Unlike mpich-gm, Open MPI does not keep the memory pinned by default.
You can force this by ading the "--mca mpi_leave_pinned 1" to your
mpirun command or by adding it into the Open MPI configuration file
as specified on the FAQ (section performance). I think that should be
the main reason what you're seeing a such degradation of performances.
If this does not solve your problem, can you please provide the new
performance as well as the output of the command "ompi_info --param
On Jun 13, 2006, at 10:01 AM, Brock Palen wrote:
> I ran a test using openmpi-1.0.2 on OSX vs mpich-1.2.6 from
> mryicom and i get lacking results from OMPI,
> at point point there is a small drop in bandwidth for both MPI
> libs, but open mpi does not recover like mpich, and further on you
> see a decreese in bandwidth for OMPI on gm.
> I have attached in png and the outputs from the test (there are
> two for OMPI )
> Brock Palen
> Center for Advanced Computing
> users mailing list