Abstract: An apparatus, program product and method utilize a virtual flight recorder to harvest a subset of events being collected by an active system tracing facility during operation of a computer system. The virtual flight recorder is “virtual” from the sense that it is not specifically instrumented into a component with which the virtual flight recorder is associated, which eliminates the burden on developers to specifically instrument components of interest, and minimizes the impact on system performance as a result of performance metric collection.

Abstract: A method, apparatus, system, and signal-bearing medium that, in an embodiment, determine a first number of execution cycles used by a calibration program for an event group with a collector inactive, determine a second number of execution cycles used by the calibration program for the event group with the collector active, and calculate a compensation value for the event group based on the difference between the second number and the first number of execution cycles. These determinations and calculations may be repeated for any number of event groups. When performance data is subsequently collected by the collector, collected events that belong to the event groups have their collected execution cycles adjusted based on the calculated compensation values.