IN: Optimization flag specifying linked-chunk I/O or multi-chunk I/O
H5P_SET_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. H5P_SET_DXPL_MPIO_CHUNK_OPT is provided so that an application can override the library's algorithm in circumstances where the library might lack the information needed to make an optimal decision.
H5P_SET_DXPL_MPIO_CHUNK_OPT works by setting one of the following flags in the parameter opt_mode:
Do one link chunked I/O
Do multi-chunked I/O
This function works by setting a corresponding property in the dataset transfer property list dxpl_id.
The library performs 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.
Returns a non-negative value if successful. Otherwise returns a negative value.