MPI C

If you have not done yet, download the Sample files by:

git clone https://hidekiCCS:@bitbucket.org/hidekiCCS/hpc-workshop.git

Hello World

/home/fuji/hpc-workshop/SimpleExample/C/hello_MPI

/*
  hello_mpi.c: display a message on the screen
 */
#include <stdio.h>
#include <mpi.h>
 
int main (int argc, char *argv[]) {
  int myid,numproc;
 
  /* Initialize */
  MPI_Init(&argc,&argv);
 
  /* get myid and # of processors */
  MPI_Comm_size(MPI_COMM_WORLD,&numproc);
  MPI_Comm_rank(MPI_COMM_WORLD,&myid);
 
  printf("hello from %d\n", myid);
 
  /* wait until all processors come here */
  MPI_Barrier (MPI_COMM_WORLD);
 
  if ( myid == 0 ) {
    /* only id = 0 do this */
    printf("%d processors said hello!\n",numproc);
  }
 
  MPI_Finalize();
}

Compile

Intel

module load intel-psxe
mpicc hello_mpi.c

OpenMPI

module load openmpi/4.1.6
mpicc hello_mpi.c

Example of Jobscript

slurmscript

#!/bin/bash
#SBATCH --partition=defq    # Partition (default is 'defq')
#SBATCH --qos=normal            # Quality of Service
#SBATCH --job-name=helloC_MPI   # Job Name
#SBATCH --time=00:10:00         # WallTime
#SBATCH --nodes=2               # Number of Nodes
#SBATCH --ntasks-per-node=1     # Number of tasks (MPI processes)
#SBATCH --cpus-per-task=1       # Number of processors per task OpenMP threads()
#SBATCH --gres=mic:0            # Number of Co-Processors

module load intel-psxe

pwd

echo "DIR=" $SLURM_SUBMIT_DIR
echo "TASKS_PER_NODE=" $SLURM_TASKS_PER_NODE
echo "NNODES=" $SLURM_NNODES
echo "NTASKS" $SLURM_NTASKS
echo "JOB_CPUS_PER_NODE" $SLURM_JOB_CPUS_PER_NODE
echo $SLURM_NODELIST

mpirun ./a.out

echo "End of Job"