Applying MPI Derived Datatypes to the NAS Benchmarks: A Case Study

MPI derived datatypes are a powerful method to define arbitrary collections of non-contiguous data in memory and to enable non-contiguous data communication in a single MPI function call. In this paper, the authors employs MPI datatypes in four NAS benchmarks (MG, LU, BT, and SP) to transfer non-contiguous data. Comprehensive performance evaluation was carried out on two clusters: an Itanium-2 Myrinet cluster and a Xeon InfiniBand cluster. Performance results show that using datatypes can achieve performance comparable to manual packing/unpacking in the original benchmarks, though the MPI implementations that were studied also perform internal packing and unpacking on noncontiguous datatype communication.