4.3 Summary

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4.3 Summary

In this chapter we introduced some basic concepts needed for computer systems performance evaluation. The concept of service time-related resources is introduced, as are some basic concepts for use of these measures. The fundamental concepts involved in probability density and probability distribution functions are developed. These are then used to develop basic definitions for expected or mean values, the nth moment of a distribution. The special second moment, called the central moment, is developed, as is the definition and formulation for variance and coefficient of variation. The discussion then changed to scheduling algorithms used in computer systems. We introduce priority scheduling, round-robin, first-come first-served, last-come first-served, and the deadline-driven value function scheduling algorithms.

This is followed by a discussion of how these items relate to computer systems modeling. The relationship scheduling algorithms have with distribution functions is presented, as is their relationship to performance studies. The last topic presented is that of workloads. The concept of what a workload is and how it is used in computer systems modeling is presented from an introductory perspective.

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