From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932837AbZHDO72 (ORCPT ); Tue, 4 Aug 2009 10:59:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932825AbZHDO70 (ORCPT ); Tue, 4 Aug 2009 10:59:26 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:57689 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932291AbZHDO7X (ORCPT ); Tue, 4 Aug 2009 10:59:23 -0400 Date: Tue, 4 Aug 2009 16:59:09 +0200 From: Ingo Molnar To: Jason Wessel Cc: Thomas Gleixner , Peter Zijlstra , lkml , "Deng, Dongdong" Subject: Re: [PATCH] softlockup: fix problem with long kernel pauses fromkgdb Message-ID: <20090804145909.GO7746@elte.hu> References: <4A6E0825.3020604@windriver.com> <1248725893.6987.2055.camel@twins> <4A6F139C.6070806@windriver.com> <20090804141623.GD7746@elte.hu> <4A784B78.2020801@windriver.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4A784B78.2020801@windriver.com> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Jason Wessel wrote: > Ingo Molnar wrote: > > * Jason Wessel wrote: > > > >> ----- > >> From: Jason Wessel > >> Subject: [PATCH] softlockup: add sched_clock_tick() to avoid kernel warning on kgdb resume > >> > >> When CONFIG_HAVE_UNSTABLE_SCHED_CLOCK is set sched_clock() gets the > >> time from hardware, such as from TSC. In this configuration kgdb will > >> report a softlock warning messages on resuming or detaching from a > >> debug session. > >> > > > > Hm, this looks quite ugly. Peter, Thomas, can you think of a > > cleaner solution? > > > > Below was a more specific test case I received from Dongdong Deng > which did not require kgdb. The test case is not something to > merge, it is just a simple module to build to demonstrate the > problem outside of kgdb. > > The patch I submitted might have been on the "ugly" side, but > there was not an obvious way to solve the problem without making > changes in kernel/sched*. I opted for something that was entirely > self contained to the softlockup code. it's not really the fault of your patch really - all these integrations along dynticks, scheduler time and softlockup feel a bit awkward. Wondering whether there's some nicer way. Ingo