Re: NO_HZ: timer interrupt stuck [Re: Linux 2.6.21-rc1]

Arjan van de Ven
2007-02-22T16:42:14Z

On Thu, 2007-02-22 at 17:27 +0100, Pierre Ossman wrote:
> Thomas Gleixner wrote:
> >
> > Here is the reason. The local APIC stops working in C3 state and we fall
> > back to the PIT in that case. Not really exciting for dynticks, but the
> > only way to keep the system alive. There is a patch coming up from
> > Intel, which finds out how to use HPET even if it is not enabled by the
> > BIOS. This will still end up on IRQ#0, but will give way longer idle
> > sleeps than the PIT.
> >
> >
>
> So then the next two questions are; is it possible to disable C3

yeah there is a commandline thingy for it
> and is
> it a net power gain to get rid of the wakeups in favor of having C3.

no; c3 saves a TON more power.

you can try enabling HPET in your BIOS...

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