Doesn't LAPIC timer stop when CPU goes to sleep state?

mnln.l4 mnln.l4 at gmail.com
Tue Jul 10 01:11:26 UTC 2012


http://wiki.freebsd.org/TuningPowerConsumption/ says LAPIC timer stops
when CPU in C3, while I saw the flag is set to 7. Of course, I can
read full spec and code
(http://fxr.watson.org/fxr/source/x86/x86/local_apic.c?im=bigexcerpts#L251)
to find out some processor's LAPIC timer runs in C3, but mailing list
could be helpful to get some quick answer.

On Mon, Jul 9, 2012 at 3:59 AM, Andriy Gapon <avg at freebsd.org> wrote:
> on 09/07/2012 08:41 mnln.l4 said the following:
>> I have FreeBSD 9.0-STABLE r237285, In my systl -a output, I see
>>
>> kern.eventimer.et.LAPIC.flags: 7
>>
>> I am under the impression LAPIC timer may stop when CPU goes to sleep
>> state. Shouldn't the flag be 15 as the example in EVENTTIMERS(4) man
>> page?
>
> You don't have to be under an impression when you can get the facts from publicly
> available specifications and code.
>
>> I have H67MA-E35 motherboard with Intel H67 chipset, and G840 dual core CPU.
>>
>> Thanks.
>
> --
> Andriy Gapon
>


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