Before we run any load tests we need to be able to collect system load metrics. These will be used to test the hypothesis and to monitor activity during the testing periods. Testing without usage statistic monitoring is equivalent to blind operation that prohibits objective reasoning. Useful tools for system resource monitoring are included with Linux and most BSD operating systems:
sar: This allows the administrator to collect, report, and save system activity information. This can be used in an interval collection state with many advanced options for resource monitoring. A number of supporting tools are available that generate graphs from sar output. Sar can be found in the
sysstat
package on most Linux systems.top: This displays current active operating system tasks. If run without flags, it will only report tasks owned by the active user. Referencing the manual page will describe the numerous flags available to alter information that is displayed...