TABLE OF CONTENTS Performance is your reality. Forget everything else.
Harold Geneen
The performance of a computer system can best be defined as the system's ability to accomplish its assigned tasks. Good performance means that the system is performing its workload in an acceptable amount of time and with acceptable usage of system resources. This can be difficult to quantify because it depends on a variety of factors that are both objective (performance indexes) and subjective (user perception). On the other hand, it's usually pretty obvious when a performance problem exists: things don't happen within acceptable (objective or subjective) time or resource constraints.
Managing system performance has two primary aspects: maximizing performance (proactive) and responding to specific performance problems (reactive). Maximizing system performance is an ongoing task of evaluating current performance, making adjustments, and observing the effects. This is a subject about which much has been written, and it is really beyond the scope of this book. Because our focus is on troubleshooting, we'll concentrate on the second aspect of performance management: responding to specific performance problems.
Among the many resources available on the subject of performance and tuning, we especially recommend the Tru64 UNIX System Configuration and Tuning Manual. This document has improved with each successive version, and the current edition is clear, informative, and practical a fine example of what computer manuals should be like. Anyone interested in system performance should spend some time going through this manual; the time spent will be a worthwhile investment.
At the...
