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0 pointscausi4y ago0 comments

That's very interesting. I didn't know it was possible for a process to use the CPU without using the CPU, as it were. Rather I thought the CPU usage was more or less a direct measurement.

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vnorilo4y ago

From [1]

On processors that have a halt instruction that stops the CPU until an interrupt occurs, such as x86's HLT instruction, it may save significant amounts of power and heat if the idle task consists of a loop which repeatedly executes HLT instructions.

I don't know how it is implemented in darwin, HLT is a privileged instruction, then again it's kernel_task.

1: https://en.m.wikipedia.org/wiki/Idle_(CPU)

remram4y ago

I would expect that the CPU frequency would throttle down, rather than regularly running halt instructions.

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