Job Scheduling in a Distributed System Using Backfilling with Inaccurate Runtime Computations

In grid and parallel systems, backfilling has proven to be a very efficient method when parallel jobs are considered. However, it requires a job´s runtime to be known in advance, which is not realistic with current technology. Various prediction methods do exist, but none is very accurate. In this study, we examine a grid system where both parallel and sequential jobs require service. Backfilling is used, but an error margin is added to a job´s runtime prediction. The impact on system performance is examined and the results are compared with the optimal case of runtimes being known. Two different scheduling techniques are considered and a simulation model is used to evaluate system performance.