The Select Java Platform to Calibrate dialog box displays the available Java platforms that are available on your system. You see this dialog box the first time that you choose Profile > Advanced Commands > Run Profiler Calibration in the main menu.
The IDE will perform the calibration after you select a platform and click OK. The IDE will display a dialog box when the calibration process is complete. You only need calibrate the profiler once for each Java platform for each JDK that you will use for profiling.
You need to calibrate the profiler because instrumenting the bytecode of the application imposes some overhead, and the time spent in code instrumentation needs to be "factored out" in order to achieve more accurate results.