From e3c1175d916b271863b47bfa4984864e1eaba11b Mon Sep 17 00:00:00 2001 From: Dietmar Eggemann Date: Thu, 17 Sep 2015 16:10:56 +0100 Subject: [PATCH] cpufreq: Frequency invariant scheduler load-tracking support Implements cpufreq_scale_freq_capacity() to provide the scheduler with a frequency scaling correction factor for more accurate load-tracking. The factor is: current_freq(cpu) << SCHED_CAPACITY_SHIFT / max_freq(cpu) In fact, 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 freq_scale. Signed-off-by: Dietmar Eggemann --- drivers/cpufreq/cpufreq.c | 29 +++++++++++++++++++++++++++++ include/linux/cpufreq.h | 3 +++ 2 files changed, 32 insertions(+) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index e49512718325..0d494c937920 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -347,6 +347,31 @@ static void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci) #endif } +/********************************************************************* + * FREQUENCY INVARIANT CPU CAPACITY * + *********************************************************************/ + +static DEFINE_PER_CPU(unsigned long, 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; + int cpu; + + pr_debug("cpus %*pbl cur/cur max freq %lu/%u kHz freq scale %lu\n", + cpumask_pr_args(policy->cpus), cur, policy->max, scale); + + for_each_cpu(cpu, policy->cpus) + per_cpu(freq_scale, cpu) = scale; +} + +unsigned long cpufreq_scale_freq_capacity(struct sched_domain *sd, int cpu) +{ + return per_cpu(freq_scale, cpu); +} + static void __cpufreq_notify_transition(struct cpufreq_policy *policy, struct cpufreq_freqs *freqs, unsigned int state) { @@ -450,6 +475,8 @@ wait: spin_unlock(&policy->transition_lock); + scale_freq_capacity(policy, freqs); + cpufreq_notify_transition(policy, freqs, CPUFREQ_PRECHANGE); } EXPORT_SYMBOL_GPL(cpufreq_freq_transition_begin); @@ -2126,6 +2153,8 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy, blocking_notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_NOTIFY, new_policy); + scale_freq_capacity(new_policy, NULL); + policy->min = new_policy->min; policy->max = new_policy->max; trace_cpu_frequency_limits(policy->max, policy->min, policy->cpu); diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index 3ac01621cd1f..5f1e66e544f5 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -619,4 +619,7 @@ unsigned int cpufreq_generic_get(unsigned int cpu); int cpufreq_generic_init(struct cpufreq_policy *policy, struct cpufreq_frequency_table *table, unsigned int transition_latency); + +struct sched_domain; +unsigned long cpufreq_scale_freq_capacity(struct sched_domain *sd, int cpu); #endif /* _LINUX_CPUFREQ_H */ -- 2.34.1