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Commit 7b619def authored by Dietmar Eggemann's avatar Dietmar Eggemann Committed by Quentin Perret
Browse files

cpufreq: implement max frequency capping 



Implements the Max Frequency Capping Engine (MFCE) getter function
cpufreq_scale_max_freq_capacity() to provide the scheduler with a
maximum frequency scaling correction factor for more accurate cpu
capacity handling by being able to deal with max frequency capping.

This scaling factor describes the influence of running a cpu with a
current maximum frequency (policy) lower than the maximum possible
frequency (cpuinfo).

The factor is:

  policy_max_freq(cpu) << SCHED_CAPACITY_SHIFT / cpuinfo_max_freq(cpu)

It also implements the MFCE setter function scale_max_freq_capacity()
which is called from cpufreq_set_policy().

Change-Id: I38ef736cfa587520cf4f97012be25cbb0c5af04d
Signed-off-by: default avatarDietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: default avatarChris Redpath <chris.redpath@arm.com>
parent da6833cf

drivers/cpufreq/cpufreq.c

+35 −1
Original line number Diff line number Diff line
@@ -315,6 +315,8 @@ static void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci) 
 *********************************************************************/



static DEFINE_PER_CPU(unsigned long, freq_scale) = SCHED_CAPACITY_SCALE;

static DEFINE_PER_CPU(unsigned long, max_freq_cpu);

static DEFINE_PER_CPU(unsigned long, max_freq_scale) = SCHED_CAPACITY_SCALE;



static void

scale_freq_capacity(const cpumask_t *cpus, unsigned long cur_freq,
@@ -323,8 +325,10 @@ scale_freq_capacity(const cpumask_t *cpus, unsigned long cur_freq, 
	unsigned long scale = (cur_freq << SCHED_CAPACITY_SHIFT) / max_freq;

	int cpu;



	for_each_cpu(cpu, cpus)

	for_each_cpu(cpu, cpus) {

		per_cpu(freq_scale, cpu) = scale;

		per_cpu(max_freq_cpu, cpu) = max_freq;

	}



	pr_debug("cpus %*pbl cur freq/max freq %lu/%lu kHz freq scale %lu\n",

		 cpumask_pr_args(cpus), cur_freq, max_freq, scale);
@@ -335,6 +339,34 @@ unsigned long cpufreq_scale_freq_capacity(struct sched_domain *sd, int cpu) 
	return per_cpu(freq_scale, cpu);

}



static void

scale_max_freq_capacity(const cpumask_t *cpus, unsigned long policy_max_freq)

{

	unsigned long scale, max_freq;

	int cpu = cpumask_first(cpus);



	if (cpu >= nr_cpu_ids)

		return;



	max_freq = per_cpu(max_freq_cpu, cpu);



	if (!max_freq)

		return;



	scale = (policy_max_freq << SCHED_CAPACITY_SHIFT) / max_freq;



	for_each_cpu(cpu, cpus)

		per_cpu(max_freq_scale, cpu) = scale;



	pr_debug("cpus %*pbl policy max freq/max freq %lu/%lu kHz max freq scale %lu\n",

		 cpumask_pr_args(cpus), policy_max_freq, max_freq, scale);

}



unsigned long cpufreq_scale_max_freq_capacity(struct sched_domain *sd, int cpu)

{

	return per_cpu(max_freq_scale, cpu);

}



static void __cpufreq_notify_transition(struct cpufreq_policy *policy,

		struct cpufreq_freqs *freqs, unsigned int state)

{
@@ -2238,6 +2270,8 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy, 
	blocking_notifier_call_chain(&cpufreq_policy_notifier_list,

			CPUFREQ_NOTIFY, new_policy);



	scale_max_freq_capacity(policy->cpus, policy->max);



	policy->min = new_policy->min;

	policy->max = new_policy->max;

	trace_cpu_frequency_limits(policy->max, policy->min, policy->cpu);

include/linux/cpufreq.h

+1 −0
Original line number Diff line number Diff line
@@ -932,4 +932,5 @@ int cpufreq_generic_init(struct cpufreq_policy *policy, 


struct sched_domain;

unsigned long cpufreq_scale_freq_capacity(struct sched_domain *sd, int cpu);

unsigned long cpufreq_scale_max_freq_capacity(struct sched_domain *sd, int cpu);

#endif /* _LINUX_CPUFREQ_H */