Update to one chunk MPI-IO for h5bench_exerciser.c (#135)

It is more optimal and mimics how most applications will run with HDF5 to set the one chunk option for MPI-IO instead of multi chunk.

Co-authored-by: Jean Luca Bez <[email protected]>

Author: pkcoff

exerciser/h5bench_exerciser.c

@@ -559,9 +559,7 @@ main(int argc, char *argv[])
             /* If we are chunking the data.. */
             if (useChunked) {
                 H5Pset_chunk(dataSetPropList, numDims, fileBlock);
-                H5Pset_dxpl_mpio_chunk_opt(xferPropList, H5FD_MPIO_CHUNK_MULTI_IO);
-                // H5Pset_dxpl_mpio_chunk_opt(xferPropList, H5FD_MPIO_CHUNK_ONE_IO); //Not implemented in CCIO
-                // yet!
+                H5Pset_dxpl_mpio_chunk_opt(xferPropList, H5FD_MPIO_CHUNK_ONE_IO);
             }
 
             H5Pset_fill_time(dataSetPropList, H5D_FILL_TIME_NEVER);