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Subject: Re: [PATCH 3/5] sched/fair: rework load_balance
To:     Vincent Guittot <vincent.guittot@linaro.org>
Cc:     linux-kernel <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Quentin Perret <quentin.perret@arm.com>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Morten Rasmussen <Morten.Rasmussen@arm.com>,
        Phil Auld <pauld@redhat.com>
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From:   Valentin Schneider <valentin.schneider@arm.com>
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Date:   Mon, 29 Jul 2019 15:28:45 +0100
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On 26/07/2019 15:47, Vincent Guittot wrote:
[...]
>> If CPU0 runs the load balancer, balancing utilization would mean pulling
>> 2 tasks from CPU1 to reach the domain-average of 40%. The good side of this
>> is that we could save ourselves from running some newidle balances, but
>> I'll admit that's all quite "finger in the air".
> 
> Don't forget that scheduler also selects a cpu when task wakeup and
> should cope with such situation
> 

Right, although I'm not sure even the slow wakeup path is any good at
balancing utilization.

>>
>>>> happen, but it'd be a shame to repeatedly do this when we could
>>>> preemptively balance utilization.
>>>>