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Commit 4eb92977 authored by Dietmar Eggemann's avatar Dietmar Eggemann Committed by Dmitry Shmidt
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ANDROID: cpufreq: Max freq invariant scheduler load-tracking and cpu capacity support 



Implements cpufreq_scale_max_freq_capacity() to provide the scheduler
with a maximum frequency scaling correction factor for more accurate
load-tracking and cpu capacity handling by being able to deal with
frequency capping.

This scaling factor describes the influence of running a cpu with a
current maximum frequency lower than the absolute possible maximum
frequency on load tracking and cpu capacity.

The factor is:

	current_max_freq(cpu) << SCHED_CAPACITY_SHIFT / max_freq(cpu)

In fact, max_freq_scale should be a struct cpufreq_policy data member.
But this would require that the scheduler hot path (__update_load_avg())
would have to grab the cpufreq lock. This can be avoided by using per-cpu
data initialized to SCHED_CAPACITY_SCALE for max_freq_scale.

Signed-off-by: default avatarDietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: default avatarAndres Oportus <andresoportus@google.com>
parent f69e2dc5

drivers/cpufreq/cpufreq.c

+19 −0
Original line number Diff line number Diff line
@@ -306,12 +306,14 @@ 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_scale) = SCHED_CAPACITY_SCALE;



static void

scale_freq_capacity(struct cpufreq_policy *policy, struct cpufreq_freqs *freqs)

{

	unsigned long cur = freqs ? freqs->new : policy->cur;

	unsigned long scale = (cur << SCHED_CAPACITY_SHIFT) / policy->max;

	struct cpufreq_cpuinfo *cpuinfo = &policy->cpuinfo;

	int cpu;



	pr_debug("cpus %*pbl cur/cur max freq %lu/%u kHz freq scale %lu\n",
@@ -319,6 +321,18 @@ scale_freq_capacity(struct cpufreq_policy *policy, struct cpufreq_freqs *freqs) 


	for_each_cpu(cpu, policy->cpus)

		per_cpu(freq_scale, cpu) = scale;



	if (freqs)

		return;



	scale = (policy->max << SCHED_CAPACITY_SHIFT) / cpuinfo->max_freq;



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

		 cpumask_pr_args(policy->cpus), policy->max, cpuinfo->max_freq,

		 scale);



	for_each_cpu(cpu, policy->cpus)

		per_cpu(max_freq_scale, cpu) = scale;

}



unsigned long cpufreq_scale_freq_capacity(struct sched_domain *sd, int cpu)
@@ -326,6 +340,11 @@ unsigned long cpufreq_scale_freq_capacity(struct sched_domain *sd, int cpu) 
	return per_cpu(freq_scale, cpu);

}



unsigned long cpufreq_scale_max_freq_capacity(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)

{

include/linux/cpufreq.h

+1 −0
Original line number Diff line number Diff line
@@ -889,4 +889,5 @@ 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(int cpu);

#endif /* _LINUX_CPUFREQ_H */