Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757405Ab3GWMeE (ORCPT ); Tue, 23 Jul 2013 08:34:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:22123 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757117Ab3GWMeC (ORCPT ); Tue, 23 Jul 2013 08:34:02 -0400 Date: Tue, 23 Jul 2013 08:33:31 -0400 From: Don Zickus To: Frederic Weisbecker Cc: Peter Zijlstra , LKML , Jiri Olsa , Namhyung Kim , Ingo Molnar , Arnaldo Carvalho de Melo , Stephane Eranian , "Srivatsa S. Bhat" , Anish Singh Subject: Re: [PATCH 8/8] watchdog: Remove hack to make full dynticks working Message-ID: <20130723123331.GE126784@redhat.com> References: <1374539466-4799-1-git-send-email-fweisbec@gmail.com> <1374539466-4799-9-git-send-email-fweisbec@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1374539466-4799-9-git-send-email-fweisbec@gmail.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 Content-Length: 2130 Lines: 59 On Tue, Jul 23, 2013 at 02:31:06AM +0200, Frederic Weisbecker wrote: > A perf event can be used without forcing the tick to > stay alive if it doesn't use a frequency but a sample > period and if it doesn't throttle (raise storm of events). > > Since the lockup detector neither use a perf event frequency > nor should ever throttle due to its high period, it can now > run concurrently with the full dynticks feature. Thanks. Dumb question, I keep wondering if the lockup detector would be better or worse off if it used the perf event frequency as opposed to using a sample period? The idea is it could follow the varying cpu frequencies better (and probably simplify some of the code too). Acked-by: Don Zickus > > Signed-off-by: Frederic Weisbecker > Cc: Jiri Olsa > Cc: Peter Zijlstra > Cc: Namhyung Kim > Cc: Ingo Molnar > Cc: Arnaldo Carvalho de Melo > Cc: Stephane Eranian > Cc: Don Zickus > Cc: Srivatsa S. Bhat > Cc: Anish Singh > --- > kernel/watchdog.c | 8 -------- > 1 files changed, 0 insertions(+), 8 deletions(-) > > diff --git a/kernel/watchdog.c b/kernel/watchdog.c > index 1241d8c..51c4f34 100644 > --- a/kernel/watchdog.c > +++ b/kernel/watchdog.c > @@ -553,14 +553,6 @@ void __init lockup_detector_init(void) > { > set_sample_period(); > > -#ifdef CONFIG_NO_HZ_FULL > - if (watchdog_user_enabled) { > - watchdog_user_enabled = 0; > - pr_warning("Disabled lockup detectors by default for full dynticks\n"); > - pr_warning("You can reactivate it with 'sysctl -w kernel.watchdog=1'\n"); > - } > -#endif > - > if (watchdog_user_enabled) > watchdog_enable_all_cpus(); > } > -- > 1.7.5.4 > -- 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/