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Date:   Fri, 2 Oct 2020 16:20:28 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Dietmar Eggemann <dietmar.eggemann@arm.com>
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, rostedt@goodmis.org,
        bsegall@google.com, mgorman@suse.de, bristot@redhat.com,
        vincent.donnefort@arm.com
Subject: Re: [PATCH 3/9] sched/hotplug: Ensure only per-cpu kthreads run
 during hotplug
Message-ID: <20201002142028.GY2628@hirez.programming.kicks-ass.net>
References: <20200921163557.234036895@infradead.org>
 <20200921163845.520504267@infradead.org>
 <b357302d-4a8c-aa2e-f31d-4501fce890b6@arm.com>
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On Fri, Sep 25, 2020 at 06:38:50PM +0200, Dietmar Eggemann wrote:
> On 21/09/2020 18:36, Peter Zijlstra wrote:
> 
> [...]
> 
> > This replaces the unlikely(rq->balance_callbacks) test at the tail of
> > context_switch with an unlikely(rq->balance_work), the fast path is
> 
> While looking for why BALANCE_WORK is needed:
> 
> Shouldn't this be unlikely(rq->balance_callback) and
> unlikely(rq->balance_flags)?

But then we have two loads in the fastpath..