I am interested in using PCM for performance monitoring on macOS 10.12 (Sierra). Before trying out the C++ API, I was toying with the command line tools. However, it asks me to reset PMU (at my own risk). If I understand correctly, there can be only one application control/program the counters at a given time. However, I found no way to figure out which application is using the counters. Is there anyway to show this kind of information? This kind of messages happens even from a cold boot, without any application open. My guess is that some system monitoring process at the background is using it. However, I would like to know what I am shutting down before reset PMU.