/* * drivers/cpufreq/cpufreq_governor.c * * CPUFREQ governors common code * * Copyright (C) 2001 Russell King * (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>. * (C) 2003 Jun Nakajima <jun.nakajima@intel.com> * (C) 2009 Alexander Clouter <alex@digriz.org.uk> * (c) 2012 Viresh Kumar <viresh.kumar@linaro.org> * * 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. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/export.h> #include <linux/kernel_stat.h> #include <linux/slab.h> #include "cpufreq_governor.h" static struct attribute_group *get_sysfs_attr(struct dbs_data *dbs_data) { if (have_governor_per_policy()) return dbs_data->cdata->attr_group_gov_pol; else return dbs_data->cdata->attr_group_gov_sys; } void dbs_check_cpu(struct dbs_data *dbs_data, int cpu) { struct cpu_dbs_common_info *cdbs = dbs_data->cdata->get_cpu_cdbs(cpu); struct od_dbs_tuners *od_tuners = dbs_data->tuners; struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; struct cpufreq_policy *policy; unsigned int sampling_rate; unsigned int max_load = 0; unsigned int ignore_nice; unsigned int j; if (dbs_data->cdata->governor == GOV_ONDEMAND) { struct od_cpu_dbs_info_s *od_dbs_info = dbs_data->cdata->get_cpu_dbs_info_s(cpu); /* * Sometimes, the ondemand governor uses an additional * multiplier to give long delays. So apply this multiplier to * the 'sampling_rate', so as to keep the wake-up-from-idle * detection logic a bit conservative. */ sampling_rate = od_tuners->sampling_rate; sampling_rate *= od_dbs_info->rate_mult; ignore_nice = od_tuners->ignore_nice_load; } else { sampling_rate = cs_tuners->sampling_rate; ignore_nice = cs_tuners->ignore_nice_load; } policy = cdbs->cur_policy; /* Get Absolute Load */ for_each_cpu(j, policy->cpus) { struct cpu_dbs_common_info *j_cdbs; u64 cur_wall_time, cur_idle_time; unsigned int idle_time, wall_time; unsigned int load; int io_busy = 0; j_cdbs = dbs_data->cdata->get_cpu_cdbs(j); /* * For the purpose of ondemand, waiting for disk IO is * an indication that you're performance critical, and * not that the system is actually idle. So do not add * the iowait time to the cpu idle time. */ if (dbs_data->cdata->governor == GOV_ONDEMAND) io_busy = od_tuners->io_is_busy; cur_idle_time = get_cpu_idle_time(j, &cur_wall_time, io_busy); wall_time = (unsigned int) (cur_wall_time - j_cdbs->prev_cpu_wall); j_cdbs->prev_cpu_wall = cur_wall_time; idle_time = (unsigned int) (cur_idle_time - j_cdbs->prev_cpu_idle); j_cdbs->prev_cpu_idle = cur_idle_time; if (ignore_nice) { u64 cur_nice; unsigned long cur_nice_jiffies; cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE] - cdbs->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); cdbs->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; /* * If the CPU had gone completely idle, and a task just woke up * on this CPU now, it would be unfair to calculate 'load' the * usual way for this elapsed time-window, because it will show * near-zero load, irrespective of how CPU intensive that task * actually is. This is undesirable for latency-sensitive bursty * workloads. * * To avoid this, we reuse the 'load' from the previous * time-window and give this task a chance to start with a * reasonably high CPU frequency. (However, we shouldn't over-do * this copy, lest we get stuck at a high load (high frequency) * for too long, even when the current system load has actually * dropped down. So we perform the copy only once, upon the * first wake-up from idle.) * * Detecting this situation is easy: the governor's deferrable * timer would not have fired during CPU-idle periods. Hence * an unusually large 'wall_time' (as compared to the sampling * rate) indicates this scenario. * * prev_load can be zero in two cases and we must recalculate it * for both cases: * - during long idle intervals * - explicitly set to zero */ if (unlikely(wall_time > (2 * sampling_rate) && j_cdbs->prev_load)) { load = j_cdbs->prev_load; /* * Perform a destructive copy, to ensure that we copy * the previous load only once, upon the first wake-up * from idle. */ j_cdbs->prev_load = 0; } else { load = 100 * (wall_time - idle_time) / wall_time; j_cdbs->prev_load = load; } if (load > max_load) max_load = load; } dbs_data->cdata->gov_check_cpu(cpu, max_load); } EXPORT_SYMBOL_GPL(dbs_check_cpu); static inline void __gov_queue_work(int cpu, struct dbs_data *dbs_data, unsigned int delay) { struct cpu_dbs_common_info *cdbs = dbs_data->cdata->get_cpu_cdbs(cpu); mod_delayed_work_on(cpu, system_wq, &cdbs->work, delay); } void gov_queue_work(struct dbs_data *dbs_data, struct cpufreq_policy *policy, unsigned int delay, bool all_cpus) { int i; mutex_lock(&cpufreq_governor_lock); if (!policy->governor_enabled) goto out_unlock; if (!all_cpus) { /* * Use raw_smp_processor_id() to avoid preemptible warnings. * We know that this is only called with all_cpus == false from * works that have been queued with *_work_on() functions and * those works are canceled during CPU_DOWN_PREPARE so they * can't possibly run on any other CPU. */ __gov_queue_work(raw_smp_processor_id(), dbs_data, delay); } else { for_each_cpu(i, policy->cpus) __gov_queue_work(i, dbs_data, delay); } out_unlock: mutex_unlock(&cpufreq_governor_lock); } EXPORT_SYMBOL_GPL(gov_queue_work); static inline void gov_cancel_work(struct dbs_data *dbs_data, struct cpufreq_policy *policy) { struct cpu_dbs_common_info *cdbs; int i; for_each_cpu(i, policy->cpus) { cdbs = dbs_data->cdata->get_cpu_cdbs(i); cancel_delayed_work_sync(&cdbs->work); } } /* Will return if we need to evaluate cpu load again or not */ bool need_load_eval(struct cpu_dbs_common_info *cdbs, unsigned int sampling_rate) { if (policy_is_shared(cdbs->cur_policy)) { ktime_t time_now = ktime_get(); s64 delta_us = ktime_us_delta(time_now, cdbs->time_stamp); /* Do nothing if we recently have sampled */ if (delta_us < (s64)(sampling_rate / 2)) return false; else cdbs->time_stamp = time_now; } return true; } EXPORT_SYMBOL_GPL(need_load_eval); static void set_sampling_rate(struct dbs_data *dbs_data, unsigned int sampling_rate) { if (dbs_data->cdata->governor == GOV_CONSERVATIVE) { struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; cs_tuners->sampling_rate = sampling_rate; } else { struct od_dbs_tuners *od_tuners = dbs_data->tuners; od_tuners->sampling_rate = sampling_rate; } } int cpufreq_governor_dbs(struct cpufreq_policy *policy, struct common_dbs_data *cdata, unsigned int event) { struct dbs_data *dbs_data; struct od_cpu_dbs_info_s *od_dbs_info = NULL; struct cs_cpu_dbs_info_s *cs_dbs_info = NULL; struct od_ops *od_ops = NULL; struct od_dbs_tuners *od_tuners = NULL; struct cs_dbs_tuners *cs_tuners = NULL; struct cpu_dbs_common_info *cpu_cdbs; unsigned int sampling_rate, latency, ignore_nice, j, cpu = policy->cpu; int io_busy = 0; int rc; if (have_governor_per_policy()) dbs_data = policy->governor_data; else dbs_data = cdata->gdbs_data; WARN_ON(!dbs_data && (event != CPUFREQ_GOV_POLICY_INIT)); switch (event) { case CPUFREQ_GOV_POLICY_INIT: if (have_governor_per_policy()) { WARN_ON(dbs_data); } else if (dbs_data) { dbs_data->usage_count++; policy->governor_data = dbs_data; return 0; } dbs_data = kzalloc(sizeof(*dbs_data), GFP_KERNEL); if (!dbs_data) { pr_err("%s: POLICY_INIT: kzalloc failed\n", __func__); return -ENOMEM; } dbs_data->cdata = cdata; dbs_data->usage_count = 1; rc = cdata->init(dbs_data); if (rc) { pr_err("%s: POLICY_INIT: init() failed\n", __func__); kfree(dbs_data); return rc; } if (!have_governor_per_policy()) WARN_ON(cpufreq_get_global_kobject()); rc = sysfs_create_group(get_governor_parent_kobj(policy), get_sysfs_attr(dbs_data)); if (rc) { cdata->exit(dbs_data); kfree(dbs_data); return rc; } policy->governor_data = dbs_data; /* policy latency is in ns. Convert it to us first */ latency = policy->cpuinfo.transition_latency / 1000; if (latency == 0) latency = 1; /* Bring kernel and HW constraints together */ dbs_data->min_sampling_rate = max(dbs_data->min_sampling_rate, MIN_LATENCY_MULTIPLIER * latency); set_sampling_rate(dbs_data, max(dbs_data->min_sampling_rate, latency * LATENCY_MULTIPLIER)); if ((cdata->governor == GOV_CONSERVATIVE) && (!policy->governor->initialized)) { struct cs_ops *cs_ops = dbs_data->cdata->gov_ops; cpufreq_register_notifier(cs_ops->notifier_block, CPUFREQ_TRANSITION_NOTIFIER); } if (!have_governor_per_policy()) cdata->gdbs_data = dbs_data; return 0; case CPUFREQ_GOV_POLICY_EXIT: if (!--dbs_data->usage_count) { sysfs_remove_group(get_governor_parent_kobj(policy), get_sysfs_attr(dbs_data)); if (!have_governor_per_policy()) cpufreq_put_global_kobject(); if ((dbs_data->cdata->governor == GOV_CONSERVATIVE) && (policy->governor->initialized == 1)) { struct cs_ops *cs_ops = dbs_data->cdata->gov_ops; cpufreq_unregister_notifier(cs_ops->notifier_block, CPUFREQ_TRANSITION_NOTIFIER); } cdata->exit(dbs_data); kfree(dbs_data); cdata->gdbs_data = NULL; } policy->governor_data = NULL; return 0; } cpu_cdbs = dbs_data->cdata->get_cpu_cdbs(cpu); if (dbs_data->cdata->governor == GOV_CONSERVATIVE) { cs_tuners = dbs_data->tuners; cs_dbs_info = dbs_data->cdata->get_cpu_dbs_info_s(cpu); sampling_rate = cs_tuners->sampling_rate; ignore_nice = cs_tuners->ignore_nice_load; } else { od_tuners = dbs_data->tuners; od_dbs_info = dbs_data->cdata->get_cpu_dbs_info_s(cpu); sampling_rate = od_tuners->sampling_rate; ignore_nice = od_tuners->ignore_nice_load; od_ops = dbs_data->cdata->gov_ops; io_busy = od_tuners->io_is_busy; } switch (event) { case CPUFREQ_GOV_START: if (!policy->cur) return -EINVAL; mutex_lock(&dbs_data->mutex); for_each_cpu(j, policy->cpus) { struct cpu_dbs_common_info *j_cdbs = dbs_data->cdata->get_cpu_cdbs(j); unsigned int prev_load; j_cdbs->cpu = j; j_cdbs->cur_policy = policy; j_cdbs->prev_cpu_idle = get_cpu_idle_time(j, &j_cdbs->prev_cpu_wall, io_busy); prev_load = (unsigned int) (j_cdbs->prev_cpu_wall - j_cdbs->prev_cpu_idle); j_cdbs->prev_load = 100 * prev_load / (unsigned int) j_cdbs->prev_cpu_wall; if (ignore_nice) j_cdbs->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE]; mutex_init(&j_cdbs->timer_mutex); INIT_DEFERRABLE_WORK(&j_cdbs->work, dbs_data->cdata->gov_dbs_timer); } if (dbs_data->cdata->governor == GOV_CONSERVATIVE) { cs_dbs_info->down_skip = 0; cs_dbs_info->enable = 1; cs_dbs_info->requested_freq = policy->cur; } else { od_dbs_info->rate_mult = 1; od_dbs_info->sample_type = OD_NORMAL_SAMPLE; od_ops->powersave_bias_init_cpu(cpu); } mutex_unlock(&dbs_data->mutex); /* Initiate timer time stamp */ cpu_cdbs->time_stamp = ktime_get(); gov_queue_work(dbs_data, policy, delay_for_sampling_rate(sampling_rate), true); break; case CPUFREQ_GOV_STOP: if (dbs_data->cdata->governor == GOV_CONSERVATIVE) cs_dbs_info->enable = 0; gov_cancel_work(dbs_data, policy); mutex_lock(&dbs_data->mutex); mutex_destroy(&cpu_cdbs->timer_mutex); cpu_cdbs->cur_policy = NULL; mutex_unlock(&dbs_data->mutex); break; case CPUFREQ_GOV_LIMITS: mutex_lock(&dbs_data->mutex); if (!cpu_cdbs->cur_policy) { mutex_unlock(&dbs_data->mutex); break; } mutex_lock(&cpu_cdbs->timer_mutex); if (policy->max < cpu_cdbs->cur_policy->cur) __cpufreq_driver_target(cpu_cdbs->cur_policy, policy->max, CPUFREQ_RELATION_H); else if (policy->min > cpu_cdbs->cur_policy->cur) __cpufreq_driver_target(cpu_cdbs->cur_policy, policy->min, CPUFREQ_RELATION_L); dbs_check_cpu(dbs_data, cpu); mutex_unlock(&cpu_cdbs->timer_mutex); mutex_unlock(&dbs_data->mutex); break; } return 0; } EXPORT_SYMBOL_GPL(cpufreq_governor_dbs);