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/* -*- Mode: C; c-basic-offset:4 ; -*- */
#include "mpi.h"
#include "mpio.h" /* not necessary with MPICH 1.1.1 or HPMPI 1.4 */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define SIZE (65536)
/* Uses asynchronous I/O. Each process writes to separate files and
reads them back. The file name is taken as a command-line argument,
and the process rank is appended to it.*/
int main(int argc, char **argv)
{
int *buf, i, rank, nints, len;
char *filename, *tmp;
MPI_File fh;
MPI_Status status;
MPIO_Request request;
MPI_Init(&argc,&argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
/* process 0 takes the file name as a command-line argument and
broadcasts it to other processes */
if (!rank) {
i = 1;
while ((i < argc) && strcmp("-fname", *argv)) {
i++;
argv++;
}
if (i >= argc) {
fprintf(stderr, "\n*# Usage: async -fname filename\n\n");
MPI_Abort(MPI_COMM_WORLD, 1);
}
argv++;
len = strlen(*argv);
filename = (char *) malloc(len+10);
strcpy(filename, *argv);
MPI_Bcast(&len, 1, MPI_INT, 0, MPI_COMM_WORLD);
MPI_Bcast(filename, len+10, MPI_CHAR, 0, MPI_COMM_WORLD);
}
else {
MPI_Bcast(&len, 1, MPI_INT, 0, MPI_COMM_WORLD);
filename = (char *) malloc(len+10);
MPI_Bcast(filename, len+10, MPI_CHAR, 0, MPI_COMM_WORLD);
}
buf = (int *) malloc(SIZE);
nints = SIZE/sizeof(int);
for (i=0; i<nints; i++) buf[i] = rank*100000 + i;
/* each process opens a separate file called filename.'myrank' */
tmp = (char *) malloc(len+10);
strcpy(tmp, filename);
sprintf(filename, "%s.%d", tmp, rank);
MPI_File_open(MPI_COMM_SELF, filename, MPI_MODE_CREATE | MPI_MODE_RDWR,
MPI_INFO_NULL, &fh);
MPI_File_set_view(fh, 0, MPI_INT, MPI_INT, "native", MPI_INFO_NULL);
MPI_File_iwrite(fh, buf, nints, MPI_INT, &request);
MPIO_Wait(&request, &status);
MPI_File_close(&fh);
/* reopen the file and read the data back */
for (i=0; i<nints; i++) buf[i] = 0;
MPI_File_open(MPI_COMM_SELF, filename, MPI_MODE_CREATE | MPI_MODE_RDWR,
MPI_INFO_NULL, &fh);
MPI_File_set_view(fh, 0, MPI_INT, MPI_INT, "native", MPI_INFO_NULL);
MPI_File_iread(fh, buf, nints, MPI_INT, &request);
MPIO_Wait(&request, &status);
MPI_File_close(&fh);
/* check if the data read is correct */
for (i=0; i<nints; i++)
if (buf[i] != (rank*100000 + i))
fprintf(stderr, "Process %d: error, read %d, should be %d\n", rank, buf[i], rank*100000+i);
if (!rank) fprintf(stderr, "Done\n");
free(buf);
free(filename);
free(tmp);
MPI_Finalize();
return 0;
}
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