linux-kernel - Re: [RFC PATCH v3 2/6] sched/cpufreq: Attach perf domain to sugov policy

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Date:   Thu, 17 Oct 2019 10:57:16 +0200
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Douglas RAILLARD <douglas.raillard@....com>,
        linux-kernel@...r.kernel.org
Cc:     linux-pm@...r.kernel.org, mingo@...hat.com, peterz@...radead.org,
        rjw@...ysocki.net, viresh.kumar@...aro.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, qperret@...rret.net,
        patrick.bellasi@...bug.net, dh.han@...sung.com
Subject: Re: [RFC PATCH v3 2/6] sched/cpufreq: Attach perf domain to sugov
 policy

On 11/10/2019 15:44, Douglas RAILLARD wrote:

[...]

> @@ -66,6 +70,38 @@ static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
>  
>  /************************ Governor internals ***********************/
>  
> +#ifdef CONFIG_ENERGY_MODEL
> +static void sugov_policy_attach_pd(struct sugov_policy *sg_policy)
> +{
> +	struct em_perf_domain *pd;
> +	struct cpufreq_policy *policy = sg_policy->policy;

Shouldn't always order local variable declarations from longest to
shortest line?

> +
> +	sg_policy->pd = NULL;
> +	pd = em_cpu_get(policy->cpu);
> +	if (!pd)
> +		return;
> +
> +	if (cpumask_equal(policy->related_cpus, to_cpumask(pd->cpus)))
> +		sg_policy->pd = pd;
> +	else
> +		pr_warn("%s: Not all CPUs in schedutil policy %u share the same perf domain, no perf domain for that policy will be registered\n",
> +			__func__, policy->cpu);

Maybe {} because of 2 lines?

> +}
> +
> +static struct em_perf_domain *sugov_policy_get_pd(
> +						struct sugov_policy *sg_policy)


Maybe this way? This format is already used in this file.

static struct em_perf_domain *
sugov_policy_get_pd(struct sugov_policy *sg_policy)


> +{
> +	return sg_policy->pd;
> +}
> +#else /* CONFIG_ENERGY_MODEL */
> +static void sugov_policy_attach_pd(struct sugov_policy *sg_policy) {}
> +static struct em_perf_domain *sugov_policy_get_pd(
> +						struct sugov_policy *sg_policy)
> +{
> +	return NULL;
> +}
> +#endif /* CONFIG_ENERGY_MODEL */
> +
>  static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
>  {
>  	s64 delta_ns;
> @@ -859,6 +895,9 @@ static int sugov_start(struct cpufreq_policy *policy)
>  							sugov_update_shared :
>  							sugov_update_single);
>  	}
> +
> +	sugov_policy_attach_pd(sg_policy);
> +
>  	return 0;
>  }

A sugov_policy_detach_pd() called from sugov_stop() (doing for instance
the g_policy->pd = NULL) is not needed?