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Date: Fri, 8 Jul 2016 18:48:49 +0200 (CEST)
From: Thomas Gleixner <tglx@linutronix.de>
To: Frederic Weisbecker <fweisbec@gmail.com>
cc: Richard Cochran <richardcochran@gmail.com>, vatikaharlalka@gmail.com,
        Preeti U Murthy <preeti@linux.vnet.ibm.com>,
        Ingo Molnar <mingo@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <peterz@infradead.org>, stable@vger.kernel.org
Subject: Re: get_nohz_timer_target?
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On Fri, 8 Jul 2016, Frederic Weisbecker wrote:
> On Fri, Jul 08, 2016 at 11:05:58AM +0200, Thomas Gleixner wrote:
> > On Mon, 18 Apr 2016, Richard Cochran wrote:
> > > Looking at kernel/sched/core.c:get_nohz_timer_target(), I don't
> > > understand the change made in:
> > > 
> > >     commit 9642d18eee2cd169b60c6ac0f20bda745b5a3d1e
> > >     Author: Vatika Harlalka <vatikaharlalka@gmail.com>
> > >     Date:   Tue Sep 1 16:50:59 2015 +0200
> > >     nohz: Affine unpinned timers to housekeepers
> > > 
> > > After that change, the code now reads like this:
> > > 
> > > 	int i, cpu = smp_processor_id();
> > > 	struct sched_domain *sd;
> > > 
> > > 	if (!idle_cpu(cpu) && is_housekeeping_cpu(cpu))
> > > 		return cpu;
> > > 
> > > 	rcu_read_lock();
> > > 	for_each_domain(cpu, sd) {
> > > 		for_each_cpu(i, sched_domain_span(sd)) {
> > > 			if (!idle_cpu(i) && is_housekeeping_cpu(cpu)) {
> > > --------------------------------------------------------------- ^^^
> > > Was this supposed to be 'i' instead?
> > 
> > Yes. Care to send a patch?
> 
> Ah this got fixed already: 444969223c81c7d0a95136b7b4cfdcfbc96ac5bd
> ("sched/nohz: Fix affine unpinned timers mess")

Good. Though that patch misses a stable tag.

Thanks,

	tglx