Here's my command: <path_to_OpenMPI_1.8.3>/bin/mpirun <unrelated MCA options> --machinefile hosts.dat -np 4 <executable>
Here's my hosts.dat file: % cat hosts.dat node01 node02 node03 node04 All 4 ranks are launched on node01. I don't believe I've ever seen this before. I had to do a sanity check, so I tried MVAPICH2-2.1a and got what I expected: 1 process runs on each of the 4 nodes. The mpirun man page says 'round-robin', which I take to mean that one process would be launched per line in the hosts file, so this really seems like incorrect behavior. What could be the possibilities here? Thanks for the help!
