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#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <mpi.h>
static int Errors;
#define ERROR(fname) \
if (err != MPI_SUCCESS) { \
int errorStringLen; \
char errorString[MPI_MAX_ERROR_STRING]; \
MPI_Error_string(err, errorString, &errorStringLen); \
Errors++; \
printf("Error at line %d when calling %s: %s\n",__LINE__,fname,errorString); \
}
#define LEN 2048
#define NVARS 1100
/*----< main() >------------------------------------------------------------*/
int main(int argc, char **argv)
{
char *filename;
size_t i, buf_len;
int err, rank, verbose = 1, nprocs, psize[2], gsize[2], count[2], start[2];
char *buf;
MPI_File fh;
MPI_Datatype subType, filetype, buftype;
MPI_Status status;
MPI_Offset fsize;
int array_of_blocklengths[NVARS];
MPI_Aint array_of_displacements[NVARS];
MPI_Datatype array_of_types[NVARS];
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
MPI_Comm_size(MPI_COMM_WORLD, &nprocs);
if (argc != 2) {
if (!rank)
printf("Usage: %s filename\n", argv[0]);
MPI_Finalize();
exit(1);
}
filename = argv[1];
/* Creates a division of processors in a cartesian grid */
psize[0] = psize[1] = 0;
err = MPI_Dims_create(nprocs, 2, psize);
ERROR("MPI_Dims_create");
/* each 2D variable is of size gsizes[0] x gsizes[1] bytes */
gsize[0] = LEN * psize[0];
gsize[1] = LEN * psize[1];
/* set subarray offset and length */
start[0] = LEN * (rank / psize[1]);
start[1] = LEN * (rank % psize[1]);
count[0] = LEN - 1; /* -1 to create holes */
count[1] = LEN - 1;
fsize = (MPI_Offset) gsize[0] * gsize[1] * NVARS - (LEN + 1);
if (verbose) {
buf_len = (size_t) NVARS *(LEN - 1) * (LEN - 1);
if (rank == 0) {
printf("nprocs=%d NVARS=%d LEN=%d\n", nprocs, NVARS, LEN);
printf("Expecting file size=%lld bytes (%.1f MB, %.1f GB)\n",
(long long) fsize, (float) fsize / 1048576, (float) fsize / 1073741824);
printf("Each global variable is of size %d bytes (%.1f MB)\n",
gsize[0] * gsize[1], (float) gsize[0] * gsize[1] / 1048576);
printf("Each process writes %zd bytes (%.1f MB, %.1f GB)\n",
buf_len, (float) buf_len / 1048576, (float) buf_len / 1073741824);
}
printf("rank %3d: gsize=%4d %4d start=%4d %4d count=%4d %4d\n", rank,
gsize[0], gsize[1], start[0], start[1], count[0], count[1]);
}
/* create 2D subarray datatype for fileview */
err = MPI_Type_create_subarray(2, gsize, count, start, MPI_ORDER_C, MPI_BYTE, &subType);
ERROR("MPI_Type_create_subarray");
err = MPI_Type_commit(&subType);
ERROR("MPI_Type_commit");
/* create a filetype by concatenating NVARS subType */
for (i = 0; i < NVARS; i++) {
array_of_blocklengths[i] = 1;
array_of_displacements[i] = gsize[0] * gsize[1] * i;
array_of_types[i] = subType;
}
err = MPI_Type_create_struct(NVARS, array_of_blocklengths,
array_of_displacements, array_of_types, &filetype);
ERROR("MPI_Type_create_struct");
err = MPI_Type_commit(&filetype);
ERROR("MPI_Type_commit");
err = MPI_Type_free(&subType);
ERROR("MPI_Type_free");
/* Create local buffer datatype: each 2D variable is of size LEN x LEN */
gsize[0] = LEN;
gsize[1] = LEN;
start[0] = 0;
start[1] = 0;
count[0] = LEN - 1; /* -1 to create holes */
count[1] = LEN - 1;
err = MPI_Type_create_subarray(2, gsize, count, start, MPI_ORDER_C, MPI_BYTE, &subType);
ERROR("MPI_Type_create_subarray");
err = MPI_Type_commit(&subType);
ERROR("MPI_Type_commit");
/* concatenate NVARS subType into a buftype */
for (i = 0; i < NVARS; i++) {
array_of_blocklengths[i] = 1;
array_of_displacements[i] = LEN * LEN * i;
array_of_types[i] = subType;
}
/* create a buftype by concatenating NVARS subTypes */
err = MPI_Type_create_struct(NVARS, array_of_blocklengths,
array_of_displacements, array_of_types, &buftype);
ERROR("MPI_Type_create_struct");
err = MPI_Type_commit(&buftype);
ERROR("MPI_Type_commit");
err = MPI_Type_free(&subType);
ERROR("MPI_Type_free");
/* allocate a local buffer */
buf_len = (size_t) NVARS *LEN * LEN;
buf = (char *) malloc(buf_len);
for (i = 0; i < buf_len; i++)
buf[i] = (char) rank;
/* open to create a file */
err =
MPI_File_open(MPI_COMM_WORLD, filename, MPI_MODE_CREATE | MPI_MODE_RDWR, MPI_INFO_NULL,
&fh);
ERROR("MPI_File_open");
/* set the file view */
err = MPI_File_set_view(fh, 0, MPI_BYTE, filetype, "native", MPI_INFO_NULL);
ERROR("MPI_File_set_view");
/* MPI collective write */
err = MPI_File_write_all(fh, buf, 1, buftype, &status);
ERROR("MPI_File_write_all");
/* do it again but use the non-blocking collectives */
err = MPI_File_seek(fh, 0, MPI_SEEK_SET);
ERROR("MPI_File_seek");
MPI_Request req;
err = MPI_File_iwrite_all(fh, buf, 1, buftype, &req);
ERROR("MPI_File_write_all");
MPI_Wait(&req, &status);
err = MPI_File_read_all(fh, buf, 1, buftype, &status);
ERROR("MPI_File_read_all");
err = MPI_File_seek(fh, 0, MPI_SEEK_SET);
ERROR("MPI_File_seek");
err = MPI_File_iread_all(fh, buf, 1, buftype, &req);
MPI_Wait(&req, &status);
MPI_File_close(&fh);
free(buf);
err = MPI_Type_free(&filetype);
ERROR("MPI_Type_free");
err = MPI_Type_free(&buftype);
ERROR("MPI_Type_free");
if (Errors > 0) {
printf(" Found %d errors\n", Errors);
} else {
printf(" No Errors\n");
}
MPI_Finalize();
return 0;
}
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