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From:   Valentin Schneider <valentin.schneider@arm.com>
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Chris Wilson <chris@chris-wilson.co.uk>,
        linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org,
        tip-bot2 for Giovanni Gherdovich <tip-bot2@linutronix.de>,
        Giovanni Gherdovich <ggherdovich@suse.cz>,
        Ingo Molnar <mingo@kernel.org>,
        Doug Smythies <dsmythies@telus.net>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        x86 <x86@kernel.org>
Subject: Re: [tip: sched/core] x86, sched: Add support for frequency invariance
In-reply-to: <20200330125219.GM20696@hirez.programming.kicks-ass.net>
Date:   Mon, 30 Mar 2020 17:03:04 +0100
Message-ID: <jhjimil25l3.mognet@arm.com>
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Sender: linux-kernel-owner@vger.kernel.org
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On Mon, Mar 30 2020, Peter Zijlstra wrote:
> +static void init_freq_invariance(bool secondary)
>  {
>  	bool ret = false;
>  
> -	if (smp_processor_id() != 0 || !boot_cpu_has(X86_FEATURE_APERFMPERF))
> +	if (!boot_cpu_has(X86_FEATURE_APERFMPERF))
>  		return;
>  
> +	if (secondary) {
> +		if (static_branch_likely(&arch_scale_freq_key)) {
> +			init_counter_refs(NULL);
> +		}
> +		return;
> +	}
> +

Oh doh, that's an "enable once and for all" thing. That makes much more
sense; sorry for the noise.