This page describes percentile metrics and how to modify default percentile collection. 

percentile is a value below which a given percentage of measurements in a set falls. For example, a 95th percentile value of 150 ms means that 95% of all values are 150 ms or less. See Quick Tour of Percentile Metrics for Java.

Disable Percentile Metric Collection

The Java Agent and the .NET Agent capture percentile metrics by default. You can disable percentile metric collection in the Configure Percentile Metrics panel on the Configuration > Slow Transaction Thresholds page. Alternatively, manually setting the disable-percentile-metrics node property to True prevents the agent from collecting percentile metrics.

Specify Percentiles to Collect

By default, app agents capture the 95th percentile. You can indicate 5 whole numbers between 1 and 99 as Percentiles to Collect on the Configuration > Slow Transaction Thresholds page. You can apply the configuration changes to all existing business transactions or only to new transactions discovered after the configuration change.

Modify the Percentile Metric Algorithm

The agent uses one of the following methods to calculate percentile metrics:

  • P Square algorithm (default): This option consumes the least amount of storage and incurs the least amount of CPU overhead. The accuracy of the percentile calculated varies depending on the nature of the distribution of the response times. You should use this option unless you doubt the accuracy of the percentiles presented.
  • Quantile Digest algorithm: This option consumes slightly more storage and CPU overhead for the machine where the agent is running, but may offer better percentiles depending on how the response times are distributed.

To adjust the algorithm option, set the App Agent Node Property to percentile-method-option.