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

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Date:	Thu, 11 Feb 2010 21:23:13 -0800
From:	Arjan van de Ven <arjan@...radead.org>
To:	Dimitrios Apostolou <jimis@....net>
Cc:	thomas@...hlinux.org, Wojciech Ploskonka <wploskonka@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Alex Chiang <achiang@...com>, Len Brown <lenb@...nel.org>,
	Bjorn Helgaas <bjorn.helgaas@...com>,
	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 Thu, 11 Feb 2010 20:00:47 +0200 (EET)
Dimitrios Apostolou <jimis@....net> wrote:

> On Wed, 10 Feb 2010, Arjan van de Ven wrote:
> > On Wed, 10 Feb 2010 22:51:38 +0200 (EET)
> > Dimitrios Apostolou <jimis@....net> wrote:
> >>
> >> As I understand, in his case the C3 state is unstable and exits
> >> immediately. I have asked him to post the dmidecode output so you
> >> can put him on the exception list too. However I now believe that
> >> more and more users will be facing the same problem, it's not
> >> something you find easily, especially on desktop machines! What do
> >> you think?
> >
> > if C3 does not work, this needs to be fixed in the code that
> > implements C3, not in the code that selects C3.
> >
> >
> > Modern systems should have working C3; if one does not it needs to
> > be investigated as to why it's not working. One cause could be a
> > PME that we're not handling (I've seen that a few times in our
> > lab), lspci -vvv will show that.
> >
> > But regardless, it's not the task of the code that selects a C
> > state to deal with....
> 
> Wojo (CC'd) can you run as root lspci -vvv and attach the output, so
> the experts can have a look?
> 
> Arjan, in this case a bisection was not performed but the symptoms
> are exactly the same as mine:
> * powertop showing thousands of interrups but showing no specific
> process causing them
> * The situation is caused only when the "processor" module is
> inserted and after a message about "marking TSC as unstable due to
> halts in idle", exactly like my case
> 
> Hmmm actually a difference is that in my case the system used the
> acpi_pm clocksource, but in Wojo's case it used hpet.
> 
> If I understand correctly what you said, this is a bug in another
> piece of code, and I assume that the previous behaviour of the
> governor was hiding it, avoiding C3 state completely, right?
> 
> 

the old governor would not avoid c3, each time it would try it a bunch
of times and eventually fall back... not very good, but mostly
invisible to you.


-- 
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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