Open MPI is very aggressive about looking for and using any tcp communications device it can find. In your case it will use both the 10.0.. network and the 192.168.. network at the same time. Open MPI does not pay attention to the hosts names for the communications channel. You want to do something like:
mpirun --mca btl_tcp_if_include lo,eth1 Please see the Open MPI FAQ: Tuning the run-time characteristics of MPI TCP communications 7. How do I tell Open MPI which TCP networks to use? http://www.open-mpi.org/faq/?category=tcp#tcp-selection george wm turner high performance systems 812 855 5156 On May 28, 2010, at 5:29 PM, Rahul Nabar wrote:
Each of our servers has twin eth cards: 1GigE and 10GigE. How does openmpi decide which card to use while sending messages on? One of the cards is on a 10.0. IP address subnet whereas the other cards are on a 192.168 adress subnet. Can I select one or the other by specifying the --host option with the correct IP addresses? How does it select the default though? Frequently I call mpirun from within a PBS wrapper and then there is no explicit --host directive. (I think PBS somehow communicates to mpirun what the assigned hostfile is) In such a case though, which interface will mpirun use? -- Rahul _______________________________________________ torqueusers mailing list torqueus...@supercluster.org http://www.supercluster.org/mailman/listinfo/torqueusers
