From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752642AbaHXKHk (ORCPT ); Sun, 24 Aug 2014 06:07:40 -0400 Received: from mail-we0-f173.google.com ([74.125.82.173]:32947 "EHLO mail-we0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752392AbaHXKHj (ORCPT ); Sun, 24 Aug 2014 06:07:39 -0400 Date: Sun, 24 Aug 2014 12:07:34 +0200 From: Ingo Molnar To: Frederic Weisbecker Cc: LKML , Viresh Kumar , Thomas Gleixner , Preeti U Murthy Subject: Re: [GIT PULL] nohz: Fix double clock write on idle ticks Message-ID: <20140824100734.GA1309@gmail.com> References: <1408727373-8166-1-git-send-email-frederic@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1408727373-8166-1-git-send-email-frederic@kernel.org> 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 * Frederic Weisbecker wrote: > From: Frederic Weisbecker > > Ingo, > > Please pull the nohz/drop-double-write-v3 branch that can be found at: > > git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git > nohz/drop-double-write-v3 > > Although the 1st patch fixes a bug, it was a longstanding issue so > that branch doesn't need to be applied in 3.17. The next merge window > looks better. > > -- > The tick reschedules itself unconditionally. It's relevant in periodic > mode but not in dynticks mode where it results in spurious double clock > writes and even spurious periodic behaviour for low-res case. > > This set fixes that: > > * 1st patch removes low-res periodic tick rescheduling in nohz mode. > This fixes spurious periodic behaviour. > > * 2nd patch does the same for high-res mode. Here there is no such > spurious periodic behaviour but it still spares a double clock write > in some cases. > --- > > > Thanks, > Frederic > --- > > Viresh Kumar (2): > nohz: Fix spurious periodic tick behaviour in low-res dynticks mode > nohz: Avoid tick's double reprogramming in highres mode > > > kernel/time/tick-sched.c | 8 ++++++++ > 1 file changed, 8 insertions(+) These fixes are pretty small - any objections against putting it into timers/urgent and including it in v3.17? Thanks, Ingo