一个调度Fork-Join任务图的最优算法

Fork-Join任务图是一种并行处理的基本结构.虽然许多算法在任务满足某些条件时能产生最优调度,但往往没有考虑节省处理器个数和减少任务集的总完成时间,从而降低算法的加速比和效率.因此,提出一种基于任务复制的平衡调度算法,其时间复杂度为O(vq+vlogv),v和q分别表示任务集中任务的个数和使用的处理器个数.通过分析已用处理器的负载和空闲时间段,把任务尽量分配到已用的处理器上以均衡负载,从而提高其利用率.实验结果表明,该算法的加速比和总体效率优于其他算法.因此,该算法对于高性能应用程序的调度是一个较好的选择.

An Optimal Scheduling Algorithm for Fork-Join Task Graphs

The Fork-Join structure is one of the basic modeling structures for parallel processing. Although some algorithms are able to find an optimal schedule under certain conditions, they ignore to economize processors and minimize the total completion time. This paper presents a Task Duplication based Balance Scheduling(TDBS)algorithm which can generate an optimal schedule for fork-join task graph with a complexity of O(vq+vlogv), where v and q are the number of tasks and processors respectively. By considering workload and idle time slots of the used processors, TDBS algorithm tries to assign tasks to scheduled processors and maximize their utilization. Simulation results show that TDBS algorithm has better speedup and efficiency than other compared algorithms. Therefore,TDBS algorithm is a viable option for practical high performance applications.