With Intel MPI 2017, Update 3 or newer, the default for I_MPI_FABRICS changed from shm:tmi to shm:ofi. I_MPI_FABRICS=shm:ofi implies the OpenFabrics Interface (OFI) library will be used for inter-node communications, and the following settings have been added to the Intel MPI 2017 and 2018 environments via modulefile:
export I_MPI_FABRICS=shm:ofi
export I_MPI_OFI_PROVIDER=psm2
With the Intel Omni-Path Software 10.5 release (the current installed version on Marconi), the OFI library will be included in the Basic and IFS packages.
export I_MPI_FABRICS=shm:tmi
export I_MPI_TMI_PROVIDER=psm2