VIA EPIA 5000 and ACPI Cx levels

Bruce Cran bruce at
Thu Oct 14 20:00:00 UTC 2010

On Thu, 14 Oct 2010 19:43:36 +0000
"b. f." <bf1783 at> wrote:

> I'm not sure what is going on here: if you set
> hint.attimer.0.timecounter="0" and kern.eventtimer.timer="i8254" in
> /boot/loader.conf, then the system should try to use the i8254 in
> one-shot mode, unless you've specifically set periodic mode.  If
> kern.eventtimer.periodic=1, then you are _not_ using one-shot mode.
> If it was 0 before your latest changes, then you were previously using
> one-shot mode.  But, as I wrote earlier, for kern.hz<128 and
> kern.eventtimer.singlemul=1, periodic mode may result in more sleeping
> than one-shot mode, though at a price.  This may be what you are
> seeing.

Sorry, that was a typo: kern.eventtimer.periodic=0 after setting
hint.attimer.0.timecounter=0. I'm seeing 145 interrupts per second now,
so setting hz=100 and using singlemul mode would further
decrease it - but I guess it's not something you would want to do on a
router or desktop.

> This or the high latency of C3 may account
> for your machine not using it. Also note that you shouldn't use a
> LAPIC timer if you are using C3 or deeper sleep states.

Thanks. It sounds like things are working as they should then. Good to
know the new timer code is working properly on this more unusual

Bruce Cran

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