From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758150Ab1EZRnn (ORCPT ); Thu, 26 May 2011 13:43:43 -0400 Received: from e8.ny.us.ibm.com ([32.97.182.138]:43231 "EHLO e8.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751748Ab1EZRnm (ORCPT ); Thu, 26 May 2011 13:43:42 -0400 Date: Thu, 26 May 2011 10:43:01 -0700 From: "Paul E. McKenney" To: Ingo Molnar Cc: Yinghai Lu , linux-kernel@vger.kernel.org, mingo@redhat.com, hpa@zytor.com, tglx@linutronix.de Subject: Re: [tip:core/rcu] Revert "rcu: Decrease memory-barrier usage based on semi-formal proof" Message-ID: <20110526174301.GA9649@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <4DDC21E1.1070502@kernel.org> <4DDC48E3.1060108@kernel.org> <20110525045253.GB2262@linux.vnet.ibm.com> <4DDD7F96.3090408@kernel.org> <20110525223437.GO2341@linux.vnet.ibm.com> <4DDD8775.1000501@kernel.org> <20110526011310.GP2341@linux.vnet.ibm.com> <20110526013029.GA28103@linux.vnet.ibm.com> <20110526061348.GA26775@elte.hu> <20110526142553.GA2386@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110526142553.GA2386@linux.vnet.ibm.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 26, 2011 at 07:25:53AM -0700, Paul E. McKenney wrote: > On Thu, May 26, 2011 at 08:13:48AM +0200, Ingo Molnar wrote: > > > > * Paul E. McKenney wrote: > > > > > rcu: Start RCU kthreads in TASK_INTERRUPTIBLE state > > > > > > Upon creation, kthreads are in TASK_UNINTERRUPTIBLE state, which can > > > result in softlockup warnings. Because some of RCU's kthreads can > > > legitimately be idle indefinitely, start them in TASK_INTERRUPTIBLE > > > state in order to avoid those warnings. > > > > > > Suggested-by: Peter Zijlstra > > > Signed-off-by: Paul E. McKenney > > > > this should also solve load average artifacts - do not > > TASK_UNINTERRUPTIBLE tasks skew the load upwards? > > Quite possibly -- in this case the artifacts would appear just after > boot, and would disappear as soon as the RCU kthreads had something > to do. By the way, how would you like to proceed with the fixes thus far? I have put them on -rcu for -next testing, FWIW. Thanx, Paul