Re: cpufreq: powernow-k8 frequency transitions question

[Gunter Ohrner <G.Ohrner@post.rwth-aachen.de>]

Nebojsa Trpkovic wrote:
> The most usefull powersaving is achieved by lowering the voltage and not 
> the further lowering of frequency.

Yes, but lower clock speeds usually allow for lower voltages, so that's what
you gain by lowering the core frequency.

> minimum stable voltage just to be 110% sure it will work stable:
> Winchester runs with 1.0GHz @1.0V and 1.8GHz @1.275V

I'm currently running my Winchester 3000+ at 1,0GHZ@1,0V and 1,8GHz@1,15V
only, and it's rock solid for me so far - it survived hours of 100% cpu
load during normal operation and using cpuburn's burnK7, either locked at
on of the frequencies or in dynamic mode using the ondemand governor.

> So, I've modified powernow-k8.c to lower the voltages read from BIOS for 
> every p-state.

Changing the vlaues returned by the BIOS by a function is a really
interesting approach, especially if there's not much point in providing
additional P-states, which is my current impression. At the moment I have
ACPI table queries turned off in powernow-k8 and supply a hand craftes PSB
table, but obviously that's not the most flexible solution. Mh, two VID and
FID mapping function's which initially are identity functions but with some
sysfs-tuneable parameters sounds interesting to me... :-)

I guess I should try that.

Greetings and thanks for that idea,

  Gunter

-- 
The question seldom addressed is *where* Medusa had snakes. Underarm 
hair is an even more embarassing problem when it keeps biting the top 
of the deodorant bottle.        -- (Terry Pratchett, Soul Music)
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