linux-kernel - Re: get_nohz_timer

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Message-ID: <alpine.DEB.2.11.1607081105260.4083@nanos>
Date:	Fri, 8 Jul 2016 11:05:58 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Richard Cochran <richardcochran@...il.com>
cc:	vatikaharlalka@...il.com, Frederic Weisbecker <fweisbec@...il.com>,
	Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: get_nohz_timer_target?

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@...il.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?

Thanks,

	tglx