Limitations of Cycle Stealing for Parallel Processing on a Network of Homogeneous Workstations

The low cost and availability of clusters of workstations have lead researchers to re-explore distributed computing using independent workstations. This approach may provide better cost/ performance than tightly coupled multiprocessors. In practice, this approach often utilizes wasted cycles to run parallel jobs. In this paper we address the feasibility and limitation of such a nondedicated parallel processing environment assuming workstation processes have priority over parallel tasks. We develop a simple analytical model to predict parallel job response times. Our model provides insight into how significantly workstation owner interference degrades parallel program performance. It forms a foundation for task partitioning and scheduling in a nondedicated network environment. A new term, task ratio, which relates the parallel task demand to the mean service demand of nonparallel workstation processes, is introduced. We propose that task ratio is a useful metric for determining how a parallel applications should be partitioned and scheduled in order to make efficient use of a nondedicated distributed system. © 1997 Academic Press