From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f45.google.com (mail-pa0-f45.google.com [209.85.220.45]) by kanga.kvack.org (Postfix) with ESMTP id 602D96B0038 for ; Tue, 29 Jul 2014 11:44:37 -0400 (EDT) Received: by mail-pa0-f45.google.com with SMTP id eu11so12527866pac.18 for ; Tue, 29 Jul 2014 08:44:37 -0700 (PDT) Received: from aserp1040.oracle.com (aserp1040.oracle.com. [141.146.126.69]) by mx.google.com with ESMTPS id go10si21456244pbd.184.2014.07.29.08.44.36 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Tue, 29 Jul 2014 08:44:36 -0700 (PDT) Message-ID: <53D7C11D.8050905@oracle.com> Date: Tue, 29 Jul 2014 11:43:25 -0400 From: Sasha Levin MIME-Version: 1.0 Subject: Re: vmstat: On demand vmstat workers V8 References: <53D31101.8000107@oracle.com> <20140729075637.GA19379@twins.programming.kicks-ass.net> <20140729120525.GA28366@mtj.dyndns.org> <20140729122303.GA3935@laptop> <20140729131226.GS7462@htj.dyndns.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter , Tejun Heo Cc: Peter Zijlstra , akpm@linux-foundation.org, Gilad Ben-Yossef , Thomas Gleixner , John Stultz , Mike Frysinger , Minchan Kim , Hakan Akkan , Max Krasnyansky , Frederic Weisbecker , "Paul E. McKenney" , linux-kernel@vger.kernel.org, linux-mm@kvack.org, hughd@google.com, viresh.kumar@linaro.org, hpa@zytor.com, mingo@kernel.org, Lai Jiangshan On 07/29/2014 11:22 AM, Christoph Lameter wrote: > On Tue, 29 Jul 2014, Tejun Heo wrote: > >> I'm not sure that's a viable way forward. It's not like we can >> readily trigger the problematic cases which can lead to long pauses >> during cpu down. Besides, we need the distinction at the API level, >> which is the whole point of this. The best way probably is converting >> all the correctness ones (these are the minorities) over to >> queue_work_on() so that the per-cpu requirement is explicit. > > Ok so we would need this fix to avoid the message: > > > Subject: vmstat: use schedule_delayed_work_on to avoid false positives > > It seems that schedule_delayed_work_on will check for preemption even > though none can occur. schedule_delayed_work_on will not do that. So > use that function to suppress false positives. > > Signed-off-by: Christoph Lameter > > Index: linux/mm/vmstat.c > =================================================================== > --- linux.orig/mm/vmstat.c 2014-07-29 10:14:42.356988271 -0500 > +++ linux/mm/vmstat.c 2014-07-29 10:18:28.205920997 -0500 > @@ -1255,7 +1255,8 @@ static void vmstat_update(struct work_st > * to occur in the future. Keep on running the > * update worker thread. > */ > - schedule_delayed_work(this_cpu_ptr(&vmstat_work), > + schedule_delayed_work_on(smp_processor_id(), > + this_cpu_ptr(&vmstat_work), > round_jiffies_relative(sysctl_stat_interval)); > else { > /* > I've tested, and this patch doesn't fix neither of the bugs reported. Thanks, Sasha -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org