Re: [PATCHSET] 0/3 A dynamic cpufreq governor

[Dominik Brodowski <linux@brodo.de>]

On Mon, Oct 27, 2003 at 05:19:05PM +0100, Ducrot Bruno wrote:
> On Mon, Oct 27, 2003 at 05:06:31PM +0100, Måns Rullgård wrote:
> > Ducrot Bruno <ducrot@poupinou.org> writes:
> > 
> > >> >> Is there any way this thing can be made to work on a Pentium 4 M,
> > >> >> using p4-clockmod for frequency changing?
> > >> >
> > >> > You should prefer the speedstep-ich driver for Pentium 4 M, as long as the
> > >> > southbridge on your notebook is from Intel - p4-clockmod doesn't save you
> > >> 
> > >> The problem is my chipset is SiS 650.
> > >> 
> > >
> > > Does the generic acpi P-state driver work?  If not, well, nobody can't
> > 
> > I think so, but it only gives two different speeds to choose from,
> > 1200 MHz and 2 GHz.  p4-clockmod give me speeds from 250 MHz to 2 GHz.
> > 
> 
> You have then voltage scaling with the acpi driver.
> >From my point-of-view, this is better than the p4-clockmod,
> the speedstep-ich would give you no more states (if
> it can be made to work with SiS southbridges), just that the acpi driver
> will be a little bit slower (it work by calling some bios functions)
> than direct access to IO like speedstep-ich does.
> Note that p4-clockmod do *not* regulate voltage.  From power comsuptions
> like, if you are at 1200 MHz, but via the acpi driver, you would be
> like at 600MHz with the p4-clockmod, and actually it may be possible
> that idle loops will be more power conservative with acpi (I am not sure for
> that one though).  Dominik have better words than me to explain that.

For more details and calculations, check this thread:

http://www.linux.org.uk/mailman/private/cpufreq/2003-September/002495.html


	Dominik