From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755111AbbJGQOz (ORCPT ); Wed, 7 Oct 2015 12:14:55 -0400 Received: from e37.co.us.ibm.com ([32.97.110.158]:49471 "EHLO e37.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754783AbbJGQOy (ORCPT ); Wed, 7 Oct 2015 12:14:54 -0400 X-IBM-Helo: d03dlp03.boulder.ibm.com X-IBM-MailFrom: paulmck@linux.vnet.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org Date: Wed, 7 Oct 2015 09:14:45 -0700 From: "Paul E. McKenney" To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com Subject: Re: [PATCH tip/core/rcu 04/18] rcu: Use single-stage IPI algorithm for RCU expedited grace period Message-ID: <20151007161445.GN3910@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20151006162907.GA12020@linux.vnet.ibm.com> <1444148977-14108-1-git-send-email-paulmck@linux.vnet.ibm.com> <1444148977-14108-4-git-send-email-paulmck@linux.vnet.ibm.com> <20151007134311.GC3604@twins.programming.kicks-ass.net> <20151007134929.GM11639@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151007134929.GM11639@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: 15100716-0025-0000-0000-00001DB49706 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 07, 2015 at 03:49:29PM +0200, Peter Zijlstra wrote: > On Wed, Oct 07, 2015 at 03:43:11PM +0200, Peter Zijlstra wrote: > > On Tue, Oct 06, 2015 at 09:29:23AM -0700, Paul E. McKenney wrote: > > > @@ -167,42 +307,18 @@ static void rcu_preempt_note_context_switch(void) > > > > > - raw_spin_unlock_irqrestore(&rnp->lock, flags); > > > > This again reminds me that we should move rcu_note_context_switch() > > under the IRQ disable section the scheduler already has or remove the > > IRQ disable from rcu_note_context_switch(). > > Ah, this is the unlikely path where we actually need to do work. The > normal fast paths no longer require IRQs disabled, you already fixed > that last time, good! But why not make the less-likely paths a bit cheaper while we are at it? ;-) Thanx, Paul