diff options
Diffstat (limited to 'kernel/sched/cpufreq_sched.c')
| -rw-r--r-- | kernel/sched/cpufreq_sched.c | 500 |
1 files changed, 500 insertions, 0 deletions
diff --git a/kernel/sched/cpufreq_sched.c b/kernel/sched/cpufreq_sched.c new file mode 100644 index 000000000000..8fe35577a131 --- /dev/null +++ b/kernel/sched/cpufreq_sched.c @@ -0,0 +1,500 @@ +/* + * Copyright (C) 2015 Michael Turquette <mturquette@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. + */ + +#include <linux/cpufreq.h> +#include <linux/module.h> +#include <linux/kthread.h> +#include <linux/percpu.h> +#include <linux/irq_work.h> +#include <linux/delay.h> +#include <linux/string.h> + +#define CREATE_TRACE_POINTS +#include <trace/events/cpufreq_sched.h> + +#include "sched.h" + +#define THROTTLE_DOWN_NSEC 50000000 /* 50ms default */ +#define THROTTLE_UP_NSEC 500000 /* 500us default */ + +struct static_key __read_mostly __sched_freq = STATIC_KEY_INIT_FALSE; +static bool __read_mostly cpufreq_driver_slow; + +#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHED +static struct cpufreq_governor cpufreq_gov_sched; +#endif + +static DEFINE_PER_CPU(unsigned long, enabled); +DEFINE_PER_CPU(struct sched_capacity_reqs, cpu_sched_capacity_reqs); + +/** + * gov_data - per-policy data internal to the governor + * @up_throttle: next throttling period expiry if increasing OPP + * @down_throttle: next throttling period expiry if decreasing OPP + * @up_throttle_nsec: throttle period length in nanoseconds if increasing OPP + * @down_throttle_nsec: throttle period length in nanoseconds if decreasing OPP + * @task: worker thread for dvfs transition that may block/sleep + * @irq_work: callback used to wake up worker thread + * @requested_freq: last frequency requested by the sched governor + * + * struct gov_data is the per-policy cpufreq_sched-specific data structure. A + * per-policy instance of it is created when the cpufreq_sched governor receives + * the CPUFREQ_GOV_START condition and a pointer to it exists in the gov_data + * member of struct cpufreq_policy. + * + * Readers of this data must call down_read(policy->rwsem). Writers must + * call down_write(policy->rwsem). + */ +struct gov_data { + ktime_t up_throttle; + ktime_t down_throttle; + unsigned int up_throttle_nsec; + unsigned int down_throttle_nsec; + struct task_struct *task; + struct irq_work irq_work; + unsigned int requested_freq; +}; + +static void cpufreq_sched_try_driver_target(struct cpufreq_policy *policy, + unsigned int freq) +{ + struct gov_data *gd = policy->governor_data; + + /* avoid race with cpufreq_sched_stop */ + if (!down_write_trylock(&policy->rwsem)) + return; + + __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L); + + gd->up_throttle = ktime_add_ns(ktime_get(), gd->up_throttle_nsec); + gd->down_throttle = ktime_add_ns(ktime_get(), gd->down_throttle_nsec); + up_write(&policy->rwsem); +} + +static bool finish_last_request(struct gov_data *gd, unsigned int cur_freq) +{ + ktime_t now = ktime_get(); + + ktime_t throttle = gd->requested_freq < cur_freq ? + gd->down_throttle : gd->up_throttle; + + if (ktime_after(now, throttle)) + return false; + + while (1) { + int usec_left = ktime_to_ns(ktime_sub(throttle, now)); + + usec_left /= NSEC_PER_USEC; + trace_cpufreq_sched_throttled(usec_left); + usleep_range(usec_left, usec_left + 100); + now = ktime_get(); + if (ktime_after(now, throttle)) + return true; + } +} + +/* + * we pass in struct cpufreq_policy. This is safe because changing out the + * policy requires a call to __cpufreq_governor(policy, CPUFREQ_GOV_STOP), + * which tears down all of the data structures and __cpufreq_governor(policy, + * CPUFREQ_GOV_START) will do a full rebuild, including this kthread with the + * new policy pointer + */ +static int cpufreq_sched_thread(void *data) +{ + struct sched_param param; + struct cpufreq_policy *policy; + struct gov_data *gd; + unsigned int new_request = 0; + unsigned int last_request = 0; + int ret; + + policy = (struct cpufreq_policy *) data; + gd = policy->governor_data; + + param.sched_priority = 50; + ret = sched_setscheduler_nocheck(gd->task, SCHED_FIFO, ¶m); + if (ret) { + pr_warn("%s: failed to set SCHED_FIFO\n", __func__); + do_exit(-EINVAL); + } else { + pr_debug("%s: kthread (%d) set to SCHED_FIFO\n", + __func__, gd->task->pid); + } + + do { + new_request = gd->requested_freq; + if (new_request == last_request) { + set_current_state(TASK_INTERRUPTIBLE); + if (kthread_should_stop()) + break; + schedule(); + } else { + /* + * if the frequency thread sleeps while waiting to be + * unthrottled, start over to check for a newer request + */ + if (finish_last_request(gd, policy->cur)) + continue; + last_request = new_request; + cpufreq_sched_try_driver_target(policy, new_request); + } + } while (!kthread_should_stop()); + + return 0; +} + +static void cpufreq_sched_irq_work(struct irq_work *irq_work) +{ + struct gov_data *gd; + + gd = container_of(irq_work, struct gov_data, irq_work); + if (!gd) + return; + + wake_up_process(gd->task); +} + +static void update_fdomain_capacity_request(int cpu) +{ + unsigned int freq_new, index_new, cpu_tmp; + struct cpufreq_policy *policy; + struct gov_data *gd; + unsigned long capacity = 0; + + /* + * Avoid grabbing the policy if possible. A test is still + * required after locking the CPU's policy to avoid racing + * with the governor changing. + */ + if (!per_cpu(enabled, cpu)) + return; + + policy = cpufreq_cpu_get(cpu); + if (IS_ERR_OR_NULL(policy)) + return; + + if (policy->governor != &cpufreq_gov_sched || + !policy->governor_data) + goto out; + + gd = policy->governor_data; + + /* find max capacity requested by cpus in this policy */ + for_each_cpu(cpu_tmp, policy->cpus) { + struct sched_capacity_reqs *scr; + + scr = &per_cpu(cpu_sched_capacity_reqs, cpu_tmp); + capacity = max(capacity, scr->total); + } + + /* Convert the new maximum capacity request into a cpu frequency */ + freq_new = capacity * policy->max >> SCHED_CAPACITY_SHIFT; + if (cpufreq_frequency_table_target(policy, policy->freq_table, + freq_new, CPUFREQ_RELATION_L, + &index_new)) + goto out; + freq_new = policy->freq_table[index_new].frequency; + + if (freq_new > policy->max) + freq_new = policy->max; + + if (freq_new < policy->min) + freq_new = policy->min; + + trace_cpufreq_sched_request_opp(cpu, capacity, freq_new, + gd->requested_freq); + if (freq_new == gd->requested_freq) + goto out; + + gd->requested_freq = freq_new; + + /* + * Throttling is not yet supported on platforms with fast cpufreq + * drivers. + */ + if (cpufreq_driver_slow) + irq_work_queue_on(&gd->irq_work, cpu); + else + cpufreq_sched_try_driver_target(policy, freq_new); + +out: + cpufreq_cpu_put(policy); +} + +void update_cpu_capacity_request(int cpu, bool request) +{ + unsigned long new_capacity; + struct sched_capacity_reqs *scr; + + /* The rq lock serializes access to the CPU's sched_capacity_reqs. */ + lockdep_assert_held(&cpu_rq(cpu)->lock); + + scr = &per_cpu(cpu_sched_capacity_reqs, cpu); + + new_capacity = scr->cfs + scr->rt; + new_capacity = new_capacity * capacity_margin + / SCHED_CAPACITY_SCALE; + new_capacity += scr->dl; + + if (new_capacity == scr->total) + return; + + trace_cpufreq_sched_update_capacity(cpu, request, scr, new_capacity); + + scr->total = new_capacity; + if (request) + update_fdomain_capacity_request(cpu); +} + +static inline void set_sched_freq(void) +{ + static_key_slow_inc(&__sched_freq); +} + +static inline void clear_sched_freq(void) +{ + static_key_slow_dec(&__sched_freq); +} + +static struct attribute_group sched_attr_group_gov_pol; +static struct attribute_group *get_sysfs_attr(void) +{ + return &sched_attr_group_gov_pol; +} + +static int cpufreq_sched_policy_init(struct cpufreq_policy *policy) +{ + struct gov_data *gd; + int cpu; + int rc; + + for_each_cpu(cpu, policy->cpus) + memset(&per_cpu(cpu_sched_capacity_reqs, cpu), 0, + sizeof(struct sched_capacity_reqs)); + + gd = kzalloc(sizeof(*gd), GFP_KERNEL); + if (!gd) + return -ENOMEM; + + gd->up_throttle_nsec = policy->cpuinfo.transition_latency ? + policy->cpuinfo.transition_latency : + THROTTLE_UP_NSEC; + gd->down_throttle_nsec = THROTTLE_DOWN_NSEC; + pr_debug("%s: throttle threshold = %u [ns]\n", + __func__, gd->up_throttle_nsec); + + policy->governor_data = gd; + + rc = sysfs_create_group(get_governor_parent_kobj(policy), get_sysfs_attr()); + if (rc) { + pr_err("%s: couldn't create sysfs attributes: %d\n", __func__, rc); + goto err; + } + + if (cpufreq_driver_is_slow()) { + cpufreq_driver_slow = true; + gd->task = kthread_create(cpufreq_sched_thread, policy, + "kschedfreq:%d", + cpumask_first(policy->related_cpus)); + if (IS_ERR_OR_NULL(gd->task)) { + pr_err("%s: failed to create kschedfreq thread\n", + __func__); + goto err; + } + get_task_struct(gd->task); + kthread_bind_mask(gd->task, policy->related_cpus); + wake_up_process(gd->task); + init_irq_work(&gd->irq_work, cpufreq_sched_irq_work); + } + + set_sched_freq(); + + return 0; + +err: + policy->governor_data = NULL; + kfree(gd); + return -ENOMEM; +} + +static int cpufreq_sched_policy_exit(struct cpufreq_policy *policy) +{ + struct gov_data *gd = policy->governor_data; + + clear_sched_freq(); + if (cpufreq_driver_slow) { + kthread_stop(gd->task); + put_task_struct(gd->task); + } + + sysfs_remove_group(get_governor_parent_kobj(policy), get_sysfs_attr()); + + policy->governor_data = NULL; + + kfree(gd); + return 0; +} + +static int cpufreq_sched_start(struct cpufreq_policy *policy) +{ + int cpu; + + for_each_cpu(cpu, policy->cpus) + per_cpu(enabled, cpu) = 1; + + return 0; +} + +static void cpufreq_sched_limits(struct cpufreq_policy *policy) +{ + unsigned int clamp_freq; + struct gov_data *gd = policy->governor_data;; + + pr_debug("limit event for cpu %u: %u - %u kHz, currently %u kHz\n", + policy->cpu, policy->min, policy->max, + policy->cur); + + clamp_freq = clamp(gd->requested_freq, policy->min, policy->max); + + if (policy->cur != clamp_freq) + __cpufreq_driver_target(policy, clamp_freq, CPUFREQ_RELATION_L); +} + +static int cpufreq_sched_stop(struct cpufreq_policy *policy) +{ + int cpu; + + for_each_cpu(cpu, policy->cpus) + per_cpu(enabled, cpu) = 0; + + return 0; +} + +static int cpufreq_sched_setup(struct cpufreq_policy *policy, + unsigned int event) +{ + switch (event) { + case CPUFREQ_GOV_POLICY_INIT: + return cpufreq_sched_policy_init(policy); + case CPUFREQ_GOV_POLICY_EXIT: + return cpufreq_sched_policy_exit(policy); + case CPUFREQ_GOV_START: + return cpufreq_sched_start(policy); + case CPUFREQ_GOV_STOP: + return cpufreq_sched_stop(policy); + case CPUFREQ_GOV_LIMITS: + cpufreq_sched_limits(policy); + break; + } + return 0; +} + +/* Tunables */ +static ssize_t show_up_throttle_nsec(struct gov_data *gd, char *buf) +{ + return sprintf(buf, "%u\n", gd->up_throttle_nsec); +} + +static ssize_t store_up_throttle_nsec(struct gov_data *gd, + const char *buf, size_t count) +{ + int ret; + long unsigned int val; + + ret = kstrtoul(buf, 0, &val); + if (ret < 0) + return ret; + gd->up_throttle_nsec = val; + return count; +} + +static ssize_t show_down_throttle_nsec(struct gov_data *gd, char *buf) +{ + return sprintf(buf, "%u\n", gd->down_throttle_nsec); +} + +static ssize_t store_down_throttle_nsec(struct gov_data *gd, + const char *buf, size_t count) +{ + int ret; + long unsigned int val; + + ret = kstrtoul(buf, 0, &val); + if (ret < 0) + return ret; + gd->down_throttle_nsec = val; + return count; +} + +/* + * Create show/store routines + * - sys: One governor instance for complete SYSTEM + * - pol: One governor instance per struct cpufreq_policy + */ +#define show_gov_pol_sys(file_name) \ +static ssize_t show_##file_name##_gov_pol \ +(struct cpufreq_policy *policy, char *buf) \ +{ \ + return show_##file_name(policy->governor_data, buf); \ +} + +#define store_gov_pol_sys(file_name) \ +static ssize_t store_##file_name##_gov_pol \ +(struct cpufreq_policy *policy, const char *buf, size_t count) \ +{ \ + return store_##file_name(policy->governor_data, buf, count); \ +} + +#define gov_pol_attr_rw(_name) \ + static struct freq_attr _name##_gov_pol = \ + __ATTR(_name, 0644, show_##_name##_gov_pol, store_##_name##_gov_pol) + +#define show_store_gov_pol_sys(file_name) \ + show_gov_pol_sys(file_name); \ + store_gov_pol_sys(file_name) +#define tunable_handlers(file_name) \ + show_gov_pol_sys(file_name); \ + store_gov_pol_sys(file_name); \ + gov_pol_attr_rw(file_name) + +tunable_handlers(down_throttle_nsec); +tunable_handlers(up_throttle_nsec); + +/* Per policy governor instance */ +static struct attribute *sched_attributes_gov_pol[] = { + &up_throttle_nsec_gov_pol.attr, + &down_throttle_nsec_gov_pol.attr, + NULL, +}; + +static struct attribute_group sched_attr_group_gov_pol = { + .attrs = sched_attributes_gov_pol, + .name = "sched", +}; + +#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHED +static +#endif +struct cpufreq_governor cpufreq_gov_sched = { + .name = "sched", + .governor = cpufreq_sched_setup, + .owner = THIS_MODULE, +}; + +static int __init cpufreq_sched_init(void) +{ + int cpu; + + for_each_cpu(cpu, cpu_possible_mask) + per_cpu(enabled, cpu) = 0; + return cpufreq_register_governor(&cpufreq_gov_sched); +} + +/* Try to make this the default governor */ +fs_initcall(cpufreq_sched_init); |