A Comparison of Dag-Scheduling Strategies for Internet-Based Computing

A fundamental challenge in Internet computing (IC) is to efficiently schedule computations having complex inter job dependencies, given the unpredictability of remote machines, in availability and time of access. The recent IC scheduling theory focuses on these sources of unpredictability by crafting schedules that maximize the number of executable jobs at every point in time. In this paper, we experimentally investigate the key question: does IC scheduling yield significant positive benefits for real IC? To this end, we develop a realistic computation model to match jobs to client machines and conduct extensive simulations to compare IC-optimal schedules against popular, intuitively compelling heuristics. Our results suggest that for a large range of computation-dags, client availability patterns, and two quite different performance metrics, IC-optimal schedules significantly outperform schedules produced by popular heuristics, by as much as 10-20%.