Lazy data-oriented evaluation strategies

Abstract

This paper presents a number of flexible parallelism control mechanisms in the form of evaluation strategies for tree-like data structures implemented in Glasgow parallel Haskell. We achieve additional flexibility by using laziness and circular programs in the coordination code. Heuristics-based parameter selection is employed to auto-tune these strategies for improved performance on a sharedmemory machine without programmer-specified parameters. In particular for unbalanced trees we demonstrate improved performance on a state-of-the-art multi-core server: giving a speedup of up to 37.5 on 48 cores for a constructed test program, and up to 15 for two other non-trivial applications using these strategies, a Barnes-Hut implementation of the n-body problem and a sparse matrix multiplication implementation.