I built mpich 3.3.2 with ./configure -with-ibverbs=/usr --with-ibverbs-include=/usr/include --with-ibverbs-lib=/usr/lib64 --with-pmi=simple --prefix=/home/admin/hammo nd/mpich Running through the queue with a command line /home/admin/hammond/mpich/bin/mpiexec -n 8 -machinefile ./machinefile myapp -i electron.in I see: srwxr-xr-x 1 root root 0 Mar 30 17:33 sock.pmi2.5442.0 So I guess it is using pmi2. But the slowness compared to srun is the same.