Abstract: Effective scheduling of a distributed application is one of the critical issues in heterogeneous computing systems．Many previous algorithms are developed based on homogeneous systems and neglect the heterogeneity of processors,which results in poor schedule efficiency．This paper proposed a heterogeneity,list and task duplication based static heuristics greedy algorithm for scheduling Out-Tree task graphs,the time complexity of which is O(hv^2p) where h,v and p are the height of the DAG,the number of tasks in the task graph and the number of processors required respectively．The experimental results show that the proposed algorithm produces an efficient schedule which has shorter schedule length and less number of used processors in comparison with other related algorithms and so is more practical.

Key words: Task scheduling,Out-Tree task graph,Heterogeneity,Task duplication,List scheduling,Schedule length