Task scheduling method considered the communication time by critical path: Application to various kinds of network topology

In parallel processing in a multiprocessor system, it is necessary to partition the user program and data to be distributed to the processors, that is, to apply scheduling. It is difficult to realize the scheduling under arbitrary conditions without any restriction of precedence constraints, number of employed processors, the multiprocessor configuration, and the communication time, by an algorithm with optimized polynomial time. Thus, the application of a heuristic algorithm is considered. This paper is based on the critical path (CP) method, and proposes a scheduling method which can be used in multiprocessor systems with various topologies, including perfect and imperfect connections. The proposed method resembles the existing method in that the task is assigned, but has the feature that the assignment is corrected and optimized from the viewpoint of the communication time. The allocation of processors and adequate modification of hopping are also considered. The effectiveness of the proposed method is evaluated through comparison to existing methods using the same task graph. In order to evaluate its effectiveness when applied to a large‐scale system, the method was implemented on a real system (a system with 32 DSP), and an analysis program for an electrical power system was run. The proposed method was demonstrated to be uniformly useful for various topologies, and exhibits sufficient performance in practice. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(1): 63–75, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10212