Hybrid MPI & OpenMP Parallel Programming (Tutorial at ISC'13)

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Hybrid MPI & OpenMP Parallel Programming (Tutorial at ISC'13)


Most HPC systems are clusters of shared memory nodes. Such systems can be PC clusters with single/multi-socket and multi-core SMP nodes, but also constellation type systems with large SMP nodes. Parallel programming may combine the distributed memory parallelization on the node interconnect with the shared memory parallelization inside of each node. This tutorial analyzes the strengths and weaknesses of several parallel programming models on clusters of SMP nodes. Multi-socket-multi-core systems in highly parallel environments are given special consideration. MPI-3.0 introduced a new shared memory programming interface, which can be combined with MPI message passing and remote memory access on the cluster interconnect. It can be used for direct neighbor accesses similar to OpenMP or for direct halo copies, and enables new hybrid programming models. These models are compared with various hybrid MPI+OpenMP approaches and pure MPI. This tutorial also includes a discussion on OpenMP support for accelerators. Benchmark results on different platforms are presented. Numerous case studies demonstrate the performance-related aspects of hybrid programming, and application categories that can take advantage of this model are identified. Tools for hybrid programming such as thread/process placement support and performance analysis are presented in a "how-to" section. Details: https://fs.hlrs.de/projects/rabenseifner/publ/SC2013-hybrid.html

General Information

Rolf Rabenseifner, Georg Hager, Gabriele Jost:

Hybrid MPI and OpenMP Parallel Programming

Half-day Tutorial at Super Computing 2013, SC13, Denver (CO), USA, Nov. 17 - 22, 2013.
Abstract, Extended Abstract, Slides as pdf.