For simplicity, let’s say you have a single-CPU system that supports “dynamic frequency scaling”, a feature that allows software to instruct the CPU to run at a lower speed, commonly known as “CPU throttling”. Assume for this scenario that the CPU has been throttled to half-speed for whatever reason, could be thermal, could be energy efficiency, could be due to workload. Finally, let’s say that there’s a program that is CPU-intensive, calculating the Maldebrot set or something.
The question is: What percentage CPU usage should performance monitoring tools report?
Should it report 100%, or 50%? This is like asking what side of the bed is the front, and which side is the back – you can make valid arguments either way, and nobody is wrong or right.