A realistic integrated model of parallel system workloads

Performance evaluation is a significant step in the study of scheduling algorithms in large-scale parallel systems ranging from supercomputers to clusters and grids. One of the key factors that have a strong effect on the evaluation results is the workloads (or traces) used in experiments. In practice, several researchers use unrealistic synthetic workloads in their scheduling evaluations because they lack models that can help generate realistic synthetic workloads. In this paper we propose a full model to capture the following characteristics of real parallel system workloads: 1) long range dependence in the job arrival process, 2) temporal and spatial burstiness, 3) bag-oftasks behaviour, and 4) correlation between the runtime and the number of processors. Validation of our model with real traces shows that our model not only captures the above characteristics but also fits the marginal distributions well. In addition, we also present an approach to quantify burstiness in a job arrival process (temporal) as well as burstiness in the load of a trace (spatial).