The same-source parallel MM5

With the March 1998 release of the Penn State University/NCAR Mesoscale Model (MM5), the official version of the model (MM5v2 Release 8) now runs on distributed memory (DM) message-passing platforms. Under an IBM-funded effort, source translation and runtime library support minimize the impact of parallelization on the original model source code with the result that the majority of code is line-for-line identical with the original version. Parallel performance and scaling are equivalent to earlier, hand-parallelized versions; the modifications have no effect when the code is compiled and run without the DM option. Supported computers include the IBM SP2, Cray T3E, and Fujitsu VPP. The approach is compatible with sharedmemory parallelism, allowing DM/SM hybrid parallelization on distributed memory clusters of SMP. Preliminary results show that scalability on distributed shared memory computers such as the SGI Origin 2000 also benefits from a distributed memory programming model.