Improving Parallel Job Scheduling by Combining Gang Scheduling and Backfilling Techniques

Two different approaches have been commonly used to address problems associated with space sharing scheduling strategies: (a) augmenting space sharing with backfilling, which performs out of order job scheduling; and (b) augmenting space sharing with time sharing, using a technique called coscheduling or gang scheduling. With three important experimental results – impact of priority queue order on backfilling, impact of overestimation of job execution times, and comparison of scheduling techniques – this paper presents an integrated strategy that combines backfilling with gang scheduling. Using extensive simulations based on detailed models of realistic workloads, the benefits of combining backfilling and gang scheduling are clearly demonstrated over a spectrum of performance criteria.