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Computer system users, administrators, and designers are all interested in performance evaluation since their goal is to obtain or provide the highest performance at the lowest cost. This goal has resulted in continuing evolution of higher performance and lower cost systems leading to todays proliferation of workstations and personal computers, many of which have better performance than earlier supercomputers. As the field of computer design matures, the computer industry is becoming more competitive, and it is more important than ever to ensure that the alternative selected provides the best cost-performance trade-off.
Performance evaluation is required at every stage in the life cycle of a computer system, including its design, manufacturing, sales/purchase, use, upgrade, and so on. A performance evaluation is required when a computer system designer wants to compare a number of alternative designs and find the best design. It is required when a system administrator wants to compare a number of systems and wants to decide which system is best for a given set of applications. Even if there are no alternatives, performance evaluation of the current system helps in determining how well it is performing and whether any improvements need to be made. Unfortunately, the types of applications of computers are so numerous that it is not possible to have a standard measure of performance, a standard measurement environment (application), or a standard technique for all cases. The first step in performance evaluation is to select the right measures of performance, the right measurement environments, and the right techniques. This part will help in making these selections.
This part provides a general introduction to the field of performance evaluation. It consists of three chapters. Chapter 1 provides an overview of the book and discusses why performance evaluation is an art. Mistakes commonly observed in performance evaluation projects and a proper methodology to avoid them are presented in Chapter 2. Selection of performance evaluation techniques and evaluation criteria are discussed in Chapter 3.
I keep six honest serving men. They taught me all I knew. Their names are What and Why and When and How and Where and Who.
Rudyard Kipling
Performance is a key criterion in the design, procurement, and use of computer systems. As such, the goal of computer systems engineers, scientists, analysts, and users is to get the highest performance for a given cost. To achieve that goal, computer systems professionals need, at least, a basic knowledge of performance evaluation terminology and techniques. Anyone associated with computer systems should be able to state the performance requirements of their systems and should be able to compare different alternatives to find the one that best meets their requirements.
The purpose of this book is to explain the performance evaluation terminology and techniques to computer systems designers and users. The goal is to emphasize simple techniques that help solve a majority of day-to-day problems. Examples of such problems are specifying performance requirements, evaluating design alternatives, comparing two or more systems, determining the optimal value of a parameter (system tuning), finding the performance bottleneck (bottleneck identification), characterizing the load on the system (workload characterization), determining the number and sizes of components (capacity planning), and predicting the performance at future loads (forecasting). Here, a system could be any collection of hardware, software, and firmware components. It could be a hardware component, for example, a central processing unit (CPU); a software system, such as a database system; or a network of several computers.
The following are examples of the types of problems that you should be able to solve after reading this book.
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