CPS-FR job example

cpi.c

#include "mpi.h"
#include <stdio.h>
#include <math.h>

//Build with
// module load gcc
// module load  mpich/ge/gcc/64/3.1
// mpicc -o cpi cpi.c
// mpirun ./cpi

double f( double );
double f( double a )
{
    return (4.0 / (1.0 + a*a));
}

int main( int argc, char *argv[])
{
    int done = 0, n, myid, numprocs, i;
    double PI25DT = 3.141592653589793238462643;
    double mypi, pi, h, sum, x;
    double startwtime = 0.0, endwtime;
    int  namelen;
    char processor_name[MPI_MAX_PROCESSOR_NAME];

    MPI_Init(&argc,&argv);
    MPI_Comm_size(MPI_COMM_WORLD,&numprocs);
    MPI_Comm_rank(MPI_COMM_WORLD,&myid);
    MPI_Get_processor_name(processor_name,&namelen);

    fprintf(stderr,"Process %d on %s\n",
            myid, processor_name);

    n = 0;
    while (!done)
    {
        if (myid == 0)
        {
/*
            printf("Enter the number of intervals: (0 quits) ");
            scanf("%d",&n);
*/
            if (n==0) n=1024*numprocs; else n=0;

            startwtime = MPI_Wtime();
        }
        MPI_Bcast(&n, 1, MPI_INT, 0, MPI_COMM_WORLD);
        if (n == 0)
            done = 1;
        else
        {
            h   = 1.0 / (double) n;
            sum = 0.0;
            for (i = myid + 1; i <= n; i += numprocs)
            {
                x = h * ((double)i - 0.5);
                sum += f(x);
            }
            mypi = h * sum;

            MPI_Reduce(&mypi, &pi, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD);

            if (myid == 0)
            {
                printf("pi is approximately %.16f, Error is %.16f\n",
                       pi, fabs(pi - PI25DT));
                endwtime = MPI_Wtime();
                printf("wall clock time = %f\n",
                       endwtime-startwtime);
            }
        }
    }
    MPI_Finalize();

    return 0;
}

cpi_cpsfr.slurm

#!/bin/bash
# submit with sbatch cpi_cpsfr.slurm
# commandline arguments may instead by supplied with #SBATCH <flag> <value>
# commandline arguments override these values

# Number of nodes
#SBATCH -N 1
# Number of processor core (32*32=1024, psfc, mit and emiliob nodes have 32 cores per node)
#SBATCH -n 32
# specify how long your job needs. Be HONEST, it affects how long the job may wait for its turn.
#SBATCH --time=0:04:00
# which partition or queue the jobs runs in
#SBATCH -p sched_mit_psfc_cpsfr
# for the CPS-FR class, we have a reservation 
#SBATCH --reservation=psfc-cpsfr
#customize the name of the stderr/stdout file. %j is the job number
#SBATCH -o cpi-%j.out

#load default system modules
. /etc/profile.d/modules.sh

#load modules your job depends on. 
#better here than in your $HOME/.bashrc to make debugging and requirements easier to track.
#here we are using gcc under MPI mpich
module load mpich/ge/gcc/64/3.1

#It is useful to echo the running environment
env

#Finally, the command to execute. 
#The job starts in the directory it was submitted from.
#Note that mpirun knows from SLURM how many processor we have
#In this case, we use all processes.

mpirun ./cpi

CPS-FR_Readme.md

Slurm script for CPS-FR 2019 class.

Pi test for CPS-FR 2019