Re: [PATCH v1 2/2] cpufreq: ACPI: Update arch scale-invariance max perf ratio if CPPC is not there

[Peter Zijlstra <peterz@infradead.org>]

On Thu, Feb 04, 2021 at 06:34:32PM +0100, Rafael J. Wysocki wrote:

>  arch/x86/kernel/smpboot.c      |    1 +
>  drivers/cpufreq/acpi-cpufreq.c |    8 ++++++++
>  2 files changed, 9 insertions(+)
> 
> Index: linux-pm/drivers/cpufreq/acpi-cpufreq.c
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/acpi-cpufreq.c
> +++ linux-pm/drivers/cpufreq/acpi-cpufreq.c
> @@ -806,6 +806,14 @@ static int acpi_cpufreq_cpu_init(struct
>  		state_count++;
>  		valid_states++;
>  		data->first_perf_state = valid_states;
> +	} else {
> +		/*
> +		 * If the maximum "boost" frequency is unknown, ask the arch
> +		 * scale-invariance code to use the "nominal" performance for
> +		 * CPU utilization scaling so as to prevent the schedutil
> +		 * governor from selecting inadequate CPU frequencies.
> +		 */
> +		arch_set_max_freq_ratio(true);
>  	}
>  
>  	freq_table = kcalloc(state_count, sizeof(*freq_table), GFP_KERNEL);
> Index: linux-pm/arch/x86/kernel/smpboot.c
> ===================================================================
> --- linux-pm.orig/arch/x86/kernel/smpboot.c
> +++ linux-pm/arch/x86/kernel/smpboot.c
> @@ -1833,6 +1833,7 @@ void arch_set_max_freq_ratio(bool turbo_
>  	arch_max_freq_ratio = turbo_disabled ? SCHED_CAPACITY_SCALE :
>  					arch_turbo_freq_ratio;
>  }
> +EXPORT_SYMBOL_GPL(arch_set_max_freq_ratio);

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>