From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751379AbeEKR3O (ORCPT ); Fri, 11 May 2018 13:29:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:36132 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750746AbeEKR3N (ORCPT ); Fri, 11 May 2018 13:29:13 -0400 Date: Fri, 11 May 2018 13:29:10 -0400 From: Steven Rostedt To: "Paul E. McKenney" Cc: Byungchul Park , jiangshanlai@gmail.com, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, linux-kernel@vger.kernel.org, kernel-team@lge.com, peterz@infradead.org Subject: Re: [PATCH] rcu: Report a quiescent state when it's exactly in the state Message-ID: <20180511132910.4e729a26@gandalf.local.home> In-Reply-To: <20180511172735.GB26088@linux.vnet.ibm.com> References: <1526027434-21237-1-git-send-email-byungchul.park@lge.com> <3af4cec0-4019-e3ac-77f9-8631252fb6da@lge.com> <20180511161746.GX26088@linux.vnet.ibm.com> <20180511122321.722a12cc@gandalf.local.home> <20180511122528.2a398d24@gandalf.local.home> <20180511122712.2d67992b@gandalf.local.home> <20180511172735.GB26088@linux.vnet.ibm.com> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 11 May 2018 10:27:35 -0700 "Paul E. McKenney" wrote: > On Fri, May 11, 2018 at 12:27:12PM -0400, Steven Rostedt wrote: > > On Fri, 11 May 2018 12:25:28 -0400 > > Steven Rostedt wrote: > > > > > I would also say that one should never call schedule() directly without > > > changing its state to something other than TASK_RUNNING. Hence, calling > > > schedule directly is saying you are ready to sleep. But that is not the > > > case with cond_resched() which should always be called with the state > > > as TASK_RUNNING. > > > > To continue this, with tracing, when a task is scheduled out in the > > RUNNING state, it is considered preempted, otherwise it is not. > > I suppose another option would be for cond_resched_tasks_rcu_qs() to set > (and later clear) a per-CPU variable that causes rcu_note_context_switch() > to ignore its "preempt" parameter. Byungchul's approach seems more > straightforward, though. I agree that I prefer Byungchul's approach better ;-) -- Steve