/* * drivers/cpufreq/cpufreq_ondemand.c * * Copyright (C) 2001 Russell King * (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>. * Jun Nakajima <jun.nakajima@intel.com> * * 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/init.h> #include <linux/cpufreq.h> #include <linux/cpu.h> #include <linux/jiffies.h> #include <linux/kernel_stat.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 MIN_FREQUENCY_UP_THRESHOLD (11) #define MAX_FREQUENCY_UP_THRESHOLD (100) /* * 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 TRANSITION_LATENCY_LIMIT (10 * 1000) static void do_dbs_timer(struct work_struct *work); /* Sampling types */ enum {DBS_NORMAL_SAMPLE, DBS_SUB_SAMPLE}; struct cpu_dbs_info_s { cputime64_t prev_cpu_idle; cputime64_t prev_cpu_wall; struct cpufreq_policy *cur_policy; struct delayed_work work; struct cpufreq_frequency_table *freq_table; unsigned int freq_lo; unsigned int freq_lo_jiffies; unsigned int freq_hi_jiffies; int cpu; unsigned int enable:1, sample_type:1; }; 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 struct workqueue_struct *kondemand_wq; static struct dbs_tuners { unsigned int sampling_rate; unsigned int up_threshold; unsigned int ignore_nice; unsigned int powersave_bias; } dbs_tuners_ins = { .up_threshold = DEF_FREQUENCY_UP_THRESHOLD, .ignore_nice = 0, .powersave_bias = 0, }; static inline cputime64_t get_cpu_idle_time(unsigned int cpu) { cputime64_t retval; retval = cputime64_add(kstat_cpu(cpu).cpustat.idle, kstat_cpu(cpu).cpustat.iowait); if (dbs_tuners_ins.ignore_nice) retval = cputime64_add(retval, kstat_cpu(cpu).cpustat.nice); return retval; } /* * Find right freq to be set now with powersave_bias on. * Returns the freq_hi to be used right now and will set freq_hi_jiffies, * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs. */ static unsigned int powersave_bias_target(struct cpufreq_policy *policy, unsigned int freq_next, unsigned int relation) { unsigned int freq_req, freq_reduc, freq_avg; unsigned int freq_hi, freq_lo; unsigned int index = 0; unsigned int jiffies_total, jiffies_hi, jiffies_lo; struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, policy->cpu); if (!dbs_info->freq_table) { dbs_info->freq_lo = 0; dbs_info->freq_lo_jiffies = 0; return freq_next; } cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next, relation, &index); freq_req = dbs_info->freq_table[index].frequency; freq_reduc = freq_req * dbs_tuners_ins.powersave_bias / 1000; freq_avg = freq_req - freq_reduc; /* Find freq bounds for freq_avg in freq_table */ index = 0; cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg, CPUFREQ_RELATION_H, &index); freq_lo = dbs_info->freq_table[index].frequency; index = 0; cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg, CPUFREQ_RELATION_L, &index); freq_hi = dbs_info->freq_table[index].frequency; /* Find out how long we have to be in hi and lo freqs */ if (freq_hi == freq_lo) { dbs_info->freq_lo = 0; dbs_info->freq_lo_jiffies = 0; return freq_lo; } jiffies_total = usecs_to_jiffies(dbs_tuners_ins.sampling_rate); jiffies_hi = (freq_avg - freq_lo) * jiffies_total; jiffies_hi += ((freq_hi - freq_lo) / 2); jiffies_hi /= (freq_hi - freq_lo); jiffies_lo = jiffies_total - jiffies_hi; dbs_info->freq_lo = freq_lo; dbs_info->freq_lo_jiffies = jiffies_lo; dbs_info->freq_hi_jiffies = jiffies_hi; return freq_hi; } static void ondemand_powersave_bias_init(void) { int i; for_each_online_cpu(i) { struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, i); dbs_info->freq_table = cpufreq_frequency_get_table(i); dbs_info->freq_lo = 0; } } /************************** 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_ondemand 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(up_threshold, up_threshold); show_one(ignore_nice_load, ignore_nice); show_one(powersave_bias, powersave_bias); 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 > MAX_FREQUENCY_UP_THRESHOLD || input < MIN_FREQUENCY_UP_THRESHOLD) { mutex_unlock(&dbs_mutex); return -EINVAL; } dbs_tuners_ins.up_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 */ for_each_online_cpu(j) { struct cpu_dbs_info_s *dbs_info; dbs_info = &per_cpu(cpu_dbs_info, j); dbs_info->prev_cpu_idle = get_cpu_idle_time(j); dbs_info->prev_cpu_wall = get_jiffies_64(); } mutex_unlock(&dbs_mutex); return count; } static ssize_t store_powersave_bias(struct cpufreq_policy *unused, const char *buf, size_t count) { unsigned int input; int ret; ret = sscanf(buf, "%u", &input); if (ret != 1) return -EINVAL; if (input > 1000) input = 1000; mutex_lock(&dbs_mutex); dbs_tuners_ins.powersave_bias = input; ondemand_powersave_bias_init(); 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(up_threshold); define_one_rw(ignore_nice_load); define_one_rw(powersave_bias); static struct attribute * dbs_attributes[] = { &sampling_rate_max.attr, &sampling_rate_min.attr, &sampling_rate.attr, &up_threshold.attr, &ignore_nice_load.attr, &powersave_bias.attr, NULL }; static struct attribute_group dbs_attr_group = { .attrs = dbs_attributes, .name = "ondemand", }; /************************** sysfs end ************************/ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info) { unsigned int idle_ticks, total_ticks; unsigned int load; cputime64_t cur_jiffies; struct cpufreq_policy *policy; unsigned int j; if (!this_dbs_info->enable) return; this_dbs_info->freq_lo = 0; policy = this_dbs_info->cur_policy; cur_jiffies = jiffies64_to_cputime64(get_jiffies_64()); total_ticks = (unsigned int) cputime64_sub(cur_jiffies, this_dbs_info->prev_cpu_wall); this_dbs_info->prev_cpu_wall = cur_jiffies; if (!total_ticks) return; /* * Every sampling_rate, we check, if current idle time is less * than 20% (default), then we try to increase frequency * Every sampling_rate, we look for a the lowest * frequency which can sustain the load while keeping idle time over * 30%. If such a frequency exist, we try to decrease to this frequency. * * Any frequency increase takes it to the maximum frequency. * Frequency reduction happens at minimum steps of * 5% (default) of current frequency */ /* Get Idle Time */ idle_ticks = UINT_MAX; for_each_cpu_mask(j, policy->cpus) { cputime64_t total_idle_ticks; unsigned int tmp_idle_ticks; struct cpu_dbs_info_s *j_dbs_info; j_dbs_info = &per_cpu(cpu_dbs_info, j); total_idle_ticks = get_cpu_idle_time(j); tmp_idle_ticks = (unsigned int) cputime64_sub(total_idle_ticks, j_dbs_info->prev_cpu_idle); j_dbs_info->prev_cpu_idle = total_idle_ticks; if (tmp_idle_ticks < idle_ticks) idle_ticks = tmp_idle_ticks; } load = (100 * (total_ticks - idle_ticks)) / total_ticks; /* Check for frequency increase */ if (load > dbs_tuners_ins.up_threshold) { /* if we are already at full speed then break out early */ if (!dbs_tuners_ins.powersave_bias) { if (policy->cur == policy->max) return; __cpufreq_driver_target(policy, policy->max, CPUFREQ_RELATION_H); } else { int freq = powersave_bias_target(policy, policy->max, CPUFREQ_RELATION_H); __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L); } return; } /* Check for frequency decrease */ /* if we cannot reduce the frequency anymore, break out early */ if (policy->cur == policy->min) 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 (load < (dbs_tuners_ins.up_threshold - 10)) { unsigned int freq_next, freq_cur; freq_cur = __cpufreq_driver_getavg(policy); if (!freq_cur) freq_cur = policy->cur; freq_next = (freq_cur * load) / (dbs_tuners_ins.up_threshold - 10); if (!dbs_tuners_ins.powersave_bias) { __cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_L); } else { int freq = powersave_bias_target(policy, freq_next, CPUFREQ_RELATION_L); __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L); } } } 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; int sample_type = dbs_info->sample_type; /* We want all CPUs to do sampling nearly on same jiffy */ int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate); delay -= jiffies % delay; if (lock_policy_rwsem_write(cpu) < 0) return; if (!dbs_info->enable) { unlock_policy_rwsem_write(cpu); return; } /* Common NORMAL_SAMPLE setup */ dbs_info->sample_type = DBS_NORMAL_SAMPLE; if (!dbs_tuners_ins.powersave_bias || sample_type == DBS_NORMAL_SAMPLE) { dbs_check_cpu(dbs_info); if (dbs_info->freq_lo) { /* Setup timer for SUB_SAMPLE */ dbs_info->sample_type = DBS_SUB_SAMPLE; delay = dbs_info->freq_hi_jiffies; } } else { __cpufreq_driver_target(dbs_info->cur_policy, dbs_info->freq_lo, CPUFREQ_RELATION_H); } queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work, delay); unlock_policy_rwsem_write(cpu); } 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; ondemand_powersave_bias_init(); dbs_info->sample_type = DBS_NORMAL_SAMPLE; INIT_DELAYED_WORK(&dbs_info->work, do_dbs_timer); queue_delayed_work_on(dbs_info->cpu, kondemand_wq, &dbs_info->work, delay); } static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info) { dbs_info->enable = 0; cancel_delayed_work(&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(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)) { printk(KERN_WARNING "ondemand governor failed to load " "due to too long transition latency\n"); return -EINVAL; } if (this_dbs_info->enable) /* Already enabled */ break; mutex_lock(&dbs_mutex); dbs_enable++; rc = sysfs_create_group(&policy->kobj, &dbs_attr_group); if (rc) { dbs_enable--; 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 = get_cpu_idle_time(j); j_dbs_info->prev_cpu_wall = get_jiffies_64(); } this_dbs_info->cpu = cpu; /* * 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 = 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(this_dbs_info); mutex_unlock(&dbs_mutex); break; case CPUFREQ_GOV_STOP: mutex_lock(&dbs_mutex); dbs_timer_exit(this_dbs_info); sysfs_remove_group(&policy->kobj, &dbs_attr_group); dbs_enable--; 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 = "ondemand", .governor = cpufreq_governor_dbs, .owner = THIS_MODULE, }; static int __init cpufreq_gov_dbs_init(void) { kondemand_wq = create_workqueue("kondemand"); if (!kondemand_wq) { printk(KERN_ERR "Creation of kondemand failed\n"); return -EFAULT; } return cpufreq_register_governor(&cpufreq_gov_dbs); } static void __exit cpufreq_gov_dbs_exit(void) { cpufreq_unregister_governor(&cpufreq_gov_dbs); destroy_workqueue(kondemand_wq); } MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>"); MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>"); MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for " "Low Latency Frequency Transition capable processors"); MODULE_LICENSE("GPL"); module_init(cpufreq_gov_dbs_init); module_exit(cpufreq_gov_dbs_exit);