linux-kernel - Re: [PATCH v2 3/6] cpufreq: use the fixed and coherent frequency for scaling capacity

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Message-ID: <20231009110111.tdehkpammwyigzia@vireshk-i7>
Date:   Mon, 9 Oct 2023 16:31:11 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     linux@...linux.org.uk, catalin.marinas@....com, will@...nel.org,
        paul.walmsley@...ive.com, palmer@...belt.com,
        aou@...s.berkeley.edu, sudeep.holla@....com,
        gregkh@...uxfoundation.org, rafael@...nel.org, mingo@...hat.com,
        peterz@...radead.org, juri.lelli@...hat.com,
        dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
        mgorman@...e.de, bristot@...hat.com, vschneid@...hat.com,
        lukasz.luba@....com, ionela.voinescu@....com,
        pierre.gondois@....com, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-pm@...r.kernel.org, conor.dooley@...rochip.com,
        suagrfillet@...il.com, ajones@...tanamicro.com, lftan@...nel.org
Subject: Re: [PATCH v2 3/6] cpufreq: use the fixed and coherent frequency for
 scaling capacity

On 09-10-23, 12:36, Vincent Guittot wrote:
> cpuinfo.max_freq can change at runtime because of boost as an example. This
> implies that the value could be different from the frequency that has been
> used to compute the capacity of a CPU.
> 
> The new arch_scale_freq_ref() returns a fixed and coherent frequency
> that can be used to compute the capacity for a given frequency.
> 
> Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
> ---
>  drivers/cpufreq/cpufreq.c | 4 ++--
>  include/linux/cpufreq.h   | 9 +++++++++
>  2 files changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 60ed89000e82..8c4f9c2f9c44 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -454,7 +454,7 @@ void cpufreq_freq_transition_end(struct cpufreq_policy *policy,
>  
>  	arch_set_freq_scale(policy->related_cpus,
>  			    policy->cur,
> -			    policy->cpuinfo.max_freq);
> +			    arch_scale_freq_ref(policy->cpu));
>  
>  	spin_lock(&policy->transition_lock);
>  	policy->transition_ongoing = false;
> @@ -2174,7 +2174,7 @@ unsigned int cpufreq_driver_fast_switch(struct cpufreq_policy *policy,
>  
>  	policy->cur = freq;
>  	arch_set_freq_scale(policy->related_cpus, freq,
> -			    policy->cpuinfo.max_freq);
> +			    arch_scale_freq_ref(policy->cpu));
>  	cpufreq_stats_record_transition(policy, freq);
>  
>  	if (trace_cpu_frequency_enabled()) {
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index 71d186d6933a..bbc483b4b6e5 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -1211,6 +1211,15 @@ void arch_set_freq_scale(const struct cpumask *cpus,
>  {
>  }
>  #endif
> +
> +#ifndef arch_scale_freq_ref
> +static __always_inline
> +unsigned int arch_scale_freq_ref(int cpu)
> +{
> +	return 0;
> +}
> +#endif
> +
>  /* the following are really really optional */
>  extern struct freq_attr cpufreq_freq_attr_scaling_available_freqs;
>  extern struct freq_attr cpufreq_freq_attr_scaling_boost_freqs;

Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

-- 
viresh