Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161353AbWALWIB (ORCPT ); Thu, 12 Jan 2006 17:08:01 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161354AbWALWIA (ORCPT ); Thu, 12 Jan 2006 17:08:00 -0500 Received: from HELIOUS.MIT.EDU ([18.248.3.87]:2482 "EHLO neo.rr.com") by vger.kernel.org with ESMTP id S1161353AbWALWH7 (ORCPT ); Thu, 12 Jan 2006 17:07:59 -0500 Date: Thu, 12 Jan 2006 17:11:33 -0500 From: Adam Belay To: Dave Jones , Con Kolivas , ck list , linux kernel mailing list Subject: Re: 2.6.15-ck1 Message-ID: <20060112221133.GA11601@neo.rr.com> Mail-Followup-To: Adam Belay , Dave Jones , Con Kolivas , ck list , linux kernel mailing list References: <200601041200.03593.kernel@kolivas.org> <20060104190554.GG10592@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060104190554.GG10592@redhat.com> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1910 Lines: 39 On Wed, Jan 04, 2006 at 02:05:54PM -0500, Dave Jones wrote: > On Wed, Jan 04, 2006 at 12:00:00PM +1100, Con Kolivas wrote: > > +2.6.15-dynticks-060101.patch > > +dynticks-disable_smp_config.patch > > Latest version of the dynticks patch. This is proving stable and effective on > > virtually all uniprocessor machines and will benefit systems that desire > > power savings. SMP kernels (even on UP machines) still misbehave so this > > config option is not available by default for this stable kernel. > > I've been curious for some time if this would actually show any measurable > power savings. So I hooked up my laptop to a gizmo[1] that shows how much > power is being sucked. > > both before, and after, it shows my laptop when idle is pulling 21W. > So either the savings here are <1W (My device can't measure more accurately > than a single watt), or this isn't actually buying us anything at all, or > something needs tuning. > > Dave I've done quite a bit of testing with dynticks and various c-state strategies. On my thinkpad T42, dynticks can save about .5 W (as read from the ACPI battery interface, but hey it's a good ballpark measurement). This is when compared to 250HZ and the stock ACPI c-state code. Both tests were running at the lowest processor frequency (600 MHZ). The savings were much greater when running at 1.7 GHZ or when comparing to a HZ value of 1000. Also the advantage was closer to 1 W when X was not running. It might be possible to do even a little better. Currently, I'm developing a new ACPI idle policy that tries to take advantage of the long time we may be able to spend in a C3 state. Thanks, Adam - 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/