After rebooting, and with only Activity Monitor open, my MacBook Pro (10.6, i7) shows a very high idle % (98% or higher) but then shortly after drops down to 40% - 50%.
In the Activity Monitor list of all processes:
- nothing accounts for this drop.
What is the reason for the drop in the idle percentage?
Does OS X run something that is not listed as a process in Activity Monitor?
Does it shut a CPU or two down?
Is there a way to force it to give me the full attention of the CPU, even though I'm not using it?
For what's below, are there better ways to measure how much total system impact an app has, since the app cpu% doesn't show all the secondary activity an app causes a system to complete?
I'm trying to measure the performance of a particular app, and one of the metrics, since some of the app activity is performed inside the kernel in the form of system calls, is CPU idle %.
If OS X runs stuff in the background I can't see, or turns CPUs off or slows them down, then it obviously impacts my measurements.