2 * CPUFreq governor based on scheduler-provided CPU utilization data.
4 * Copyright (C) 2016, Intel Corporation
5 * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14 #include <linux/cpufreq.h>
15 #include <linux/module.h>
16 #include <linux/slab.h>
17 #include <trace/events/power.h>
21 struct sugov_tunables {
22 struct gov_attr_set attr_set;
23 unsigned int rate_limit_us;
27 struct cpufreq_policy *policy;
29 struct sugov_tunables *tunables;
30 struct list_head tunables_hook;
32 raw_spinlock_t update_lock; /* For shared policies */
33 u64 last_freq_update_time;
34 s64 freq_update_delay_ns;
35 unsigned int next_freq;
37 /* The next fields are only needed if fast switch cannot be used. */
38 struct irq_work irq_work;
39 struct work_struct work;
40 struct mutex work_lock;
41 bool work_in_progress;
43 bool need_freq_update;
47 struct update_util_data update_util;
48 struct sugov_policy *sg_policy;
50 /* The fields below are only needed when sharing a policy. */
56 static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
58 /************************ Governor internals ***********************/
60 static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
64 if (sg_policy->work_in_progress)
67 if (unlikely(sg_policy->need_freq_update)) {
68 sg_policy->need_freq_update = false;
70 * This happens when limits change, so forget the previous
71 * next_freq value and force an update.
73 sg_policy->next_freq = UINT_MAX;
77 delta_ns = time - sg_policy->last_freq_update_time;
78 return delta_ns >= sg_policy->freq_update_delay_ns;
81 static void sugov_update_commit(struct sugov_policy *sg_policy, u64 time,
82 unsigned int next_freq)
84 struct cpufreq_policy *policy = sg_policy->policy;
86 sg_policy->last_freq_update_time = time;
88 if (policy->fast_switch_enabled) {
89 if (sg_policy->next_freq == next_freq) {
90 trace_cpu_frequency(policy->cur, smp_processor_id());
93 sg_policy->next_freq = next_freq;
94 next_freq = cpufreq_driver_fast_switch(policy, next_freq);
95 if (next_freq == CPUFREQ_ENTRY_INVALID)
98 policy->cur = next_freq;
99 trace_cpu_frequency(next_freq, smp_processor_id());
100 } else if (sg_policy->next_freq != next_freq) {
101 sg_policy->next_freq = next_freq;
102 sg_policy->work_in_progress = true;
103 irq_work_queue(&sg_policy->irq_work);
108 * get_next_freq - Compute a new frequency for a given cpufreq policy.
109 * @policy: cpufreq policy object to compute the new frequency for.
110 * @util: Current CPU utilization.
111 * @max: CPU capacity.
113 * If the utilization is frequency-invariant, choose the new frequency to be
114 * proportional to it, that is
116 * next_freq = C * max_freq * util / max
118 * Otherwise, approximate the would-be frequency-invariant utilization by
119 * util_raw * (curr_freq / max_freq) which leads to
121 * next_freq = C * curr_freq * util_raw / max
123 * Take C = 1.25 for the frequency tipping point at (util / max) = 0.8.
125 static unsigned int get_next_freq(struct cpufreq_policy *policy,
126 unsigned long util, unsigned long max)
128 unsigned int freq = arch_scale_freq_invariant() ?
129 policy->cpuinfo.max_freq : policy->cur;
131 return (freq + (freq >> 2)) * util / max;
134 static void sugov_update_single(struct update_util_data *hook, u64 time,
135 unsigned long util, unsigned long max)
137 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
138 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
139 struct cpufreq_policy *policy = sg_policy->policy;
142 if (!sugov_should_update_freq(sg_policy, time))
145 next_f = util == ULONG_MAX ? policy->cpuinfo.max_freq :
146 get_next_freq(policy, util, max);
147 sugov_update_commit(sg_policy, time, next_f);
150 static unsigned int sugov_next_freq_shared(struct sugov_policy *sg_policy,
151 unsigned long util, unsigned long max)
153 struct cpufreq_policy *policy = sg_policy->policy;
154 unsigned int max_f = policy->cpuinfo.max_freq;
155 u64 last_freq_update_time = sg_policy->last_freq_update_time;
158 if (util == ULONG_MAX)
161 for_each_cpu(j, policy->cpus) {
162 struct sugov_cpu *j_sg_cpu;
163 unsigned long j_util, j_max;
166 if (j == smp_processor_id())
169 j_sg_cpu = &per_cpu(sugov_cpu, j);
171 * If the CPU utilization was last updated before the previous
172 * frequency update and the time elapsed between the last update
173 * of the CPU utilization and the last frequency update is long
174 * enough, don't take the CPU into account as it probably is
177 delta_ns = last_freq_update_time - j_sg_cpu->last_update;
178 if (delta_ns > TICK_NSEC)
181 j_util = j_sg_cpu->util;
182 if (j_util == ULONG_MAX)
185 j_max = j_sg_cpu->max;
186 if (j_util * max > j_max * util) {
192 return get_next_freq(policy, util, max);
195 static void sugov_update_shared(struct update_util_data *hook, u64 time,
196 unsigned long util, unsigned long max)
198 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
199 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
202 raw_spin_lock(&sg_policy->update_lock);
206 sg_cpu->last_update = time;
208 if (sugov_should_update_freq(sg_policy, time)) {
209 next_f = sugov_next_freq_shared(sg_policy, util, max);
210 sugov_update_commit(sg_policy, time, next_f);
213 raw_spin_unlock(&sg_policy->update_lock);
216 static void sugov_work(struct work_struct *work)
218 struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
220 mutex_lock(&sg_policy->work_lock);
221 __cpufreq_driver_target(sg_policy->policy, sg_policy->next_freq,
223 mutex_unlock(&sg_policy->work_lock);
225 sg_policy->work_in_progress = false;
228 static void sugov_irq_work(struct irq_work *irq_work)
230 struct sugov_policy *sg_policy;
232 sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
233 schedule_work_on(smp_processor_id(), &sg_policy->work);
236 /************************** sysfs interface ************************/
238 static struct sugov_tunables *global_tunables;
239 static DEFINE_MUTEX(global_tunables_lock);
241 static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
243 return container_of(attr_set, struct sugov_tunables, attr_set);
246 static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
248 struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
250 return sprintf(buf, "%u\n", tunables->rate_limit_us);
253 static ssize_t rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf,
256 struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
257 struct sugov_policy *sg_policy;
258 unsigned int rate_limit_us;
260 if (kstrtouint(buf, 10, &rate_limit_us))
263 tunables->rate_limit_us = rate_limit_us;
265 list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
266 sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
271 static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
273 static struct attribute *sugov_attributes[] = {
278 static struct kobj_type sugov_tunables_ktype = {
279 .default_attrs = sugov_attributes,
280 .sysfs_ops = &governor_sysfs_ops,
283 /********************** cpufreq governor interface *********************/
285 static struct cpufreq_governor schedutil_gov;
287 static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
289 struct sugov_policy *sg_policy;
291 sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
295 sg_policy->policy = policy;
296 init_irq_work(&sg_policy->irq_work, sugov_irq_work);
297 INIT_WORK(&sg_policy->work, sugov_work);
298 mutex_init(&sg_policy->work_lock);
299 raw_spin_lock_init(&sg_policy->update_lock);
303 static void sugov_policy_free(struct sugov_policy *sg_policy)
305 mutex_destroy(&sg_policy->work_lock);
309 static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
311 struct sugov_tunables *tunables;
313 tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
315 gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
316 if (!have_governor_per_policy())
317 global_tunables = tunables;
322 static void sugov_tunables_free(struct sugov_tunables *tunables)
324 if (!have_governor_per_policy())
325 global_tunables = NULL;
330 static int sugov_init(struct cpufreq_policy *policy)
332 struct sugov_policy *sg_policy;
333 struct sugov_tunables *tunables;
337 /* State should be equivalent to EXIT */
338 if (policy->governor_data)
341 sg_policy = sugov_policy_alloc(policy);
345 mutex_lock(&global_tunables_lock);
347 if (global_tunables) {
348 if (WARN_ON(have_governor_per_policy())) {
352 policy->governor_data = sg_policy;
353 sg_policy->tunables = global_tunables;
355 gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
359 tunables = sugov_tunables_alloc(sg_policy);
365 tunables->rate_limit_us = LATENCY_MULTIPLIER;
366 lat = policy->cpuinfo.transition_latency / NSEC_PER_USEC;
368 tunables->rate_limit_us *= lat;
370 policy->governor_data = sg_policy;
371 sg_policy->tunables = tunables;
373 ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
374 get_governor_parent_kobj(policy), "%s",
380 mutex_unlock(&global_tunables_lock);
382 cpufreq_enable_fast_switch(policy);
386 policy->governor_data = NULL;
387 sugov_tunables_free(tunables);
390 mutex_unlock(&global_tunables_lock);
392 sugov_policy_free(sg_policy);
393 pr_err("initialization failed (error %d)\n", ret);
397 static int sugov_exit(struct cpufreq_policy *policy)
399 struct sugov_policy *sg_policy = policy->governor_data;
400 struct sugov_tunables *tunables = sg_policy->tunables;
403 cpufreq_disable_fast_switch(policy);
405 mutex_lock(&global_tunables_lock);
407 count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
408 policy->governor_data = NULL;
410 sugov_tunables_free(tunables);
412 mutex_unlock(&global_tunables_lock);
414 sugov_policy_free(sg_policy);
418 static int sugov_start(struct cpufreq_policy *policy)
420 struct sugov_policy *sg_policy = policy->governor_data;
423 sg_policy->freq_update_delay_ns = sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
424 sg_policy->last_freq_update_time = 0;
425 sg_policy->next_freq = UINT_MAX;
426 sg_policy->work_in_progress = false;
427 sg_policy->need_freq_update = false;
429 for_each_cpu(cpu, policy->cpus) {
430 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
432 sg_cpu->sg_policy = sg_policy;
433 if (policy_is_shared(policy)) {
434 sg_cpu->util = ULONG_MAX;
436 sg_cpu->last_update = 0;
437 cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
438 sugov_update_shared);
440 cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
441 sugov_update_single);
447 static int sugov_stop(struct cpufreq_policy *policy)
449 struct sugov_policy *sg_policy = policy->governor_data;
452 for_each_cpu(cpu, policy->cpus)
453 cpufreq_remove_update_util_hook(cpu);
457 irq_work_sync(&sg_policy->irq_work);
458 cancel_work_sync(&sg_policy->work);
462 static int sugov_limits(struct cpufreq_policy *policy)
464 struct sugov_policy *sg_policy = policy->governor_data;
466 if (!policy->fast_switch_enabled) {
467 mutex_lock(&sg_policy->work_lock);
469 if (policy->max < policy->cur)
470 __cpufreq_driver_target(policy, policy->max,
472 else if (policy->min > policy->cur)
473 __cpufreq_driver_target(policy, policy->min,
476 mutex_unlock(&sg_policy->work_lock);
479 sg_policy->need_freq_update = true;
483 int sugov_governor(struct cpufreq_policy *policy, unsigned int event)
485 if (event == CPUFREQ_GOV_POLICY_INIT) {
486 return sugov_init(policy);
487 } else if (policy->governor_data) {
489 case CPUFREQ_GOV_POLICY_EXIT:
490 return sugov_exit(policy);
491 case CPUFREQ_GOV_START:
492 return sugov_start(policy);
493 case CPUFREQ_GOV_STOP:
494 return sugov_stop(policy);
495 case CPUFREQ_GOV_LIMITS:
496 return sugov_limits(policy);
502 static struct cpufreq_governor schedutil_gov = {
504 .governor = sugov_governor,
505 .owner = THIS_MODULE,
508 static int __init sugov_module_init(void)
510 return cpufreq_register_governor(&schedutil_gov);
513 static void __exit sugov_module_exit(void)
515 cpufreq_unregister_governor(&schedutil_gov);
518 MODULE_AUTHOR("Rafael J. Wysocki <rafael.j.wysocki@intel.com>");
519 MODULE_DESCRIPTION("Utilization-based CPU frequency selection");
520 MODULE_LICENSE("GPL");
522 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
523 struct cpufreq_governor *cpufreq_default_governor(void)
525 return &schedutil_gov;
528 fs_initcall(sugov_module_init);
530 module_init(sugov_module_init);
532 module_exit(sugov_module_exit);