Hiërarchical Job Scheduling for Clusters of Workstations

In this paper we study hierarchical job scheduling strategies for clusters of workstations. Our approach uses two-level scheduling: global scheduling and local scheduling. The local scheduler refines the scheduling decisions made by the global scheduler, taking into account the most recent information. In previous work, we explored the First Come First Served (FCFS), the Shortest Job First (SJF), and the First Fit (FF) policies at the global level. Now, we will apply all three policies both at the global and the local level. In addition, we use separate queues at the global level for arriving jobs, where the jobs with the same number of tasks are placed in one queue. At both levels, the schedulers strive to maintain a good load balance. The unit of load balancing at the global level is the job consisting of one or more parallel tasks; at the local level it is the task.