From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763914AbYASEYh (ORCPT ); Fri, 18 Jan 2008 23:24:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758400AbYASEYb (ORCPT ); Fri, 18 Jan 2008 23:24:31 -0500 Received: from one.firstfloor.org ([213.235.205.2]:44528 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757890AbYASEYa (ORCPT ); Fri, 18 Jan 2008 23:24:30 -0500 Date: Sat, 19 Jan 2008 05:27:50 +0100 From: Andi Kleen To: Matt Mackall Cc: Andi Kleen , Chodorenko Michail , linux-kernel@vger.kernel.org Subject: Re: PROBLEM: Celeron Core Message-ID: <20080119042750.GA24481@one.firstfloor.org> References: <3ed23423adebae08e8f75b6a6a7ce7ff@one.by> <1200702477.25782.41.camel@cinder.waste.org> <20080119011506.GA23798@one.firstfloor.org> <1200715842.25782.95.camel@cinder.waste.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1200715842.25782.95.camel@cinder.waste.org> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > So while throttling may be less efficient in terms of watt seconds used > to compile something than running at full speed, it is incorrect to say > it uses less power. One machine running for an hour throttled to 50% > uses less power (and therefore less battery and cooling) than another > running at full speed for that same hour. Not for the same unit of work. If you just run endless loops you might be true, but most systems don't do that. In terms of laptops (or rather in most other systems too) you usually care about battery life time while the system is mostly idling (waiting for your key strokes etc.). In this case enabling throttling as a cpufreq driver will not make your battery last longer. Also skipping the clocks does not actually safe all very much power compared to the other measures C-states or speedstep do (like dropping voltage) This means enabling it will likely make your laptop battery last shorter. -Andi