From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759124Ab1EMB3K (ORCPT ); Thu, 12 May 2011 21:29:10 -0400 Received: from rcsinet10.oracle.com ([148.87.113.121]:53996 "EHLO rcsinet10.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759075Ab1EMB3J (ORCPT ); Thu, 12 May 2011 21:29:09 -0400 Message-ID: <4DCC894D.3070204@kernel.org> Date: Thu, 12 May 2011 18:28:45 -0700 From: Yinghai Lu User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.17) Gecko/20110414 SUSE/3.1.10 Thunderbird/3.1.10 MIME-Version: 1.0 To: paulmck@linux.vnet.ibm.com CC: Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: [GIT PULL rcu/next] rcu commits for 2.6.40 References: <4DC9A5A4.1050308@kernel.org> <20110511045443.GS2258@linux.vnet.ibm.com> <20110511201852.GC2258@linux.vnet.ibm.com> <4DCAF894.7030707@kernel.org> <4DCAFFD8.2080605@kernel.org> <4DCB157F.20202@kernel.org> <20110512060344.GB3191@elte.hu> <4DCB8BCD.1080607@kernel.org> <4DCB8F7A.90603@kernel.org> <20110512092013.GJ2258@linux.vnet.ibm.com> <4DCC52FB.6030500@kernel.org> In-Reply-To: <4DCC52FB.6030500@kernel.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Source-IP: rtcsinet22.oracle.com [66.248.204.30] X-CT-RefId: str=0001.0A090201.4DCC895A.0016,ss=1,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/12/2011 02:36 PM, Yinghai Lu wrote: > On 05/12/2011 02:20 AM, Paul E. McKenney wrote: >> On Thu, May 12, 2011 at 12:42:50AM -0700, Yinghai Lu wrote: >>> On 05/12/2011 12:27 AM, Yinghai Lu wrote: >>>> On 05/11/2011 11:03 PM, Ingo Molnar wrote: >>>>> >>>>> * Yinghai Lu wrote: >>>>> >>>>>> e59fb3120becfb36b22ddb8bd27d065d3cdca499 is the first bad commit >>>>>> commit e59fb3120becfb36b22ddb8bd27d065d3cdca499 >>>>>> Author: Paul E. McKenney >>>>>> Date: Tue Sep 7 10:38:22 2010 -0700 >>>>>> >>>>>> rcu: Decrease memory-barrier usage based on semi-formal proof >>>>> >>>>> Find below an (untested!) attempt at reverting it for debugging purposes: could >>>>> you please try it, does your system now boot up fine? >>>>> >>>>> Thanks, >>>>> >>>>> Ingo >>>>> >>>> >>>> yes, reverted manually that commit fix the problem. >>> >>> on system with 8 sockets westmere-ex >>> >>> it seems other commits after that commit contribute some delay too. >>> >>> [ 32.240739] cpu_dev_init done >>> [ 73.587288] memory_dev_init done >> >> I am testing a revert of e59fb3120becfb36b22ddb8bd27d065d3cdca499 and >> will chase down the delay. >> > > it seems still need to revert following one in addition e59fb3120becfb36b22ddb8bd27d065d3cdca499. > > [root@mpk14-2404-239-158 linux-2.6]# git bisect good > a26ac2455ffcf3be5c6ef92bc6df7182700f2114 is the first bad commit > commit a26ac2455ffcf3be5c6ef92bc6df7182700f2114 > Author: Paul E. McKenney > Date: Wed Jan 12 14:10:23 2011 -0800 > > rcu: move TREE_RCU from softirq to kthread > > If RCU priority boosting is to be meaningful, callback invocation must > be boosted in addition to preempted RCU readers. Otherwise, in presence > of CPU real-time threads, the grace period ends, but the callbacks don't > get invoked. If the callbacks don't get invoked, the associated memory > doesn't get freed, so the system is still subject to OOM. > > But it is not reasonable to priority-boost RCU_SOFTIRQ, so this commit > moves the callback invocations to a kthread, which can be boosted easily. > > Also add comments and properly synchronized all accesses to > rcu_cpu_kthread_task, as suggested by Lai Jiangshan. > > Signed-off-by: Paul E. McKenney > Signed-off-by: Paul E. McKenney > Reviewed-by: Josh Triplett > > :040000 040000 e40306ac6405952c1d387325a98588442209abe8 efe9ea2f408c62daaccf49e6d1339dff3a74f049 M Documentation > :040000 040000 8f9e7a8fa3a728d4ae58e2efb8ada7cf08aed00e 9b44deba45ba905c5d9b3cc314812f0ba3f7e639 M include > :040000 040000 4b10b719a2d56ed4bc796a9f43775732bb5ff144 4db269277ccf607e1a6a7d7f4c2a7cf8d592d46a M kernel > :040000 040000 881f102e6831381beed016ed240d690f6a2ccd5e 57d2fc6f84e47394c116bc617a9a0ef9b8b6dbd4 M tools more info: if only reverting: e59fb3120becfb36b22ddb8bd27d065d3cdca499 when compiled with gcc from opensuse 11.3 [ 32.579585] cpu_dev_init done [ 81.203193] memory_dev_init done but when compile that with gcc from fedora 14, then will less delay. [ 32.404140] cpu_dev_init done [ 37.602986] memory_dev_init done gcc version on opensuse 11.3 gcc (SUSE Linux) 4.5.0 20100604 [gcc-4_5-branch revision 160292] gcc version on fedora 14: gcc (GCC) 4.5.1 20100924 (Red Hat 4.5.1-4) Thanks Yinghai