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

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Message-ID: <20100109201527.77dd1714@infradead.org>
Date:	Sat, 9 Jan 2010 20:15:27 -0800
From:	Arjan van de Ven <arjan@...radead.org>
To:	Ray Lee <ray-lk@...rabbit.org>
Cc:	Dimitrios Apostolou <jimis@....net>, 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 18:07:14 -0800
Ray Lee <ray-lk@...rabbit.org> wrote:

> On Sat, Jan 9, 2010 at 4:42 PM, Arjan van de Ven
> <arjan@...radead.org> wrote:
> > 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.
> 
> This change of behavior will certainly bite more users out there. Is
> there any way we can detect the systems that aren't honoring the C2
> request and limit back to C1?

it's not very likely that there are many such systems; it takes work to
break C2....
so far in 6 months 2 systems showed up, and this includes a fedora
release.

on the other hand, it's not so easy to detect the situation; exiting c2
quickly can also happen in normal use, so we'd have to have some sort of
threshold, which will be fragile by itself.


-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
visit http://www.lesswatts.org
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