Commit 75d65931 authored by Vincent Guittot's avatar Vincent Guittot Committed by Ingo Molnar
Browse files

cpufreq: Add a cpufreq pressure feedback for the scheduler 



Provide to the scheduler a feedback about the temporary max available
capacity. Unlike arch_update_thermal_pressure(), this doesn't need to be
filtered as the pressure will happen for dozens of ms or more.

Signed-off-by: default avatarVincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Tested-by: default avatarLukasz Luba <lukasz.luba@arm.com>
Reviewed-by: default avatarQais Yousef <qyousef@layalina.io>
Reviewed-by: default avatarLukasz Luba <lukasz.luba@arm.com>
Reviewed-by: default avatarDhruva Gole <d-gole@ti.com>
Acked-by: default avatarRafael J. Wysocki <rafael@kernel.org>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Link: https://lore.kernel.org/r/20240326091616.3696851-2-vincent.guittot@linaro.org
parent cd18bec6

drivers/cpufreq/cpufreq.c

+36 −0
Original line number Diff line number Diff line
@@ -2582,6 +2582,40 @@ int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu) 
}

EXPORT_SYMBOL(cpufreq_get_policy);



DEFINE_PER_CPU(unsigned long, cpufreq_pressure);



/**

 * cpufreq_update_pressure() - Update cpufreq pressure for CPUs

 * @policy: cpufreq policy of the CPUs.

 *

 * Update the value of cpufreq pressure for all @cpus in the policy.

 */

static void cpufreq_update_pressure(struct cpufreq_policy *policy)

{

	unsigned long max_capacity, capped_freq, pressure;

	u32 max_freq;

	int cpu;



	cpu = cpumask_first(policy->related_cpus);

	max_freq = arch_scale_freq_ref(cpu);

	capped_freq = policy->max;



	/*

	 * Handle properly the boost frequencies, which should simply clean

	 * the cpufreq pressure value.

	 */

	if (max_freq <= capped_freq) {

		pressure = 0;

	} else {

		max_capacity = arch_scale_cpu_capacity(cpu);

		pressure = max_capacity -

			   mult_frac(max_capacity, capped_freq, max_freq);

	}



	for_each_cpu(cpu, policy->related_cpus)

		WRITE_ONCE(per_cpu(cpufreq_pressure, cpu), pressure);

}



/**

 * cpufreq_set_policy - Modify cpufreq policy parameters.

 * @policy: Policy object to modify.
@@ -2637,6 +2671,8 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy, 
	policy->max = __resolve_freq(policy, policy->max, CPUFREQ_RELATION_H);

	trace_cpu_frequency_limits(policy);



	cpufreq_update_pressure(policy);



	policy->cached_target_freq = UINT_MAX;



	pr_debug("new min and max freqs are %u - %u kHz\n",

include/linux/cpufreq.h

+10 −0
Original line number Diff line number Diff line
@@ -241,6 +241,12 @@ struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy); 
void cpufreq_enable_fast_switch(struct cpufreq_policy *policy);

void cpufreq_disable_fast_switch(struct cpufreq_policy *policy);

bool has_target_index(void);



DECLARE_PER_CPU(unsigned long, cpufreq_pressure);

static inline unsigned long cpufreq_get_pressure(int cpu)

{

	return READ_ONCE(per_cpu(cpufreq_pressure, cpu));

}

#else

static inline unsigned int cpufreq_get(unsigned int cpu)

{
@@ -264,6 +270,10 @@ static inline bool cpufreq_supports_freq_invariance(void) 
}

static inline void disable_cpufreq(void) { }

static inline void cpufreq_update_limits(unsigned int cpu) { }

static inline unsigned long cpufreq_get_pressure(int cpu)

{

	return 0;

}

#endif



#ifdef CONFIG_CPU_FREQ_STAT