A simulation model of backfilling and I/O scheduling in a partitionable parallel system

A special type of scheduling called backfilling is presented using a parallel system upon which multiple jobs can be executed simultaneously. Jobs consist of parallel tasks scheduled to execute concurrently on processor partitions, where each task starts at the same time and computes at the same pace. The impact of I/O scheduling on system performance is also examined. The goal is to achieve high system performance and maintain fairness in terms of individual job execution. The performance of different backfilling schemes and different I/O scheduling strategies is compared over various processor service time coefficients of variation and for various degrees of multiprogramming. Simulation results demonstrate that backfilling improves system performance while preserving job sequencing. Also, the results show that when there is contention for the disk resources, trends in system can differ from those appearing in the research literature if I/O behavior is negligible or it is not explicitly considered