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cpufreq: Add a cpufreq pressure feedback for the scheduler

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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: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Qais Yousef <qyousef@layalina.io>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Dhruva Gole <d-gole@ti.com>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lore.kernel.org/r/20240326091616.3696851-2-vincent.guittot@linaro.org
This commit is contained in:
Vincent Guittot 2024-03-26 10:16:12 +01:00 committed by Ingo Molnar
parent cd18bec668
commit 75d659317b
2 changed files with 46 additions and 0 deletions
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36
drivers/cpufreq/cpufreq.c
View file

@ -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",

10
include/linux/cpufreq.h
View file

@ -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