From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754832Ab3FMNLG (ORCPT ); Thu, 13 Jun 2013 09:11:06 -0400 Received: from mail-wi0-f180.google.com ([209.85.212.180]:60981 "EHLO mail-wi0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751139Ab3FMNLE (ORCPT ); Thu, 13 Jun 2013 09:11:04 -0400 Date: Thu, 13 Jun 2013 15:10:59 +0200 From: Frederic Weisbecker To: Don Zickus Cc: LKML , Steven Rostedt , "Paul E. McKenney" , Ingo Molnar , Andrew Morton , Thomas Gleixner , Peter Zijlstra , Li Zhong , "Srivatsa S. Bhat" , Anish Singh Subject: Re: [PATCH 4/6] watchdog: Boot-disable by default on full dynticks Message-ID: <20130613131057.GA15997@somewhere> References: <1371045758-5296-1-git-send-email-fweisbec@gmail.com> <1371045758-5296-5-git-send-email-fweisbec@gmail.com> <20130612170316.GO133453@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130612170316.GO133453@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 12, 2013 at 01:03:16PM -0400, Don Zickus wrote: > On Wed, Jun 12, 2013 at 04:02:36PM +0200, Frederic Weisbecker wrote: > > When the watchdog runs, it prevents the full dynticks > > CPUs from stopping their tick because the hard lockup > > detector uses perf events internally, which in turn > > rely on the periodic tick. > > > > Since this is a rather confusing behaviour that is not > > easy to track down and identify for those who want to > > test CONFIG_NO_HZ_FULL, let's default disable the > > watchdog on boot time when full dynticks is enabled. > > > > The user can still enable it later on runtime using > > proc or sysctl. > > I thought we had a conversation awhile ago, where we agreed this was going > to be fixed for 3.11? Didn't Peter find the patch and apply it to his > tree? I am confused why this is still needed? We agreed on the patch but it hasn't been applied yet. I'm trying to get a sane series of nohz patches before sending to Ingo. Thanks.