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On Effective Execution of Nonuniform DOACROSS Loops
May 1996 (vol. 7 no. 5)
pp. 463-476

Abstract—It is extremely difficult to parallelize DOACROSS loops with nonuniform loop-carried dependences. In this paper, we present a static scheduling scheme with an accompanying synchronization strategy that can execute such DOACROSS loops effectively and efficiently. Our approach uses one of the parallelization techniques called Dependence Uniformization, which finds a small set of uniform dependence vectors to cover all possible nonuniform dependences in a DOACROSS loop. It differs from the previous schemes in that we demonstrate a better way to select the uniform dependence vectors. When used with the Static Strip Scheduling scheme, the proposed uniform dependence vector set allows us to enforce dependences with more locality, which reduces the requirement of explicit synchronization considerably while retaining most of the parallelism. This paper describes the uniform dependence vectors selection strategy and the static strip scheduling scheme. The performance analysis and examples are also presented.

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Index Terms:
Compiler transformation, data dependence, loop parallelization, parallelism, scheduling, synchronization.
Citation:
Ding-Kai Chen, Pen-Chung Yew, "On Effective Execution of Nonuniform DOACROSS Loops," IEEE Transactions on Parallel and Distributed Systems, vol. 7, no. 5, pp. 463-476, May 1996, doi:10.1109/71.503771
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