High performance computing using MPI and OpenMP on multi-core parallel systems

The rapidly increasing number of cores in modern microprocessors is pushing the current high performance computing (HPC) systems into the petascale and exascale era. The hybrid nature of these systems – distributed memory across nodes and shared memory with non-uniform memory access within each node – poses a challenge to application developers. In this paper, we study a hybrid approach to programming such systems – a combination of two traditional programming models, MPI and OpenMP. We present the performance of standard benchmarks from the multi-zone NAS Parallel Benchmarks and two full applications using this approach on several multi-core based systems including an SGI Altix 4700, an IBM p575+ and an SGI Altix ICE 8200EX. We also present new data locality extensions to OpenMP to better match the hierarchical memory structure of multi-core architectures.

► We study the hybrid MPI + OpenMP approach to programming multi-core parallel systems.
► The hybrid approach is compared with pure MPI using benchmarks and full applications.
► Case studies show advantages and issues of the approach on modern parallel systems.
► We propose new extensions to OpenMP to better handle data locality on NUMA systems.