/****************************************************************************
* FILE: poe_bandwidth.c
* DESCRIPTION:  
*   This code conducts timing tests on messages sent between two processes.
*   It sends/receives N roundtrips of incrementally sized messages
*   from start size J to finish size K by increment I.  
* AUTHOR:  10/09/98 Blaise Barney
* LAST REVISED: 
******************************************************************************/

#include "mpi.h"
#include <stdio.h>
#include <sys/time.h>
#include <time.h>

#define MAXSIZE         1000000
#define task0           0
#define task1           1
#define tag0            0
#define tag1            1

int     numtasks,rank,n,i,rndtrps,mbytes,startsize,finishsize,incr;
float   tbytes,ttime;
char    c[MAXSIZE],host0[35], host1[35];
struct 	timeval tv1, tv2;
MPI_Status Stat;

int main(argc,argv)
int argc;
char *argv[];  {

MPI_Init(&argc,&argv);
MPI_Comm_size(MPI_COMM_WORLD, &numtasks);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);

/**************************** task 0 ***********************************/
if (rank == task0) {
  gethostname(host0,&n);
  MPI_Recv(&host1, 35, MPI_CHAR, task1, tag1, MPI_COMM_WORLD, &Stat);
  for (i=0; i<MAXSIZE; i++)
    c[i] = 'x';

  startsize = 100000;
  finishsize = MAXSIZE;
  incr = 100000;
  rndtrps = 3;
  printf("\n****** MPI/POE Bandwidth Test ******\n");
  printf("Message start size= %8d bytes\n",startsize);
  printf("Message finish size= %8d bytes\n",finishsize);
  printf("Roundtrips/iteration= %8d\n",rndtrps);
  printf("Incremented by %8d bytes per iteration\n",incr);
  printf("Using nodes: %s    %s\n\n",host0,host1);
  printf("Message Size   Bandwidth (bytes/sec)\n");

  MPI_Send(&startsize, 1, MPI_INT, task1, tag0, MPI_COMM_WORLD);
  MPI_Send(&finishsize, 1, MPI_INT, task1, tag0, MPI_COMM_WORLD);
  MPI_Send(&incr, 1, MPI_INT, task1, tag0, MPI_COMM_WORLD);
  MPI_Send(&rndtrps, 1, MPI_INT, task1, tag0, MPI_COMM_WORLD);
  for (n=startsize; n<=finishsize; n=n+incr) {
    ttime = 0.0;
    mbytes =  sizeof(char) * n;
    for (i=1; i<=rndtrps; i++){
      gettimeofday(&tv1, (struct timeval*)0);       /* before time */
      MPI_Send(&c, n, MPI_CHAR, task1, tag0, MPI_COMM_WORLD);
      MPI_Recv(&c, n, MPI_CHAR, task1, tag1, MPI_COMM_WORLD, &Stat);
      gettimeofday(&tv2, (struct timeval*)0);       /* after time */
      ttime = ttime +  ((tv2.tv_sec - tv1.tv_sec) * 1000000) + 
              tv2.tv_usec - tv1.tv_usec;
      }
    tbytes = (float)mbytes * 2.0 * (float)rndtrps;
    printf("%9d %16d\n",mbytes,(int)(tbytes/(ttime/1000000.0)));
    }
  }   /* end of task 0 */	


/****************************  task 1 ************************************/
if (rank == task1) {
  gethostname(host1,&n);
  MPI_Send(&host1, 35, MPI_CHAR, task0, tag1, MPI_COMM_WORLD);
  MPI_Recv(&startsize, 1, MPI_INT, task0, tag0, MPI_COMM_WORLD, &Stat);
  MPI_Recv(&finishsize, 1, MPI_INT, task0, tag0, MPI_COMM_WORLD, &Stat);
  MPI_Recv(&incr, 1, MPI_INT, task0, tag0, MPI_COMM_WORLD, &Stat);
  MPI_Recv(&rndtrps, 1, MPI_INT, task0, tag0, MPI_COMM_WORLD, &Stat);
  for (n=startsize; n<=finishsize; n=n+incr) {
    for (i=1; i<=rndtrps; i++){
      MPI_Recv(&c, n, MPI_CHAR, task0, tag0, MPI_COMM_WORLD, &Stat);
      MPI_Send(&c, n, MPI_CHAR, task0, tag1, MPI_COMM_WORLD);
      }
    }
  }  /* end of task 1 */

MPI_Finalize();
}  /* end of main */