Re: [PATCH v3 3/4] sched: scheduler-driven cpu frequency selection

[Dietmar Eggemann <dietmar.eggemann@arm.com>]

Hi Mike,

On 27/06/15 00:53, Michael Turquette wrote:
> From: Michael Turquette <mturquette@baylibre.com>
> 

[...]

>  comment "CPU frequency scaling drivers"
> 
>  config CPUFREQ_DT
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index 1f2c9a1..30241c9 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -494,6 +494,9 @@ extern struct cpufreq_governor cpufreq_gov_ondemand;
>  #elif defined(CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE)
>  extern struct cpufreq_governor cpufreq_gov_conservative;
>  #define CPUFREQ_DEFAULT_GOVERNOR       (&cpufreq_gov_conservative)
> +#elif defined(CONFIG_CPU_FREQ_DEFAULT_GOV_SCHED_GOV)
> +extern struct cpufreq_governor cpufreq_gov_sched_gov;

To get it building with CONFIG_CPU_FREQ_DEFAULT_GOV_SCHED=y .

-#elif defined(CONFIG_CPU_FREQ_DEFAULT_GOV_SCHED_GOV)
-extern struct cpufreq_governor cpufreq_gov_sched_gov;
+#elif defined(CONFIG_CPU_FREQ_DEFAULT_GOV_SCHED)
+extern struct cpufreq_governor cpufreq_gov_sched;

> +#define CPUFREQ_DEFAULT_GOVERNOR       (&cpufreq_gov_sched)
>  #endif

> +
> +/**
> + * cpufreq_sched_set_capacity - interface to scheduler for changing capacity values

[...]

minor nit:

s/cpufreq_sched_set_capacity/cpufreq_sched_set_cap

> + * @cpu: cpu whose capacity utilization has recently changed
> + * @capacity: the new capacity requested by cpu
> + *
> + * cpufreq_sched_sched_capacity is an interface exposed to the scheduler so
> + * that the scheduler may inform the governor of updates to capacity
> + * utilization and make changes to cpu frequency. Currently this interface is
> + * designed around PELT values in CFS. It can be expanded to other scheduling
> + * classes in the future if needed.
> + *
> + * cpufreq_sched_set_capacity raises an IPI. The irq_work handler for that IPI
> + * wakes up the thread that does the actual work, cpufreq_sched_thread.
> + *
> + * This functions bails out early if either condition is true:
> + * 1) this cpu did not the new maximum capacity for its frequency domain
> + * 2) no change in cpu frequency is necessary to meet the new capacity request
> + */
> +void cpufreq_sched_set_cap(int cpu, unsigned long capacity)
> +{
> +       unsigned int freq_new, cpu_tmp;
> +       struct cpufreq_policy *policy;
> +       struct gov_data *gd;
> +       unsigned long capacity_max = 0;

[...]