Re: C2/C3 on SMP [Was: Re: 2.6.X not recognizing second CPU]

[Erik Slagter <erik@slagter.name>]

On Wed, 2005-06-29 at 10:07 +0200, Dominik Brodowski wrote:
> > > > Still no C2/C3 handling :-( 
> > > Uh, wasn't there a small, nice patch implementing this in bk-acpi a few 
> > > weeks ago?
> > > *clicketyclick* Oh yes,
> > > http://bugzilla.kernel.org/show_bug.cgi?id=4401
> > > states it was merged into bk-acpi-test on 2005-04-22. However, I can't find
> > > it in current -mm any more...
> > You're probably talking about the amd768 module.
> No, I'm not. I'm talking about plain ACPI C-States.

OK, in that case, good!

> > I could use it, but I
> > never got it working correctly, there is no actual power reduction. It
> > may have to do with the fast (1000 Hz) 2.6 clock though, making it sleep
> > in C2/C3 for only very short intervals. Also the selection for idle
> > CPU's seems to be too simple.
> 
> The ACPI C-State selection algorithm needs a major overhaul, that's true.

The current C-state selection (as used on e.g. my laptop) is good enough
for me. It was the idle selection of the amd768 module that was ehrm...
suboptimal.

I am holding my breath here ;-) (and watching the -mm commits).