Date: Thu, 20 Oct 2005 11:25:59 -0700 From: Nate Lawson <nate@root.org> To: Alexander Leidinger <Alexander@Leidinger.net> Cc: current@freebsd.org Subject: Re: 1kHz noise from C3 sleep Message-ID: <4357E137.5090703@root.org> In-Reply-To: <20051020141023.0ejwdv4dss48wko0@netchild.homeip.net> References: <200510172310.j9HNAVPL013057@repoman.freebsd.org> <20051018094402.A29138@grasshopper.cs.duke.edu> <435501B9.4070401@samsco.org> <43553162.5040802@root.org> <20051020141023.0ejwdv4dss48wko0@netchild.homeip.net>
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Alexander Leidinger wrote: > 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? Sure, you can do it from a tunable (kern.hz I think), you don't have to recompile. > 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)? It's possible it doesn't. Windows 2000 and newer uses hz=1000. -- Nate
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