This chapter focused on the system-wide performance metric of CPU usage. These metrics mainly demonstrate how the operating system and machine are behaving, rather than a particular application.
This chapter demonstrated how performance tools, such as sar and vmstat, can be used to extract this system-wide performance information from a running system. These tools are the first line of defense when diagnosing a system problem. They help to determine how the system is behaving and which subsystem or application may be particularly stressed. The next chapter focuses on the system-wide performance tools that enable you to analyze the memory usage of the entire system.