Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759414AbXHULVY (ORCPT ); Tue, 21 Aug 2007 07:21:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758878AbXHULVM (ORCPT ); Tue, 21 Aug 2007 07:21:12 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:52441 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758854AbXHULVK (ORCPT ); Tue, 21 Aug 2007 07:21:10 -0400 Date: Tue, 21 Aug 2007 13:20:32 +0200 From: Ingo Molnar To: Andi Kleen Cc: Martin Schwidefsky , Christian Borntraeger , Linus Torvalds , Andrew Morton , linux-kernel@vger.kernel.org, Jan Glauber , heiko.carstens@de.ibm.com, Paul Mackerras Subject: Re: [accounting regression since rc1] scheduler updates Message-ID: <20070821112032.GA648@elte.hu> References: <20070812163225.GA11996@elte.hu> <200708141037.48001.borntraeger@de.ibm.com> <20070820154529.GA300@elte.hu> <1187629438.8541.40.camel@localhost> <20070820180810.GA25160@elte.hu> <20070821070922.GA16695@elte.hu> <20070821100717.GA692@one.firstfloor.org> <20070821102023.GA24111@elte.hu> <20070821111523.GA3795@one.firstfloor.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070821111523.GA3795@one.firstfloor.org> User-Agent: Mutt/1.5.14 (2007-02-12) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.0.3 -1.0 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: 1602 Lines: 37 * Andi Kleen wrote: > > i know there are some incredibly broken (but rare) boxes where the bios > > will report it only knows C1 and do C2? Is that the case you are > > referring to, or is there something else too? > > There are first a couple of older and not so old (Centaur) chips that > generally stop the TSC in C1. there's not much we can do about them: the ACPI code doesnt measure their idle time, right? This is mostly for statistics purposes, so unless "broken" means tons of boxes, we dont have to have 100% coverage. > And also some boxes who shouldn't have anything deeper than C2 have > trouble with the TSC. For example I got a Opteron machine (which > definitely shouldn't have any C2 since it's two socket) where the TSC > appears to stop or at least slow down a lot in C1. how much is "a lot" in C1? There's an AMD TSC-slows-down-C1 erratum but that should be less than 1%. (which is fine enough for idle time measurements) > And thirdly it's just unclean to add all kinds of custom hooks there. > It was already ugly in NOHZ, please don't continue that. i'm not opposed to the idle notifiers but iirc the idle notifiers caused problems in themselves so part of them were reverted. We can do this more cleanly in .24 - it will make the benefits of the notifier cleanup even more apparent. 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/