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-rw-r--r--src/H5Dmpio.c63
1 files changed, 33 insertions, 30 deletions
diff --git a/src/H5Dmpio.c b/src/H5Dmpio.c
index 8c78af2..f2f3efa 100644
--- a/src/H5Dmpio.c
+++ b/src/H5Dmpio.c
@@ -172,10 +172,43 @@ H5D_mpio_opt_possible(const H5D_io_info_t *io_info, const H5S_t *file_space,
HDassert(file_space);
HDassert(type_info);
+ /* Global decisions. These conditions are common to all processes and they
+ * will all arrive at the same conclusions, without requiring communication.
+ */
+
/* For independent I/O, get out quickly and don't try to form consensus */
if(io_info->dxpl_cache->xfer_mode == H5FD_MPIO_INDEPENDENT)
HGOTO_DONE(FALSE);
+ /* Optimized MPI types flag must be set and it must be collective IO */
+ /* (Don't allow parallel I/O for the MPI-posix driver, since it doesn't do real collective I/O) */
+ /* (Global decision if all processes share the same environment, which is reasonable) */
+ if(!(H5S_mpi_opt_types_g && io_info->dxpl_cache->xfer_mode == H5FD_MPIO_COLLECTIVE
+ && !IS_H5FD_MPIPOSIX(io_info->dset->oloc.file)))
+ HGOTO_DONE(FALSE);
+
+ /* Dataset storage must be contiguous or chunked */
+ if(!(io_info->dset->shared->layout.type == H5D_CONTIGUOUS ||
+ io_info->dset->shared->layout.type == H5D_CHUNKED))
+ HGOTO_DONE(FALSE);
+
+ /* The handling of memory space is different for chunking and contiguous
+ * storage. For contiguous storage, mem_space and file_space won't change
+ * when it it is doing disk IO. For chunking storage, mem_space will
+ * change for different chunks. So for chunking storage, whether we can
+ * use collective IO will defer until each chunk IO is reached.
+ */
+
+ /* Don't allow collective operations if filters need to be applied */
+ if(io_info->dset->shared->layout.type == H5D_CHUNKED &&
+ io_info->dset->shared->dcpl_cache.pline.nused > 0)
+ HGOTO_DONE(FALSE);
+
+
+ /* Local decisions. These conditions could be different on each process,
+ * and require communication to verify.
+ */
+
/* Don't allow collective operations if datatype conversions need to happen */
if(!type_info->is_conv_noop) {
local_opinion = FALSE;
@@ -188,14 +221,6 @@ H5D_mpio_opt_possible(const H5D_io_info_t *io_info, const H5S_t *file_space,
goto broadcast;
} /* end if */
- /* Optimized MPI types flag must be set and it must be collective IO */
- /* (Don't allow parallel I/O for the MPI-posix driver, since it doesn't do real collective I/O) */
- if(!(H5S_mpi_opt_types_g && io_info->dxpl_cache->xfer_mode == H5FD_MPIO_COLLECTIVE
- && !IS_H5FD_MPIPOSIX(io_info->dset->oloc.file))) {
- local_opinion = FALSE;
- goto broadcast;
- } /* end if */
-
/* Check whether these are both simple or scalar dataspaces */
if(!((H5S_SIMPLE == H5S_GET_EXTENT_TYPE(mem_space) || H5S_SCALAR == H5S_GET_EXTENT_TYPE(mem_space))
&& (H5S_SIMPLE == H5S_GET_EXTENT_TYPE(file_space) || H5S_SCALAR == H5S_GET_EXTENT_TYPE(file_space)))) {
@@ -210,28 +235,6 @@ H5D_mpio_opt_possible(const H5D_io_info_t *io_info, const H5S_t *file_space,
goto broadcast;
} /* end if */
- /* Dataset storage must be contiguous or chunked */
- if(!(io_info->dset->shared->layout.type == H5D_CONTIGUOUS ||
- io_info->dset->shared->layout.type == H5D_CHUNKED)) {
- local_opinion = FALSE;
- goto broadcast;
- } /* end if */
-
- /* The handling of memory space is different for chunking and contiguous
- * storage. For contiguous storage, mem_space and file_space won't change
- * when it it is doing disk IO. For chunking storage, mem_space will
- * change for different chunks. So for chunking storage, whether we can
- * use collective IO will defer until each chunk IO is reached.
- */
-
- /* Don't allow collective operations if filters need to be applied */
- if(io_info->dset->shared->layout.type == H5D_CHUNKED) {
- if(io_info->dset->shared->dcpl_cache.pline.nused > 0) {
- local_opinion = FALSE;
- goto broadcast;
- } /* end if */
- } /* end if */
-
broadcast:
/* Form consensus opinion among all processes about whether to perform
* collective I/O