An Efficient OpenMP Runtime System for Hierarchical Architectures

Samuel Thibault (1, 2) , François Broquedis (1, 2) , Brice Goglin (1, 2) , Raymond Namyst (1, 2) , Pierre-André Wacrenier (1, 2)

1 RUNTIME - Efficient runtime systems for parallel architectures
2 LaBRI - Laboratoire Bordelais de Recherche en Informatique

Exploiting the full computational power of always deeper hierarchical multiprocessor machines requires a very careful distribution of threads and data among the underlying non-uniform architecture. The emergence of multi-core chips and NUMA machines makes it important to minimize the number of remote memory accesses, to favor cache affinities, and to guarantee fast completion of synchronization steps. By using the BubbleSched platform as a threading backend for the GOMP OpenMP compiler, we are able to easily transpose affinities of thread teams into scheduling hints using abstractions called bubbles. We then propose a scheduling strategy suited to nested OpenMP parallelism. The resulting preliminary performance evaluations show an important improvement of the speedup on a typical NAS OpenMP benchmark application.

Mots clés: SMP; OpenMP; Nested Parallelism; Hierarchical Thread Scheduling; Bubbles; Multi-Core; NUMA; SMP.

Domaines: Architectures Matérielles [cs.AR]; Calcul parallèle, distribué et partagé [cs.DC]

Samuel Thibault, François Broquedis, Brice Goglin, Raymond Namyst, Pierre-André Wacrenier. An Efficient OpenMP Runtime System for Hierarchical Architectures. International Workshop on OpenMP (IWOMP), Jun 2007, Beijing, China. pp.148--159, ⟨10.1007/978-3-540-69303-1_19⟩. ⟨inria-00154502⟩