From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753629AbaHMSZf (ORCPT ); Wed, 13 Aug 2014 14:25:35 -0400 Received: from e34.co.us.ibm.com ([32.97.110.152]:49217 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751518AbaHMSZd (ORCPT ); Wed, 13 Aug 2014 14:25:33 -0400 Date: Wed, 13 Aug 2014 11:25:28 -0700 From: "Paul E. McKenney" To: Peter Zijlstra Cc: Steven Rostedt , linux-kernel@vger.kernel.org, mingo@kernel.org, laijs@cn.fujitsu.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com Subject: Re: [PATCH v5 tip/core/rcu 15/16] rcu: Make RCU-tasks wait for idle tasks Message-ID: <20140813182528.GF4752@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <1407797345-28227-1-git-send-email-paulmck@linux.vnet.ibm.com> <1407797345-28227-15-git-send-email-paulmck@linux.vnet.ibm.com> <20140813081215.GB9918@twins.programming.kicks-ass.net> <20140813124818.GQ4752@linux.vnet.ibm.com> <20140813134025.GN9918@twins.programming.kicks-ass.net> <20140813095132.56d288f2@gandalf.local.home> <20140813140705.GO9918@twins.programming.kicks-ass.net> <20140813101301.08019895@gandalf.local.home> <20140813144332.GW4752@linux.vnet.ibm.com> <20140813163522.GU9918@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140813163522.GU9918@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14081318-1542-0000-0000-000003FAE903 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 13, 2014 at 06:35:22PM +0200, Peter Zijlstra wrote: > On Wed, Aug 13, 2014 at 07:43:32AM -0700, Paul E. McKenney wrote: > > So the first three look OK to hook rcu_idle_enter() and rcu_idle_exit() > > into, but the last two don't look so good. > > > > That said, if you are OK not tracing the stuff under stop_critical_timings(), > > then I can use the RCU dyntick-idle state and not wake anything up. > > Either way, Steve could easily whip up a debug thing that could validate > that. Simply WARN whenever an __mcount happens when under rcu_idle. > > And if we make these idle functions small enough that should not be a > problem at all. Right now, the CPU-idle drivers look quite hairy and error-prone. Thanx, Paul