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Date:   Thu, 1 Oct 2020 18:12:30 +0100
From:   Vincent Donnefort <vincent.donnefort@arm.com>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     tglx@linutronix.de, mingo@kernel.org, linux-kernel@vger.kernel.org,
        bigeasy@linutronix.de, qais.yousef@arm.com, swood@redhat.com,
        valentin.schneider@arm.com, juri.lelli@redhat.com,
        vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
        rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
        bristot@redhat.com
Subject: Re: [PATCH 5/9] sched/hotplug: Consolidate task migration on CPU
 unplug
Message-ID: <20201001171138.GA299736@e120877-lin.cambridge.arm.com>
References: <20200921163557.234036895@infradead.org>
 <20200921163845.644634229@infradead.org>
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On Mon, Sep 21, 2020 at 06:36:02PM +0200, Peter Zijlstra wrote:

[...]

> +
> +     [CPUHP_AP_SCHED_WAIT_EMPTY] = {
> +             .name                   = "sched:waitempty",
> +             .startup.single         = NULL,
> +             .teardown.single        = sched_cpu_wait_empty,
> +     },
> +
>       /* Handle smpboot threads park/unpark */

Unless I missed something, now that the wait has its own HP step, this
patch can probably also get rid of the balance_hotplug_wait() in
sched_cpu_deactivate() introduced by: 

  [PATCH 4/9] sched/core: Wait for tasks being pushed away on hotplug

-- 
Vincent