Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932655AbWBYE0x (ORCPT ); Fri, 24 Feb 2006 23:26:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932657AbWBYE0x (ORCPT ); Fri, 24 Feb 2006 23:26:53 -0500 Received: from mx1.redhat.com ([66.187.233.31]:58274 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S932655AbWBYE0w (ORCPT ); Fri, 24 Feb 2006 23:26:52 -0500 Date: Fri, 24 Feb 2006 23:24:56 -0500 From: Dave Jones To: Johannes Stezenbach , Adrian Bunk , Dmitry Torokhov , davej@codemonkey.org.uk, Zwane Mwaikambo , Samuel Masham , Jan Engelhardt , linux-kernel@vger.kernel.org, Andrew Morton , cpufreq@lists.linux.org.uk, ak@suse.de Subject: Re: Status of X86_P4_CLOCKMOD? Message-ID: <20060225042456.GA7851@redhat.com> Mail-Followup-To: Dave Jones , Johannes Stezenbach , Adrian Bunk , Dmitry Torokhov , davej@codemonkey.org.uk, Zwane Mwaikambo , Samuel Masham , Jan Engelhardt , linux-kernel@vger.kernel.org, Andrew Morton , cpufreq@lists.linux.org.uk, ak@suse.de References: <20060214152218.GI10701@stusta.de> <20060222024438.GI20204@MAIL.13thfloor.at> <20060222031001.GC4661@stusta.de> <200602212220.05642.dtor_core@ameritech.net> <20060223195937.GA5087@stusta.de> <20060223204110.GE6213@redhat.com> <20060225015722.GC8132@linuxtv.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060225015722.GC8132@linuxtv.org> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1627 Lines: 38 On Sat, Feb 25, 2006 at 02:57:22AM +0100, Johannes Stezenbach wrote: > On Thu, Feb 23, 2006, Dave Jones wrote: > > On Thu, Feb 23, 2006 at 08:59:37PM +0100, Adrian Bunk wrote: > > > And if the option is mostly useless, what is it good for? > > > > It's sometimes useful in cases where the target CPU doesn't have any better > > option (Speedstep/Powernow). The big misconception is that it > > somehow saves power & increases battery life. Not so. > > All it does is 'not do work so often'. The upside of this is > > that in some situations, we generate less heat this way. > > Doesn't less heat imply less power consumption? Not really. The only energy you're saving is that your CPU fan will turn slightly slower, which is probably going to be < 1W of difference. Generated heat drop in a large room of servers *may* mean the aircon has less to do, but I'd be surprised if it made a noticable difference. > - after some minutes of idling without user activity > go into lowest power mode (could be triggered > from xscreensaver) > - at the slightest hint of user activity or CPU load jump > back to max performance mode > (- optionally use intermediate clock mod steps for > non-interactive loads, but I'm not convinced it's > worth it) You should be able to modify cpuspeed or some other userspace governor to do this quite easily. Dave - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/