## start_pes

#### Purpose

Called at the beginning of a SHMEM program to identify the number of processes desired.

#### C syntax

    #include <shmem.h>

    void start_pes(int npes);

#### Parameters

INPUT
npes
  Identifies the total number of processing elements (PEs) desired. If npes is 0, the number of PEs is selected by the MP_PROCS environment variable.

#### Description

The start_pes routine identifies the number of processes for a program. This statement must be the first statement in a program that uses IBM SHMEM communication routines.

The value of npes must be less than or equal to the value specified by MP_PROCS environment variable.

#### IBM NOTES

For current implementation, any npes value other than 0 is ignored. Users can only do the initialization once by invoking either shmem_init or start_pes in the beginning of their programs

#### C examples

    #include <shmem.h>
    #include <stdio.h>

    int main (int argc, char* argv[])
    {
        int total_tasks = -1;
        int my_task = -1;

        start_pes(0);

        total_tasks = _num_pes();

        if (total_tasks <= 0) {
            printf("FAILED\n");
            return 0;
        } else {
            printf("number of pes is %d\n", total_tasks);
        }

        my_task = _my_pe();

        if (my_task < 0){
            printf("FAILED\n");
            return 0;
        } else {
            printf("my pe id is %d\n", my_task);
        }

        printf("PASSED\n");
        return 0;
    }

#### Related information

Subroutines: num_pes, my_pe

OpenSHMEM API Index