Towards automatic translation of OpenMP to MPI

Abstract

We present compiler techniques for translating OpenMP shared-memory parallel applications into MPI message-passing programs for execution on distributed memory systems. This translation aims to extend the ease of creating parallel applications with OpenMP to a wider variety of platforms, such as commodity cluster systems. We present key concepts and describe techniques to analyze and efficiently handle both regular and irregular accesses to shared data.We evaluate the performance achieved by our translation scheme on seven representative OpenMP applications, two from SPEC OMPM2001 and five from the NAS Parallel Benchmarks suite, on two different platforms. The average scalability (execution time relative to the serial version) achieved is within 12% of that achieved by corresponding hand-tuned MPI applications. We also compare our programs with versions deployed for a Software Distributed Shared Memory (SDSM) system and find that the direct translation to MPI achieves up to 30% higher scalability. A comparison with High Performance Fortran (HPF) versions of two NAS benchmarks indicates that our translated OpenMP versions achieve 12% to 89% better performance than the HPF versions.