1kHz noise from C3 sleep (was: Re: cvs commit: src/sys/amd64/amd64 cpu_switch.S machdep.c)

[Alexander Leidinger]

Nate Lawson <nate at root.org> wrote:

[Moving to -current]

>> I wonder if moving to HZ=1000 on amd64 and i386 was really all that good
>> of an idea.  Having preemption in the kernel means that ithreads can run
>> right away instead of having to wait for a tick, and various fixes to
>> 4BSD in the past year have eliminated bugs that would make the CPU wait
>> for up to a tick to schedule a thread.  So all we're getting now is a
>> 10x increase in scheduler overhead, including reading the timecounters.
>
> I use hz=100 on my systems due to the 1 khz noise from C3 sleep. 
> Windows has the same problem.

My laptop makes noises when being (more or less) idle (I think I enabled
C3...). Does this mean I should try to change HZ?

If yes: Windows doesn't make such a noise, does this mean it doesn't use C3
on this system (your comment suggests that Windows does use a HZ=1000 like
behavior)?

Bye,
Alexander.

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