/*
 * Copyright (c) 2004-2005 The Trustees of Indiana University.
 *                         All rights reserved.
 * Copyright (c) 2004-2005 The Trustees of the University of Tennessee.
 *                         All rights reserved.
 * Copyright (c) 2004-2005 High Performance Computing Center Stuttgart, 
 *                         University of Stuttgart.  All rights reserved.
 * Copyright (c) 2004-2005 The Regents of the University of California.
 *                         All rights reserved.
 * $COPYRIGHT$
 * 
 * Additional copyrights may follow
 * 
 * $HEADER$
 */

#include "ompi_config.h"
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <math.h>
#include <sys/time.h>
#include "mpi.h"
#include "test_util.h"

#define MYBUFSIZE (4*1024*1024)

char        s_buf[MYBUFSIZE];
char        r_buf[MYBUFSIZE];
int         skip = 40;

int
main (int argc, char *argv[])
{
    MPI_Status  stat;
    int         myid, numprocs, i, j;
    double      startwtime = 0.0, endwtime;
    int         namelen;
    int         min, max, size;
    int         loop = 1;

    struct timeval t_start, t_end;

    if (argc < 4) {
        fprintf (stderr, "Usage: %s min max loop_size\n", argv[0]);
        return 0;
    } else {
	min  = atoi (argv[1]);
	max  = atoi (argv[2]);
	loop = atoi (argv[3]);
    }

    /* Get some environmental variables set for Open MPI, OOB */
    /*env_init_for_elan();*/

    MPI_Init (&argc, &argv);
    MPI_Comm_size (MPI_COMM_WORLD, &numprocs);
    MPI_Comm_rank (MPI_COMM_WORLD, &myid);

    if (myid == 0) 
	fprintf(stdout, "%10s %10s \n", "#   length", "latency(us)");

    for (size = min; size <= max; size = (size == 0) ? 1 : 2*size) {
	for (i = 0; i < loop + skip; i++) {
	    if (i == skip)
		gettimeofday (&t_start, 0);
	    if (myid == 0) {
		MPI_Send (s_buf, size, MPI_CHAR, 1, i, MPI_COMM_WORLD);
		MPI_Recv (r_buf, size, MPI_CHAR, 1, i, MPI_COMM_WORLD, &stat);
	    } else {
		MPI_Recv (r_buf, size, MPI_CHAR, 0, i, MPI_COMM_WORLD, &stat);
		MPI_Send (s_buf, size, MPI_CHAR, 0, i, MPI_COMM_WORLD);
	    }
	}
	gettimeofday (&t_end, 0);
	if (myid == 0) {
	    double      latency;
	    latency = ((1.0e6 * t_end.tv_sec + t_end.tv_usec) 
		    - (1.0e6 * t_start.tv_sec + t_start.tv_usec)) 
		/ (2.0 * loop);
	    fprintf(stdout, " %8d  %10.2f \n", size, latency);
	}
	fflush(stdout);
    }

    MPI_Finalize ();
    return 0;
}