Question

I want to run parallel codes on single pc with core i7 cpu I can compile my code but I have problem with running it.

I compile my code with mpicxx and when I run it by ” mpirun -np 8 ./a.out” only one process is. My operating system is linux ubuntu 11.04.

Working what must I do?

For example I want to run this code:

#include <iostream>
#include <mpi.h>
using namespace std;

int main(int argc, char **argv)
{
    int mynode, totalnodes;
    MPI_Init(&argc,&argv);
    MPI_Comm_size(MPI_COMM_WORLD, &totalnodes);
    MPI_Comm_rank(MPI_COMM_WORLD, &mynode);
    cout << "Hello world from process " << mynode;
    cout << " of " << totalnodes << endl;
    MPI_Finalize();
}

I use mpich2 with mpirun –version:1.3.1

Answer 1

If you use ubuntu operating system you can execute your codes with mpiexec -n 8 /path/to/application too and no machine file is required just be sure that you installed mpich library properly for doing this you can use synaptic package manager for installing library.