Algorithms for queueing network analysis of distributed systems

Recently there has been an increasing number of large distributed computer system implementations based on local area networks. In these systems a number of resources (CPU's, file servers, disks, etc.) are shared among jobs originating at different sites. Evaluating the performance of such large systems typically requires the solution of a queueing network model with a large number of closed chains, precluding the use of exact solution techniques. Therefore it is important to develop accurate and cost effective methods for the approximate analysis of closed queueing networks with many chains. An approach based on the clustering of chains and service centers is presented here. The method is applicable to queueing networks with single server fixed rate, infinite server, and multiple server service centers. Results obtained when the method is used to solve large queueing network models are given. Extensive comparison of this method with existing approximation technique indicates that the approach has better accuracy/cost characteristics.