Message-ID: <487A212E.1080505@linux.intel.com>
Date: Sun, 13 Jul 2008 08:37:18 -0700
From: Arjan van de Ven <arjan@linux.intel.com>
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To: Pavel Machek <pavel@suse.cz>
CC: Vegard Nossum <vegard.nossum@gmail.com>, Ingo Molnar <mingo@elte.hu>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: v2.6.26-rc7: Negative powertop values
References: <19f34abd0806211216y4695c532ndb4935082bd8ea1@mail.gmail.com> <20080621141615.51f7100c@linux.intel.com> <20080706194845.GA5617@ucw.cz> <20080708065251.1d7d681f@linux.intel.com> <20080713115818.GA7517@elf.ucw.cz>
In-Reply-To: <20080713115818.GA7517@elf.ucw.cz>
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Pavel Machek wrote:
> On Tue 2008-07-08 06:52:51, Arjan van de Ven wrote:
>> On Sun, 6 Jul 2008 21:48:45 +0200
>> Pavel Machek <pavel@suse.cz> wrote:
>>
>>>> [I assume you know that doing a software unplug you burn more power
>>>> than by leaving the cpu idle]
>>> We should really fix that one day...
>> yeah but it's incredibly hard to get right (in the light of the bios
>> constantly changing what our allowed C-states are)... and the best case
> 
> What can happen there? So BIOS decides C4 may no longer be cool idea
> because we have AC power now, but that does not mean C4 stops working,
> right?

it's also the other way around; you put the sleepy core in C4 because C6 is not available;
then C6 becomes available and the sleepy core is wasting power;

Either way, the *best* case you get is to be equal to being idle.....

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