We measure the distribution of lifetimes for UNIX processes and propose a functional form that fits this distribution well. We use this functional form to derive a policy for preemptive migration, and then use a trace-driven simulator to compare our proposed policy with other preemptive migration policies, and with a non-preemptive load balancing strategy. We find that, contrary to previous reports, the performance benefits of preemptive migration are significantly greater than those of non-preemptive migration, even when the memorytransfer cost is high. Using a model of migration costs representative of current systems, we find that preemptive migration reduces the mean delay (queueing and migration) by 35 -- 50%, compared to non-preemptive migration. 1 Introduction Most systems that perform load balancing use remote execution (i.e. non-preemptive migration) based on a priori knowledge of process behavior, often in the form of a list of process names eligible for migration. Althoug...

Distributed computing systems consist of computers interconnected by communications links. In such systems, statistical fluctuations in job arrival and service patterns cause episodes of load imbalance during which some computers are lightly loaded while others are simultaneously overloaded. Load sharing is the process of transferring jobs from overloaded to underloaded computers to improve overall system performance. Load sharing is implemented by means of load sharing algorithms. However, since little has been known about the temporal characteristics of load imbalance, various pitfalls arise in the operation of load sharing algorithms which prevent full realization of the potential benefits of load sharing. In this paper, we present a stochastic analysis of time durations of load imbalance. The notions of Transfer Pair , and Load Sharing Window are introduced. Using first passage times, a general expression for the probability distribution function of the Load Sharing Wi...

this paper are given in units of mean task sizes (mts). E.g., if the waiting time for a system is "1.3" then an arriving task expects to leave the system in 1.3 times the mean task duration