From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dominik Brodowski Subject: Re: Which cpufreq driver is best for ... Date: Wed, 3 Sep 2003 21:27:49 +0200 Sender: cpufreq-bounces+glkc-cpufreq=gmane.org@www.linux.org.uk Message-ID: <20030903192749.GA30360@brodo.de> References: <20030903055749.GA21721@gamma.logic.tuwien.ac.at> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <20030903055749.GA21721@gamma.logic.tuwien.ac.at> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: cpufreq-bounces+glkc-cpufreq=gmane.org@www.linux.org.uk Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Norbert Preining Cc: cpufreq@www.linux.org.uk On Wed, Sep 03, 2003 at 07:57:49AM +0200, Norbert Preining wrote: > Hi! > > Which cpufreq driver is best for > Mobile Intel(R) Pentium(R) 4 - M CPU 2.20GHz > I can use the > p4-clockmod > and the > speedstep-ich > With the p4-clockmod I can adapt the freq between 274MHz and 2.2GHz, > while with speedstep-ich I can only go between 1.2GHz and 2.2GHz. So I > guess p4-clockmod is superior for my chip/cpu. No, speedstep-ich is "superior". p4-clockmod only "throttles" the CPU, i.e. it scales down the frequency but not the voltage. This results in an approximately linear saving of energy. speedstep-ich also scales the voltage, which causes much better saving of energy. And as long as ACPI C-States "idling" or APM "hlt" instructions work, the CPU is "throttled"[*] if there is no work to do anyway, so the p4-clockmod driver doesn't save you anything. The p4-clockmod driver almost only is useful where ACPI or APM "idling" is borken. > In the same line - are there any new governors with `intelligent' > scaling techniques. Not yet. Stay tuned, please. Dominik [*] I know, this isn't technically true. But it's a good approximation...