Hello Gary, It depends on how the Open MPI was built, and on mca parameters passed to the job either via settings in an mca params conf file or the mpirun command line or env. variables. If you have mxm (MLNX) or psm (qlogic/intel) installed on the system where your open mpi was built, you may actually be using one of those via the MTL path.
Try mpirun -np 2 -H hosta,hostb -mca btl self,vader,openib ./your_favorite_test That should force open mpi to try using openib between the pair of hosts. Note you don't need "vader" on the command line if you are running only one mpi rank/node. Howard 2014-12-23 11:48 GMT-07:00 Gary Jackson <ga...@cs.umd.edu>: > > How does OpenMPI decide whether to use the IB BTL between a given pair of > hosts, assuming there is an IB interface available? > > -- > Gary > _______________________________________________ > users mailing list > us...@open-mpi.org > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users > Link to this post: http://www.open-mpi.org/community/lists/users/2014/12/ > 26063.php >
