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Date: Thu, 24 Aug 2006 17:15:14 +0100
From: Matthew Garrett <mjg59@srcf.ucam.org>
To: Mark Lord <lkml@rtr.ca>
Cc: Pavel Machek <pavel@ucw.cz>,
       "Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>,
       Dave Jones <davej@redhat.com>,
       Linux Kernel <linux-kernel@vger.kernel.org>,
       Andrew Morton <akpm@osdl.org>
Subject: Re: cpufreq stops working after a while
Message-ID: <20060824161514.GA19753@srcf.ucam.org>
References: <EB12A50964762B4D8111D55B764A84546F8EC3@scsmsx413.amr.corp.intel.com> <44DCE8BA.2070601@rtr.ca> <44DCEAF7.5020005@rtr.ca> <20060811210104.GL26930@redhat.com> <44DCF360.7050305@rtr.ca> <44DCF5C1.4040506@rtr.ca> <20060818151122.GA8275@ucw.cz> <44EDBB4C.6040203@rtr.ca>
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On Thu, Aug 24, 2006 at 10:44:28AM -0400, Mark Lord wrote:

> By definition, "passive" cooling never needs enabling -- this just refers
> to things like heat sinks and air vents.

In ACPI terms, passive cooling is forced downthrottling of the CPU in 
order to reduce heat generation. This is normally done if the 
temperature is continuing to rise despite active cooling being enabled.

On some hardware you can set the values at which different types of 
cooling will be enabled in /proc/acpi/thermal_zone/*/trip_points. Echo a 
colon separated list of values in there to rewrite them. Some BIOSes 
will change the trip points in response to various events, which will 
then overwrite your values.

-- 
Matthew Garrett | mjg59@srcf.ucam.org
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