Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760772AbYGRQa6 (ORCPT ); Fri, 18 Jul 2008 12:30:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760513AbYGRQa0 (ORCPT ); Fri, 18 Jul 2008 12:30:26 -0400 Received: from mtagate6.uk.ibm.com ([195.212.29.139]:23090 "EHLO mtagate6.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760504AbYGRQaY (ORCPT ); Fri, 18 Jul 2008 12:30:24 -0400 Date: Fri, 18 Jul 2008 18:29:05 +0200 From: Heiko Carstens To: Thomas Gleixner Cc: eric miao , Ingo Molnar , LKML , Jack Ren , Peter Zijlstra , Dmitry Adamushko Subject: Re: [PATCH] sched: do not stop ticks when cpu is not idle Message-ID: <20080718162905.GA4781@osiris.boeblingen.de.ibm.com> References: <20080718102446.GV6875@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1664 Lines: 41 On Fri, Jul 18, 2008 at 05:27:28PM +0200, Thomas Gleixner wrote: > On Fri, 18 Jul 2008, eric miao wrote: > > On Fri, Jul 18, 2008 at 9:52 PM, Thomas Gleixner wrote: > > >> Thomas, Peter, Dmitry, do you concur with the analysis? (commit below) > > > > > > Yes. I did not understand the issue when Jack pointed it out to me, > > > but with Erics explanation it's really clear. Thanks for tracking that > > > down. > > > > Actually, Jack did most of the analysis and came up with this quick > > fix. > > > > > > > >> It looks a bit ugly to me in the middle of schedule() - is there no wait > > >> to solve this within kernel/time/*.c ? > > > > > > Hmm, yes. I think the proper fix is to enable the tick stop mechanism > > > in the idle loop and disable it before we go to schedule. That takes > > > an additional parameter to tick_nohz_stop_sched_tick(), but we then > > > gain a very clear section where the nohz mimic can be active. > > > > > > I'll whip up a patch. > > > > Sounds great, thanks. > > Hey, thanks for tracking that down. I was banging my head against the > wall when I understood the problem. > > I tried to pinpoint the occasional softlockup bug reports, but I > probably stared too long into that code so I just saw what I expected > to see. > > Can you give the patch below a try please ? If this patch works, could you also add the s390 hunk before submitting? Thanks! ;) -- 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/