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H5P_SET_DXPL_MPIO_CHUNK_OPT

Sets a flag specifying linked-chunk I/O or multi-chunk I/O

Procedure:

H5P_SET_DXPL_MPIO_CHUNK_OPT ( dxpl_id, opt_mode )

Signature:

herr_t H5Pset_dxpl_mpio_chunk_opt 
      (hid_t dxpl_id, 
      H5FD_mpio_chunk_opt_t opt_mode)

  

Parameters:
hid_t dxpl_idIN: 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

Description:

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:

H5FD_MPIO_CHUNK_ONE_IODo one link chunked I/O
H5FD_MPIO_CHUNK_MULTI_IO    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:

Returns a non-negative value if successful. Otherwise returns a negative value.

Example:

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History:

 

--- Last Modified: January 03, 2018 | 02:55 PM