More likely the difference is due to the fact that MPICH does some automatic process binding and OMPI doesn't. There have been a number of discussions on this list about this issue. You might search the list for "MPICH" to find them.
See the OMPI FAQ on affinity: http://www.open-mpi.org/faq/?category=tuning#using-paffinity On Jan 13, 2010, at 6:01 PM, Aaron Knister wrote: > Does your application do a lot of printing to stdout/stderr? > > On Jan 11, 2010, at 8:00 AM, Mathieu Gontier wrote: > >> Hi all >> >> I want to migrate my CFD application from MPICH-1.2.4 (ch_p4 device) to >> OpenMPI-1.4. Hence, I compared the two libraries compiled with my >> application and I noted OpenMPI is less efficient thant MPICH on ethernet >> (170min with MPICH against 200min with OpenMPI). So, I wonder if someone has >> more information/explanation. >> >> Here the configure options of OpenMPI: >> >> export FC=gfortran >> export F77=$FC >> export CC=gcc >> export PREFIX=/usr/local/bin/openmpi-1.4 >> ./configure --prefix=$PREFIX --enable-cxx-exceptions --enable-mpi-f77 >> --enable-mpi-f90 --enable-mpi-cxx --enable-mpi-cxx-seek --enable-dist >> --enable-mpi-profile --enable-binaries --enable-cxx-exceptions >> --enable-mpi-threads --enable-memchecker --with-pic --with-threads >> --with-valgrind --with-libnuma --with-openib >> >> Despite my OpenMPI compilation supports OpenIB, I did not specified any >> mca/btl options because the machine does not have access to a Infiniband >> interconnect. So, I guess tcp, sm and self are used (or at least something >> close). >> >> Thank you for your help. >> Mathieu. >> _______________________________________________ >> users mailing list >> us...@open-mpi.org >> http://www.open-mpi.org/mailman/listinfo.cgi/users > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users
