Assessing Contention Effects of All-to-All Communications on Clusters and Grids

Luiz Angelo Steffenel (1) , Maxime Martinasso (2) , Denis Trystram (2)

1 CRESTIC - Centre de Recherche en Sciences et Technologies de l'Information et de la Communication - EA 3804
2 MESCAL - Middleware efficiently scalable

One of the most important collective communication patterns used in scientific applications is the complete exchange, also called All-to-All. Although efficient algorithms have been studied for specific networks, general solutions like those available in well-known MPI distributions (e.g. the MPI_Alltoall operation) are strongly influenced by the congestion of network resources. In this paper we present an integrated approach to model the performance of the All-to-All collective operation, which consists in identifying a contention signature that characterizes a given network environment, using it to augment a contention-free communication model. This approach, assessed by experimental results, allows an accurate prediction of the performance of the All-to-All operation over different network architectures with a small overhead. We also discuss the problem of network contention in a grid environment, studying some strategies to minimize the impact of contention on the performance of an All-to-All operation.

Mots clés: MPI; all-to-all; total exchange; network contention; performance modeling; computational grid; personalized many-to-many communications

Domaines: Calcul parallèle, distribué et partagé [cs.DC]

Luiz Angelo Steffenel, Maxime Martinasso, Denis Trystram. Assessing Contention Effects of All-to-All Communications on Clusters and Grids. International Journal of Pervasive Computing and Communications, 2008, 4 (4). ⟨hal-00338855⟩