linux-kernel - Re: [PATCH] sched: Do not zero sg->cpumask and sg->sgp->power in build_sched

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Message-ID: <20140513103244.GY30445@twins.programming.kicks-ass.net>
Date:	Tue, 13 May 2014 12:32:44 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Dietmar Eggemann <dietmar.eggemann@....com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] sched: Do not zero sg->cpumask and sg->sgp->power in
 build_sched_groups

On Tue, May 13, 2014 at 09:32:53AM +0100, Dietmar Eggemann wrote:
> Hi Peter,
> 
> On 30/04/14 14:39, Dietmar Eggemann wrote:
> > From: Dietmar Eggemann <Dietmar.Eggemann@....com>
> > 
> > There is no need to zero struct sched_group member cpumask and struct
> > sched_group_power member power since both structures are already allocated
> > as zeroed memory in __sdt_alloc().
> > 
> > This patch has been tested with
> > BUG_ON(!cpumask_empty(sched_group_cpus(sg))); and BUG_ON(sg->sgp->power);
> > in build_sched_groups() on ARM TC2 and INTEL i5 M520 platform including
> > CPU hotplug scenarios.
> > 
> > Signed-off-by: Dietmar Eggemann <dietmar.eggemann@....com>
> > ---
> >  kernel/sched/core.c |    2 --
> >  1 file changed, 2 deletions(-)
> > 
> > diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> > index 9cae286824bb..6bc51aebbf1b 100644
> > --- a/kernel/sched/core.c
> > +++ b/kernel/sched/core.c
> > @@ -5807,8 +5807,6 @@ build_sched_groups(struct sched_domain *sd, int cpu)
> >  			continue;
> >  
> >  		group = get_group(i, sdd, &sg);
> > -		cpumask_clear(sched_group_cpus(sg));
> > -		sg->sgp->power = 0;
> >  		cpumask_setall(sched_group_mask(sg));
> >  
> >  		for_each_cpu(j, span) {
> > 
> 
> I think this one slipped through the cracks. Could you have a look?

Yeah, got stuck in the backlog :/

Seems simple enough, queued it, we'll see if anything explodes ;-)

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