HUNTing the Overlap

Hiding communication latency is an important optimization for parallel programs. Programmers or compilers achieve this by using non-blocking communication primitives and overlapping communication with computation or other communication operations. Using non-blocking communication raises two issues: performance and programmability. In terms of performance, optimizers need to find a good communication schedule and are sometimes constrained by lack of full application knowledge. In terms of programmability, efficiently managing nonblocking communication can prove cumbersome for complex applications. In this paper we present the design principles of HUNT, a runtime system designed to search and exploit some of the available overlap present at execution time in UPC programs. Using virtual memory support, our runtime implements demand-driven synchronization for data involved in communication operations. It also employs message decomposition and scheduling heuristics to transparently impro...

• Type: Conference
• Year: 2005
• Where: IEEEPACT
• Authors: Costin Iancu, Parry Husbands, Paul Hargrove
• Keywords: Communication, Hardware, IEEEPACT 2005, Non-blocking Communication, Non-blocking Communication Primitives