Update example in docs/polaris /running-jobs.md to use 1 rank / GPU

[saforem2]

Update the

Running Multiple MPI Applications on a node
from docs/polaris/running-jobs.md#L47

example to instead use 1 MPI rank / GPU. e.g.

#!/bin/bash --login
setupPolaris()  {
  if [[ $(hostname) == x* ]]; then
    # -- MPI / Comms Setup -----------------
    NHOSTS=$(wc -l < "${PBS_NODEFILE}")
    NGPU_PER_HOST=$(nvidia-smi -L | wc -l)
    NGPUS=$((${NHOSTS}*${NGPU_PER_HOST}))
    MPI_COMMAND=$(which mpiexec)
    MPI_DEFAULTS="\
      --envall \
      --verbose \
      --hostfile ${HOSTFILE}"
    MPI_ELASTIC="\
      -n ${NGPUS} \
      --ppn ${NGPU_PER_HOST}"
    MPI_EXEC="\
      ${MPI_COMMAND} \
      ${MPI_DEFAULTS} \
      ${MPI_ELASTIC}"
  else
    echo "Unexpected hostname: $(hostname)"
  fi
}

setupPolaris
"${MPI_EXEC}" $@

[felker]

Is this still an issue @saforem2 ?