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The Liberty Research Group

Parallelization Project

Decoupled Software Pipelining Creates Parallelization Opportunities [abstract] (ACM DL, PDF)
Jialu Huang, Arun Raman, Yun Zhang, Thomas B. Jablin, Tzu-Han Hung, and David I. August
Proceedings of the 2010 International Symposium on Code Generation and Optimization (CGO), April 2010.
Accept Rate: 41% (29/70).

Decoupled Software Pipelining (DSWP) is one approach to automatically extract threads from loops. It partitions loops into long-running threads that communicate in a pipelined manner via inter-core queues. This work recognizes that DSWP can also be an enabling transformation for other loop parallelization techniques. This use of DSWP, called DSWP+, splits a loop into new loops with dependence patterns amenable to parallelization using techniques that were originally either inapplicable or poorly-performing. By parallelizing each stage of the DSWP+ pipeline using (potentially) different techniques, not only is the benefit of DSWP increased, but the applicability and performance of other parallelization techniques are enhanced. This paper evaluates DSWP+ as an enabling framework for other transformations by applying it in conjunction with DOALL, LOCALWRITE, and SpecDOALL to individual stages of the pipeline. This paper demonstrates significant performance gains on a commodity 8-core multicore machine running a variety of codes transformed with DSWP+.