[svn-r8906] Purpose:

Adding the first round of patches about supporting collective chunk IO in HDF5

Description:
The current HDF5 library doesn't support collective MPIO with chunk storage. When users set collective option in their data transfer with chunk storage, the library silently converted the option to INDEPENDENT and that caused trememdous performance penalty. Some application like
WRF-parallel HDF5 IO module has to use contiguous storage for this reason. However, chunking storage has its own advantage(supporting compression filters and extensible dataset), so to make collective MPIO possible inside HDF5 with chunking storage is a very important task.

This check-in make collective chunk IO possible for some special cases. The condition is as follows(either case is fine with using collective chunk IO)
1. for each process, the hyperslab selection of the file data space of each dataset is regular and it is fit in one chunk.

2. for each process, the hyperslab selection of the file data space of each dataset is single and the number of chunks for the hyperslab selection should be equal.

Solution:
Lift up the contiguous storage requirement for collective IO.
Use H5D_isstore_get_addr to get the corresponding chunk address. Then the original library routines will take care of getting the correct address to make sure that MPI FILE TYPE is built correctly for collective IO>

Platforms tested:
arabica(sol), copper(AIX), eirene(Linux)
parallel test is checked at copper.

Misc. update:

1 files changed, 7 insertions, 0 deletions

diff --git a/src/H5Dprivate.h b/src/H5Dprivate.h
index 42f5eb5..6ca207e 100644
--- a/src/H5Dprivate.h
+++ b/src/H5Dprivate.h
@@ -193,6 +193,8 @@ typedef struct H5D_dcpl_cache_t {
     H5D_fill_time_t fill_time;  /* Fill time (H5D_CRT_FILL_TIME_NAME) */
 } H5D_dcpl_cache_t;
 
+/* forward reference for collective-chunk IO use */
+struct H5D_istore_ud1_t; /*define at H5Distore.c*/
 /* Library-private functions defined in H5D package */
 H5_DLL herr_t H5D_init(void);
 H5_DLL hid_t H5D_open(H5G_entry_t *ent, hid_t dxpl_id);
@@ -263,4 +265,9 @@ H5_DLL ssize_t H5D_istore_writevv(H5F_t *f, const H5D_dxpl_cache_t *dxpl_cache,
 H5_DLL herr_t H5D_istore_debug(H5F_t *f, hid_t dxpl_id, haddr_t addr, FILE * stream,
 				int indent, int fwidth, int ndims);
 
+/* Functions that obtain the dataset address */
+H5_DLL haddr_t H5D_istore_get_addr(H5F_t *f, hid_t dxpl_id, 
+                      const H5O_layout_t *layout,const hssize_t offset[], 
+                      struct H5D_istore_ud1_t *_udata);
+
 #endif