H5Pset_dxpl_mpio_chunk_opt
(hid_t dxpl_id
,
H5FD_mpio_chunk_opt_t opt_mode
)
H5Pset_dxpl_mpio_chunk_opt
specifies whether I/O
is to be performed as linked-chunk I/O or as multi-chunk I/O.
This function overrides the HDF5 Library's internal algorithm
for determining which mechanism to use.
When an application uses collective I/O with chunked storage,
the HDF5 Library normally uses an internal algorithm to determine
whether that I/O activity should be conducted as one linked-chunk I/O
or as multi-chunk I/O.
H5Pset_dxpl_mpio_chunk_opt
is provided so that an
application can override the library's alogorithm in circumstances
where the library might lack the information needed to make
an optimal desision.
H5Pset_dxpl_mpio_chunk_opt
works by setting one of the
following flags in the parameter opt_mode
:
H5FD_MPIO_CHUNK_ONE_IO |
Do one link chunked I/O. |
H5FD_MPIO_CHUNK_MULTI_IO |
Do multi-chunked I/O. |
dxpl_id
.
The library perform I/O in the specified manner unless it determines that the low-level MPI IO package does not support the requested behavior; in such cases, the HDF5 Library will internally use independent I/O.
Use of this function is optional.
hid_t dxpl_id |
IN: Data transfer property list identifier |
H5FD_mpio_chunk_opt_t opt_mode |
IN: Optimization flag specifying linked-chunk I/O or multi-chunk I/O |