Re: CVS commit: src/sys/dev/acpi

[Jukka Ruohonen <jruohonen%iki.fi@localhost>]

On Mon, Aug 09, 2010 at 07:30:52AM +0200, Christoph Egger wrote:
> > Log Message:
> > Downgrade the currently supported maximum C-state to C1. There appears to be
> > timer-related interrupt issues also in C2. With C1 it is guaranteed that
> > acpicpu(4) will not cause any slowdowns due stalled local APIC timer.
> 
> Before you switch into C3-state you need to move away from using
> the local APIC timer. You can use any external timer such as HPET or
> PIT. You use local APIC timer after wakeup again.

Yes, I am well aware of that. But it is evident that the local APIC timer is
stopped also in C2 on some systems. Thus, for now the only entirely safe
option is to use C1, i.e. operate identically with or without acpicpu(4).

OpenSolaris is considering to use HPET as a proxy for the stalled timers.[1]
But I think there are many other available options as well.

- Jukka.

[1] http://hub.opensolaris.org/bin/view/Project+tesla/CPUPM