Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758824AbYCBTLg (ORCPT ); Sun, 2 Mar 2008 14:11:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753533AbYCBTL3 (ORCPT ); Sun, 2 Mar 2008 14:11:29 -0500 Received: from bombadil.infradead.org ([18.85.46.34]:52820 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752738AbYCBTL2 (ORCPT ); Sun, 2 Mar 2008 14:11:28 -0500 Subject: Re: 2.6.25-rc: complete lockup on boot/start of X (bisected) From: Peter Zijlstra To: Marcin Slusarz Cc: LKML , Ingo Molnar In-Reply-To: <20080302185935.GA6100@joi> References: <20080302185935.GA6100@joi> Content-Type: text/plain Date: Sun, 02 Mar 2008 20:11:11 +0100 Message-Id: <1204485071.6240.56.camel@lappy> Mime-Version: 1.0 X-Mailer: Evolution 2.21.90 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2831 Lines: 68 On Sun, 2008-03-02 at 20:00 +0100, Marcin Slusarz wrote: > Hi > Since early 2.6.25 days I'm having strange lockup on boot. As it happens > rarely (in ~10% of boots), I couldn't bisect it. No kernel panic, SysRq > didn't work, so I couldn't provide any useful informations to LK community. > I hoped someone else would fix it... :) > > It's rc3 so I decided to narrow it down myself. I enabled netconsole > to see whether some other informations are printed before lockup. > It didn't help, but I noticed that lockup happens much more frequenly! (~50%) > So I bisected it down to: > > 8f4d37ec073c17e2d4aa8851df5837d798606d6f is first bad commit > commit 8f4d37ec073c17e2d4aa8851df5837d798606d6f > Author: Peter Zijlstra > Date: Fri Jan 25 21:08:29 2008 +0100 > > sched: high-res preemption tick > > Use HR-timers (when available) to deliver an accurate preemption tick. > > The regular scheduler tick that runs at 1/HZ can be too coarse when nice > level are used. The fairness system will still keep the cpu utilisation 'fair' > by then delaying the task that got an excessive amount of CPU time but try to > minimize this by delivering preemption points spot-on. > > The average frequency of this extra interrupt is sched_latency / nr_latency. > Which need not be higher than 1/HZ, its just that the distribution within the > sched_latency period is important. > > Signed-off-by: Peter Zijlstra > Signed-off-by: Ingo Molnar > > :040000 040000 ab225228500f7a19d5ad20ca12ca3fc8ff5f5ad1 f1742e1d225a72aecea9d6961ed989b5943d31d8 M arch > :040000 040000 25d85e4ef7a71b0cc76801a2526ebeb4dce180fe ae61510186b4fad708ef0211ac169decba16d4e5 M include > :040000 040000 9247cec7dd506c648ac027c17e5a07145aa41b26 950832cc1dc4d30923f593ecec883a06b45d62e9 M kernel > > I can't revert it on top of rc3 because of conflicts. This should do, I guess. Weird though, I haven't had trouble with this patch in a long long while. Nor I suppose has Ingo's QA setup. Will try if I can reproduce using your .config. --- diff --git a/kernel/sched.c b/kernel/sched.c index b73ee9e..02cbf34 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -741,7 +741,7 @@ const_debug unsigned int sysctl_sched_features = SCHED_FEAT_NEW_FAIR_SLEEPERS * 1 | SCHED_FEAT_WAKEUP_PREEMPT * 1 | SCHED_FEAT_START_DEBIT * 1 | - SCHED_FEAT_HRTICK * 1 | + SCHED_FEAT_HRTICK * 0 | SCHED_FEAT_DOUBLE_TICK * 0; #define sched_feat(x) (sysctl_sched_features & SCHED_FEAT_##x) -- 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/