Mycorrhiza/benchmarks/mpi/send_recv.c

#include <mpi.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

int main (int argc, char *argv []) {
	int message_size = atoi (argv [1]);
	int message_count = atoi (argv [2]);
  unsigned long throughput;
  double megabits;

	// Initialize the MPI environment
	MPI_Init(NULL, NULL);
	// Find out rank, size
	int world_rank;
	MPI_Comm_rank(MPI_COMM_WORLD, &world_rank);
	int world_size;
	MPI_Comm_size(MPI_COMM_WORLD, &world_size);

	if (world_size < 2) {
		fprintf(stderr, "World size must be greater than 1 for %s\n", argv[0]);
		MPI_Abort(MPI_COMM_WORLD, 1);
	}

	int data[message_size];

  clock_t start, end;
  long double elapsed;
  start = clock();
  
	for (int i = 0; i != message_count; i++) {
		if (world_rank == 0) {
			data[0] = 1234;
			MPI_Send(data, message_size, MPI_INT, 1, 0, MPI_COMM_WORLD);
		} else if (world_rank == 1) {
			MPI_Recv(data, message_size, MPI_INT, 0, 0, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
		}
	}
	
	end = clock();
	
	if (world_rank == 1) {
  	elapsed = end - start;
    if (elapsed == 0)
        elapsed = 1;
  	
  	throughput = (unsigned long)
        ((double) message_count / (double) elapsed * 1000000);
    megabits = ((double) throughput * message_size * 8) / 1000000;

  	
  	printf("message size: %d [B]\n", message_size);
  	printf("message count: %d [B]\n", message_count);
  	printf("mean throughput: %d [msg/s]\n", (int)throughput);
  	printf("mean throughput: %.3f [Mb/s]\n", (double)megabits);

	}

	MPI_Finalize();
	
}