HT201464: Use Activity Monitor on your Mac

Learn about Use Activity Monitor on your Mac
jwilm

Q: What does CPU time mean in Activity Monitor?

It is not clear to me how CPU is to be understood. According to Wikipedia, CPU time

is the amount of time for which a central processing unit(CPU) was used for processing instructions of a computer program or operating system, as opposed to, for example, waiting for input/output (I/O) operations or entering low-power (idle) mode.

In Activity Monitor, I see the CPU time for e.g. kernel_task go up about 3 seconds per wall clock second while the %CPU is below 5 for that process.

If %CPU is below 5, I would expect the CPU time to increase much slower than wall clock time. Any explanations?

Posted on Oct 15, 2015 7:11 AM