Pegasus Parallel

We recommend using Intel MPI unless you have specific reason for using OpenMP.  Intel MPI scales better and has better performance than OpenMP.

Note

Only one MPI module should be loaded at a time.

C++ program and compilation:

mpi_example1.cpp

---

//=================================================================
// C++ example: MPI Example 1
//=================================================================
#include <iostream>
#include <mpi.h>
using namespace std;
int main(int argc, char** argv){
  int iproc;
  MPI_Comm icomm;
  int nproc;
  int i;
  MPI_Init(&argc,&argv);
  icomm = MPI_COMM_WORLD;
  MPI_Comm_rank(icomm,&iproc);
  MPI_Comm_size(icomm,&nproc);
  for ( i = 0; i <= nproc - 1; i++ ){
    MPI_Barrier(icomm);
    if ( i == iproc ){
      cout << "Rank " << iproc << " out of " << nproc << endl;
    }
  }
  MPI_Finalize();
  return 0;
}

[username@pegasus ~]$ mpicxx -o mpi_example1.x mpi_example1.cpp

C program and compilation:

mpi_example1.c

---

//=================================================================
// C example: MPI Example 1
//=================================================================
#include <stdio.h>
#include "mpi.h"
int main(int argc, char** argv){
int iproc;
int icomm;
int nproc;
int i;
MPI_Init(&argc,&argv);
icomm = MPI_COMM_WORLD;
MPI_Comm_rank(icomm,&iproc);
MPI_Comm_size(icomm,&nproc);
for ( i = 0; i <= nproc - 1; i++ ){
  MPI_Barrier(icomm);
  if ( i == iproc ){
    printf("%s %d %s %d \n","Rank",iproc,"out of",nproc);
  }
}
MPI_Finalize();
return 0;
}

[username@pegasus ~]$ mpicc -o mpi_example1.x mpi_example1.c

Fortran 90 program and compilation:

mpi_example1.f90

---

!=====================================================
! Fortran 90 example: MPI test
!=====================================================
program mpiexample1
implicit none
include 'mpif.h'
integer(4) :: ierr
integer(4) :: iproc
integer(4) :: nproc
integer(4) :: icomm
integer(4) :: i
call MPI_INIT(ierr)
icomm = MPI_COMM_WORLD
call MPI_COMM_SIZE(icomm,nproc,ierr)
call MPI_COMM_RANK(icomm,iproc,ierr)
do i = 0, nproc-1
  call MPI_BARRIER(icomm,ierr)
  if ( iproc == i ) then
    write (6,*) "Rank",iproc,"out of",nproc
  end if
end do
call MPI_FINALIZE(ierr)
if ( iproc == 0 ) write(6,*)'End of program.'
  stop
end program mpiexample1

[username@pegasus ~]$ mpif90 -o mpi_example1.x mpi_example1.f90

Fortran 77 program and compilation:

mpi_example1.f

---

c=====================================================
c Fortran 77 example: MPI Example 1
c=====================================================
program mpitest
implicit none
include 'mpif.h'
integer(4) :: ierr
integer(4) :: iproc
integer(4) :: nproc
integer(4) :: icomm
integer(4) :: i
call MPI_INIT(ierr)
icomm = MPI_COMM_WORLD
call MPI_COMM_SIZE(icomm,nproc,ierr)
call MPI_COMM_RANK(icomm,iproc,ierr)
do i = 0, nproc-1
  call MPI_BARRIER(icomm,ierr)
  if ( iproc == i ) then
    write (6,*) "Rank",iproc,"out of",nproc
  end if
end do
call MPI_FINALIZE(ierr)
if ( iproc == 0 ) write(6,*)'End of program.'
  stop
end

[username@pegasus ~]$ mpif77 -o mpi_example1.x mpi_example1.f

LSF script example

This batch script mpi_example1.job instructs LSF to reserve computational resources for your job. Change the -P flag argument to your project before running.

mpi_example1.job

---

#!/bin/sh
#BSUB -n 16
#BSUB -J test
#BSUB -o test.out
#BSUB -e test.err
#BSUB -a openmpi
#BSUB -R "span[ptile=16]"
#BSUB -q parallel
#BSUB -P hpc
mpirun.lsf ./mpi_example1.x

Submit this scriptfile using bsub. For job script information, see Scheduling Jobs on Pegasus.

[username@pegasus ~]$ bsub -q parallel < mpi_example1.job
Job <6021006> is submitted to queue <parallel>.
...