Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965483AbXBFVKW (ORCPT ); Tue, 6 Feb 2007 16:10:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965487AbXBFVKW (ORCPT ); Tue, 6 Feb 2007 16:10:22 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:40156 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965483AbXBFVKU (ORCPT ); Tue, 6 Feb 2007 16:10:20 -0500 Date: Tue, 6 Feb 2007 22:09:59 +0100 From: Ingo Molnar To: Daniel Walker Cc: Thomas Gleixner , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: 2.6.20-rc6-mm3 Message-ID: <20070206210959.GC25430@elte.hu> References: <20070129204528.eb8d695e.akpm@osdl.org> <1170777802.9781.353.camel@imap.mvista.com> <1170786992.3785.0.camel@chaos> <1170787543.9781.362.camel@imap.mvista.com> <1170788870.3785.9.camel@chaos> <1170791739.3455.3.camel@dwalker1> <1170793206.3785.16.camel@chaos> <1170794437.3455.20.camel@dwalker1> <20070206205231.GA25430@elte.hu> <1170795378.3455.31.camel@dwalker1> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1170795378.3455.31.camel@dwalker1> User-Agent: Mutt/1.4.2.2i X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -5.3 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-5.3 required=5.9 tests=ALL_TRUSTED,BAYES_00 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1211 Lines: 28 * Daniel Walker wrote: > > it's quite easy to explain: because of the new dynticks feature. > > Both 'timer' and 'LOC' counts go way down. > > I don't have that enabled tho .. This is with HRT/dynamic tick both > off.. your kernel utilizes the kernelin a more optimal way: the new clockevents code now utilizes the local APIC timer irq (represented by the LOC field) for periodic interrupts. The local APIC timer irq has a cost of ~2 usecs per IRQ, while the PIT irq is ~10 usecs per irq. With HZ=1000 this means savings of ~8000 usecs per second - i.e. 8 msecs per second, which is 0.8% more raw CPU power available - which isnt that bad. we could make this clearer by renaming 'LOC' (which stands for 'LOCal timer interupts' and was added [and misnamed] by yours truly many moons ago) to 'apic-timer' and 'timer' to 'PIT-timer' but /that/ would be more of a userspace visible change than the change in the counter rates. Ingo - 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/