IN: Optimization flag specifying the use of independent or collective I/O
H5P_SET_DXPL_MPIO_COLLECTIVE_OPT enables an application to specify that the HDF5 library will use independent I/O internally when the dataset transfer property list dxpl_id is set for collective I/O, i.e., with H5FD_MPIO_COLLECTIVE specified. This allows the application greater control over low-level I/O while maintaining the collective interface at the application level.
H5P_SET_DXPL_MPIO_COLLECTIVE_OPT works by setting one of the following flags in the parameter opt_mode:
Use collective I/O (Default)
Use independent I/O
This function should be used only when H5FD_MPIO_COLLECTIVE has been set through H5P_SET_DXPL_MPIO. In such situations, normal behavior would be to use low-level collective I/O functions, but the library will use low-level MPI independent I/O functions when H5FD_MPIO_INDIVIDUAL_IO is set.
Use of this function is optional.
Returns a non-negative value if successful. Otherwise returns a negative value.