Overview

This chapter discusses UNIX commands that analyze and affect the use of system resources such as the CPU, physical memory, virtual memory, and disk space. Monitoring system resources is of major concern to the system administrator in maintaining a balanced workload. Users become interested in this subject when, for example, the system responds sluggishly to terminal input, or when they wish to estimate the running time of a particular application. Unfortunately, users can usually do nothing to improve the situation except to alter processes they own, which is often self-defeating.

Applications programmers may consider this position narrow-minded, reflecting only a system administrator's perspective. Indeed, programmers can examine how a particular application consumes resources and often see how to improve the performance of their code. This chapter, however, is not a lesson in programming and therefore offers no insight into how such improvements might be made. It simply describes the commands that monitor how processes utilize system resources and that affect the system resources devoted to processes.

UNIX users familiar with the OpenVMS commands MONITOR, SHOW, and ANALYZE, with their easily understood output, will likely be disappointed by the commands UNIX offers to analyze system resource utilization due to the original UNIX design constraints. These constraints required that output be displayed as hard copy on slow Teletype devices. The designers of the original operating system could not, of course, avail themselves of the fast screen...