From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261786AbVGKOKF (ORCPT ); Mon, 11 Jul 2005 10:10:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261779AbVGKOHc (ORCPT ); Mon, 11 Jul 2005 10:07:32 -0400 Received: from thunk.org ([69.25.196.29]:53398 "EHLO thunker.thunk.org") by vger.kernel.org with ESMTP id S261755AbVGKOGb (ORCPT ); Mon, 11 Jul 2005 10:06:31 -0400 Date: Mon, 11 Jul 2005 10:05:10 -0400 From: "Theodore Ts'o" To: Alan Cox Cc: Lee Revell , Andrew Morton , arjan@infradead.org, azarah@nosferatu.za.org, cw@f00f.org, Linux Kernel Mailing List , torvalds@osdl.org, christoph@lameter.org Subject: Re: [PATCH] i386: Selectable Frequency of the Timer Interrupt Message-ID: <20050711140510.GB14529@thunk.org> Mail-Followup-To: Theodore Ts'o , Alan Cox , Lee Revell , Andrew Morton , arjan@infradead.org, azarah@nosferatu.za.org, cw@f00f.org, Linux Kernel Mailing List , torvalds@osdl.org, christoph@lameter.org References: <200506231828.j5NISlCe020350@hera.kernel.org> <20050708214908.GA31225@taniwha.stupidest.org> <20050708145953.0b2d8030.akpm@osdl.org> <1120928891.17184.10.camel@lycan.lan> <1120932991.6488.64.camel@mindpipe> <1120933916.3176.57.camel@laptopd505.fenrus.org> <1120934163.6488.72.camel@mindpipe> <20050709121212.7539a048.akpm@osdl.org> <1120936561.6488.84.camel@mindpipe> <1121088186.7407.61.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1121088186.7407.61.camel@localhost.localdomain> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 11, 2005 at 02:23:08PM +0100, Alan Cox wrote: > > > Because some machines exhibit appreciable latency in entering low power > > > state via ACPI, and 1000Hz reduces their battery life. By about half, > > > iirc. > > > > > Then the owners of such machines can use HZ=250 and leave the default > > alone. Why should everyone have to bear the cost? > > They need 100 really it seems, 250-500 have no real effect and on the > Dell I tried 250 didn't stop the wild clock slew from the APM bios > either. I played with this a fair bit on a couple of laptops. I've not > seen anything > 20% saving however so I've no idea who/why someone saw > 50% The real answer here is for the tickless patches to cleaned up to the point where they can be merged, and then we won't waste battery power entering the timer interrupt in the first place. :-) - Ted