Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756856AbdGLLzN (ORCPT ); Wed, 12 Jul 2017 07:55:13 -0400 Received: from merlin.infradead.org ([205.233.59.134]:32864 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756235AbdGLLzI (ORCPT ); Wed, 12 Jul 2017 07:55:08 -0400 Date: Wed, 12 Jul 2017 13:54:51 +0200 From: Peter Zijlstra To: "Paul E. McKenney" Cc: Frederic Weisbecker , Christoph Lameter , "Li, Aubrey" , Andi Kleen , Aubrey Li , tglx@linutronix.de, len.brown@intel.com, rjw@rjwysocki.net, tim.c.chen@linux.intel.com, arjan@linux.intel.com, yang.zhang.wz@gmail.com, x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods Message-ID: <20170712115451.xxz3jkau7ape76n5@hirez.programming.kicks-ass.net> References: <1499650721-5928-1-git-send-email-aubrey.li@intel.com> <20170710084647.zs6wkl3fumszd33g@hirez.programming.kicks-ass.net> <20170710144609.GD31832@tassilo.jf.intel.com> <20170710164206.5aon5kelbisxqyxq@hirez.programming.kicks-ass.net> <20170710172705.GA3441@tassilo.jf.intel.com> <20170711094157.5xcwkloxnjehieqv@hirez.programming.kicks-ass.net> <20170711160926.GA18805@lerouge> <20170711163422.etydkhhtgfthpfi5@hirez.programming.kicks-ass.net> <20170711180931.GP2393@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170711180931.GP2393@linux.vnet.ibm.com> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1077 Lines: 40 On Tue, Jul 11, 2017 at 11:09:31AM -0700, Paul E. McKenney wrote: > On Tue, Jul 11, 2017 at 06:34:22PM +0200, Peter Zijlstra wrote: > > But I think we can at the very least do this; it only gets called from > > kernel/sched/idle.c and both callsites have IRQs explicitly disabled by > > that point. > > > > > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > > index 51d4c3acf32d..dccf2dc8155a 100644 > > --- a/kernel/rcu/tree.c > > +++ b/kernel/rcu/tree.c > > @@ -843,13 +843,8 @@ static void rcu_eqs_enter(bool user) > > */ > > void rcu_idle_enter(void) > > { > > - unsigned long flags; > > - > > - local_irq_save(flags); > > With this addition, I am all for it: > > RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_idle_enter() invoked with irqs enabled!!!"); > > If you are OK with this addition, may I please have your Signed-off-by? Sure, Signed-off-by: Peter Zijlstra (Intel) > > > rcu_eqs_enter(false); > > - local_irq_restore(flags); > > } > > -EXPORT_SYMBOL_GPL(rcu_idle_enter); > > > > #ifdef CONFIG_NO_HZ_FULL > > /** > > >