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authorRobert Kim Yates <rkyates@llnl.gov>1999-12-01 20:53:18 (GMT)
committerRobert Kim Yates <rkyates@llnl.gov>1999-12-01 20:53:18 (GMT)
commit290bf31554941900aabc928f556bffe6db49ff38 (patch)
treeb7e3a47e51d7534d1b614d4c4f8b3fd0c7f1193f /src
parent9c40226b31cec9f01d7facc4fde77db6ee702341 (diff)
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[svn-r1849] Performance improvement to H5FD_mpio_open: eliminated unnecessary truncation.
Diffstat (limited to 'src')
-rw-r--r--src/H5FDmpio.c57
1 files changed, 38 insertions, 19 deletions
diff --git a/src/H5FDmpio.c b/src/H5FDmpio.c
index 03db98e..d0b511c 100644
--- a/src/H5FDmpio.c
+++ b/src/H5FDmpio.c
@@ -673,6 +673,10 @@ H5FD_mpio_fapl_get(H5FD_t *_file)
*
* Robb Matzke, 1999-08-06
* Modified to work with the virtual file layer.
+ *
+ * rky & ppw, 1999-11-07
+ * Modified "H5FD_mpio_open" so that file-truncation is
+ * avoided for brand-new files (with zero filesize).
*-------------------------------------------------------------------------
*/
static H5FD_t *
@@ -682,11 +686,12 @@ H5FD_mpio_open(const char *name, unsigned flags, hid_t fapl_id,
H5FD_mpio_t *file=NULL;
MPI_File fh;
int mpi_amode;
- int mpierr;
+ int mpi_rank;
MPI_Offset size;
const H5FD_mpio_fapl_t *fa=NULL;
H5FD_mpio_fapl_t _fa;
+
FUNC_ENTER(H5FD_mpio_open, NULL);
#ifdef H5FDmpio_DEBUG
@@ -698,21 +703,19 @@ H5FD_mpio_open(const char *name, unsigned flags, hid_t fapl_id,
/* Obtain a pointer to mpio-specific file access properties */
if (H5P_DEFAULT==fapl_id || H5FD_MPIO!=H5Pget_driver(fapl_id)) {
- _fa.comm = MPI_COMM_SELF; /*default*/
- _fa.info = MPI_INFO_NULL; /*default*/
- fa = &_fa;
+ _fa.comm = MPI_COMM_SELF; /*default*/
+ _fa.info = MPI_INFO_NULL; /*default*/
+ fa = &_fa;
} else {
- fa = H5Pget_driver_info(fapl_id);
- assert(fa);
+ fa = H5Pget_driver_info(fapl_id);
+ assert(fa);
}
/* convert HDF5 flags to MPI-IO flags */
/* some combinations are illegal; let MPI-IO figure it out */
mpi_amode = (flags&H5F_ACC_RDWR) ? MPI_MODE_RDWR : MPI_MODE_RDONLY;
- if (flags&H5F_ACC_CREAT)
- mpi_amode |= MPI_MODE_CREATE;
- if (flags&H5F_ACC_EXCL)
- mpi_amode |= MPI_MODE_EXCL;
+ if (flags&H5F_ACC_CREAT) mpi_amode |= MPI_MODE_CREATE;
+ if (flags&H5F_ACC_EXCL) mpi_amode |= MPI_MODE_EXCL;
#ifdef H5FDmpio_DEBUG
{
@@ -750,35 +753,51 @@ H5FD_mpio_open(const char *name, unsigned flags, hid_t fapl_id,
if (MPI_SUCCESS != MPI_File_open(fa->comm, (char*)name, mpi_amode, fa->info, &fh))
HRETURN_ERROR(H5E_INTERNAL, H5E_MPI, NULL, "MPI_File_open failed");
- /* truncate the file, if requested */
- if (flags & H5F_ACC_TRUNC) {
+
+/* Following changes in handling file-truncation made be rkyates and ppweidhaas, sep 99 */
+ if (MPI_SUCCESS != MPI_Comm_rank (fa->comm, &mpi_rank))
+ HRETURN_ERROR(H5E_INTERNAL, H5E_MPI, NULL, "MPI_Comm_rank failed");
+
+ /* Only processor p0 will get the filesize and broadcast it. */
+ if (mpi_rank == 0) {
+ /* Get current file size */
+ if (MPI_SUCCESS != MPI_File_get_size(fh, &size)) {
+ H5MM_xfree(file);
+ MPI_File_close(&fh);
+ HRETURN_ERROR(H5E_INTERNAL, H5E_MPI, NULL, "MPI_File_get_size failed");
+ }
+ }
+
+ /* Broadcast file-size */
+ if (MPI_SUCCESS != MPI_Bcast(&size, sizeof(MPI_Offset), MPI_BYTE, 0, fa->comm))
+ HRETURN_ERROR(H5E_INTERNAL, H5E_MPI, NULL, "MPI_Bcast failed");
+
+ /* Only if size > 0, truncate the file - if requested */
+ if (size && (flags & H5F_ACC_TRUNC)) {
if (MPI_SUCCESS != MPI_File_set_size(fh, (MPI_Offset)0)) {
MPI_File_close(&fh);
HRETURN_ERROR(H5E_INTERNAL, H5E_MPI, NULL, "MPI_File_set_size failed");
}
- /* Don't let any proc return until all have truncated the file. */
+ /* Don't let any proc return until all have truncated the file. */
if (MPI_SUCCESS!= MPI_Barrier(fa->comm)) {
MPI_File_close(&fh);
HRETURN_ERROR(H5E_INTERNAL, H5E_MPI, NULL, "MPI_Barrier failed");
}
+ size = 0;
}
/* Build the return value and initialize it */
if (NULL==(file=H5MM_calloc(sizeof(H5FD_mpio_t))))
HRETURN_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
+
file->f = fh;
file->comm = fa->comm;
file->info = fa->info;
file->btype = MPI_DATATYPE_NULL;
file->ftype = MPI_DATATYPE_NULL;
- /* Get current file size */
- if (MPI_SUCCESS != MPI_File_get_size(fh, &size)) {
- H5MM_xfree(file);
- MPI_File_close(&fh);
- HRETURN_ERROR(H5E_INTERNAL, H5E_MPI, NULL, "MPI_File_get_size failed");
- }
+
file->eof = MPIOff_to_haddr(size);
#ifdef H5FDmpio_DEBUG