From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [patch 1/4] Ignore stolen time in the softlockup watchdog Date: Tue, 24 Apr 2007 22:59:18 +0200 Message-ID: <20070424205918.GA25383@elte.hu> References: <20070327214919.800272641@goop.org> <20070327215827.871954359@goop.org> <20070423234910.50149faf.akpm@linux-foundation.org> <462E43A7.1050001@goop.org> <20070424105738.e0ce36a9.akpm@linux-foundation.org> <462E4969.6070802@goop.org> <20070424113222.ed2e1314.akpm@linux-foundation.org> <462E61F1.7060403@goop.org> <462E6778.7070305@goop.org> <1177447948.12796.66.camel@imap.mvista.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1177447948.12796.66.camel@imap.mvista.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Daniel Walker Cc: Prarit Bhargava , Rick Lindsley , john stultz , Linux Kernel , Eric Dumazet , virtualization@lists.osdl.org, Chris Lalancette , Paul Mackerras , Martin Schwidefsky , Andrew Morton , Thomas Gleixner List-Id: virtualization@lists.linuxfoundation.org * Daniel Walker wrote: > On Tue, 2007-04-24 at 13:24 -0700, Jeremy Fitzhardinge wrote: > > > And sched_clock's use of local_irq_save/restore appears to be absolutely > > correct, so I think it must be triggering a bug in either the self-tests > > or lockdep itself. > > Why does sched_clock need to disable interrupts? i concur. To me it appears not "absolutely correct" that someone apparently added local_irq_save/restore to sched_clock(), but "absolute madness". sched_clock() is _very_ performance-sensitive for the scheduler, do not mess with it. Ingo From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1423112AbXDXVA3 (ORCPT ); Tue, 24 Apr 2007 17:00:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1423102AbXDXVA3 (ORCPT ); Tue, 24 Apr 2007 17:00:29 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:53531 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423112AbXDXVA2 (ORCPT ); Tue, 24 Apr 2007 17:00:28 -0400 Date: Tue, 24 Apr 2007 22:59:18 +0200 From: Ingo Molnar To: Daniel Walker Cc: Jeremy Fitzhardinge , Andrew Morton , Prarit Bhargava , Rick Lindsley , john stultz , Linux Kernel , Eric Dumazet , virtualization@lists.osdl.org, Chris Lalancette , Paul Mackerras , Martin Schwidefsky , Thomas Gleixner Subject: Re: [patch 1/4] Ignore stolen time in the softlockup watchdog Message-ID: <20070424205918.GA25383@elte.hu> References: <20070327214919.800272641@goop.org> <20070327215827.871954359@goop.org> <20070423234910.50149faf.akpm@linux-foundation.org> <462E43A7.1050001@goop.org> <20070424105738.e0ce36a9.akpm@linux-foundation.org> <462E4969.6070802@goop.org> <20070424113222.ed2e1314.akpm@linux-foundation.org> <462E61F1.7060403@goop.org> <462E6778.7070305@goop.org> <1177447948.12796.66.camel@imap.mvista.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1177447948.12796.66.camel@imap.mvista.com> User-Agent: Mutt/1.4.2.2i X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.0.3 -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 * Daniel Walker wrote: > On Tue, 2007-04-24 at 13:24 -0700, Jeremy Fitzhardinge wrote: > > > And sched_clock's use of local_irq_save/restore appears to be absolutely > > correct, so I think it must be triggering a bug in either the self-tests > > or lockdep itself. > > Why does sched_clock need to disable interrupts? i concur. To me it appears not "absolutely correct" that someone apparently added local_irq_save/restore to sched_clock(), but "absolute madness". sched_clock() is _very_ performance-sensitive for the scheduler, do not mess with it. Ingo