Book excerpt: Performance evaluation is not just determining whether or not a system meets certain objectives; it is also understanding if and how system performance can be improved. A computer system analyst must master a number of techniques to ascertain important factors and their effect on system performance. The purpose of this book is to develop a better understanding of the problem of performance evaluation and to analyze available techniques within this concept. Directed to present and future computer analysts and designers, readers should be familiar with concepts of hardware organization, system architecture, and operating systems.