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How to pass hints to MPI from HDF5

To set hints for MPI using HDF5, see: H5P_SET_FAPL_MPIO

You use the 'info' parameter to pass these kinds of low-level MPI-IO tuning tweaks. In C, the calls are like this:

   MPI_Info info;

   /* strange thing about MPI hints: the key and value are strings */ 
   MPI_Info_set(info, "bg_nodes_pset", "1");

   H5Pset_fapl_mpio(plist_id, MPI_COMM_WORLD, info);

   /* and now pass plist_id to H5Fopen or H5Fcreate */
   file_id = H5Fcreate(H5FILE_NAME, H5F_ACC_TRUNC, H5P_DEFAULT, plist_id);