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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <mpi.h>
#define NITER 100000
#define MAXSZ 65536*2*2
int main(int argc, char **argv) {
int i, j;
char *in, *out;
double t_start, t_stop;
MPI_Comm copy_comm;
MPI_Init(&argc, &argv);
MPI_Comm_dup(MPI_COMM_SELF, ©_comm);
in = malloc(MAXSZ);
out = malloc(MAXSZ);
for (i = 0; i < MAXSZ; i++) {
in[i] = 0xAA;
out[i] = 0x55;
}
for (i = 1; i <= MAXSZ; i *= 2) {
t_start = MPI_Wtime();
for (j = 0; j < NITER; j++) {
memcpy(out, in, i);
}
t_stop = MPI_Wtime();
printf("MEMCPY: %7d\t%0.9f\n", i, t_stop-t_start);
}
for (i = 0; i < MAXSZ; i++) {
in[i] = 0xAA;
out[i] = 0x55;
}
for (i = 1; i <= MAXSZ; i *= 2) {
t_start = MPI_Wtime();
for (j = 0; j < NITER; j++) {
MPI_Sendrecv(in, i, MPI_BYTE,
0 /* rank */, 0 /* tag */,
out, i, MPI_BYTE,
0 /* rank */, 0 /* tag */,
copy_comm, MPI_STATUS_IGNORE);
}
t_stop = MPI_Wtime();
printf("SNDRCV: %7d\t%0.9f\n", i, t_stop-t_start);
}
MPI_Comm_free(©_comm);
MPI_Finalize();
return 0;
}
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