Mapping Workflows on Grid Resources: Experiments with the Montage Workflow

Scientific workflows have received considerable attention in Grid computing. This paper is concerned with the issue of scheduling scientific workflows and, by considering a commonly used astronomy workflow, Montage, investigates the impact of different strategies to schedule the workflow graph. Our experiments suggest that the rather regular and symmetric nature of the Montage graph allows rather simple to implement scheduling heuristics that do not take into account the whole structure of the graph, such as Min-min, to deliver competitive performance in most cases of interest. The results support the view that sophisticated graph scheduling heuristics may not be always a prerequisite for good performance in workflow execution. Instead, mechanisms to deal with uncertainties in execution time may be of comparatively higher importance.