linux-kernel - Re: [PATCH 3/4] cpufreq/schedutil: use a fixed reference frequency

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Message-ID: <20230905112455.GD28319@noisy.programming.kicks-ass.net>
Date:   Tue, 5 Sep 2023 13:24:55 +0200
From:   Peter Zijlstra <peterz@...radead.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,
        juri.lelli@...hat.com, dietmar.eggemann@....com,
        rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
        bristot@...hat.com, vschneid@...hat.com, viresh.kumar@...aro.org,
        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 3/4] cpufreq/schedutil: use a fixed reference frequency

On Fri, Sep 01, 2023 at 03:03:11PM +0200, Vincent Guittot wrote:

> +#ifdef arch_scale_freq_ref
> +/**
> + * arch_scale_freq_ref_policy - get the reference frequency of a given CPU that
> + * has been used to correlate frequency and compute capacity.
> + * @cpu: the CPU in question.
> + *
> + * Return: the reference CPU frequency.
> + */
> +static __always_inline
> +unsigned long  arch_scale_freq_ref_policy(struct cpufreq_policy *policy)
> +{
> +	return arch_scale_freq_ref(policy->cpu);
> +}
> +#else
> +static __always_inline
> +unsigned long  arch_scale_freq_ref_policy(struct cpufreq_policy *policy)

double space    ^^

> +{
> +	if (arch_scale_freq_invariant())
> +		return policy->cpuinfo.max_freq;
> +
> +

superfluous whitespace there.

> +	return policy->cur;
> +}
> +#endif

static __always_inline
unsigned long arch_scale_freq_ref_policy(struct cpufreq_policy *policy)
{
#ifdef arch_scale_freq_ref
	return arch_scale_freq_ref(policy->cpu);
#endif

	if (arch_scale_freq_invariant())
		return policy->cpuinfo.max_freq;

	return policy->cur;
}

Would have the lot in a single function and possibly easier to read?

> +
>  /**
>   * get_next_freq - Compute a new frequency for a given cpufreq policy.
>   * @sg_policy: schedutil policy object to compute the new frequency for.
> @@ -139,11 +164,11 @@ static void sugov_deferred_update(struct sugov_policy *sg_policy)
>  static unsigned int get_next_freq(struct sugov_policy *sg_policy,
>  				  unsigned long util, unsigned long max)
>  {
> +	unsigned int freq;
>  	struct cpufreq_policy *policy = sg_policy->policy;
> -	unsigned int freq = arch_scale_freq_invariant() ?
> -				policy->cpuinfo.max_freq : policy->cur;

Leave the variable below per the inverse christmas thing.

>  
>  	util = map_util_perf(util);
> +	freq = arch_scale_freq_ref_policy(policy);
>  	freq = map_util_freq(util, freq, max);
>  
>  	if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)
> -- 
> 2.34.1
>