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We present the Java Modelling Tools (JMT) suite, an integrated framework of Java tools for performance evaluation of computer systems using queueing models. The suite offers a rich user interface that simplifies the definition of performance models by means of wizard dialogs and of a graphical design workspace. The performance evaluation features of JMT(More)
The availability of reliable models of computer virus propagation would prove useful in a number of ways, in order both to predict future threats, and to develop new containment measures. In this paper , we review the most popular models of virus propagation, analyzing the underlying assumptions of each of them, their strengths and their weaknesses. We also(More)
Various techniques for multiprogramming parallel multiprocessor systems have been proposed recently as a way to improve performance. A natural approach is to divide the set of processing elements into independent partitions, and simultaneously execute a diierent parallel program in each partition. Several issues arise, including the determination of the(More)
In this paper we systematically examine various performance issues involved in the coordinated allocation of processor and disk resources in large-scale parallel computer systems. Models are formulated to investigate the I/O and computation behavior of parallel programs and workloads, and to analyze parallel scheduling policies under such workloads. These(More)
—The load generated by new types of communications services related to multimedia and video transmission is becoming one of the major sources of traffic in WAN networks. Modeling this type of load is a prerequisite for any performance study. In this paper, we approach the load-characterization problem from a global point of view by analyzing a set of 20(More)
ÐA fundamental understanding of the interplay between computation and I/O activities in parallel applications that manipulate huge amounts of data is critical to achieving good application performance, as well as correctly characterizing the workloads of large-scale high-performance parallel systems. In this paper, we present a formal model of the behavior(More)
It is known that the resources that limit the overall performance of a system are the congested ones, referred to as bottlenecks. From knowledge of bottleneck stations, it is possible, with limited computational effort, to derive asymptotic values of several performance indices. While identifying the bottleneck stations is a well-established practice under(More)