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/*
* MPIO independent overlapping writes.
*
* First n-1 processes open 1 file.
* Each of the n-1 process writes chunks of data to the file in round-robin
* fashion, in a interleaved but not overlapped fashion. Using increasing
* chunk sizes for the benefits of testing different write sizes and also
* reducing the numbers of writes.
*
* Last process (n-1) just waits.
* First n-1 processes finish writing and cloose the file.
* Last process opens the same file and verifies the data.
*/
#include <testphdf5.h>
#define MPIO_TEST_WRITE_SIZE 1024*1024 /* 1 MB */
void
test_mpio_overlap_writes(char *filename)
{
int mpi_size, mpi_rank;
MPI_Comm comm;
MPI_Info info = MPI_INFO_NULL;
int color, mrc;
MPI_File fh;
int newrank, newprocs;
hid_t fid; /* file IDs */
hid_t acc_tpl; /* File access properties */
herr_t ret; /* generic return value */
int i;
char buf[4093]; /* use some prime number for size */
int bufsize = sizeof(buf);
int stride;
MPI_Offset mpi_off;
MPI_Status mpi_stat;
if (verbose)
printf("MPIO independent overlapping writes test on file %s\n",
filename);
/* set up MPI parameters */
MPI_Comm_size(MPI_COMM_WORLD,&mpi_size);
MPI_Comm_rank(MPI_COMM_WORLD,&mpi_rank);
/* Need at least 2 processes */
if (mpi_size < 2) {
if (MAINPROCESS)
printf("Need at least 2 processes to run MPIO test.\n");
printf(" -SKIP- \n");
return;
}
/* splits processes 0 to n-2 into one comm. and the last one into another */
color = ((mpi_rank < (mpi_size - 1)) ? 0 : 1);
mrc = MPI_Comm_split (MPI_COMM_WORLD, color, mpi_rank, &comm);
VRFY((mrc==MPI_SUCCESS), "Comm_split succeeded");
if (color==0){
/* First n-1 processes (color==0) open a file and write it */
mrc = MPI_File_open(comm, filename, MPI_MODE_CREATE|MPI_MODE_RDWR,
info, &fh);
VRFY((mrc==MPI_SUCCESS), "");
stride = 1;
mpi_off = mpi_rank*stride;
while (mpi_off < MPIO_TEST_WRITE_SIZE){
/* make sure the write does not exceed the TEST_WRITE_SIZE */
if (mpi_off+stride > MPIO_TEST_WRITE_SIZE)
stride = MPIO_TEST_WRITE_SIZE - mpi_off;
/* set data to some trivial pattern for easy verification */
for (i=0; i<stride; i++)
buf[i] = (mpi_off+i) & 0x7f;
mrc = MPI_File_write_at(fh, mpi_off, buf, stride, MPI_BYTE,
&mpi_stat);
VRFY((mrc==MPI_SUCCESS), "");
/* move the offset pointer to last byte written by all processes */
mpi_off += (mpi_size - 1 - mpi_rank) * stride;
/* Increase chunk size without exceeding buffer size. */
/* Then move the starting offset for next write. */
stride *= 2;
if (stride > bufsize)
stride = bufsize;
mpi_off += mpi_rank*stride;
}
/* close file and free the communicator */
mrc = MPI_File_close(&fh);
VRFY((mrc==MPI_SUCCESS), "MPI_FILE_CLOSE");
mrc = MPI_Comm_free(&comm);
VRFY((mrc==MPI_SUCCESS), "MPI_Comm_free");
/* sync with the other waiting processes */
mrc = MPI_Barrier(MPI_COMM_WORLD);
VRFY((mrc==MPI_SUCCESS), "Sync after writes");
}else{
/* last process waits till writes are done,
* then opens file to verify data.
*/
mrc = MPI_Barrier(MPI_COMM_WORLD);
VRFY((mrc==MPI_SUCCESS), "Sync after writes");
mrc = MPI_File_open(comm, filename, MPI_MODE_RDONLY,
info, &fh);
VRFY((mrc==MPI_SUCCESS), "");
stride = bufsize;
for (mpi_off=0; mpi_off < MPIO_TEST_WRITE_SIZE; mpi_off += bufsize){
/* make sure it does not read beyond end of data */
if (mpi_off+stride > MPIO_TEST_WRITE_SIZE)
stride = MPIO_TEST_WRITE_SIZE - mpi_off;
mrc = MPI_File_read_at(fh, mpi_off, buf, stride, MPI_BYTE,
&mpi_stat);
VRFY((mrc==MPI_SUCCESS), "");
for (i=0; i<stride; i++){
char expected;
expected = (mpi_off+i) & 0x7f;
if (buf[i] != expected)
printf("proc %d: found data error at [%ld], expect %d, got %d\n",
mpi_rank, mpi_off+i, expected, buf[i]);
}
}
/* close file and free the communicator */
mrc = MPI_File_close(&fh);
VRFY((mrc==MPI_SUCCESS), "MPI_FILE_CLOSE");
mrc = MPI_Comm_free(&comm);
VRFY((mrc==MPI_SUCCESS), "MPI_Comm_free");
}
/*
* one more sync to ensure all processes have done reading
* before ending this test.
*/
mrc = MPI_Barrier(MPI_COMM_WORLD);
VRFY((mrc==MPI_SUCCESS), "Sync before leaving test");
}
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