From b03f1ba3d5bb9db0ca495c8c33ef88588daaae50 Mon Sep 17 00:00:00 2001 From: Dietmar Eggemann Date: Tue, 22 Sep 2015 16:47:48 +0100 Subject: [PATCH] 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: Dietmar Eggemann --- drivers/cpufreq/cpufreq.c | 19 +++++++++++++++++++ include/linux/cpufreq.h | 1 + 2 files changed, 20 insertions(+) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 46a7d62c8174..96f1a8860819 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -352,12 +352,14 @@ 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", @@ -365,6 +367,18 @@ 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) @@ -372,6 +386,11 @@ 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) { diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index 11c65f536b6c..9b1d61e1f1d7 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -619,4 +619,5 @@ 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 */ -- 2.20.1