From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751618AbaHIMou (ORCPT ); Sat, 9 Aug 2014 08:44:50 -0400 Received: from cdptpa-outbound-snat.email.rr.com ([107.14.166.227]:49734 "EHLO cdptpa-oedge-vip.email.rr.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751023AbaHIMot (ORCPT ); Sat, 9 Aug 2014 08:44:49 -0400 Date: Sat, 9 Aug 2014 08:44:39 -0400 From: Steven Rostedt To: Peter Zijlstra Cc: "Paul E. McKenney" , 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 v3 tip/core/rcu 1/9] rcu: Add call_rcu_tasks() Message-ID: <20140809084439.05778e33@gandalf.local.home> In-Reply-To: <20140809061514.GK9918@twins.programming.kicks-ass.net> References: <20140731215445.GA21933@linux.vnet.ibm.com> <1406843709-23396-1-git-send-email-paulmck@linux.vnet.ibm.com> <20140808191326.GE3935@laptop> <20140808205826.GG5821@linux.vnet.ibm.com> <20140809061514.GK9918@twins.programming.kicks-ass.net> X-Mailer: Claws Mail 3.10.1 (GTK+ 2.24.24; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-RR-Connecting-IP: 107.14.168.142:25 X-Cloudmark-Score: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 9 Aug 2014 08:15:14 +0200 Peter Zijlstra wrote: > As for idle tasks, I'm not sure about those, I think that we should say > NO to anything that would require waking idle CPUs, push the pain to > ftrace/kprobes, we should _not_ be waking idle cpus. I agree, but I haven't had a chance to review the patch set (will probably do that on Monday, just got back from vacation last week and was inundated by other things). Does the idle waking happen only when there's something queued in the call_rcu_tasks()? It should definitely not be waking all the time. That's just wrong. But if it only wakes when something is queued, it wouldn't be burdening anything, unless it is needed. -- Steve