Parallelization Methods for Three-Dimensional Fluid Code using High Performance Fortran

Abstract. We have compared the HPF capability among Japanese HPF compilers that were implemented on NEC SX-4, SX-5, Fujitsu VPP800 and Hitachi SR8000 with a three-dimensional fluid code, which is originally written in Fortran77, and have investigated the compatibility for these machines, using the same codes. We have found that HPF could achieve good performance with almost the same source code, but some improvements should be needed to preserve the complete compatibility of HPF source codes. We have also manually tuned communications by HPF/JA extensions, which give users more control over sophisticated parallelization and communication optimizations, to improve sustained performance on Fujitsu VPP800. Unfortunately we could not achieve significant improvement with this hardware, because a computation grain was not large enough to exhibit effects of optimizations with HPF/JA directives. The manual methods to tune communications by users, however, are essential especially for a large number of processors due to the Amdahl’s law.