/* * drivers/cpufreq/cpufreq_governor.c * * CPUFREQ governors common code * * Copyright (C) 2001 Russell King * (C) 2003 Venkatesh Pallipadi . * (C) 2003 Jun Nakajima * (C) 2009 Alexander Clouter * (c) 2012 Viresh Kumar * * 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 #include #include #include "cpufreq_governor.h" DEFINE_MUTEX(dbs_data_mutex); EXPORT_SYMBOL_GPL(dbs_data_mutex); static struct attribute_group *get_sysfs_attr(struct dbs_governor *gov) { return have_governor_per_policy() ? gov->attr_group_gov_pol : gov->attr_group_gov_sys; } void dbs_check_cpu(struct cpufreq_policy *policy) { int cpu = policy->cpu; struct dbs_governor *gov = dbs_governor_of(policy); struct policy_dbs_info *policy_dbs = policy->governor_data; struct dbs_data *dbs_data = policy_dbs->dbs_data; struct od_dbs_tuners *od_tuners = dbs_data->tuners; struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; unsigned int sampling_rate; unsigned int max_load = 0; unsigned int ignore_nice; unsigned int j; if (gov->governor == GOV_ONDEMAND) { struct od_cpu_dbs_info_s *od_dbs_info = gov->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; } /* Get Absolute Load */ for_each_cpu(j, policy->cpus) { struct cpu_dbs_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 = gov->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 (gov->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; if (cur_idle_time < j_cdbs->prev_cpu_idle) cur_idle_time = j_cdbs->prev_cpu_idle; idle_time = (unsigned int) (cur_idle_time - j_cdbs->prev_cpu_idle); j_cdbs->prev_cpu_idle = cur_idle_time; if (ignore_nice) { struct cpu_dbs_info *cdbs = gov->get_cpu_cdbs(cpu); 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 utilization * update handler would not have run 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; } gov->gov_check_cpu(cpu, max_load); } EXPORT_SYMBOL_GPL(dbs_check_cpu); void gov_set_update_util(struct policy_dbs_info *policy_dbs, unsigned int delay_us) { struct cpufreq_policy *policy = policy_dbs->policy; struct dbs_governor *gov = dbs_governor_of(policy); int cpu; gov_update_sample_delay(policy_dbs, delay_us); policy_dbs->last_sample_time = 0; for_each_cpu(cpu, policy->cpus) { struct cpu_dbs_info *cdbs = gov->get_cpu_cdbs(cpu); cpufreq_set_update_util_data(cpu, &cdbs->update_util); } } EXPORT_SYMBOL_GPL(gov_set_update_util); static inline void gov_clear_update_util(struct cpufreq_policy *policy) { int i; for_each_cpu(i, policy->cpus) cpufreq_set_update_util_data(i, NULL); synchronize_rcu(); } static void gov_cancel_work(struct policy_dbs_info *policy_dbs) { /* Tell dbs_update_util_handler() to skip queuing up work items. */ atomic_inc(&policy_dbs->skip_work); /* * If dbs_update_util_handler() is already running, it may not notice * the incremented skip_work, so wait for it to complete to prevent its * work item from being queued up after the cancel_work_sync() below. */ gov_clear_update_util(policy_dbs->policy); irq_work_sync(&policy_dbs->irq_work); cancel_work_sync(&policy_dbs->work); atomic_set(&policy_dbs->skip_work, 0); } static void dbs_work_handler(struct work_struct *work) { struct policy_dbs_info *policy_dbs; struct cpufreq_policy *policy; struct dbs_governor *gov; unsigned int delay; policy_dbs = container_of(work, struct policy_dbs_info, work); policy = policy_dbs->policy; gov = dbs_governor_of(policy); /* * Make sure cpufreq_governor_limits() isn't evaluating load or the * ondemand governor isn't updating the sampling rate in parallel. */ mutex_lock(&policy_dbs->timer_mutex); delay = gov->gov_dbs_timer(policy); policy_dbs->sample_delay_ns = jiffies_to_nsecs(delay); mutex_unlock(&policy_dbs->timer_mutex); /* * If the atomic operation below is reordered with respect to the * sample delay modification, the utilization update handler may end * up using a stale sample delay value. */ smp_mb__before_atomic(); atomic_dec(&policy_dbs->skip_work); } static void dbs_irq_work(struct irq_work *irq_work) { struct policy_dbs_info *policy_dbs; policy_dbs = container_of(irq_work, struct policy_dbs_info, irq_work); schedule_work(&policy_dbs->work); } static inline void gov_queue_irq_work(struct policy_dbs_info *policy_dbs) { #ifdef CONFIG_SMP irq_work_queue_on(&policy_dbs->irq_work, smp_processor_id()); #else irq_work_queue(&policy_dbs->irq_work); #endif } static void dbs_update_util_handler(struct update_util_data *data, u64 time, unsigned long util, unsigned long max) { struct cpu_dbs_info *cdbs = container_of(data, struct cpu_dbs_info, update_util); struct policy_dbs_info *policy_dbs = cdbs->policy_dbs; /* * The work may not be allowed to be queued up right now. * Possible reasons: * - Work has already been queued up or is in progress. * - The governor is being stopped. * - It is too early (too little time from the previous sample). */ if (atomic_inc_return(&policy_dbs->skip_work) == 1) { u64 delta_ns; delta_ns = time - policy_dbs->last_sample_time; if ((s64)delta_ns >= policy_dbs->sample_delay_ns) { policy_dbs->last_sample_time = time; gov_queue_irq_work(policy_dbs); return; } } atomic_dec(&policy_dbs->skip_work); } static void set_sampling_rate(struct dbs_data *dbs_data, struct dbs_governor *gov, unsigned int sampling_rate) { if (gov->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; } } static struct policy_dbs_info *alloc_policy_dbs_info(struct cpufreq_policy *policy, struct dbs_governor *gov) { struct policy_dbs_info *policy_dbs; int j; /* Allocate memory for the common information for policy->cpus */ policy_dbs = kzalloc(sizeof(*policy_dbs), GFP_KERNEL); if (!policy_dbs) return NULL; /* Set policy_dbs for all CPUs, online+offline */ for_each_cpu(j, policy->related_cpus) gov->get_cpu_cdbs(j)->policy_dbs = policy_dbs; mutex_init(&policy_dbs->timer_mutex); atomic_set(&policy_dbs->skip_work, 0); init_irq_work(&policy_dbs->irq_work, dbs_irq_work); INIT_WORK(&policy_dbs->work, dbs_work_handler); return policy_dbs; } static void free_policy_dbs_info(struct cpufreq_policy *policy, struct dbs_governor *gov) { struct cpu_dbs_info *cdbs = gov->get_cpu_cdbs(policy->cpu); struct policy_dbs_info *policy_dbs = cdbs->policy_dbs; int j; mutex_destroy(&policy_dbs->timer_mutex); for_each_cpu(j, policy->cpus) gov->get_cpu_cdbs(j)->policy_dbs = NULL; kfree(policy_dbs); } static int cpufreq_governor_init(struct cpufreq_policy *policy) { struct dbs_governor *gov = dbs_governor_of(policy); struct dbs_data *dbs_data = gov->gdbs_data; struct policy_dbs_info *policy_dbs; unsigned int latency; int ret; /* State should be equivalent to EXIT */ if (policy->governor_data) return -EBUSY; policy_dbs = alloc_policy_dbs_info(policy, gov); if (!policy_dbs) return -ENOMEM; if (dbs_data) { if (WARN_ON(have_governor_per_policy())) { ret = -EINVAL; goto free_policy_dbs_info; } dbs_data->usage_count++; policy_dbs->dbs_data = dbs_data; policy->governor_data = policy_dbs; return 0; } dbs_data = kzalloc(sizeof(*dbs_data), GFP_KERNEL); if (!dbs_data) { ret = -ENOMEM; goto free_policy_dbs_info; } dbs_data->usage_count = 1; ret = gov->init(dbs_data, !policy->governor->initialized); if (ret) goto free_policy_dbs_info; /* 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, gov, max(dbs_data->min_sampling_rate, latency * LATENCY_MULTIPLIER)); if (!have_governor_per_policy()) gov->gdbs_data = dbs_data; policy_dbs->dbs_data = dbs_data; policy->governor_data = policy_dbs; ret = sysfs_create_group(get_governor_parent_kobj(policy), get_sysfs_attr(gov)); if (ret) goto reset_gdbs_data; return 0; reset_gdbs_data: policy->governor_data = NULL; if (!have_governor_per_policy()) gov->gdbs_data = NULL; gov->exit(dbs_data, !policy->governor->initialized); kfree(dbs_data); free_policy_dbs_info: free_policy_dbs_info(policy, gov); return ret; } static int cpufreq_governor_exit(struct cpufreq_policy *policy) { struct dbs_governor *gov = dbs_governor_of(policy); struct policy_dbs_info *policy_dbs = policy->governor_data; struct dbs_data *dbs_data = policy_dbs->dbs_data; /* State should be equivalent to INIT */ if (policy_dbs->policy) return -EBUSY; if (!--dbs_data->usage_count) { sysfs_remove_group(get_governor_parent_kobj(policy), get_sysfs_attr(gov)); policy->governor_data = NULL; if (!have_governor_per_policy()) gov->gdbs_data = NULL; gov->exit(dbs_data, policy->governor->initialized == 1); kfree(dbs_data); } else { policy->governor_data = NULL; } free_policy_dbs_info(policy, gov); return 0; } static int cpufreq_governor_start(struct cpufreq_policy *policy) { struct dbs_governor *gov = dbs_governor_of(policy); struct policy_dbs_info *policy_dbs = policy->governor_data; struct dbs_data *dbs_data = policy_dbs->dbs_data; unsigned int sampling_rate, ignore_nice, j, cpu = policy->cpu; int io_busy = 0; if (!policy->cur) return -EINVAL; /* State should be equivalent to INIT */ if (policy_dbs->policy) return -EBUSY; if (gov->governor == GOV_CONSERVATIVE) { struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; sampling_rate = cs_tuners->sampling_rate; ignore_nice = cs_tuners->ignore_nice_load; } else { struct od_dbs_tuners *od_tuners = dbs_data->tuners; sampling_rate = od_tuners->sampling_rate; ignore_nice = od_tuners->ignore_nice_load; io_busy = od_tuners->io_is_busy; } for_each_cpu(j, policy->cpus) { struct cpu_dbs_info *j_cdbs = gov->get_cpu_cdbs(j); unsigned int prev_load; 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]; j_cdbs->update_util.func = dbs_update_util_handler; } policy_dbs->policy = policy; if (gov->governor == GOV_CONSERVATIVE) { struct cs_cpu_dbs_info_s *cs_dbs_info = gov->get_cpu_dbs_info_s(cpu); cs_dbs_info->down_skip = 0; cs_dbs_info->requested_freq = policy->cur; } else { struct od_ops *od_ops = gov->gov_ops; struct od_cpu_dbs_info_s *od_dbs_info = gov->get_cpu_dbs_info_s(cpu); od_dbs_info->rate_mult = 1; od_dbs_info->sample_type = OD_NORMAL_SAMPLE; od_ops->powersave_bias_init_cpu(cpu); } gov_set_update_util(policy_dbs, sampling_rate); return 0; } static int cpufreq_governor_stop(struct cpufreq_policy *policy) { struct policy_dbs_info *policy_dbs = policy->governor_data; /* State should be equivalent to START */ if (!policy_dbs->policy) return -EBUSY; gov_cancel_work(policy_dbs); policy_dbs->policy = NULL; return 0; } static int cpufreq_governor_limits(struct cpufreq_policy *policy) { struct policy_dbs_info *policy_dbs = policy->governor_data; /* State should be equivalent to START */ if (!policy_dbs->policy) return -EBUSY; mutex_lock(&policy_dbs->timer_mutex); if (policy->max < policy->cur) __cpufreq_driver_target(policy, policy->max, CPUFREQ_RELATION_H); else if (policy->min > policy->cur) __cpufreq_driver_target(policy, policy->min, CPUFREQ_RELATION_L); dbs_check_cpu(policy); mutex_unlock(&policy_dbs->timer_mutex); return 0; } int cpufreq_governor_dbs(struct cpufreq_policy *policy, unsigned int event) { int ret = -EINVAL; /* Lock governor to block concurrent initialization of governor */ mutex_lock(&dbs_data_mutex); if (event == CPUFREQ_GOV_POLICY_INIT) { ret = cpufreq_governor_init(policy); } else if (policy->governor_data) { switch (event) { case CPUFREQ_GOV_POLICY_EXIT: ret = cpufreq_governor_exit(policy); break; case CPUFREQ_GOV_START: ret = cpufreq_governor_start(policy); break; case CPUFREQ_GOV_STOP: ret = cpufreq_governor_stop(policy); break; case CPUFREQ_GOV_LIMITS: ret = cpufreq_governor_limits(policy); break; } } mutex_unlock(&dbs_data_mutex); return ret; } EXPORT_SYMBOL_GPL(cpufreq_governor_dbs);