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.
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).