From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ducrot Bruno Subject: Re: p4-clockmod doesn't seem to allow the highest possible speed Date: Mon, 12 Jan 2004 13:26:13 +0100 Sender: cpufreq-bounces@www.linux.org.uk Message-ID: <20040112122613.GE14031@poupinou.org> References: <20040110101534.GA10003@dominikbrodowski.de> <20040110110800.GA8294@grep.be> <20040110131824.GA5010@dominikbrodowski.de> <20040110152145.GA10160@grep.be> <20040110154110.GA8735@dominikbrodowski.de> <20040110163212.GD10531@grep.be> <20040110185308.GZ14031@poupinou.org> <20040110193526.GM10531@grep.be> <20040111173547.GB5485@dominikbrodowski.de> <20040111195619.GA25048@grep.be> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <20040111195619.GA25048@grep.be> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: cpufreq-bounces@www.linux.org.uk Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Wouter Verhelst Cc: cpufreq@www.linux.org.uk On Sun, Jan 11, 2004 at 08:56:19PM +0100, Wouter Verhelst wrote: > On Sun, Jan 11, 2004 at 06:35:47PM +0100, Dominik Brodowski wrote: > > On Sat, Jan 10, 2004 at 08:35:26PM +0100, Wouter Verhelst wrote: > > > That happens both when it's in P0 or P1. > > > > So ACPI works to set the processor in P0 and P1? > > Yes. > > > If so, you really really should use the ACPI cpufreq driver instead of > > the p4-clockmod driver. The former will offer you true "SpeedStep" > > support, the latter only some clock modulation which won't save you > > much energy as ACPI supports the C2 idle state anyway. > > Ah, so what p4-clockmod does is not SpeedStep? > > Hm. That sucks. No. p4-clockmod is not SpeedStep. Normal. As Dominik say, p4-clockmod is *not* intended for power comsuption issues. There is normally two reasons for slowing a CPU: 1- change voltage of processor (SpeedStep, Powernow, etc.) The usage for is to get more battery life, or to get less power comsuption for the system. 2- throttling the CPU via clock modulation (P4 only), or by generating a signal which toggle the STP# pin of a CPU. The usage for it is to cool the CPU instead of turning on/off the CPU fan. It is also used if the fan is not sufficiant to cool enough the CPU. 1 and 2 do not have the same goal. The CPUFreq project currently only handle case 1- (via policy, governor, etc.). But I'm thinking about designing case 2- for the cpufreq core (there is already something for, but it is not exactly what I would expect), and that should rely on lm-sensors or/and ACPI thermal. Cheers, -- Ducrot Bruno -- Which is worse: ignorance or apathy? -- Don't know. Don't care.