Improving Compiler and Run-Time Support for Irregular Reductions (1998)
| Citations: | 17 - 1 self |
BibTeX
@MISC{Han98improvingcompiler,
author = {Hwansoo Han and Chau-Wen Tseng},
title = {Improving Compiler and Run-Time Support for Irregular Reductions},
year = {1998}
}
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Abstract
Compilers for distributed-memory multiprocessors parallelize irregular reductions either by generating calls to sophisticated run-time systems or relying on the sharedmemory interface supported by software DSMs. Run-time systems gather/scatter nonlocal results (e.g., CHAOS, PI-LAR) while software DSMs apply local reductions to replicated buffers (e.g., CVM, TreadMarks). We introduce LO-CALWRITE, a new technique for parallelizing irregular reductions based on the owner-computes rule. It eliminates the need for buffers or synchronized writes, but may replicate computation. We investigate the impact of connectivity (node/edge ratio), locality (accesses to local data) and adaptivity (edge modifications) on their relative performance. LOCALWRITE improves performance by 50-150% compared to using replicated buffers. Gather/scatter using CHAOS generally provides the best performance, but LO-CALWRITE can outperform CHAOS for applications with low locality or high adaptivity. We also discover the flushupdate coherence protocol can improve performance by 15-25 % for software DSMs over an invalidate protocol.
