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From: Arjan van de Ven <arjan@linux.intel.com>
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
Date: Sun, 13 Jul 2008 08:35:59 -0700	[thread overview]
Message-ID: <487A20DF.7060701@linux.intel.com> (raw)
In-Reply-To: <20080713115818.GA7517@elf.ucw.cz>

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?

or it decides that your voltage regulator needs to operate in a certain mode and the voltage for C4 is no longer
available. or .. or ...

> 
> How is changing allowed C-states list supposed to work, anyway? I
> mean, we may be in one of those on other CPU when BIOS decides to
> change the list...

you get an interrupt to notify you of the change ;-)


  reply	other threads:[~2008-07-13 15:36 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-06-21 19:16 v2.6.26-rc7: Negative powertop values Vegard Nossum
2008-06-21 21:16 ` Arjan van de Ven
2008-06-21 21:22   ` Vegard Nossum
2008-07-06 19:48   ` Pavel Machek
2008-07-08 13:52     ` Arjan van de Ven
2008-07-13 11:58       ` Pavel Machek
2008-07-13 15:35         ` Arjan van de Ven [this message]
2008-07-14  6:26           ` Pavel Machek
2008-07-13 15:37         ` Arjan van de Ven

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