An Efficient Algorithm for Scheduling Irregular Communication of GEN_BLOCK Redistribution

• Main Authors: Shih-Chang Chen, 陳世璋
• Other Authors: Ching-Hsien Hsu
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/08893040177419215780

碩士 === 中華大學 === 資訊工程學系碩士班 === 93 === Many scientific problems have been solved on distributed memory multi-computers. For solving those problems, efficient data redistribution algorithm is necessary. Irregular array redistribution has been paid attention to recently since it can distribute different size of data segment to processors according to their computation ability. High Performance Fortran Version 2 (HPF2) provides GEN_BLOCK (generalized block) distribution format which facilitates generalized block distributions. In this thesis, we present a two-phase degree-reduction (TPDR) method for scheduling HPF2 irregular array redistribution. In a bipartite graph representation, the first phase schedules communications of processors that have node degree greater than two. Every communication step will be scheduled after a degree-reduction iteration. The second phase schedules all messages of processors that have degree-2 and degree-1 using an adjustable coloring mechanism. An extended algorithm based on TPDR is also presented in this thesis. Effectiveness of the proposed methods not only avoids node contention but also shortens the overall communication length. To evaluate the performance of our methods, our algorithm has been implemented along with the divide-and-conquer algorithm, list scheduling algorithm and coloring scheduling mechanism. The experimental results show improvement of communication costs. The proposed methods are also practicable due to their low algorithmic complexity.