linux-kernel - Re: [PATCH 1/7] sched: Add static_key for asymmetric cpu capacity optimizations

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Message-ID: <20180216134704.GE25201@hirez.programming.kicks-ass.net>
Date:   Fri, 16 Feb 2018 14:47:04 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Morten Rasmussen <morten.rasmussen@....com>
Cc:     mingo@...hat.com, valentin.schneider@....com,
        dietmar.eggemann@....com, vincent.guittot@...aro.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/7] sched: Add static_key for asymmetric cpu capacity
 optimizations

On Thu, Feb 15, 2018 at 04:20:48PM +0000, Morten Rasmussen wrote:
> +static void update_asym_cpucapacity(int cpu)
> +{
> +	if (!static_branch_unlikely(&sched_asym_cpucapacity) &&
> +	    lowest_flag_domain(cpu, SD_ASYM_CPUCAPACITY))
> +		static_branch_enable(&sched_asym_cpucapacity);
> +}

That looks odd, why not just:

	if (lowest_flag_domain(cpu, SD_ASYM_CPUCAPACITY))
		static_branch_enable(&sched_asym_cpucapacity);

? possibly with:

	else
		static_branch_disable(&sched_asym_cpucapacity);

if you want to play funny games :-)