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Date:   Mon, 6 Jan 2020 11:23:41 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Peng Liu <iwtbavbm@gmail.com>
Cc:     linux-kernel@vger.kernel.org, mingo@redhat.com,
        juri.lelli@redhat.com, vincent.guittot@linaro.org,
        dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com,
        mgorman@suse.de, qais.yousef@arm.com, morten.rasmussen@arm.com,
        valentin.schneider@arm.com
Subject: Re: [PATCH v2] sched/fair: fix sgc->{min,max}_capacity miscalculate
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On Sat, Jan 04, 2020 at 09:08:28PM +0800, Peng Liu wrote:
> commit bf475ce0a3dd ("sched/fair: Add per-CPU min capacity to
> sched_group_capacity") introduced per-cpu min_capacity.
> 
> commit e3d6d0cb66f2 ("sched/fair: Add sched_group per-CPU max capacity")
> introduced per-cpu max_capacity.
> 
> Here, capacity is the accumulated sum of (maybe) many CPUs' capacity.
> Compare with capacity to get {min,max}_capacity makes no sense. Instead,
> we should compare one by one in each iteration to get
> sgc->{min,max}_capacity of the group.
> 
> Also, the only CPU in rq->sd->groups should be rq's CPU. Thus,
> capacity_of(cpu_of(rq)) should be equal to rq->sd->groups->sgc->capacity.
> Code can be simplified by removing the if/else.
> 
> Signed-off-by: Peng Liu <iwtbavbm@gmail.com>
> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
> ---
> v1: https://lkml.org/lkml/2019/12/30/502

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