How can Intel MPI be tuned for the JURECA InfiniBand network?

By default, Intel MPI uses uDAPL (Direct Access Programming Library) for inter-node MPI communication via the InfiniBand fabric. In many cases better performance can be achieved with the low-level OFED libibverbs library. In order to select the ofa fabric for Intel MPI inter-node communication, export the following environment variable in your job script or salloc session:

export I_MPI_FABRIC=shm:ofa