/* * drivers/cpufreq/cpufreq_conservative.c * * Copyright (C) 2001 Russell King * (C) 2003 Venkatesh Pallipadi . * Jun Nakajima * (C) 2009 Alexander Clouter * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include #include #include #include #include #include #include #include #include #include #include #include /* * dbs is used in this file as a shortform for demandbased switching * It helps to keep variable names smaller, simpler */ #define DEF_FREQUENCY_UP_THRESHOLD (80) #define DEF_FREQUENCY_DOWN_THRESHOLD (20) /* * The polling frequency of this governor depends on the capability of * the processor. Default polling frequency is 1000 times the transition * latency of the processor. The governor will work on any processor with * transition latency <= 10mS, using appropriate sampling * rate. * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL) * this governor will not work. * All times here are in uS. */ #define MIN_SAMPLING_RATE_RATIO (2) static unsigned int min_sampling_rate; #define LATENCY_MULTIPLIER (1000) #define MIN_LATENCY_MULTIPLIER (100) #define DEF_SAMPLING_DOWN_FACTOR (1) #define MAX_SAMPLING_DOWN_FACTOR (10) #define TRANSITION_LATENCY_LIMIT (10 * 1000 * 1000) static void do_dbs_timer(struct work_struct *work); struct cpu_dbs_info_s { cputime64_t prev_cpu_idle; cputime64_t prev_cpu_wall; cputime64_t prev_cpu_nice; struct cpufreq_policy *cur_policy; struct delayed_work work; unsigned int down_skip; unsigned int requested_freq; int cpu; unsigned int enable:1; /* * percpu mutex that serializes governor limit change with * do_dbs_timer invocation. We do not want do_dbs_timer to run * when user is changing the governor or limits. */ struct mutex timer_mutex; }; static DEFINE_PER_CPU(struct cpu_dbs_info_s, cs_cpu_dbs_info); static unsigned int dbs_enable; /* number of CPUs using this policy */ /* * dbs_mutex protects dbs_enable in governor start/stop. */ static DEFINE_MUTEX(dbs_mutex); static struct dbs_tuners { unsigned int sampling_rate; unsigned int sampling_down_factor; unsigned int up_threshold; unsigned int down_threshold; unsigned int ignore_nice; unsigned int freq_step; } dbs_tuners_ins = { .up_threshold = DEF_FREQUENCY_UP_THRESHOLD, .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD, .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR, .ignore_nice = 0, .freq_step = 5, }; static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall) { u64 idle_time; cputime64_t cur_wall_time; u64 busy_time; cur_wall_time = jiffies64_to_cputime64(get_jiffies_64()); busy_time = kcpustat_cpu(cpu).cpustat[CPUTIME_USER] + kcpustat_cpu(cpu).cpustat[CPUTIME_SYSTEM]; busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_IRQ]; busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SOFTIRQ]; busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_STEAL]; busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_NICE]; idle_time = cputime64_sub(cur_wall_time, busy_time); if (wall) *wall = jiffies_to_usecs(cur_wall_time); return jiffies_to_usecs(idle_time); } static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall) { u64 idle_time = get_cpu_idle_time_us(cpu, NULL); if (idle_time == -1ULL) return get_cpu_idle_time_jiffy(cpu, wall); else idle_time += get_cpu_iowait_time_us(cpu, wall); return idle_time; } /* keep track of frequency transitions */ static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val, void *data) { struct cpufreq_freqs *freq = data; struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cs_cpu_dbs_info, freq->cpu); struct cpufreq_policy *policy; if (!this_dbs_info->enable) return 0; policy = this_dbs_info->cur_policy; /* * we only care if our internally tracked freq moves outside * the 'valid' ranges of freqency available to us otherwise * we do not change it */ if (this_dbs_info->requested_freq > policy->max || this_dbs_info->requested_freq < policy->min) this_dbs_info->requested_freq = freq->new; return 0; } static struct notifier_block dbs_cpufreq_notifier_block = { .notifier_call = dbs_cpufreq_notifier }; /************************** sysfs interface ************************/ static ssize_t show_sampling_rate_min(struct kobject *kobj, struct attribute *attr, char *buf) { return sprintf(buf, "%u\n", min_sampling_rate); } define_one_global_ro(sampling_rate_min); /* cpufreq_conservative Governor Tunables */ #define show_one(file_name, object) \ static ssize_t show_##file_name \ (struct kobject *kobj, struct attribute *attr, char *buf) \ { \ return sprintf(buf, "%u\n", dbs_tuners_ins.object); \ } show_one(sampling_rate, sampling_rate); show_one(sampling_down_factor, sampling_down_factor); show_one(up_threshold, up_threshold); show_one(down_threshold, down_threshold); show_one(ignore_nice_load, ignore_nice); show_one(freq_step, freq_step); static ssize_t store_sampling_down_factor(struct kobject *a, struct attribute *b, const char *buf, size_t count) { unsigned int input; int ret; ret = sscanf(buf, "%u", &input); if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1) return -EINVAL; dbs_tuners_ins.sampling_down_factor = input; return count; } static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b, const char *buf, size_t count) { unsigned int input; int ret; ret = sscanf(buf, "%u", &input); if (ret != 1) return -EINVAL; dbs_tuners_ins.sampling_rate = max(input, min_sampling_rate); return count; } static ssize_t store_up_threshold(struct kobject *a, struct attribute *b, const char *buf, size_t count) { unsigned int input; int ret; ret = sscanf(buf, "%u", &input); if (ret != 1 || input > 100 || input <= dbs_tuners_ins.down_threshold) return -EINVAL; dbs_tuners_ins.up_threshold = input; return count; } static ssize_t store_down_threshold(struct kobject *a, struct attribute *b, const char *buf, size_t count) { unsigned int input; int ret; ret = sscanf(buf, "%u", &input); /* cannot be lower than 11 otherwise freq will not fall */ if (ret != 1 || input < 11 || input > 100 || input >= dbs_tuners_ins.up_threshold) return -EINVAL; dbs_tuners_ins.down_threshold = input; return count; } static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b, const char *buf, size_t count) { unsigned int input; int ret; unsigned int j; ret = sscanf(buf, "%u", &input); if (ret != 1) return -EINVAL; if (input > 1) input = 1; if (input == dbs_tuners_ins.ignore_nice) /* nothing to do */ return count; dbs_tuners_ins.ignore_nice = input; /* we need to re-evaluate prev_cpu_idle */ for_each_online_cpu(j) { struct cpu_dbs_info_s *dbs_info; dbs_info = &per_cpu(cs_cpu_dbs_info, j); dbs_info->prev_cpu_idle = get_cpu_idle_time(j, &dbs_info->prev_cpu_wall); if (dbs_tuners_ins.ignore_nice) dbs_info->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE]; } return count; } static ssize_t store_freq_step(struct kobject *a, struct attribute *b, const char *buf, size_t count) { unsigned int input; int ret; ret = sscanf(buf, "%u", &input); if (ret != 1) return -EINVAL; if (input > 100) input = 100; /* no need to test here if freq_step is zero as the user might actually * want this, they would be crazy though :) */ dbs_tuners_ins.freq_step = input; return count; } define_one_global_rw(sampling_rate); define_one_global_rw(sampling_down_factor); define_one_global_rw(up_threshold); define_one_global_rw(down_threshold); define_one_global_rw(ignore_nice_load); define_one_global_rw(freq_step); static struct attribute *dbs_attributes[] = { &sampling_rate_min.attr, &sampling_rate.attr, &sampling_down_factor.attr, &up_threshold.attr, &down_threshold.attr, &ignore_nice_load.attr, &freq_step.attr, NULL }; static struct attribute_group dbs_attr_group = { .attrs = dbs_attributes, .name = "conservative", }; /************************** sysfs end ************************/ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info) { unsigned int load = 0; unsigned int max_load = 0; unsigned int freq_target; struct cpufreq_policy *policy; unsigned int j; policy = this_dbs_info->cur_policy; /* * Every sampling_rate, we check, if current idle time is less * than 20% (default), then we try to increase frequency * Every sampling_rate*sampling_down_factor, we check, if current * idle time is more than 80%, then we try to decrease frequency * * Any frequency increase takes it to the maximum frequency. * Frequency reduction happens at minimum steps of * 5% (default) of maximum frequency */ /* Get Absolute Load */ for_each_cpu(j, policy->cpus) { struct cpu_dbs_info_s *j_dbs_info; cputime64_t cur_wall_time, cur_idle_time; unsigned int idle_time, wall_time; j_dbs_info = &per_cpu(cs_cpu_dbs_info, j); cur_idle_time = get_cpu_idle_time(j, &cur_wall_time); wall_time = (unsigned int) cputime64_sub(cur_wall_time, j_dbs_info->prev_cpu_wall); j_dbs_info->prev_cpu_wall = cur_wall_time; idle_time = (unsigned int) cputime64_sub(cur_idle_time, j_dbs_info->prev_cpu_idle); j_dbs_info->prev_cpu_idle = cur_idle_time; if (dbs_tuners_ins.ignore_nice) { u64 cur_nice; unsigned long cur_nice_jiffies; cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE] - j_dbs_info->prev_cpu_nice; /* * Assumption: nice time between sampling periods will * be less than 2^32 jiffies for 32 bit sys */ cur_nice_jiffies = (unsigned long) cputime64_to_jiffies64(cur_nice); j_dbs_info->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE]; idle_time += jiffies_to_usecs(cur_nice_jiffies); } if (unlikely(!wall_time || wall_time < idle_time)) continue; load = 100 * (wall_time - idle_time) / wall_time; if (load > max_load) max_load = load; } /* * break out if we 'cannot' reduce the speed as the user might * want freq_step to be zero */ if (dbs_tuners_ins.freq_step == 0) return; /* Check for frequency increase */ if (max_load > dbs_tuners_ins.up_threshold) { this_dbs_info->down_skip = 0; /* if we are already at full speed then break out early */ if (this_dbs_info->requested_freq == policy->max) return; freq_target = (dbs_tuners_ins.freq_step * policy->max) / 100; /* max freq cannot be less than 100. But who knows.... */ if (unlikely(freq_target == 0)) freq_target = 5; this_dbs_info->requested_freq += freq_target; if (this_dbs_info->requested_freq > policy->max) this_dbs_info->requested_freq = policy->max; __cpufreq_driver_target(policy, this_dbs_info->requested_freq, CPUFREQ_RELATION_H); return; } /* * The optimal frequency is the frequency that is the lowest that * can support the current CPU usage without triggering the up * policy. To be safe, we focus 10 points under the threshold. */ if (max_load < (dbs_tuners_ins.down_threshold - 10)) { freq_target = (dbs_tuners_ins.freq_step * policy->max) / 100; this_dbs_info->requested_freq -= freq_target; if (this_dbs_info->requested_freq < policy->min) this_dbs_info->requested_freq = policy->min; /* * if we cannot reduce the frequency anymore, break out early */ if (policy->cur == policy->min) return; __cpufreq_driver_target(policy, this_dbs_info->requested_freq, CPUFREQ_RELATION_H); return; } } static void do_dbs_timer(struct work_struct *work) { struct cpu_dbs_info_s *dbs_info = container_of(work, struct cpu_dbs_info_s, work.work); unsigned int cpu = dbs_info->cpu; /* We want all CPUs to do sampling nearly on same jiffy */ int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate); delay -= jiffies % delay; mutex_lock(&dbs_info->timer_mutex); dbs_check_cpu(dbs_info); schedule_delayed_work_on(cpu, &dbs_info->work, delay); mutex_unlock(&dbs_info->timer_mutex); } static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info) { /* We want all CPUs to do sampling nearly on same jiffy */ int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate); delay -= jiffies % delay; dbs_info->enable = 1; INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer); schedule_delayed_work_on(dbs_info->cpu, &dbs_info->work, delay); } static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info) { dbs_info->enable = 0; cancel_delayed_work_sync(&dbs_info->work); } static int cpufreq_governor_dbs(struct cpufreq_policy *policy, unsigned int event) { unsigned int cpu = policy->cpu; struct cpu_dbs_info_s *this_dbs_info; unsigned int j; int rc; this_dbs_info = &per_cpu(cs_cpu_dbs_info, cpu); switch (event) { case CPUFREQ_GOV_START: if ((!cpu_online(cpu)) || (!policy->cur)) return -EINVAL; mutex_lock(&dbs_mutex); for_each_cpu(j, policy->cpus) { struct cpu_dbs_info_s *j_dbs_info; j_dbs_info = &per_cpu(cs_cpu_dbs_info, j); j_dbs_info->cur_policy = policy; j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j, &j_dbs_info->prev_cpu_wall); if (dbs_tuners_ins.ignore_nice) j_dbs_info->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE]; } this_dbs_info->down_skip = 0; this_dbs_info->requested_freq = policy->cur; mutex_init(&this_dbs_info->timer_mutex); dbs_enable++; /* * Start the timerschedule work, when this governor * is used for first time */ if (dbs_enable == 1) { unsigned int latency; /* policy latency is in nS. Convert it to uS first */ latency = policy->cpuinfo.transition_latency / 1000; if (latency == 0) latency = 1; rc = sysfs_create_group(cpufreq_global_kobject, &dbs_attr_group); if (rc) { mutex_unlock(&dbs_mutex); return rc; } /* * conservative does not implement micro like ondemand * governor, thus we are bound to jiffes/HZ */ min_sampling_rate = MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10); /* Bring kernel and HW constraints together */ min_sampling_rate = max(min_sampling_rate, MIN_LATENCY_MULTIPLIER * latency); dbs_tuners_ins.sampling_rate = max(min_sampling_rate, latency * LATENCY_MULTIPLIER); cpufreq_register_notifier( &dbs_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER); } mutex_unlock(&dbs_mutex); dbs_timer_init(this_dbs_info); break; case CPUFREQ_GOV_STOP: dbs_timer_exit(this_dbs_info); mutex_lock(&dbs_mutex); dbs_enable--; mutex_destroy(&this_dbs_info->timer_mutex); /* * Stop the timerschedule work, when this governor * is used for first time */ if (dbs_enable == 0) cpufreq_unregister_notifier( &dbs_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER); mutex_unlock(&dbs_mutex); if (!dbs_enable) sysfs_remove_group(cpufreq_global_kobject, &dbs_attr_group); break; case CPUFREQ_GOV_LIMITS: mutex_lock(&this_dbs_info->timer_mutex); if (policy->max < this_dbs_info->cur_policy->cur) __cpufreq_driver_target( this_dbs_info->cur_policy, policy->max, CPUFREQ_RELATION_H); else if (policy->min > this_dbs_info->cur_policy->cur) __cpufreq_driver_target( this_dbs_info->cur_policy, policy->min, CPUFREQ_RELATION_L); mutex_unlock(&this_dbs_info->timer_mutex); break; } return 0; } #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE static #endif struct cpufreq_governor cpufreq_gov_conservative = { .name = "conservative", .governor = cpufreq_governor_dbs, .max_transition_latency = TRANSITION_LATENCY_LIMIT, .owner = THIS_MODULE, }; static int __init cpufreq_gov_dbs_init(void) { return cpufreq_register_governor(&cpufreq_gov_conservative); } static void __exit cpufreq_gov_dbs_exit(void) { cpufreq_unregister_governor(&cpufreq_gov_conservative); } MODULE_AUTHOR("Alexander Clouter "); MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for " "Low Latency Frequency Transition capable processors " "optimised for use in a battery environment"); MODULE_LICENSE("GPL"); #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE fs_initcall(cpufreq_gov_dbs_init); #else module_init(cpufreq_gov_dbs_init); #endif module_exit(cpufreq_gov_dbs_exit);