From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ducrot Bruno Subject: Re: [PATCH 2.6] update passive cooling algorithm Date: Mon, 12 Jan 2004 20:11:22 +0100 Sender: cpufreq-bounces@www.linux.org.uk Message-ID: <20040112191122.GK14031@poupinou.org> References: <20040111211255.GA31105@dominikbrodowski.de> <20040112154611.GH14031@poupinou.org> <20040112173922.GA6154@dominikbrodowski.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20040112173922.GA6154@dominikbrodowski.de> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: cpufreq-bounces@www.linux.org.uk To: len.brown@intel.com, acpi-devel@lists.sourceforge.net, cpufreq@www.linux.org.uk List-Id: linux-acpi@vger.kernel.org On Mon, Jan 12, 2004 at 06:39:22PM +0100, Dominik Brodowski wrote: > On Mon, Jan 12, 2004 at 04:46:11PM +0100, Ducrot Bruno wrote: > > On Sun, Jan 11, 2004 at 10:12:55PM +0100, Dominik Brodowski wrote: > > > [Len, could you test and verify this patch, and push it to Linus, please?] > > > > > > The current algorithm used by Linux ACPI for passive thermal management has > > > two shortcomings: > > > > ... > > > > > +/* If a passive cooling situation is detected, primarily CPUfreq is used, as it > > > + * offers (in most cases) voltage scaling in addition to frequency scaling, and > > > + * thus a cubic (instead of linear) reduction of energy. Also, we allow for > > > + * _any_ cpufreq driver and not only the acpi-cpufreq driver. > > > + */ > > > > Just a stupid question: > > > > What is best if processor heat issues (apart turning on the fan)? > > > > Reducing voltage of the processor, but still allowing it to run execution > > at 100% (which is the case if the processor is heating), or reduce > > amount of time allowed for the processor to execute? > > voltage scaling. It offers a much better (quadratic) saving than clock > modulation (linear saving). Doing both [and you need to do it, as the CPU > won't run with fewer volts at the same frequency] gives you cubic savings. Yes I know. But does it offer more 'cooling'? -- Ducrot Bruno -- Which is worse: ignorance or apathy? -- Don't know. Don't care.