Re: [PATCH v3 4/6] cpufreq: Skip inefficient frequencies in cpufreq_driver_resolve_freq()

[Matthias Kaehlcke <mka@chromium.org>]

On Fri, Jun 04, 2021 at 12:05:59PM +0100, Vincent Donnefort wrote:
> Avoid using frequencies marked as inefficient. This change affects
> schedutil, which is the only in-tree governor using the function
> cpufreq_driver_resolve_freq().
> 
> Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com>
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 802abc9..7431f40a 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -546,6 +546,10 @@ unsigned int cpufreq_driver_resolve_freq(struct cpufreq_policy *policy,
>  
>  		idx = cpufreq_frequency_table_target(policy, target_freq,
>  						     CPUFREQ_RELATION_L);
> +
> +		/* Replace the target with an efficient one */
> +		idx = cpufreq_frequency_find_efficient(policy, idx);
> +
>  		policy->cached_resolved_idx = idx;
>  		return policy->freq_table[idx].frequency;
>  	}
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index d10784c..0ca4c9a 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -994,6 +994,17 @@ static inline int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
>  	}
>  }
>  
> +static inline unsigned int
> +cpufreq_frequency_find_efficient(struct cpufreq_policy *policy,
> +				 unsigned int idx)
> +{
> +	struct cpufreq_frequency_table *table = policy->freq_table;
> +	unsigned int efficient_idx = table[idx].efficient;
> +
> +	return table[efficient_idx].frequency <= policy->max ? efficient_idx :
> +							       idx;
> +}
> +
>  static inline int cpufreq_table_count_valid_entries(const struct cpufreq_policy *policy)
>  {
>  	struct cpufreq_frequency_table *pos;

Reviewed-by: Matthias Kaehlcke <mka@chromium.org>