Re: [tip: sched/core] x86, sched: Add support for frequency invariance

[Valentin Schneider]

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.