Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932523Ab1BWTfP (ORCPT ); Wed, 23 Feb 2011 14:35:15 -0500 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:45402 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932317Ab1BWTfO (ORCPT ); Wed, 23 Feb 2011 14:35:14 -0500 X-Authority-Analysis: v=1.1 cv=3uSaImBeuprzHBlOOPjkqgu+7PcxSRW0m2Aphm9Zmck= c=1 sm=0 a=x5lYFldHaXAA:10 a=Q9fys5e9bTEA:10 a=OPBmh+XkhLl+Enan7BmTLg==:17 a=41f9gDDPBCUqm97kbLUA:9 a=Pa3ajuvgpB4zC1qcuYKMaYLhE8EA:4 a=PUjeQqilurYA:10 a=OPBmh+XkhLl+Enan7BmTLg==:117 X-Cloudmark-Score: 0 X-Originating-IP: 67.242.120.143 Subject: Re: [PATCH RFC tip/core/rcu 11/11] rcu: move TREE_RCU from softirq to kthread From: Steven Rostedt To: Peter Zijlstra Cc: Christoph Lameter , Mathieu Desnoyers , Frederic Weisbecker , "Paul E. McKenney" , linux-kernel@vger.kernel.org, mingo@elte.hu, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, josh@joshtriplett.org, niv@us.ibm.com, tglx@linutronix.de, Valdis.Kletnieks@vt.edu, dhowells@redhat.com, eric.dumazet@gmail.com, darren@dvhart.com, "Paul E. McKenney" In-Reply-To: <1298489030.2217.818.camel@twins> References: <20110223013917.GA20996@linux.vnet.ibm.com> <1298425183-21265-11-git-send-email-paulmck@linux.vnet.ibm.com> <20110223161645.GA1819@nowhere> <1298479302.7666.94.camel@gandalf.stny.rr.com> <1298485027.7666.98.camel@gandalf.stny.rr.com> <1298485965.7666.102.camel@gandalf.stny.rr.com> <1298489030.2217.818.camel@twins> Content-Type: text/plain; charset="ISO-8859-15" Date: Wed, 23 Feb 2011 14:35:10 -0500 Message-ID: <1298489710.7666.125.camel@gandalf.stny.rr.com> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 947 Lines: 23 On Wed, 2011-02-23 at 20:23 +0100, Peter Zijlstra wrote: > On Wed, 2011-02-23 at 13:19 -0600, Christoph Lameter wrote: > > > this_cpu_inc is already percpu atomic. On x86 it is an instruction that > > cannot be interrupted nor preempted while in progress. > > On x86, yes, but is this true for all architectures? I guess the > fallback is implemented with local_irq_disable() which might be good > enough for some but not for NMI usage. IIRC, those archs that can not do an atomic inc or cmpxchg have NMIs that are basically "The Sh*t hit the fan, bail". Where the NMIs are used only to dump out the state of the system and not something more advanced that can do things like profiling. -- Steve -- 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/