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Date:      Thu, 20 Oct 2005 14:10:23 +0200
From:      Alexander Leidinger <Alexander@Leidinger.net>
To:        Nate Lawson <nate@root.org>
Cc:        current@freebsd.org
Subject:   1kHz noise from C3 sleep (was: Re: cvs commit: src/sys/amd64/amd64 cpu_switch.S machdep.c)
Message-ID:  <20051020141023.0ejwdv4dss48wko0@netchild.homeip.net>
In-Reply-To: <43553162.5040802@root.org>
References:  <200510172310.j9HNAVPL013057@repoman.freebsd.org> <20051018094402.A29138@grasshopper.cs.duke.edu> <435501B9.4070401@samsco.org> <43553162.5040802@root.org>

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Nate Lawson <nate@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.

-- 
http://www.Leidinger.net  Alexander @ Leidinger.net: PGP ID = B0063FE7
http://www.FreeBSD.org     netchild @ FreeBSD.org  : PGP ID = 72077137
The last person who quit or was fired will be held
responsible for everything that goes wrong -- until
the next person quits or is fired.





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