Imperial College London

ISE-2 Surprise 97 Project

Approaches to Performance Evaluation

Written by Wan Ling Li

Performance - the capabilities of a machine

Introduction

Performance Evaluation is used to examine a system, to model it and then to try to change the various parameters in the model. Usually the model is used to help increase the effectiveness or efficiency of a system. This article is written to give the reader an insight into the many aspects of Performance Evaluation.

Firstly though, what is a system? A system takes some form of input, processes it and then returns an output accordingly. So an example would be a car manufacturing plant, which say takes raw metal, paints and plastics and from the plant we produce a car. Another extreme example is the use in the design of microprocessors. In this case we have instructions and code flowing into the processor. The instructions are decoded and executed, then the processor produces output accordingly.

If we look at a multi-tasking operating system, such as Unix, it is also possible to apply the techniques of performance evaluation to it. In an operating system, there are many threads and processes trying to run concurrently. The threads can be thought of as the input to the system, and the action of the operating system/processor executing the thread are the processes in the system.

In the above given examples, when effective performance evaluation is applied substantial gains can be made. In the respect of the car manufacturer, it is possible to reduce the costs of production and to increase the output of the plant. In the case of the microprocessor it may lead to a more efficient design and consequently a higher performance processor. The operating systems stand to gain increased responsiveness and efficiency.