Performance of cluster-enabled OpenMP for the SCASH software distributed shared memory system

OpenMP has attracted widespread interest because it is an easy-to-use parallel programming model for shared memory multiprocessor systems. Implementation of a "cluster-enabled" OpenMP compiler is presented. Compiled programs are linked to the page-based software distributed-shared-memory system, SCASH, which runs on PC clusters. This allows OpenMP programs to be run transparently in a distributed memory environment. The compiler converts programs written for OpenMP into parallel programs using the SCASH static library, moving all shared global variables into SCASH shared address space at runtime. As data mapping has a great impact on the performance of OpenMP programs compiled for software distributed-shared-memory, extensions to OpenMP directives are defined for specifying data mapping and loop scheduling behavior, allowing data to be allocated to the node where it is to be processed. Experimental results of benchmark programs on PC clusters using both Myrinet and fast Ethernet are reported.