main.c

#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <mpi.h>
#include <string.h>

const int N = 50;
// const int SIZE = 32;
const int SIZE = 32000000;
const char charset[] = "abcdefghijklmnopqrstuvwxyzABC";

int main(void) {
    char msg[SIZE];
    int com_size, rank;
    double start, finish;
    double durations_sum = 0;
    double delay = 0;

    MPI_Init(NULL, NULL);
    MPI_Comm_size(MPI_COMM_WORLD, &com_size);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);

    for (int s=0;s < SIZE-1;s++) {
        msg[s] = charset[s % strlen(charset)];
    }
    msg[SIZE-1] = '\0';

    MPI_Barrier(MPI_COMM_WORLD);

    if (rank == 0) {
        for(int i=0;i < N; i++) {
            start = MPI_Wtime();
            MPI_Send(msg, SIZE, MPI_CHAR, 1, 0, MPI_COMM_WORLD);
            MPI_Recv(msg, SIZE, MPI_CHAR, 1, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
            finish = MPI_Wtime();
            durations_sum += finish - start;
            // printf("Ping pong #%d done on %d of %.9fs\n", value_tx, rank, duration);
        }
        delay = (durations_sum / N) / 2;
        printf("Delay: %lf\n", delay);

    } 
    else if (rank == 1) {
        for(int i=0;i < N; i++) {
            MPI_Recv(msg, SIZE, MPI_CHAR, 0, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
            MPI_Send(msg, SIZE, MPI_CHAR, 0, 0, MPI_COMM_WORLD);
        }
    }
    MPI_Finalize();
    return 0;
}