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?