Characterizing Computation-Communication Overlap in Message-Passing Systems

Bernholdt, David E. ; Nieplocha, Jarek ; Sadayappan, P. ; Shet, Aniruddha G. ; Tipparaju, Vinod

The Ohio State University

关键词: Performance Parallel Processing, Communication Overlap, Performance Instrumentation;    Computers;    Implementation;    Communications;    Parallel Processing, Communication Overlap, Performance Instrumentation;   

DOI  :  10.2172/948730
RP-ID  :  None
RP-ID  :  FG02-05ER25660
RP-ID  :  948730

美国|英语

来源: UNT Digital Library

【 摘 要 】

Effective overlap of computation and communication is a well understood technique for latency hiding and can yield significant performance gains for applications on high-end computers. In this report, we describe an instrumentation framework developed for messagepassing systems to characterize the degree of overlap of communication with computation in the execution of parallel applications. The inability to obtain precise time-stamps for pertinent communication events is a significant problem, and is addressed by generation of minimum and maximum bounds on achieved overlap. The overlap measures can aid application developers and system designers in investigating scalability issues. The approach has been used to instrument two MPI implementations as well as the ARMCI system. The implementation resides entirely within the communication library and thus integrates well with existing approaches that operate outside the library. The utility of the framework is demonstrated by analyzing communication-computation overlap for micro-benchmarks and the NAS benchmarks, and the insights obtained are used to modify the NAS SP benchmark, resulting in improved overlap.