Evaluation of a Compiler with User-Selectable Execution Strategies for Parallel Recursion

摘要

The strategy of evenly distributing processors to each recursive call and the strategy of performing dynamic load-balancing exist as strategies for executing parallel recursions. There are cases in which an execution strategy efficient for a certain parallel recursive algorithm is not efficient for another parallel recursive algorithm depending on the operation of the parallel recursion algorithm. In addition, there are cases in which the execution efficiency decreases due to overparallelization of recursive calls due to factors such as the communication efficiency of a parallel computing environment. On the one hand, it is not easy for a compiler to analyze these factors mechanically from source programs of a parallel recursive algorithm, select an optimal execution strategy, and suppress overparallelization. In general, in many cases, a programmer understands parallel recursive algorithms and can predict which execution strategy is suitable for the algorithm. Thus, if a programmer can specify a parallel recursive execution strategy or specify a decision to suppress overparallelization, parallel recursive algorithms can be executed efficiently. This paper proposes a strategy for a programmer to clearly designate information useful for efficiently executing parallel recursion. In addition, it shows differences in the performance of various execution strategies of parallel recursive algorithms and shows the usefulness of a programmer having the capability to select an execution strategy.