Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754412AbaG2WEu (ORCPT ); Tue, 29 Jul 2014 18:04:50 -0400 Received: from mail-wg0-f50.google.com ([74.125.82.50]:40205 "EHLO mail-wg0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754240AbaG2WEt (ORCPT ); Tue, 29 Jul 2014 18:04:49 -0400 Date: Wed, 30 Jul 2014 00:04:45 +0200 From: Frederic Weisbecker To: Peter Zijlstra Cc: LKML , Ingo Molnar , Nicolas Pitre , "Paul E. McKenney" , Steven Rostedt , Thomas Gleixner , Viresh Kumar Subject: Re: [PATCH 09/10] nohz: Switch nohz full timekeeper to dynticks idle on top of sysidle detection Message-ID: <20140729220443.GD14520@localhost.localdomain> References: <1406569056-30217-1-git-send-email-fweisbec@gmail.com> <1406569056-30217-10-git-send-email-fweisbec@gmail.com> <20140729121753.GZ3935@laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140729121753.GZ3935@laptop> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 29, 2014 at 02:17:53PM +0200, Peter Zijlstra wrote: > On Mon, Jul 28, 2014 at 07:37:35PM +0200, Frederic Weisbecker wrote: > > > @@ -745,7 +747,7 @@ static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) > > * if there are full dynticks CPUs around > > */ > > if (tick_do_timer_cpu == cpu) > > - return false; > > + return rcu_sys_is_idle(); > > } > > I still feel its entirely upside down to rely on RCU for this... RCU had this feature internally for a while. Then comes nohz. I guess in a perfect world we would make it a library that RCU and nohz could use. It's probably possible to do but right now it is too tied to RCU internals. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/