Assessing Contention Effects on MPI_Alltoall Communications

Abstract. 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. Keywords. Network Contention, MPI, Collective Communications, Performance Modeling

• Type: Conference
• Year: 2007
• Where: GPC
• Authors: Luiz Angelo Steffenel, Maxime Martinasso, Denis Trystram
• Keywords: Collective Communications, Distributed And Parallel Computing, GPC 2007, Important Collective Communication, Well-known Mpi Distributions