From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752092AbaLSPPP (ORCPT ); Fri, 19 Dec 2014 10:15:15 -0500 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:42769 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751281AbaLSPPN (ORCPT ); Fri, 19 Dec 2014 10:15:13 -0500 Date: Fri, 19 Dec 2014 10:14:29 -0500 From: Chris Mason Subject: Re: frequent lockups in 3.18rc4 To: Dave Jones CC: Linus Torvalds , Mike Galbraith , Ingo Molnar , Peter Zijlstra , =?iso-8859-1?q?D=E2niel?= Fraga , Sasha Levin , "Paul E. McKenney" , Linux Kernel Mailing List , Suresh Siddha , Oleg Nesterov , Peter Anvin Message-ID: <1419002069.13012.4@mail.thefacebook.com> In-Reply-To: <20141219145528.GC13404@redhat.com> References: <20141218051327.GA31988@redhat.com> <1418918059.17358.6@mail.thefacebook.com> <20141218161230.GA6042@redhat.com> <20141219024549.GB1671@redhat.com> <20141219035859.GA20022@redhat.com> <20141219040308.GB20022@redhat.com> <20141219145528.GC13404@redhat.com> X-Mailer: geary/0.8.2 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed X-Originating-IP: [192.168.16.4] X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.13.68,1.0.33,0.0.0000 definitions=2014-12-19_04:2014-12-19,2014-12-19,1970-01-01 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=5 kscore.is_bulkscore=0 kscore.compositescore=0 circleOfTrustscore=145.191669734525 compositescore=0.160988131301636 urlsuspect_oldscore=0.160988131301636 suspectscore=0 recipient_domain_to_sender_totalscore=0 phishscore=0 bulkscore=0 kscore.is_spamscore=0 recipient_to_sender_totalscore=0 recipient_domain_to_sender_domain_totalscore=1996008 rbsscore=0.160988131301636 spamscore=5 recipient_to_sender_domain_totalscore=7 urlsuspectscore=0.9 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=7.0.1-1402240000 definitions=main-1412190151 X-FB-Internal: deliver Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 19, 2014 at 9:55 AM, Dave Jones wrote: > On Thu, Dec 18, 2014 at 08:48:24PM -0800, Linus Torvalds wrote: > > On Thu, Dec 18, 2014 at 8:03 PM, Dave Jones > wrote: > > > > > > So the only thing that was on that could cause spinlock overhead > > > was DEBUG_SPINLOCK (and LOCK_STAT, though iirc that's not huge > either) > > > > So DEBUG_SPINLOCK does have one big downside if I recall correctly > - > > the debugging spinlocks are very much not fair. So they don't work > > like the real ticket spinlocks. That might have serious effects on > the > > contention case, with some thread not making any progress due to > just > > the implementation of the debug spinlocks. > > Wish DEBUG_SPINLOCK disabled, I see the same behaviour. > Lots of traces spewed, but it seems to run and run (at least so far). Not quite the same, the spinlocks are gone. -chris