linux-kernel - Re: Strange entries in /proc/acpi/thermal

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Message-id: <452F0EB7.2060508@shaw.ca>
Date:	Thu, 12 Oct 2006 21:57:43 -0600
From:	Robert Hancock <hancockr@...w.ca>
To:	Jeremy Fitzhardinge <jeremy@...p.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Cc:	"Brown, Len" <len.brown@...el.com>,
	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>
Subject: Re: Strange entries in /proc/acpi/thermal_zone for Thinkpad X60

Jeremy Fitzhardinge wrote:
> I have a Thinkpad X60 with an Intel Core Duo T2400.  In 
> /proc/acpi/thermal_zone, I'm getting two subdirectories, each with their 
> own set of files:
> 

So your machine has two thermal zones..

> The interesting thing is that the two sets of files are not consistent - 
> sometimes they don't even show the same temperature.

I would expect they wouldn't, otherwise there would be no reason for the 
BIOS people to set up two thermal zones..

> 
> The reason I'm interested in this is that I think it's behind some of my 
> cpufreq problems.  Sometimes the kernel decides that I just can't raise 
> the max frequency above 1GHz, because its been thermally limited (I've 
> put printks in to confirm that its the ACPI thermal limit on the policy 
> notifier chain which is limiting the max speed).  It seems to me that 
> having a thermal zone for each core is a BIOS bug, since they're really 
> the same chip, but the THM1 entries should be ignored.  I don't believe 

How do you know they are one for each core? ACPI thermal zones can be 
anywhere in the machine that needs OS-controlled cooling. Could be the 
CPU heatsink, voltage regulator, or someplace else.

> the CPU has ever approached either 97 C, let alone 127; while I put it 
> under a fair amount of load, it is sitting on a desktop with no airflow 
> obstructions, so if it really is overheating it suggests a serious 
> design problem with the hardware.
> 
> But I'm just speculating; I'm not really sure what all this means.  Any 
> clues?

I think we need more information to decide what is going on here.. what 
temperatures are registering in the thermal zones when the CPU clock is 
being limited?

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@...pamshaw.ca
Home Page: http://www.roberthancock.com/

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