Dynamic Multiple Work Stealing Strategy for Flexible Load Balancing

Lazy-task creation is an efficient method of overcoming the overhead of the grain-size problem in parallel computing. Work stealing is an effective load balancing strategy for parallel computing. In this paper, we present dynamic work stealing strategies in a lazy-task creation technique for efficient fine-grain task scheduling. The basic idea is to control load balancing granularity depending on the number of task parents in a stack. The dynamic-length strategy of work stealing uses run-time information, which is information on the load of the victim, to determine the number of tasks that a thief is allowed to steal. We compare it with the bottommost first work stealing strategy used in StackThread/MP, and the fixed-length strategy of work stealing, where a thief requests to steal a fixed number of tasks, as well as other multithreaded frameworks such as Cilk and OpenMP task implementations. The experiments show that the dynamic-length strategy of work stealing performs well in irregular workloads such as in UTS benchmarks, as well as in regular workloads such as Fibonacci, Strassen\u27s matrix multiplication, FFT, and Sparse-LU factorization. The dynamic-length strategy works better than the fixed-length strategy because it is more flexible than the latter; this strategy can avoid load imbalance due to overstealing

筑波大学計算科学研究センター 平成24年度 年次報告書

1 平成23年度 重点施策・改善目標　……　22 平成24年度 実施報告　……　53 各研究部門の報告　……　11Ⅰ.素粒子物理研究部門　……　11Ⅱ.宇宙・原子核物理研究部門　……　40 Ⅱ-1.宇宙分野　……　40 Ⅱ-2.原子核分野　……　65Ⅲ.量子物性研究部門　……　88Ⅳ.生命科学研究部門　……　115 Ⅳ-1.生命機能情報分野　……　115 Ⅳ-2.分子進化分野　……　125Ⅴ.地球環境研究部門　……　136Ⅵ.高性能計算システム研究部門　……　146Ⅶ.計算情報学研究部門　……　165 Ⅶ-1.データ基盤分野　……　165 Ⅶ-2.計算メディア分野　……　17