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Configuring Performance Monitoring Sampling Rate

To reduce the overhead that is incurred by monitoring performance, you may not want to monitor every request that is submitted to your system. You can set a sampling rate for your monitored systems so that only one out of every N server requests generate PMUs. For the Nth request, all PMUs are generated at the filter level that is set for each agent type involved in processing the request. Examples of server requests would be browser requests to a web server or Application Designer requests to an application server (when running in a three-tier configuration). You set the sampling rate for PMUs using the Agent PMU Sample Rate option on the System Definitions page.

Note: This sampling rate applies only to PMUs, not events.

For example, if you set the sampling rate to 1/10, the system monitors the first PIA request, but does not monitor another request until the 11th request arrives at the system.

Some PMUs are always monitored regardless of the sampling rate. The PMUs that are never ignored are those that have the Enable Sampling optioncleared on the PMU Definitions page. Examples of such PMUs are those related to users signing on, signing off, and being redirected to other sites.

Note: Setting the sampling rate to 0 (zero) disables sampling.

The web server and the application server maintain separate counters. The web server counts all browser requests, and the application server counts all requests that are submitted directly to the application server, such as component interfaces or Microsoft Windows workstations running Application Designer.