Re: get_nohz_timer_target?

From: Thomas Gleixner
Date: Fri Jul 08 2016 - 12:51:14 EST


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@xxxxxxxxx>
> > > 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