Re: enhanced intel speedstep feature was Re: speedstep-centrino on dothan

[Dominik Brodowski <linux@dominikbrodowski.net>]

On Thu, Jul 07, 2005 at 03:51:17PM -0500, Joseph Pingenot wrote:
> >Just a latest question: can be p4-clockmod used together with
> >speedstep-centrino? If not, would it make any sense to patch
> >speedstep-centrino to use this feature too?
> 
> I'm a little confused.  How is this different from the ACPI CPU throttling
>   states (/proc/acpi/processor/CPUn/limit to set, throttling to see all
>   T-states available)?

T-states _tend_ to be utilized using chipset logic, while p4-clockmod is
done in-CPU.

> On my 1.5-year-old Pentium-M, frequency scaling and T-states are different
>   beasties, and act entirely differently.  I'm currently in the process of
>   rewriting my governor's brain to deal with the two more intelligently.

In your case, I would care about throttling. In very most cases it actually
increases energy consumption, as the state being entered is technically the
same to ACPI C2 (IIRC), so it is only "forced" idling and only useful if
"forced" idling is needed to not need active cooling.

	Dominik