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/* -*- c-file-style: "GNU" -*- */
/*
* Copyright (C) CNRS, INRIA, Université Bordeaux 1, Télécom SudParis
* See COPYING in top-level directory.
*/
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <mpi.h>
#define LEN 16
#define LOOPS 10000
#define WARMUP 100
static unsigned char *main_buffer = NULL;
void SEND(char* buffer, int len, int dest, int tag) {
MPI_Send(buffer, len, MPI_CHAR, dest, tag, MPI_COMM_WORLD);
}
void RECV(char* buffer, int len, int src, int tag) {
MPI_Recv(buffer, len, MPI_CHAR, src, tag, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
}
void fill_buffer(char *buffer, int len) {
int i;
for (i = 0; i < len; i++) {
buffer[i] = 'a' + (i % 26);
}
}
void compute(unsigned usec) {
double t1, t2;
t1 = MPI_Wtime();
do {
t2 = MPI_Wtime();
} while ((t2 - t1) * 1e6 < usec);
}
int main(int argc, char **argv) {
int comm_rank = -1;
int comm_size = -1;
char host_name[1024] = "";
int dest;
int len = LEN;
int iterations = LOOPS;
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &comm_size);
MPI_Comm_rank(MPI_COMM_WORLD, &comm_rank);
if (gethostname(host_name, 1023) < 0) {
perror("gethostname");
exit(1);
}
if (comm_size != 2) {
fprintf(stderr, "This program requires 2 MPI processes, aborting...\n");
goto out;
}
fprintf(stdout, "(%s): My rank is %d\n", host_name, comm_rank);
dest = (comm_rank + 1) % 2;
main_buffer = malloc(len);
fill_buffer(main_buffer, len);
int i;
for (i = 0; i < WARMUP; i++) {
if (!comm_rank) {
SEND(main_buffer, len, dest, 0);
RECV(main_buffer, len, dest, 0);
} else {
RECV(main_buffer, len, dest, 0);
SEND(main_buffer, len, dest, 0);
}
}
double t1, t2;
t1 = MPI_Wtime();
MPI_Barrier(MPI_COMM_WORLD);
for (i = 0; i < iterations; i++) {
if (!comm_rank) {
SEND(main_buffer, len, dest, 0);
RECV(main_buffer, len, dest, 0);
} else {
RECV(main_buffer, len, dest, 0);
SEND(main_buffer, len, dest, 0);
}
}
MPI_Barrier(MPI_COMM_WORLD);
t2 = MPI_Wtime();
if (!comm_rank) {
double latency = 1e6 * (t2 - t1) / (2 * iterations);
printf("%d\t%d\t%lf\n", iterations, len, latency);
}
out: free(main_buffer);
MPI_Finalize();
return 0;
}
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