diff options
Diffstat (limited to 'kernel/sched/cpufreq_schedutil.c')
| -rw-r--r-- | kernel/sched/cpufreq_schedutil.c | 770 |
1 files changed, 770 insertions, 0 deletions
diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c new file mode 100644 index 000000000000..75bfbb336722 --- /dev/null +++ b/kernel/sched/cpufreq_schedutil.c @@ -0,0 +1,770 @@ +/* + * CPUFreq governor based on scheduler-provided CPU utilization data. + * + * Copyright (C) 2016, Intel Corporation + * Author: Rafael J. Wysocki <rafael.j.wysocki@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. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/cpufreq.h> +#include <linux/kthread.h> +#include <linux/slab.h> +#include <trace/events/power.h> + +#include "sched.h" +#include "tune.h" + +unsigned long boosted_cpu_util(int cpu); + +/* Stub out fast switch routines present on mainline to reduce the backport + * overhead. */ +#define cpufreq_driver_fast_switch(x, y) 0 +#define cpufreq_enable_fast_switch(x) +#define cpufreq_disable_fast_switch(x) +#define LATENCY_MULTIPLIER (1000) +#define SUGOV_KTHREAD_PRIORITY 50 + +struct sugov_tunables { + struct gov_attr_set attr_set; + unsigned int up_rate_limit_us; + unsigned int down_rate_limit_us; +}; + +struct sugov_policy { + struct cpufreq_policy *policy; + + struct sugov_tunables *tunables; + struct list_head tunables_hook; + + raw_spinlock_t update_lock; /* For shared policies */ + u64 last_freq_update_time; + s64 min_rate_limit_ns; + s64 up_rate_delay_ns; + s64 down_rate_delay_ns; + unsigned int next_freq; + + /* The next fields are only needed if fast switch cannot be used. */ + struct irq_work irq_work; + struct kthread_work work; + struct mutex work_lock; + struct kthread_worker worker; + struct task_struct *thread; + bool work_in_progress; + + bool need_freq_update; +}; + +struct sugov_cpu { + struct update_util_data update_util; + struct sugov_policy *sg_policy; + + unsigned int cached_raw_freq; + unsigned long iowait_boost; + unsigned long iowait_boost_max; + u64 last_update; + + /* The fields below are only needed when sharing a policy. */ + unsigned long util; + unsigned long max; + unsigned int flags; +}; + +static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu); + +/************************ Governor internals ***********************/ + +static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time) +{ + s64 delta_ns; + + if (sg_policy->work_in_progress) + return false; + + if (unlikely(sg_policy->need_freq_update)) { + sg_policy->need_freq_update = false; + /* + * This happens when limits change, so forget the previous + * next_freq value and force an update. + */ + sg_policy->next_freq = UINT_MAX; + return true; + } + + delta_ns = time - sg_policy->last_freq_update_time; + + /* No need to recalculate next freq for min_rate_limit_us at least */ + return delta_ns >= sg_policy->min_rate_limit_ns; +} + +static bool sugov_up_down_rate_limit(struct sugov_policy *sg_policy, u64 time, + unsigned int next_freq) +{ + s64 delta_ns; + + delta_ns = time - sg_policy->last_freq_update_time; + + if (next_freq > sg_policy->next_freq && + delta_ns < sg_policy->up_rate_delay_ns) + return true; + + if (next_freq < sg_policy->next_freq && + delta_ns < sg_policy->down_rate_delay_ns) + return true; + + return false; +} + +static void sugov_update_commit(struct sugov_policy *sg_policy, u64 time, + unsigned int next_freq) +{ + struct cpufreq_policy *policy = sg_policy->policy; + + if (sugov_up_down_rate_limit(sg_policy, time, next_freq)) + return; + + if (policy->fast_switch_enabled) { + if (sg_policy->next_freq == next_freq) { + trace_cpu_frequency(policy->cur, smp_processor_id()); + return; + } + sg_policy->next_freq = next_freq; + sg_policy->last_freq_update_time = time; + next_freq = cpufreq_driver_fast_switch(policy, next_freq); + if (next_freq == CPUFREQ_ENTRY_INVALID) + return; + + policy->cur = next_freq; + trace_cpu_frequency(next_freq, smp_processor_id()); + } else if (sg_policy->next_freq != next_freq) { + sg_policy->next_freq = next_freq; + sg_policy->last_freq_update_time = time; + sg_policy->work_in_progress = true; + irq_work_queue(&sg_policy->irq_work); + } +} + +/** + * get_next_freq - Compute a new frequency for a given cpufreq policy. + * @sg_cpu: schedutil cpu object to compute the new frequency for. + * @util: Current CPU utilization. + * @max: CPU capacity. + * + * If the utilization is frequency-invariant, choose the new frequency to be + * proportional to it, that is + * + * next_freq = C * max_freq * util / max + * + * Otherwise, approximate the would-be frequency-invariant utilization by + * util_raw * (curr_freq / max_freq) which leads to + * + * next_freq = C * curr_freq * util_raw / max + * + * Take C = 1.25 for the frequency tipping point at (util / max) = 0.8. + * + * The lowest driver-supported frequency which is equal or greater than the raw + * next_freq (as calculated above) is returned, subject to policy min/max and + * cpufreq driver limitations. + */ +static unsigned int get_next_freq(struct sugov_cpu *sg_cpu, unsigned long util, + unsigned long max) +{ + struct sugov_policy *sg_policy = sg_cpu->sg_policy; + struct cpufreq_policy *policy = sg_policy->policy; + unsigned int freq = arch_scale_freq_invariant() ? + policy->cpuinfo.max_freq : policy->cur; + + freq = (freq + (freq >> 2)) * util / max; + + if (freq == sg_cpu->cached_raw_freq && sg_policy->next_freq != UINT_MAX) + return sg_policy->next_freq; + sg_cpu->cached_raw_freq = freq; + return cpufreq_driver_resolve_freq(policy, freq); +} + +static inline bool use_pelt(void) +{ +#ifdef CONFIG_SCHED_WALT + return (!sysctl_sched_use_walt_cpu_util || walt_disabled); +#else + return true; +#endif +} + +static void sugov_get_util(unsigned long *util, unsigned long *max, u64 time) +{ + int cpu = smp_processor_id(); + struct rq *rq = cpu_rq(cpu); + unsigned long max_cap, rt; + s64 delta; + + max_cap = arch_scale_cpu_capacity(NULL, cpu); + + sched_avg_update(rq); + delta = time - rq->age_stamp; + if (unlikely(delta < 0)) + delta = 0; + rt = div64_u64(rq->rt_avg, sched_avg_period() + delta); + rt = (rt * max_cap) >> SCHED_CAPACITY_SHIFT; + + *util = boosted_cpu_util(cpu); + if (likely(use_pelt())) + *util = min((*util + rt), max_cap); + + *max = max_cap; +} + +static void sugov_set_iowait_boost(struct sugov_cpu *sg_cpu, u64 time, + unsigned int flags) +{ + if (flags & SCHED_CPUFREQ_IOWAIT) { + sg_cpu->iowait_boost = sg_cpu->iowait_boost_max; + } else if (sg_cpu->iowait_boost) { + s64 delta_ns = time - sg_cpu->last_update; + + /* Clear iowait_boost if the CPU apprears to have been idle. */ + if (delta_ns > TICK_NSEC) + sg_cpu->iowait_boost = 0; + } +} + +static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, unsigned long *util, + unsigned long *max) +{ + unsigned long boost_util = sg_cpu->iowait_boost; + unsigned long boost_max = sg_cpu->iowait_boost_max; + + if (!boost_util) + return; + + if (*util * boost_max < *max * boost_util) { + *util = boost_util; + *max = boost_max; + } + sg_cpu->iowait_boost >>= 1; +} + +static void sugov_update_single(struct update_util_data *hook, u64 time, + unsigned int flags) +{ + struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util); + struct sugov_policy *sg_policy = sg_cpu->sg_policy; + struct cpufreq_policy *policy = sg_policy->policy; + unsigned long util, max; + unsigned int next_f; + + sugov_set_iowait_boost(sg_cpu, time, flags); + sg_cpu->last_update = time; + + if (!sugov_should_update_freq(sg_policy, time)) + return; + + if (flags & SCHED_CPUFREQ_DL) { + next_f = policy->cpuinfo.max_freq; + } else { + sugov_get_util(&util, &max, time); + sugov_iowait_boost(sg_cpu, &util, &max); + next_f = get_next_freq(sg_cpu, util, max); + } + sugov_update_commit(sg_policy, time, next_f); +} + +static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, + unsigned long util, unsigned long max, + unsigned int flags) +{ + struct sugov_policy *sg_policy = sg_cpu->sg_policy; + struct cpufreq_policy *policy = sg_policy->policy; + unsigned int max_f = policy->cpuinfo.max_freq; + u64 last_freq_update_time = sg_policy->last_freq_update_time; + unsigned int j; + + if (flags & SCHED_CPUFREQ_DL) + return max_f; + + sugov_iowait_boost(sg_cpu, &util, &max); + + for_each_cpu(j, policy->cpus) { + struct sugov_cpu *j_sg_cpu; + unsigned long j_util, j_max; + s64 delta_ns; + + if (j == smp_processor_id()) + continue; + + j_sg_cpu = &per_cpu(sugov_cpu, j); + /* + * If the CPU utilization was last updated before the previous + * frequency update and the time elapsed between the last update + * of the CPU utilization and the last frequency update is long + * enough, don't take the CPU into account as it probably is + * idle now (and clear iowait_boost for it). + */ + delta_ns = last_freq_update_time - j_sg_cpu->last_update; + if (delta_ns > TICK_NSEC) { + j_sg_cpu->iowait_boost = 0; + continue; + } + if (j_sg_cpu->flags & SCHED_CPUFREQ_DL) + return max_f; + + j_util = j_sg_cpu->util; + j_max = j_sg_cpu->max; + if (j_util * max > j_max * util) { + util = j_util; + max = j_max; + } + + sugov_iowait_boost(j_sg_cpu, &util, &max); + } + + return get_next_freq(sg_cpu, util, max); +} + +static void sugov_update_shared(struct update_util_data *hook, u64 time, + unsigned int flags) +{ + struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util); + struct sugov_policy *sg_policy = sg_cpu->sg_policy; + unsigned long util, max; + unsigned int next_f; + + sugov_get_util(&util, &max, time); + + raw_spin_lock(&sg_policy->update_lock); + + sg_cpu->util = util; + sg_cpu->max = max; + sg_cpu->flags = flags; + + sugov_set_iowait_boost(sg_cpu, time, flags); + sg_cpu->last_update = time; + + if (sugov_should_update_freq(sg_policy, time)) { + next_f = sugov_next_freq_shared(sg_cpu, util, max, flags); + sugov_update_commit(sg_policy, time, next_f); + } + + raw_spin_unlock(&sg_policy->update_lock); +} + +static void sugov_work(struct kthread_work *work) +{ + struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work); + + mutex_lock(&sg_policy->work_lock); + __cpufreq_driver_target(sg_policy->policy, sg_policy->next_freq, + CPUFREQ_RELATION_L); + mutex_unlock(&sg_policy->work_lock); + + sg_policy->work_in_progress = false; +} + +static void sugov_irq_work(struct irq_work *irq_work) +{ + struct sugov_policy *sg_policy; + + sg_policy = container_of(irq_work, struct sugov_policy, irq_work); + + /* + * For Real Time and Deadline tasks, schedutil governor shoots the + * frequency to maximum. And special care must be taken to ensure that + * this kthread doesn't result in that. + * + * This is (mostly) guaranteed by the work_in_progress flag. The flag is + * updated only at the end of the sugov_work() and before that schedutil + * rejects all other frequency scaling requests. + * + * Though there is a very rare case where the RT thread yields right + * after the work_in_progress flag is cleared. The effects of that are + * neglected for now. + */ + queue_kthread_work(&sg_policy->worker, &sg_policy->work); +} + +/************************** sysfs interface ************************/ + +static struct sugov_tunables *global_tunables; +static DEFINE_MUTEX(global_tunables_lock); + +static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set) +{ + return container_of(attr_set, struct sugov_tunables, attr_set); +} + +static DEFINE_MUTEX(min_rate_lock); + +static void update_min_rate_limit_us(struct sugov_policy *sg_policy) +{ + mutex_lock(&min_rate_lock); + sg_policy->min_rate_limit_ns = min(sg_policy->up_rate_delay_ns, + sg_policy->down_rate_delay_ns); + mutex_unlock(&min_rate_lock); +} + +static ssize_t up_rate_limit_us_show(struct gov_attr_set *attr_set, char *buf) +{ + struct sugov_tunables *tunables = to_sugov_tunables(attr_set); + + return sprintf(buf, "%u\n", tunables->up_rate_limit_us); +} + +static ssize_t down_rate_limit_us_show(struct gov_attr_set *attr_set, char *buf) +{ + struct sugov_tunables *tunables = to_sugov_tunables(attr_set); + + return sprintf(buf, "%u\n", tunables->down_rate_limit_us); +} + +static ssize_t up_rate_limit_us_store(struct gov_attr_set *attr_set, + const char *buf, size_t count) +{ + struct sugov_tunables *tunables = to_sugov_tunables(attr_set); + struct sugov_policy *sg_policy; + unsigned int rate_limit_us; + + if (kstrtouint(buf, 10, &rate_limit_us)) + return -EINVAL; + + tunables->up_rate_limit_us = rate_limit_us; + + list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook) { + sg_policy->up_rate_delay_ns = rate_limit_us * NSEC_PER_USEC; + update_min_rate_limit_us(sg_policy); + } + + return count; +} + +static ssize_t down_rate_limit_us_store(struct gov_attr_set *attr_set, + const char *buf, size_t count) +{ + struct sugov_tunables *tunables = to_sugov_tunables(attr_set); + struct sugov_policy *sg_policy; + unsigned int rate_limit_us; + + if (kstrtouint(buf, 10, &rate_limit_us)) + return -EINVAL; + + tunables->down_rate_limit_us = rate_limit_us; + + list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook) { + sg_policy->down_rate_delay_ns = rate_limit_us * NSEC_PER_USEC; + update_min_rate_limit_us(sg_policy); + } + + return count; +} + +static struct governor_attr up_rate_limit_us = __ATTR_RW(up_rate_limit_us); +static struct governor_attr down_rate_limit_us = __ATTR_RW(down_rate_limit_us); + +static struct attribute *sugov_attributes[] = { + &up_rate_limit_us.attr, + &down_rate_limit_us.attr, + NULL +}; + +static struct kobj_type sugov_tunables_ktype = { + .default_attrs = sugov_attributes, + .sysfs_ops = &governor_sysfs_ops, +}; + +/********************** cpufreq governor interface *********************/ +#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL +static +#endif +struct cpufreq_governor cpufreq_gov_schedutil; + +static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy) +{ + struct sugov_policy *sg_policy; + + sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL); + if (!sg_policy) + return NULL; + + sg_policy->policy = policy; + init_irq_work(&sg_policy->irq_work, sugov_irq_work); + mutex_init(&sg_policy->work_lock); + raw_spin_lock_init(&sg_policy->update_lock); + return sg_policy; +} + +static void sugov_policy_free(struct sugov_policy *sg_policy) +{ + mutex_destroy(&sg_policy->work_lock); + kfree(sg_policy); +} + +static int sugov_kthread_create(struct sugov_policy *sg_policy) +{ + struct task_struct *thread; + struct sched_param param = { .sched_priority = MAX_USER_RT_PRIO / 2 }; + struct cpufreq_policy *policy = sg_policy->policy; + int ret; + + /* kthread only required for slow path */ + if (policy->fast_switch_enabled) + return 0; + + init_kthread_work(&sg_policy->work, sugov_work); + init_kthread_worker(&sg_policy->worker); + thread = kthread_create(kthread_worker_fn, &sg_policy->worker, + "sugov:%d", + cpumask_first(policy->related_cpus)); + if (IS_ERR(thread)) { + pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread)); + return PTR_ERR(thread); + } + + ret = sched_setscheduler_nocheck(thread, SCHED_FIFO, ¶m); + if (ret) { + kthread_stop(thread); + pr_warn("%s: failed to set SCHED_FIFO\n", __func__); + return ret; + } + + sg_policy->thread = thread; + kthread_bind_mask(thread, policy->related_cpus); + wake_up_process(thread); + + return 0; +} + +static void sugov_kthread_stop(struct sugov_policy *sg_policy) +{ + /* kthread only required for slow path */ + if (sg_policy->policy->fast_switch_enabled) + return; + + flush_kthread_worker(&sg_policy->worker); + kthread_stop(sg_policy->thread); +} + +static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy) +{ + struct sugov_tunables *tunables; + + tunables = kzalloc(sizeof(*tunables), GFP_KERNEL); + if (tunables) { + gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook); + if (!have_governor_per_policy()) + global_tunables = tunables; + } + return tunables; +} + +static void sugov_tunables_free(struct sugov_tunables *tunables) +{ + if (!have_governor_per_policy()) + global_tunables = NULL; + + kfree(tunables); +} + +static int sugov_init(struct cpufreq_policy *policy) +{ + struct sugov_policy *sg_policy; + struct sugov_tunables *tunables; + unsigned int lat; + int ret = 0; + + /* State should be equivalent to EXIT */ + if (policy->governor_data) + return -EBUSY; + + sg_policy = sugov_policy_alloc(policy); + if (!sg_policy) + return -ENOMEM; + + ret = sugov_kthread_create(sg_policy); + if (ret) + goto free_sg_policy; + + mutex_lock(&global_tunables_lock); + + if (global_tunables) { + if (WARN_ON(have_governor_per_policy())) { + ret = -EINVAL; + goto stop_kthread; + } + policy->governor_data = sg_policy; + sg_policy->tunables = global_tunables; + + gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook); + goto out; + } + + tunables = sugov_tunables_alloc(sg_policy); + if (!tunables) { + ret = -ENOMEM; + goto stop_kthread; + } + + tunables->up_rate_limit_us = LATENCY_MULTIPLIER; + tunables->down_rate_limit_us = LATENCY_MULTIPLIER; + lat = policy->cpuinfo.transition_latency / NSEC_PER_USEC; + if (lat) { + tunables->up_rate_limit_us *= lat; + tunables->down_rate_limit_us *= lat; + } + + policy->governor_data = sg_policy; + sg_policy->tunables = tunables; + + ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype, + get_governor_parent_kobj(policy), "%s", + cpufreq_gov_schedutil.name); + if (ret) + goto fail; + + out: + mutex_unlock(&global_tunables_lock); + + cpufreq_enable_fast_switch(policy); + return 0; + + fail: + policy->governor_data = NULL; + sugov_tunables_free(tunables); + +stop_kthread: + sugov_kthread_stop(sg_policy); + +free_sg_policy: + mutex_unlock(&global_tunables_lock); + + sugov_policy_free(sg_policy); + pr_err("initialization failed (error %d)\n", ret); + return ret; +} + +static int sugov_exit(struct cpufreq_policy *policy) +{ + struct sugov_policy *sg_policy = policy->governor_data; + struct sugov_tunables *tunables = sg_policy->tunables; + unsigned int count; + + cpufreq_disable_fast_switch(policy); + + mutex_lock(&global_tunables_lock); + + count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook); + policy->governor_data = NULL; + if (!count) + sugov_tunables_free(tunables); + + mutex_unlock(&global_tunables_lock); + + sugov_kthread_stop(sg_policy); + sugov_policy_free(sg_policy); + + return 0; +} + +static int sugov_start(struct cpufreq_policy *policy) +{ + struct sugov_policy *sg_policy = policy->governor_data; + unsigned int cpu; + + sg_policy->up_rate_delay_ns = + sg_policy->tunables->up_rate_limit_us * NSEC_PER_USEC; + sg_policy->down_rate_delay_ns = + sg_policy->tunables->down_rate_limit_us * NSEC_PER_USEC; + update_min_rate_limit_us(sg_policy); + sg_policy->last_freq_update_time = 0; + sg_policy->next_freq = UINT_MAX; + sg_policy->work_in_progress = false; + sg_policy->need_freq_update = false; + + for_each_cpu(cpu, policy->cpus) { + struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu); + + sg_cpu->sg_policy = sg_policy; + if (policy_is_shared(policy)) { + sg_cpu->util = 0; + sg_cpu->max = 0; + sg_cpu->flags = SCHED_CPUFREQ_DL; + sg_cpu->last_update = 0; + sg_cpu->cached_raw_freq = 0; + sg_cpu->iowait_boost = 0; + sg_cpu->iowait_boost_max = policy->cpuinfo.max_freq; + cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util, + sugov_update_shared); + } else { + cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util, + sugov_update_single); + } + } + return 0; +} + +static int sugov_stop(struct cpufreq_policy *policy) +{ + struct sugov_policy *sg_policy = policy->governor_data; + unsigned int cpu; + + for_each_cpu(cpu, policy->cpus) + cpufreq_remove_update_util_hook(cpu); + + synchronize_sched(); + + irq_work_sync(&sg_policy->irq_work); + kthread_cancel_work_sync(&sg_policy->work); + + return 0; +} + +static int sugov_limits(struct cpufreq_policy *policy) +{ + struct sugov_policy *sg_policy = policy->governor_data; + + if (!policy->fast_switch_enabled) { + mutex_lock(&sg_policy->work_lock); + cpufreq_policy_apply_limits(policy); + mutex_unlock(&sg_policy->work_lock); + } + + sg_policy->need_freq_update = true; + + return 0; +} + +static int cpufreq_schedutil_cb(struct cpufreq_policy *policy, + unsigned int event) +{ + switch(event) { + case CPUFREQ_GOV_POLICY_INIT: + return sugov_init(policy); + case CPUFREQ_GOV_POLICY_EXIT: + return sugov_exit(policy); + case CPUFREQ_GOV_START: + return sugov_start(policy); + case CPUFREQ_GOV_STOP: + return sugov_stop(policy); + case CPUFREQ_GOV_LIMITS: + return sugov_limits(policy); + default: + BUG(); + } +} + +#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL +static +#endif +struct cpufreq_governor cpufreq_gov_schedutil = { + .name = "schedutil", + .governor = cpufreq_schedutil_cb, + .owner = THIS_MODULE, +}; + +static int __init sugov_register(void) +{ + return cpufreq_register_governor(&cpufreq_gov_schedutil); +} +fs_initcall(sugov_register); |