMACS' to compare the performance of MPICH2 & OpenMPI. Both >> have been compiled with GNU compilers. >> >> After this benchmark, I came to know that OpenMPI is slower than MPICH2. >> >> This benchmark is run on a AMD dual core, dual opteron processor. Both >> have compiled with default configurations. >> >> The job is run on 2 nodes - 8 cores. >> >> OpenMPI - 25 m 39 s. >> MPICH2 - 15 m 53 s. >> > > > A few things: > > - What version of Open MPI are you using? Please send the information > listed here: > 1.2.7 > > http://www.open-mpi.org/community/help/ > > - Did you specify to use mpi_leave_pinned? No > Use "--mca mpi_leave_pinned 1" on your mpirun command line (I don't know if > leave pinned behavior benefits Gromacs or not, but it likely won't hurt) > > - Did you enable processor affinity? No > Use "--mca mpi_paffinity_alone 1" on your mpirun command line. > Will use these options in the next benchmark > > - Are you sure that Open MPI didn't fall back to ethernet (and not use IB)? > Use "--mca btl openib,self" on your mpirun command line. > I'm using TCP. There is no infiniband support. But eventhough the results can be compared? > > - Have you tried compiling Open MPI with something other than GCC? No. > Just this week, we've gotten some reports from an OMPI member that they > are sometimes seeing *huge* performance differences with OMPI compiled with > GCC vs. any other compiler (Intel, PGI, Pathscale). We are working to > figure out why; no root cause has been identified yet. > I'll try for other than gcc and comeback to you > > -- > Jeff Squyres > Cisco Systems > > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users >
