From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261896AbVGaVKt (ORCPT ); Sun, 31 Jul 2005 17:10:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261906AbVGaVKt (ORCPT ); Sun, 31 Jul 2005 17:10:49 -0400 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:17594 "EHLO amd.ucw.cz") by vger.kernel.org with ESMTP id S261896AbVGaVKr (ORCPT ); Sun, 31 Jul 2005 17:10:47 -0400 Date: Sun, 31 Jul 2005 23:10:20 +0200 From: Pavel Machek To: James Bruce Cc: Lee Revell , Marc Ballarin , linux-kernel@vger.kernel.org Subject: Re: Power consumption HZ100, HZ250, HZ1000: new numbers Message-ID: <20050731211020.GB27433@elf.ucw.cz> References: <20050730004924.087a7630.Ballarin.Marc@gmx.de> <1122678943.9381.44.camel@mindpipe> <20050730120645.77a33a34.Ballarin.Marc@gmx.de> <1122746718.14769.4.camel@mindpipe> <20050730195116.GB9188@elf.ucw.cz> <1122753864.14769.18.camel@mindpipe> <20050730201049.GE2093@elf.ucw.cz> <42ED32D3.9070208@andrew.cmu.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <42ED32D3.9070208@andrew.cmu.edu> X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > >First numbers were 0.5W on idle system; that shows what kind of > >powersaving can be done. Powersaving is no longer possible when artsd > >is not running, but that should not be used as argument against it. > > It was an idle system with no display, zero daemons running, and the > hard drive off. In other words, a machine that nobody could use which > might as well be hibrinating. While it was an important test to find > out the most one could hope to save, its unrealistic for an actual usage > case. The later test was more realistic, and not suprisingly showed > quite a bit less power savings. Then the second test was probably flawed, possibly because we have some more work to do. No display is irrelevant, HZ=100 will still save 0.5W with running display. Spinning disk also does not produce CPU load (and we *will* want to have disk spinned down). No daemons... if some daemon wakes every msec, we want to fix the daemon. > I really like having 250HZ as an _option_, but what I don't see is why > it should be the _default_. I believe this is Lee's position as > Last I checked, ACPI and CPU speed scaling were not enabled by default; Kernel defaults are irelevant; distros change them anyway. [But we probably want to enable ACPI and cpufreq by default, because that matches what 99% of users will use.] > I have a fixed-framerate app that had to busywait in the days of 2.4.x. > It was nice in 2.6.x to not have to busywait, but with 250HZ that code > will be coming back again. And unfortunately this app can't be made > variable-framerate, as it is simulating video hardware. The same goes > for apps playing movies/animations; Sometimes programs just need a > semi-accurate sleep, and can't demand root priveledges to get it. I really don't think default HZ in kernel config is such a big deal. You'll want to support HZ=100 on 2.6.X, anyway... > In a sense I feel this whole thing boils down to the fact that we don't > have something like "make laptop-config" and "make server-config". I'm > glad we could save 5.2% of the power for a laptop user by changing > the defconfig on i386 is Linus' configuration. Maybe server-config and laptop-config would be good idea... Pavel -- if you have sharp zaurus hardware you don't need... you know my address