linux-kernel - Re: [Patch v5 5/6] thermal/cpu-cooling: Update thermal pressure in case of a maximum frequency capping

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Date:   Wed, 6 Nov 2019 13:50:29 +0100
From:   Dietmar Eggemann <dietmar.eggemann@....com>
To:     Thara Gopinath <thara.gopinath@...aro.org>, mingo@...hat.com,
        peterz@...radead.org, ionela.voinescu@....com,
        vincent.guittot@...aro.org, rui.zhang@...el.com,
        edubezval@...il.com, qperret@...gle.com
Cc:     linux-kernel@...r.kernel.org, amit.kachhap@...il.com,
        javi.merino@...nel.org, daniel.lezcano@...aro.org
Subject: Re: [Patch v5 5/6] thermal/cpu-cooling: Update thermal pressure in
 case of a maximum frequency capping

On 05/11/2019 19:49, Thara Gopinath wrote:

[...]

> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
> index 391f397..c65b7c4 100644
> --- a/drivers/thermal/cpu_cooling.c
> +++ b/drivers/thermal/cpu_cooling.c
> @@ -218,6 +218,27 @@ static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_cdev,
>  }
>  
>  /**
> + * update_sched_max_capacity - update scheduler about change in cpu
> + *				max frequency.
> + * @cpus: list of cpus whose max capacity needs udating in scheduler.
> + * @cur_max_freq: current maximum frequency.
> + * @max_freq: highest possible frequency.
> + */
> +static void update_sched_max_capacity(struct cpumask *cpus,
> +				      unsigned int cur_max_freq,
> +				      unsigned int max_freq)
> +{
> +	int cpu;
> +	unsigned long capacity;
> +
> +	for_each_cpu(cpu, cpus) {
> +		capacity = cur_max_freq * arch_scale_cpu_capacity(cpu);
> +		capacity /= max_freq;
> +		update_thermal_pressure(cpu, capacity);
> +	}
> +}
> +
> +/**

Have you seen
https://lore.kernel.org/r/2b19d7da-412c-932f-7251-110eadbef3e3@arm.com ?

Also the naming 'update_thermal_pressure()' is not really suitable for
an external task scheduler interface. If I see this called in the
cooling device code, I wouldn't guess that this is a task scheduler
interface.

[...]