Date: Sun, 10 Oct 2010 22:28:33 +0100 From: Bruce Cran <bruce@cran.org.uk> To: bf1783@gmail.com Cc: freebsd-questions@freebsd.org Subject: Re: VIA EPIA 5000 and ACPI Cx levels Message-ID: <201010102228.33095.bruce@cran.org.uk> In-Reply-To: <AANLkTimnavr=uZhwSgRnBtNFPuPbQq6Ta4Tvhi8MQ1aS@mail.gmail.com> References: <AANLkTimnavr=uZhwSgRnBtNFPuPbQq6Ta4Tvhi8MQ1aS@mail.gmail.com>
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On Sunday 10 October 2010 21:49:30 b. f. wrote: > If it has an i8254, that can also be used in one-shot mode if > hint.attimer.0.timecounter=0 is used, since r212778. Thanks, I didn't know about that. After enabling it things are quite different: kern.eventtimer.periodic is now 1, and setting hw.acpi.cpu.cx_lowest=C2 results in 100% time being reported as being spent in C2 mode according to dev.cpu.0.cx_usage - using C3 causes the system to hang. Shouldn't a fully loaded CPU spent more time in C1 state though? When I run a program that results in 0% idle time cx_usage still reports that no time was spent in C1 state. > But for low > values of kern.hz, I've found that periodic mode can result in fewer > interrupts (albeit increased latencies and lower accuracy in > accounting) than one-shot mode, if kern.eventtimer.singlemul=1. As > for the power-saving states, are you using a simple 'sysctl > dev.cpu.0.cx_usage' to find the percentages? If you're doing > something more involved, you may be affecting the measurements. Also, > does the system think that the deeper sleep states are available on > your machine? If so, what are their latencies? If they are high, > they may be used less often, or not at all. I'm just using dev.cpu.0.cx_usage to check the Cx level usage. According to dev.cpu.0.cx_supported, I have: C1/0, C2/90, C3/900 > Did you follow some of > the other recommendations to allow more sleeping, like at: > > http://wiki.freebsd.org/TuningPowerConsumption I haven't done anything extra yet, since I was mainly interested in seeing if one-shot mode worked on this box. I can't use powerd because running at 266MHz (I only have 533 and 266 available) results in too much of a slowdown. -- Bruce Cran
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