linux-kernel - Re: cpufreq doesn't seem to work in Intel Q9300

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Date:	Mon, 11 Aug 2008 16:58:16 -0700
From:	Arjan van de Ven <arjan@...radead.org>
To:	Dominik Brodowski <linux@...inikbrodowski.net>
Cc:	Adrian Bunk <bunk@...nel.org>, S K <nospamnoham@...il.com>,
	Zhao Yakui <yakui.zhao@...el.com>,
	Thomas Renninger <trenn@...e.de>,
	Alan Jenkins <alan-jenkins@...fmail.co.uk>,
	linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org
Subject: Re: cpufreq doesn't seem to work in Intel Q9300

On Mon, 11 Aug 2008 21:33:17 +0200
Dominik Brodowski <linux@...inikbrodowski.net> wrote:

> Hi,
> 
> On Mon, Aug 11, 2008 at 07:11:28AM -0700, Arjan van de Ven wrote:
> > 1) when the cpu is idle (as in "idle loop C states/hlt"; p4_clockmod
> > doesn't mean anything.. the clock is stopped not just skipped.
> > 2) when the cpu is executing code (eg non-idle), it takes more power
> > for a unit of time than it takes when it's idle
> 
> This statement might be true, but might also be wrong:
> 	a) on systems where only C1 is exported, p4-clockmod most
> often equals the state the CPU is in when in C1[*], 

that's.. not entirely true btw.

>so we're in a 
> 	   win-win, or lose-lose situation.

even if it were EXACTLY identical (which it isn't).. you would be at
BEST a tie... not a savings. so it's lose-lose or tie-tie, but never win


> 	b) IIRC 50% throttling is not "execute-one-statement
> 	   skip-one-statement execute-one-statement, etc." but instead
> 	   work for N us, skip for N us, work for N us, etc.
> Therefore, the situation is a bit more compilcated.

doesn't change the fundamental math though.


-- 
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