Running MPI Jobs

The Message Passing Interface (MPI) is a library specification for message-passing. It is a standard API (Application Programming Interface) that can be used to create parallel applications. An MPI job can considered as a cross-node and multi-process job.

An example Slurm MPI job script

#SBATCH --job-name=MyJob
... ...
#SBATCH --ntasks=32
#SBATCH --ntasks-per-node=16
#SBATCH --cpus-per-tasks=1
... ...
module load openmpi/1.10.7-mlx
mpirun <program>

This script tells Slurm this is a multi-processing job. It has 32 MPI processes, with 16 MPI processes on each node (implicitly requesting 2 nodes). For each MPI process, it needs 1 CPU core.