Code execution

For examples for code execution, please visit Slurm partition CPU CLX.

Code compilation

For code compilation please use gnu compiler.

module load gcc/13.3.0
module load openmpi/gcc/5.0.3
mpicc -Wl,-rpath,$LD_RUN_PATH -o hello.bin hello.c

module load gcc/13.3.0
module load openmpi/gcc/5.0.3
mpicc -fopenmp -Wl,-rpath,$LD_RUN_PATH -o hello.bin hello.c

Slurm job script

A slurm script is submitted to the job scheduler slurm. It contains

the request for compute nodes of a Slurm partition CPU CLX and
commands to start your binary. You have two options to start an MPI binary.
- using mpirun
- using srun

Using mpirun

Using mpirun (from the MPI library) to start the binary you need to switch off slurm binding by adding export SLURM_CPU_BIND=none.

#!/bin/bash
#SBATCH --nodes=2
#SBATCH --partition=cpu-clx:test
module load openmpi/gcc/5.0.3
export SLURM_CPU_BIND=none
mpirun -np 192 --map-by ppr:96:node ./hello.bin

#!/bin/bash
#SBATCH --nodes=2
#SBATCH --partition=cpu-clx:test
module load openmpi/gcc/5.0.3
export SLURM_CPU_BIND=none
mpirun -np 96 --map-by ppr:48:node ./hello.bin

You can run one code compiled with MPI and OpenMP. The example covers the setup

2 nodes,
4 processes per node, 24 threads per process.

#!/bin/bash
#SBATCH --nodes=2
#SBATCH --partition=cpu-clx:test
module load openmpi/gcc/5.0.3
export SLURM_CPU_BIND=none
export OMP_NUM_THREADS=24
mpirun -np 8 --map-by ppr:4:node:pe=24 ./hello.bin

Using srun

#!/bin/bash
#SBATCH --nodes=2
#SBATCH --partition=cpu-clx:test
srun --ntasks-per-node=96 ./hello.bin