Revealing the Performance of MPI RMA Implementations

The MPI remote-memory access (RMA) operations provide a different programming model from the regular MPI-1 point-to-point operations. This model is particularly appropriate for cases where there are multiple communication events for each synchronization and where the target memory locations are known by the source processes. In this paper, we describe a benchmark designed to illustrate the performance of RMA with multiple RMA operations for each synchronization, as compared with point-to-point communication. We measured the performance of this benchmark on several platforms (SGI Altix, Sun Fire, IBM SMP, Linux cluster) and MPI implementations (SGI, Sun, IBM, MPICH2, Open MPI). We also investigated the effectiveness of the various optimization options specified by the MPI standard. Our results show that MPI RMA can provide substantially higher performance than point-topoint communication on some platforms, such as SGI Altix and Sun Fire. The results also show that many opportunities still exist for performance improvements in the implementation of MPI RMA.