Sample job script to run two MPI tasks within one job script concurrently:

Sample Job when for running multiple mpi jobs on a VSC-4 node.

Note: The “mem_per_task” should be set such that

mem_per_task * mytasks < mem_per_node - 2Gb

The approx 2Gb reduction in available memory is due to operating system stored in memory. For a standard node with 96 Gb of Memory this would be eg.:

23 Gb * 4 = 92 Gb < 94 Gb

#!/bin/bash
#SBATCH -J many
#SBATCH -N 1

export SLURM_STEP_GRES=none

mytasks=4
cmd="stress -c 24"
mem_per_task=10G

for i in `seq 1 $mytasks`
do
        srun --mem=$mem_per_task --cpus-per-task=2 --ntasks=1 $cmd &
done
wait

#!/bin/bash
#SBATCH -J test
#SBATCH -N 1
#SBATCH --ntasks-per-core=1
#SBATCH --ntasks-per-node=2

export SLURM_STEP_GRES=none

module load intel/18 intel-mpi/2018

for i in 0 8
do
  j=$(($i+1))
  srun -n 2 --cpu_bind=map_cpu:$i,$j ./hello_world_intelmpi2018 &
done
wait

exit 0

#!/bin/bash
#SBATCH -J test
#SBATCH -N 1
#SBATCH --ntasks-per-core=1
#SBATCH --ntasks-per-node=2

export SLURM_STEP_GRES=none

module load intel/18 intel-mpi/2018

for i in 0 8
do
  j=$(($i+1))
  mpirun -env I_MPI_PIN_PROCESSOR_LIST $i,$j -np 2 ./hello_world_intelmpi2018 &
done
wait

exit 0

You can download the C code example here: hello_world.c

Compile it e.g. with:

# module load intel/18 intel-mpi/2018
# mpiicc -lhwloc hello_world.c -o hello_world_intelmpi2018