Learn to Use HPC Systems and Supercomputers/

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MPI - hello world!

MPI - hello world!

We'll cover the following...

In this lesson, we will show you a basic MPI hello world code and also discuss how to run an MPI program. The lesson will cover the basics of initializing MPI and running an MPI job across several processes.

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#include <mpi.h>
#include <stdio.h>
int main(int argc, char** argv) {
    // Initialize the MPI environment
    MPI_Init(NULL, NULL);
    // Get the number of processes
    int world_size;
    MPI_Comm_size(MPI_COMM_WORLD, &world_size);
    // Get the rank of the process
    int world_rank;
    MPI_Comm_rank(MPI_COMM_WORLD, &world_rank);
    // Get the name of the processor
    char processor_name[MPI_MAX_PROCESSOR_NAME];
    int name_len;
    MPI_Get_processor_name(processor_name, &name_len);
    // Print off a hello world message
    printf("Hello world from processor %s, rank %d"
           " out of %d processors\n",
           processor_name, world_rank, world_size);
    // Finalize the MPI environment.
    MPI_Finalize();
}

Let’s get introduced with the functions and environment veriables used in the code:

  • MPI_Init, all of MPI’s global and internal variables
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