hwloc: A Generic Framework for Managing Hardware Affinities in HPC Applications

The increasing numbers of cores, shared caches and memory nodes within machines introduces a complex hardware topology. High-performance computing applications now have to carefully adapt their placement and behavior according to the underlying hierarchy of hardware resources and their software affinities. We introduce the Hardware Locality (hwloc) software which gathers hardware information about processors, caches, memory nodes and more, and exposes it to applications and runtime in a abstracted and portable hierarchical manner. hwloc may significantly help performance by having runtime systems place their tasks or adapt their communication strategies depending on hardware affinities. We show that hwloc can already be used by popular highperformance OPENMP or MPI software. Indeed, scheduling OPENMP threads according to their affinities or placing MPI processes according to their communication patterns shows interesting performance improvement thanks to hwloc. An optimized MPI communi...

• Type: Conference
• Year: 2010
• Where: PDP
• Authors: François Broquedis, Jérôme Clet-Ortega, Stephanie Moreaud, Nathalie Furmento, Brice Goglin, Guillaume Mercier, Samuel Thibault, Raymond Namyst
• Keywords: Complex Hardware Topology, Distributed And Parallel Computing, Hardware, Memory Nodes, PDP 2010