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Date:   Tue, 18 May 2021 12:18:28 -0700
From:   Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
To:     Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc:     "Peter Zijlstra (Intel)" <peterz@infradead.org>,
        Ingo Molnar <mingo@kernel.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
        Len Brown <len.brown@intel.com>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Aubrey Li <aubrey.li@linux.intel.com>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        Ricardo Neri <ricardo.neri@intel.com>,
        Quentin Perret <qperret@google.com>,
        "Joel Fernandes (Google)" <joel@joelfernandes.org>,
        linux-kernel@vger.kernel.org, Aubrey Li <aubrey.li@intel.com>,
        Daniel Bristot de Oliveira <bristot@redhat.com>
Subject: Re: [PATCH v3 4/6] sched/fair: Carve out logic to mark a group for
 asymmetric packing
Message-ID: <20210518191828.GC15251@ranerica-svr.sc.intel.com>
References: <20210513154909.6385-1-ricardo.neri-calderon@linux.intel.com>
 <20210513154909.6385-5-ricardo.neri-calderon@linux.intel.com>
 <51599adc-d7e6-9d29-9c17-a49e0c2e315e@arm.com>
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On Mon, May 17, 2021 at 04:21:36PM +0200, Dietmar Eggemann wrote:
> On 13/05/2021 17:49, Ricardo Neri wrote:
> 
> [...]
> 
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index c8c04e9d0d3b..c8b66a5d593e 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -8447,6 +8447,20 @@ group_type group_classify(unsigned int imbalance_pct,
> >  	return group_has_spare;
> >  }
> >  
> > +static inline bool
> > +sched_asym(struct lb_env *env, struct sd_lb_stats *sds,  struct sg_lb_stats *sgs,
> > +	   struct sched_group *group)
> > +{
> > +	/*
> > +	 * Because sd->groups starts with the local group, anything that isn't
> > +	 * the local group will have access to the local state.
> > +	 */
> > +	if (group == sds->local)
> > +		return false;
> 
> sched_asym() is called under if(!local_group ...) from
> update_sg_lb_stats(). So why checking this here again?

This is true. It looks to me that this check is not needed. I makes
sense to me to keep the check in update_sg_lb_stats() so that we can
avoid the extra checks, right?

Thanks and BR,
Ricardo