linux-kernel - Re: High cpu temperature with 2.6.32, bisection shows commit 69d258 (fwd)

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Date:	Sun, 10 Jan 2010 03:05:38 +0200 (EET)
From:	Dimitrios Apostolou <jimis@....net>
To:	Arjan van de Ven <arjan@...radead.org>
cc:	Alex Chiang <achiang@...com>, Len Brown <lenb@...nel.org>,
	Bjorn Helgaas <bjorn.helgaas@...com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Yinghai Lu <yinghai@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: High cpu temperature with 2.6.32, bisection shows commit 69d258
 (fwd)

On Sat, 9 Jan 2010, Arjan van de Ven wrote:

> On Sun, 10 Jan 2010 02:32:11 +0200 (EET)
> Dimitrios Apostolou <jimis@....net> wrote:
>
>> On Sat, 9 Jan 2010, Arjan van de Ven wrote:
>>
>>> On Sun, 10 Jan 2010 01:55:42 +0200 (EET)
>>> Dimitrios Apostolou <jimis@....net> wrote:
>>>
>>>> L8400B series Notebook PC
>>>
>>> can you try this patch?
>>>
>>
>> OK I'm compiling a new kernel right now but that will take a while, I
>> only have access to old hardware at the moment... What exactly this
>> patch does?
>>
>
> basically it appears that your machine, when the kernel asks for C2,
> exits C2 immediately again.
>
> The old algorithm somehow caught this and stopped asking for C2 most of
> the time; the new algorithm doesn't see any activity and asks for C2
> again.
>
> What the patch does is tell the kernel to just not use C2 at all...

Indeed, in the past powertop always showed my processor idling in C1 
state, and I wondered why it never entered C2. :-)

So thanks for the patch, I guess it works, and my bet is that this 
case applies to L8400* (not only B models), except if it is fixed by some 
old BIOS upgrade that I must have missed.

While testing your patch, indeed the temperature was not rising and 
everything was normal, but the tsc was not marked as unstable so it didn't 
switch to acpi_pm clocksource, so that was probably the reason.


Dimitris
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