Monitoring System Performance
Most Linux systems behave well under a distribution's default settings, and you can spend hours and days trying to tune your machine's performance without attaining any meaningful results. Sometimes performance can be improved, though, and this section concentrates primarily on memory and processor performance, and looks at how you can find out if a hardware upgrade might be worthwhile.
The two most important things that you should know about performance on your system are the load average and the system's swap/page fault behavior. The load average is the average number of processes currently ready to run. The
uptime command tells you three load averages in addition to how long the kernel has been running:
... up 91 ...