Re: Re: Centrino speedstep

Dominik Brodowski
2005-01-02T11:08:26Z

On Sat, Jan 01, 2005 at 11:50:59AM +0100, Johan Vromans wrote:
> Dominik Brodowski <linux-X3ehHDuj6sIIGcDfoQAp7BvVK+yQ3ZXh@public.gmane.org> writes:
>
> > On Fri, Dec 31, 2004 at 01:25:51AM +0000, Pedro Venda wrote:
> >> also, how exactly can I use ACPI throttling? because with the speestep
> >> driver, I can't go below 600MHz, but 12% of maximum frequency is 180MHz
> >> which I can reach using ACPI throttling.
> >
> > but throttling doesn't save you anything.
>
> Do you have any idea of the actual power savings in relation to
> frequency scaling and sleep states? E.g., stepping down from 1.6Ghz to
> 800Mhz will save a lot (50%?), but how much is saved by using C3
> state. More interesting, how much savings are lost by not being able
> to use C3 state?
C0 C1 C2 C3
----------------------------------------------------------------------------------------------------------------
Intel Pentium(R) M Processor, 1400 MHz & 1.484V[19] 22 W 7.3 W 7.3 W 7.0 W/5.1 W/0.55W[**][20]

Intel Pentium(R) M Processor, 1400 MHz & 1.484V,
scaled down to 600 MHz 6 W 1.8 W 1.8 W 1.7 W/1.1 W/0.55W[**]

[**] first value: Sleep State; second value: Deep Sleep State; third value: Deeper Sleep State.

[19] Intel(R) Pentium(R) M Processor Datasheet, Order Nr. 252612,
rev. 02, June 2003, p. 72.

[20] The extremely lower power consumption in Deeper Sleep and the fact that Deeper Sleep most
commonly is only made available by the _CST method expresses the urgency needed in
implementing it in the Linux kernel, and it has been merged into the latest
2.6.-sources for 2.6.11-rc1.

Dominik