/* * drivers/cpufreq/cpufreq_conservative.c * * Copyright (C) 2001 Russell King * (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>. * Jun Nakajima <jun.nakajima@intel.com> * (C) 2004 Alexander Clouter <alex-kernel@digriz.org.uk> * * 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 <linux/kernel.h> #include <linux/module.h> #include <linux/smp.h> #include <linux/init.h> #include <linux/interrupt.h> #include <linux/ctype.h> #include <linux/cpufreq.h> #include <linux/sysctl.h> #include <linux/types.h> #include <linux/fs.h> #include <linux/sysfs.h> #include <linux/cpu.h> #include <linux/kmod.h> #include <linux/workqueue.h> #include <linux/jiffies.h> #include <linux/kernel_stat.h> #include <linux/percpu.h> #include <linux/mutex.h> /* * 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. */ static unsigned int def_sampling_rate; #define MIN_SAMPLING_RATE_RATIO (2) /* for correct statistics, we need at least 10 ticks between each measure */ #define MIN_STAT_SAMPLING_RATE \ (MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10)) #define MIN_SAMPLING_RATE \ (def_sampling_rate / MIN_SAMPLING_RATE_RATIO) #define MAX_SAMPLING_RATE (500 * def_sampling_rate) #define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER (1000) #define DEF_SAMPLING_DOWN_FACTOR (1) #define MAX_SAMPLING_DOWN_FACTOR (10) #define TRANSITION_LATENCY_LIMIT (10 * 1000) static void do_dbs_timer(struct work_struct *work); struct cpu_dbs_info_s { struct cpufreq_policy *cur_policy; unsigned int prev_cpu_idle_up; unsigned int prev_cpu_idle_down; unsigned int enable; unsigned int down_skip; unsigned int requested_freq; }; static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info); static unsigned int dbs_enable; /* number of CPUs using this policy */ /* * DEADLOCK ALERT! There is a ordering requirement between cpu_hotplug * lock and dbs_mutex. cpu_hotplug lock should always be held before * dbs_mutex. If any function that can potentially take cpu_hotplug lock * (like __cpufreq_driver_target()) is being called with dbs_mutex taken, then * cpu_hotplug lock should be taken before that. Note that cpu_hotplug lock * is recursive for the same process. -Venki */ static DEFINE_MUTEX (dbs_mutex); static DECLARE_DELAYED_WORK(dbs_work, do_dbs_timer); 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; }; static struct dbs_tuners 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 unsigned int get_cpu_idle_time(unsigned int cpu) { unsigned int add_nice = 0, ret; if (dbs_tuners_ins.ignore_nice) add_nice = kstat_cpu(cpu).cpustat.nice; ret = kstat_cpu(cpu).cpustat.idle + kstat_cpu(cpu).cpustat.iowait + add_nice; return ret; } /************************** sysfs interface ************************/ static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf) { return sprintf (buf, "%u\n", MAX_SAMPLING_RATE); } static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf) { return sprintf (buf, "%u\n", MIN_SAMPLING_RATE); } #define define_one_ro(_name) \ static struct freq_attr _name = \ __ATTR(_name, 0444, show_##_name, NULL) define_one_ro(sampling_rate_max); define_one_ro(sampling_rate_min); /* cpufreq_conservative Governor Tunables */ #define show_one(file_name, object) \ static ssize_t show_##file_name \ (struct cpufreq_policy *unused, 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 cpufreq_policy *unused, 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; mutex_lock(&dbs_mutex); dbs_tuners_ins.sampling_down_factor = input; mutex_unlock(&dbs_mutex); return count; } static ssize_t store_sampling_rate(struct cpufreq_policy *unused, const char *buf, size_t count) { unsigned int input; int ret; ret = sscanf (buf, "%u", &input); mutex_lock(&dbs_mutex); if (ret != 1 || input > MAX_SAMPLING_RATE || input < MIN_SAMPLING_RATE) { mutex_unlock(&dbs_mutex); return -EINVAL; } dbs_tuners_ins.sampling_rate = input; mutex_unlock(&dbs_mutex); return count; } static ssize_t store_up_threshold(struct cpufreq_policy *unused, const char *buf, size_t count) { unsigned int input; int ret; ret = sscanf (buf, "%u", &input); mutex_lock(&dbs_mutex); if (ret != 1 || input > 100 || input <= dbs_tuners_ins.down_threshold) { mutex_unlock(&dbs_mutex); return -EINVAL; } dbs_tuners_ins.up_threshold = input; mutex_unlock(&dbs_mutex); return count; } static ssize_t store_down_threshold(struct cpufreq_policy *unused, const char *buf, size_t count) { unsigned int input; int ret; ret = sscanf (buf, "%u", &input); mutex_lock(&dbs_mutex); if (ret != 1 || input > 100 || input >= dbs_tuners_ins.up_threshold) { mutex_unlock(&dbs_mutex); return -EINVAL; } dbs_tuners_ins.down_threshold = input; mutex_unlock(&dbs_mutex); return count; } static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy, 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; mutex_lock(&dbs_mutex); if ( input == dbs_tuners_ins.ignore_nice ) { /* nothing to do */ mutex_unlock(&dbs_mutex); return count; } dbs_tuners_ins.ignore_nice = input; /* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */ for_each_online_cpu(j) { struct cpu_dbs_info_s *j_dbs_info; j_dbs_info = &per_cpu(cpu_dbs_info, j); j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j); j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up; } mutex_unlock(&dbs_mutex); return count; } static ssize_t store_freq_step(struct cpufreq_policy *policy, 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 :) */ mutex_lock(&dbs_mutex); dbs_tuners_ins.freq_step = input; mutex_unlock(&dbs_mutex); return count; } #define define_one_rw(_name) \ static struct freq_attr _name = \ __ATTR(_name, 0644, show_##_name, store_##_name) define_one_rw(sampling_rate); define_one_rw(sampling_down_factor); define_one_rw(up_threshold); define_one_rw(down_threshold); define_one_rw(ignore_nice_load); define_one_rw(freq_step); static struct attribute * dbs_attributes[] = { &sampling_rate_max.attr, &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(int cpu) { unsigned int idle_ticks, up_idle_ticks, down_idle_ticks; unsigned int tmp_idle_ticks, total_idle_ticks; unsigned int freq_step; unsigned int freq_down_sampling_rate; struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cpu_dbs_info, cpu); struct cpufreq_policy *policy; if (!this_dbs_info->enable) return; policy = this_dbs_info->cur_policy; /* * The default safe range is 20% to 80% * Every sampling_rate, we check * - If current idle time is less than 20%, 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 max_frequency */ /* Check for frequency increase */ idle_ticks = UINT_MAX; /* Check for frequency increase */ total_idle_ticks = get_cpu_idle_time(cpu); tmp_idle_ticks = total_idle_ticks - this_dbs_info->prev_cpu_idle_up; this_dbs_info->prev_cpu_idle_up = total_idle_ticks; if (tmp_idle_ticks < idle_ticks) idle_ticks = tmp_idle_ticks; /* Scale idle ticks by 100 and compare with up and down ticks */ idle_ticks *= 100; up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) * usecs_to_jiffies(dbs_tuners_ins.sampling_rate); if (idle_ticks < up_idle_ticks) { this_dbs_info->down_skip = 0; this_dbs_info->prev_cpu_idle_down = this_dbs_info->prev_cpu_idle_up; /* if we are already at full speed then break out early */ if (this_dbs_info->requested_freq == policy->max) return; freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100; /* max freq cannot be less than 100. But who knows.... */ if (unlikely(freq_step == 0)) freq_step = 5; this_dbs_info->requested_freq += freq_step; 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; } /* Check for frequency decrease */ this_dbs_info->down_skip++; if (this_dbs_info->down_skip < dbs_tuners_ins.sampling_down_factor) return; /* Check for frequency decrease */ total_idle_ticks = this_dbs_info->prev_cpu_idle_up; tmp_idle_ticks = total_idle_ticks - this_dbs_info->prev_cpu_idle_down; this_dbs_info->prev_cpu_idle_down = total_idle_ticks; if (tmp_idle_ticks < idle_ticks) idle_ticks = tmp_idle_ticks; /* Scale idle ticks by 100 and compare with up and down ticks */ idle_ticks *= 100; this_dbs_info->down_skip = 0; freq_down_sampling_rate = dbs_tuners_ins.sampling_rate * dbs_tuners_ins.sampling_down_factor; down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) * usecs_to_jiffies(freq_down_sampling_rate); if (idle_ticks > down_idle_ticks) { /* * if we are already at the lowest speed then break out early * or if we 'cannot' reduce the speed as the user might want * freq_step to be zero */ if (this_dbs_info->requested_freq == policy->min || dbs_tuners_ins.freq_step == 0) return; freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100; /* max freq cannot be less than 100. But who knows.... */ if (unlikely(freq_step == 0)) freq_step = 5; this_dbs_info->requested_freq -= freq_step; if (this_dbs_info->requested_freq < policy->min) this_dbs_info->requested_freq = policy->min; __cpufreq_driver_target(policy, this_dbs_info->requested_freq, CPUFREQ_RELATION_H); return; } } static void do_dbs_timer(struct work_struct *work) { int i; mutex_lock(&dbs_mutex); for_each_online_cpu(i) dbs_check_cpu(i); schedule_delayed_work(&dbs_work, usecs_to_jiffies(dbs_tuners_ins.sampling_rate)); mutex_unlock(&dbs_mutex); } static inline void dbs_timer_init(void) { schedule_delayed_work(&dbs_work, usecs_to_jiffies(dbs_tuners_ins.sampling_rate)); return; } static inline void dbs_timer_exit(void) { cancel_delayed_work(&dbs_work); return; } 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(cpu_dbs_info, cpu); switch (event) { case CPUFREQ_GOV_START: if ((!cpu_online(cpu)) || (!policy->cur)) return -EINVAL; if (policy->cpuinfo.transition_latency > (TRANSITION_LATENCY_LIMIT * 1000)) return -EINVAL; if (this_dbs_info->enable) /* Already enabled */ break; mutex_lock(&dbs_mutex); rc = sysfs_create_group(&policy->kobj, &dbs_attr_group); if (rc) { mutex_unlock(&dbs_mutex); return rc; } for_each_cpu_mask(j, policy->cpus) { struct cpu_dbs_info_s *j_dbs_info; j_dbs_info = &per_cpu(cpu_dbs_info, j); j_dbs_info->cur_policy = policy; j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(cpu); j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up; } this_dbs_info->enable = 1; this_dbs_info->down_skip = 0; this_dbs_info->requested_freq = policy->cur; 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; def_sampling_rate = 10 * latency * DEF_SAMPLING_RATE_LATENCY_MULTIPLIER; if (def_sampling_rate < MIN_STAT_SAMPLING_RATE) def_sampling_rate = MIN_STAT_SAMPLING_RATE; dbs_tuners_ins.sampling_rate = def_sampling_rate; dbs_timer_init(); } mutex_unlock(&dbs_mutex); break; case CPUFREQ_GOV_STOP: mutex_lock(&dbs_mutex); this_dbs_info->enable = 0; sysfs_remove_group(&policy->kobj, &dbs_attr_group); dbs_enable--; /* * Stop the timerschedule work, when this governor * is used for first time */ if (dbs_enable == 0) dbs_timer_exit(); mutex_unlock(&dbs_mutex); break; case CPUFREQ_GOV_LIMITS: mutex_lock(&dbs_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(&dbs_mutex); break; } return 0; } static struct cpufreq_governor cpufreq_gov_dbs = { .name = "conservative", .governor = cpufreq_governor_dbs, .owner = THIS_MODULE, }; static int __init cpufreq_gov_dbs_init(void) { return cpufreq_register_governor(&cpufreq_gov_dbs); } static void __exit cpufreq_gov_dbs_exit(void) { /* Make sure that the scheduled work is indeed not running */ flush_scheduled_work(); cpufreq_unregister_governor(&cpufreq_gov_dbs); } MODULE_AUTHOR ("Alexander Clouter <alex-kernel@digriz.org.uk>"); 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"); module_init(cpufreq_gov_dbs_init); module_exit(cpufreq_gov_dbs_exit);