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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * CPUFreq governor based on scheduler-provided CPU utilization data.
4 *
5 * Copyright (C) 2016, Intel Corporation
6 * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
7 */
8
9#define IOWAIT_BOOST_MIN (SCHED_CAPACITY_SCALE / 8)
10
11struct sugov_tunables {
12 struct gov_attr_set attr_set;
13 unsigned int rate_limit_us;
14};
15
16struct sugov_policy {
17 struct cpufreq_policy *policy;
18
19 struct sugov_tunables *tunables;
20 struct list_head tunables_hook;
21
22 raw_spinlock_t update_lock;
23 u64 last_freq_update_time;
24 s64 freq_update_delay_ns;
25 unsigned int next_freq;
26 unsigned int cached_raw_freq;
27
28 /* The next fields are only needed if fast switch cannot be used: */
29 struct irq_work irq_work;
30 struct kthread_work work;
31 struct mutex work_lock;
32 struct kthread_worker worker;
33 struct task_struct *thread;
34 bool work_in_progress;
35
36 bool limits_changed;
37 bool need_freq_update;
38};
39
40struct sugov_cpu {
41 struct update_util_data update_util;
42 struct sugov_policy *sg_policy;
43 unsigned int cpu;
44
45 bool iowait_boost_pending;
46 unsigned int iowait_boost;
47 u64 last_update;
48
49 unsigned long util;
50 unsigned long bw_dl;
51 unsigned long max;
52
53 /* The field below is for single-CPU policies only: */
54#ifdef CONFIG_NO_HZ_COMMON
55 unsigned long saved_idle_calls;
56#endif
57};
58
59static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
60
61/************************ Governor internals ***********************/
62
63static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
64{
65 s64 delta_ns;
66
67 /*
68 * Since cpufreq_update_util() is called with rq->lock held for
69 * the @target_cpu, our per-CPU data is fully serialized.
70 *
71 * However, drivers cannot in general deal with cross-CPU
72 * requests, so while get_next_freq() will work, our
73 * sugov_update_commit() call may not for the fast switching platforms.
74 *
75 * Hence stop here for remote requests if they aren't supported
76 * by the hardware, as calculating the frequency is pointless if
77 * we cannot in fact act on it.
78 *
79 * This is needed on the slow switching platforms too to prevent CPUs
80 * going offline from leaving stale IRQ work items behind.
81 */
82 if (!cpufreq_this_cpu_can_update(sg_policy->policy))
83 return false;
84
85 if (unlikely(sg_policy->limits_changed)) {
86 sg_policy->limits_changed = false;
87 sg_policy->need_freq_update = true;
88 return true;
89 }
90
91 delta_ns = time - sg_policy->last_freq_update_time;
92
93 return delta_ns >= sg_policy->freq_update_delay_ns;
94}
95
96static bool sugov_update_next_freq(struct sugov_policy *sg_policy, u64 time,
97 unsigned int next_freq)
98{
99 if (sg_policy->need_freq_update)
100 sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);
101 else if (sg_policy->next_freq == next_freq)
102 return false;
103
104 sg_policy->next_freq = next_freq;
105 sg_policy->last_freq_update_time = time;
106
107 return true;
108}
109
110static void sugov_deferred_update(struct sugov_policy *sg_policy)
111{
112 if (!sg_policy->work_in_progress) {
113 sg_policy->work_in_progress = true;
114 irq_work_queue(&sg_policy->irq_work);
115 }
116}
117
118/**
119 * get_next_freq - Compute a new frequency for a given cpufreq policy.
120 * @sg_policy: schedutil policy object to compute the new frequency for.
121 * @util: Current CPU utilization.
122 * @max: CPU capacity.
123 *
124 * If the utilization is frequency-invariant, choose the new frequency to be
125 * proportional to it, that is
126 *
127 * next_freq = C * max_freq * util / max
128 *
129 * Otherwise, approximate the would-be frequency-invariant utilization by
130 * util_raw * (curr_freq / max_freq) which leads to
131 *
132 * next_freq = C * curr_freq * util_raw / max
133 *
134 * Take C = 1.25 for the frequency tipping point at (util / max) = 0.8.
135 *
136 * The lowest driver-supported frequency which is equal or greater than the raw
137 * next_freq (as calculated above) is returned, subject to policy min/max and
138 * cpufreq driver limitations.
139 */
140static unsigned int get_next_freq(struct sugov_policy *sg_policy,
141 unsigned long util, unsigned long max)
142{
143 struct cpufreq_policy *policy = sg_policy->policy;
144 unsigned int freq = arch_scale_freq_invariant() ?
145 policy->cpuinfo.max_freq : policy->cur;
146
147 util = map_util_perf(util);
148 freq = map_util_freq(util, freq, max);
149
150 if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)
151 return sg_policy->next_freq;
152
153 sg_policy->cached_raw_freq = freq;
154 return cpufreq_driver_resolve_freq(policy, freq);
155}
156
157static void sugov_get_util(struct sugov_cpu *sg_cpu)
158{
159 struct rq *rq = cpu_rq(sg_cpu->cpu);
160
161 sg_cpu->max = arch_scale_cpu_capacity(sg_cpu->cpu);
162 sg_cpu->bw_dl = cpu_bw_dl(rq);
163 sg_cpu->util = effective_cpu_util(sg_cpu->cpu, cpu_util_cfs(sg_cpu->cpu),
164 FREQUENCY_UTIL, NULL);
165}
166
167/**
168 * sugov_iowait_reset() - Reset the IO boost status of a CPU.
169 * @sg_cpu: the sugov data for the CPU to boost
170 * @time: the update time from the caller
171 * @set_iowait_boost: true if an IO boost has been requested
172 *
173 * The IO wait boost of a task is disabled after a tick since the last update
174 * of a CPU. If a new IO wait boost is requested after more then a tick, then
175 * we enable the boost starting from IOWAIT_BOOST_MIN, which improves energy
176 * efficiency by ignoring sporadic wakeups from IO.
177 */
178static bool sugov_iowait_reset(struct sugov_cpu *sg_cpu, u64 time,
179 bool set_iowait_boost)
180{
181 s64 delta_ns = time - sg_cpu->last_update;
182
183 /* Reset boost only if a tick has elapsed since last request */
184 if (delta_ns <= TICK_NSEC)
185 return false;
186
187 sg_cpu->iowait_boost = set_iowait_boost ? IOWAIT_BOOST_MIN : 0;
188 sg_cpu->iowait_boost_pending = set_iowait_boost;
189
190 return true;
191}
192
193/**
194 * sugov_iowait_boost() - Updates the IO boost status of a CPU.
195 * @sg_cpu: the sugov data for the CPU to boost
196 * @time: the update time from the caller
197 * @flags: SCHED_CPUFREQ_IOWAIT if the task is waking up after an IO wait
198 *
199 * Each time a task wakes up after an IO operation, the CPU utilization can be
200 * boosted to a certain utilization which doubles at each "frequent and
201 * successive" wakeup from IO, ranging from IOWAIT_BOOST_MIN to the utilization
202 * of the maximum OPP.
203 *
204 * To keep doubling, an IO boost has to be requested at least once per tick,
205 * otherwise we restart from the utilization of the minimum OPP.
206 */
207static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
208 unsigned int flags)
209{
210 bool set_iowait_boost = flags & SCHED_CPUFREQ_IOWAIT;
211
212 /* Reset boost if the CPU appears to have been idle enough */
213 if (sg_cpu->iowait_boost &&
214 sugov_iowait_reset(sg_cpu, time, set_iowait_boost))
215 return;
216
217 /* Boost only tasks waking up after IO */
218 if (!set_iowait_boost)
219 return;
220
221 /* Ensure boost doubles only one time at each request */
222 if (sg_cpu->iowait_boost_pending)
223 return;
224 sg_cpu->iowait_boost_pending = true;
225
226 /* Double the boost at each request */
227 if (sg_cpu->iowait_boost) {
228 sg_cpu->iowait_boost =
229 min_t(unsigned int, sg_cpu->iowait_boost << 1, SCHED_CAPACITY_SCALE);
230 return;
231 }
232
233 /* First wakeup after IO: start with minimum boost */
234 sg_cpu->iowait_boost = IOWAIT_BOOST_MIN;
235}
236
237/**
238 * sugov_iowait_apply() - Apply the IO boost to a CPU.
239 * @sg_cpu: the sugov data for the cpu to boost
240 * @time: the update time from the caller
241 *
242 * A CPU running a task which woken up after an IO operation can have its
243 * utilization boosted to speed up the completion of those IO operations.
244 * The IO boost value is increased each time a task wakes up from IO, in
245 * sugov_iowait_apply(), and it's instead decreased by this function,
246 * each time an increase has not been requested (!iowait_boost_pending).
247 *
248 * A CPU which also appears to have been idle for at least one tick has also
249 * its IO boost utilization reset.
250 *
251 * This mechanism is designed to boost high frequently IO waiting tasks, while
252 * being more conservative on tasks which does sporadic IO operations.
253 */
254static void sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time)
255{
256 unsigned long boost;
257
258 /* No boost currently required */
259 if (!sg_cpu->iowait_boost)
260 return;
261
262 /* Reset boost if the CPU appears to have been idle enough */
263 if (sugov_iowait_reset(sg_cpu, time, false))
264 return;
265
266 if (!sg_cpu->iowait_boost_pending) {
267 /*
268 * No boost pending; reduce the boost value.
269 */
270 sg_cpu->iowait_boost >>= 1;
271 if (sg_cpu->iowait_boost < IOWAIT_BOOST_MIN) {
272 sg_cpu->iowait_boost = 0;
273 return;
274 }
275 }
276
277 sg_cpu->iowait_boost_pending = false;
278
279 /*
280 * sg_cpu->util is already in capacity scale; convert iowait_boost
281 * into the same scale so we can compare.
282 */
283 boost = (sg_cpu->iowait_boost * sg_cpu->max) >> SCHED_CAPACITY_SHIFT;
284 boost = uclamp_rq_util_with(cpu_rq(sg_cpu->cpu), boost, NULL);
285 if (sg_cpu->util < boost)
286 sg_cpu->util = boost;
287}
288
289#ifdef CONFIG_NO_HZ_COMMON
290static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
291{
292 unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu);
293 bool ret = idle_calls == sg_cpu->saved_idle_calls;
294
295 sg_cpu->saved_idle_calls = idle_calls;
296 return ret;
297}
298#else
299static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
300#endif /* CONFIG_NO_HZ_COMMON */
301
302/*
303 * Make sugov_should_update_freq() ignore the rate limit when DL
304 * has increased the utilization.
305 */
306static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu)
307{
308 if (cpu_bw_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->bw_dl)
309 sg_cpu->sg_policy->limits_changed = true;
310}
311
312static inline bool sugov_update_single_common(struct sugov_cpu *sg_cpu,
313 u64 time, unsigned int flags)
314{
315 sugov_iowait_boost(sg_cpu, time, flags);
316 sg_cpu->last_update = time;
317
318 ignore_dl_rate_limit(sg_cpu);
319
320 if (!sugov_should_update_freq(sg_cpu->sg_policy, time))
321 return false;
322
323 sugov_get_util(sg_cpu);
324 sugov_iowait_apply(sg_cpu, time);
325
326 return true;
327}
328
329static void sugov_update_single_freq(struct update_util_data *hook, u64 time,
330 unsigned int flags)
331{
332 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
333 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
334 unsigned int cached_freq = sg_policy->cached_raw_freq;
335 unsigned int next_f;
336
337 if (!sugov_update_single_common(sg_cpu, time, flags))
338 return;
339
340 next_f = get_next_freq(sg_policy, sg_cpu->util, sg_cpu->max);
341 /*
342 * Do not reduce the frequency if the CPU has not been idle
343 * recently, as the reduction is likely to be premature then.
344 *
345 * Except when the rq is capped by uclamp_max.
346 */
347 if (!uclamp_rq_is_capped(cpu_rq(sg_cpu->cpu)) &&
348 sugov_cpu_is_busy(sg_cpu) && next_f < sg_policy->next_freq) {
349 next_f = sg_policy->next_freq;
350
351 /* Restore cached freq as next_freq has changed */
352 sg_policy->cached_raw_freq = cached_freq;
353 }
354
355 if (!sugov_update_next_freq(sg_policy, time, next_f))
356 return;
357
358 /*
359 * This code runs under rq->lock for the target CPU, so it won't run
360 * concurrently on two different CPUs for the same target and it is not
361 * necessary to acquire the lock in the fast switch case.
362 */
363 if (sg_policy->policy->fast_switch_enabled) {
364 cpufreq_driver_fast_switch(sg_policy->policy, next_f);
365 } else {
366 raw_spin_lock(&sg_policy->update_lock);
367 sugov_deferred_update(sg_policy);
368 raw_spin_unlock(&sg_policy->update_lock);
369 }
370}
371
372static void sugov_update_single_perf(struct update_util_data *hook, u64 time,
373 unsigned int flags)
374{
375 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
376 unsigned long prev_util = sg_cpu->util;
377
378 /*
379 * Fall back to the "frequency" path if frequency invariance is not
380 * supported, because the direct mapping between the utilization and
381 * the performance levels depends on the frequency invariance.
382 */
383 if (!arch_scale_freq_invariant()) {
384 sugov_update_single_freq(hook, time, flags);
385 return;
386 }
387
388 if (!sugov_update_single_common(sg_cpu, time, flags))
389 return;
390
391 /*
392 * Do not reduce the target performance level if the CPU has not been
393 * idle recently, as the reduction is likely to be premature then.
394 *
395 * Except when the rq is capped by uclamp_max.
396 */
397 if (!uclamp_rq_is_capped(cpu_rq(sg_cpu->cpu)) &&
398 sugov_cpu_is_busy(sg_cpu) && sg_cpu->util < prev_util)
399 sg_cpu->util = prev_util;
400
401 cpufreq_driver_adjust_perf(sg_cpu->cpu, map_util_perf(sg_cpu->bw_dl),
402 map_util_perf(sg_cpu->util), sg_cpu->max);
403
404 sg_cpu->sg_policy->last_freq_update_time = time;
405}
406
407static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
408{
409 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
410 struct cpufreq_policy *policy = sg_policy->policy;
411 unsigned long util = 0, max = 1;
412 unsigned int j;
413
414 for_each_cpu(j, policy->cpus) {
415 struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
416 unsigned long j_util, j_max;
417
418 sugov_get_util(j_sg_cpu);
419 sugov_iowait_apply(j_sg_cpu, time);
420 j_util = j_sg_cpu->util;
421 j_max = j_sg_cpu->max;
422
423 if (j_util * max > j_max * util) {
424 util = j_util;
425 max = j_max;
426 }
427 }
428
429 return get_next_freq(sg_policy, util, max);
430}
431
432static void
433sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags)
434{
435 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
436 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
437 unsigned int next_f;
438
439 raw_spin_lock(&sg_policy->update_lock);
440
441 sugov_iowait_boost(sg_cpu, time, flags);
442 sg_cpu->last_update = time;
443
444 ignore_dl_rate_limit(sg_cpu);
445
446 if (sugov_should_update_freq(sg_policy, time)) {
447 next_f = sugov_next_freq_shared(sg_cpu, time);
448
449 if (!sugov_update_next_freq(sg_policy, time, next_f))
450 goto unlock;
451
452 if (sg_policy->policy->fast_switch_enabled)
453 cpufreq_driver_fast_switch(sg_policy->policy, next_f);
454 else
455 sugov_deferred_update(sg_policy);
456 }
457unlock:
458 raw_spin_unlock(&sg_policy->update_lock);
459}
460
461static void sugov_work(struct kthread_work *work)
462{
463 struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
464 unsigned int freq;
465 unsigned long flags;
466
467 /*
468 * Hold sg_policy->update_lock shortly to handle the case where:
469 * in case sg_policy->next_freq is read here, and then updated by
470 * sugov_deferred_update() just before work_in_progress is set to false
471 * here, we may miss queueing the new update.
472 *
473 * Note: If a work was queued after the update_lock is released,
474 * sugov_work() will just be called again by kthread_work code; and the
475 * request will be proceed before the sugov thread sleeps.
476 */
477 raw_spin_lock_irqsave(&sg_policy->update_lock, flags);
478 freq = sg_policy->next_freq;
479 sg_policy->work_in_progress = false;
480 raw_spin_unlock_irqrestore(&sg_policy->update_lock, flags);
481
482 mutex_lock(&sg_policy->work_lock);
483 __cpufreq_driver_target(sg_policy->policy, freq, CPUFREQ_RELATION_L);
484 mutex_unlock(&sg_policy->work_lock);
485}
486
487static void sugov_irq_work(struct irq_work *irq_work)
488{
489 struct sugov_policy *sg_policy;
490
491 sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
492
493 kthread_queue_work(&sg_policy->worker, &sg_policy->work);
494}
495
496/************************** sysfs interface ************************/
497
498static struct sugov_tunables *global_tunables;
499static DEFINE_MUTEX(global_tunables_lock);
500
501static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
502{
503 return container_of(attr_set, struct sugov_tunables, attr_set);
504}
505
506static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
507{
508 struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
509
510 return sprintf(buf, "%u\n", tunables->rate_limit_us);
511}
512
513static ssize_t
514rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf, size_t count)
515{
516 struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
517 struct sugov_policy *sg_policy;
518 unsigned int rate_limit_us;
519
520 if (kstrtouint(buf, 10, &rate_limit_us))
521 return -EINVAL;
522
523 tunables->rate_limit_us = rate_limit_us;
524
525 list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
526 sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
527
528 return count;
529}
530
531static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
532
533static struct attribute *sugov_attrs[] = {
534 &rate_limit_us.attr,
535 NULL
536};
537ATTRIBUTE_GROUPS(sugov);
538
539static void sugov_tunables_free(struct kobject *kobj)
540{
541 struct gov_attr_set *attr_set = to_gov_attr_set(kobj);
542
543 kfree(to_sugov_tunables(attr_set));
544}
545
546static struct kobj_type sugov_tunables_ktype = {
547 .default_groups = sugov_groups,
548 .sysfs_ops = &governor_sysfs_ops,
549 .release = &sugov_tunables_free,
550};
551
552/********************** cpufreq governor interface *********************/
553
554struct cpufreq_governor schedutil_gov;
555
556static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
557{
558 struct sugov_policy *sg_policy;
559
560 sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
561 if (!sg_policy)
562 return NULL;
563
564 sg_policy->policy = policy;
565 raw_spin_lock_init(&sg_policy->update_lock);
566 return sg_policy;
567}
568
569static void sugov_policy_free(struct sugov_policy *sg_policy)
570{
571 kfree(sg_policy);
572}
573
574static int sugov_kthread_create(struct sugov_policy *sg_policy)
575{
576 struct task_struct *thread;
577 struct sched_attr attr = {
578 .size = sizeof(struct sched_attr),
579 .sched_policy = SCHED_DEADLINE,
580 .sched_flags = SCHED_FLAG_SUGOV,
581 .sched_nice = 0,
582 .sched_priority = 0,
583 /*
584 * Fake (unused) bandwidth; workaround to "fix"
585 * priority inheritance.
586 */
587 .sched_runtime = 1000000,
588 .sched_deadline = 10000000,
589 .sched_period = 10000000,
590 };
591 struct cpufreq_policy *policy = sg_policy->policy;
592 int ret;
593
594 /* kthread only required for slow path */
595 if (policy->fast_switch_enabled)
596 return 0;
597
598 kthread_init_work(&sg_policy->work, sugov_work);
599 kthread_init_worker(&sg_policy->worker);
600 thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
601 "sugov:%d",
602 cpumask_first(policy->related_cpus));
603 if (IS_ERR(thread)) {
604 pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread));
605 return PTR_ERR(thread);
606 }
607
608 ret = sched_setattr_nocheck(thread, &attr);
609 if (ret) {
610 kthread_stop(thread);
611 pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__);
612 return ret;
613 }
614
615 sg_policy->thread = thread;
616 kthread_bind_mask(thread, policy->related_cpus);
617 init_irq_work(&sg_policy->irq_work, sugov_irq_work);
618 mutex_init(&sg_policy->work_lock);
619
620 wake_up_process(thread);
621
622 return 0;
623}
624
625static void sugov_kthread_stop(struct sugov_policy *sg_policy)
626{
627 /* kthread only required for slow path */
628 if (sg_policy->policy->fast_switch_enabled)
629 return;
630
631 kthread_flush_worker(&sg_policy->worker);
632 kthread_stop(sg_policy->thread);
633 mutex_destroy(&sg_policy->work_lock);
634}
635
636static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
637{
638 struct sugov_tunables *tunables;
639
640 tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
641 if (tunables) {
642 gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
643 if (!have_governor_per_policy())
644 global_tunables = tunables;
645 }
646 return tunables;
647}
648
649static void sugov_clear_global_tunables(void)
650{
651 if (!have_governor_per_policy())
652 global_tunables = NULL;
653}
654
655static int sugov_init(struct cpufreq_policy *policy)
656{
657 struct sugov_policy *sg_policy;
658 struct sugov_tunables *tunables;
659 int ret = 0;
660
661 /* State should be equivalent to EXIT */
662 if (policy->governor_data)
663 return -EBUSY;
664
665 cpufreq_enable_fast_switch(policy);
666
667 sg_policy = sugov_policy_alloc(policy);
668 if (!sg_policy) {
669 ret = -ENOMEM;
670 goto disable_fast_switch;
671 }
672
673 ret = sugov_kthread_create(sg_policy);
674 if (ret)
675 goto free_sg_policy;
676
677 mutex_lock(&global_tunables_lock);
678
679 if (global_tunables) {
680 if (WARN_ON(have_governor_per_policy())) {
681 ret = -EINVAL;
682 goto stop_kthread;
683 }
684 policy->governor_data = sg_policy;
685 sg_policy->tunables = global_tunables;
686
687 gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
688 goto out;
689 }
690
691 tunables = sugov_tunables_alloc(sg_policy);
692 if (!tunables) {
693 ret = -ENOMEM;
694 goto stop_kthread;
695 }
696
697 tunables->rate_limit_us = cpufreq_policy_transition_delay_us(policy);
698
699 policy->governor_data = sg_policy;
700 sg_policy->tunables = tunables;
701
702 ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
703 get_governor_parent_kobj(policy), "%s",
704 schedutil_gov.name);
705 if (ret)
706 goto fail;
707
708out:
709 mutex_unlock(&global_tunables_lock);
710 return 0;
711
712fail:
713 kobject_put(&tunables->attr_set.kobj);
714 policy->governor_data = NULL;
715 sugov_clear_global_tunables();
716
717stop_kthread:
718 sugov_kthread_stop(sg_policy);
719 mutex_unlock(&global_tunables_lock);
720
721free_sg_policy:
722 sugov_policy_free(sg_policy);
723
724disable_fast_switch:
725 cpufreq_disable_fast_switch(policy);
726
727 pr_err("initialization failed (error %d)\n", ret);
728 return ret;
729}
730
731static void sugov_exit(struct cpufreq_policy *policy)
732{
733 struct sugov_policy *sg_policy = policy->governor_data;
734 struct sugov_tunables *tunables = sg_policy->tunables;
735 unsigned int count;
736
737 mutex_lock(&global_tunables_lock);
738
739 count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
740 policy->governor_data = NULL;
741 if (!count)
742 sugov_clear_global_tunables();
743
744 mutex_unlock(&global_tunables_lock);
745
746 sugov_kthread_stop(sg_policy);
747 sugov_policy_free(sg_policy);
748 cpufreq_disable_fast_switch(policy);
749}
750
751static int sugov_start(struct cpufreq_policy *policy)
752{
753 struct sugov_policy *sg_policy = policy->governor_data;
754 void (*uu)(struct update_util_data *data, u64 time, unsigned int flags);
755 unsigned int cpu;
756
757 sg_policy->freq_update_delay_ns = sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
758 sg_policy->last_freq_update_time = 0;
759 sg_policy->next_freq = 0;
760 sg_policy->work_in_progress = false;
761 sg_policy->limits_changed = false;
762 sg_policy->cached_raw_freq = 0;
763
764 sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);
765
766 for_each_cpu(cpu, policy->cpus) {
767 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
768
769 memset(sg_cpu, 0, sizeof(*sg_cpu));
770 sg_cpu->cpu = cpu;
771 sg_cpu->sg_policy = sg_policy;
772 }
773
774 if (policy_is_shared(policy))
775 uu = sugov_update_shared;
776 else if (policy->fast_switch_enabled && cpufreq_driver_has_adjust_perf())
777 uu = sugov_update_single_perf;
778 else
779 uu = sugov_update_single_freq;
780
781 for_each_cpu(cpu, policy->cpus) {
782 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
783
784 cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util, uu);
785 }
786 return 0;
787}
788
789static void sugov_stop(struct cpufreq_policy *policy)
790{
791 struct sugov_policy *sg_policy = policy->governor_data;
792 unsigned int cpu;
793
794 for_each_cpu(cpu, policy->cpus)
795 cpufreq_remove_update_util_hook(cpu);
796
797 synchronize_rcu();
798
799 if (!policy->fast_switch_enabled) {
800 irq_work_sync(&sg_policy->irq_work);
801 kthread_cancel_work_sync(&sg_policy->work);
802 }
803}
804
805static void sugov_limits(struct cpufreq_policy *policy)
806{
807 struct sugov_policy *sg_policy = policy->governor_data;
808
809 if (!policy->fast_switch_enabled) {
810 mutex_lock(&sg_policy->work_lock);
811 cpufreq_policy_apply_limits(policy);
812 mutex_unlock(&sg_policy->work_lock);
813 }
814
815 sg_policy->limits_changed = true;
816}
817
818struct cpufreq_governor schedutil_gov = {
819 .name = "schedutil",
820 .owner = THIS_MODULE,
821 .flags = CPUFREQ_GOV_DYNAMIC_SWITCHING,
822 .init = sugov_init,
823 .exit = sugov_exit,
824 .start = sugov_start,
825 .stop = sugov_stop,
826 .limits = sugov_limits,
827};
828
829#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
830struct cpufreq_governor *cpufreq_default_governor(void)
831{
832 return &schedutil_gov;
833}
834#endif
835
836cpufreq_governor_init(schedutil_gov);
837
838#ifdef CONFIG_ENERGY_MODEL
839static void rebuild_sd_workfn(struct work_struct *work)
840{
841 rebuild_sched_domains_energy();
842}
843static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);
844
845/*
846 * EAS shouldn't be attempted without sugov, so rebuild the sched_domains
847 * on governor changes to make sure the scheduler knows about it.
848 */
849void sched_cpufreq_governor_change(struct cpufreq_policy *policy,
850 struct cpufreq_governor *old_gov)
851{
852 if (old_gov == &schedutil_gov || policy->governor == &schedutil_gov) {
853 /*
854 * When called from the cpufreq_register_driver() path, the
855 * cpu_hotplug_lock is already held, so use a work item to
856 * avoid nested locking in rebuild_sched_domains().
857 */
858 schedule_work(&rebuild_sd_work);
859 }
860
861}
862#endif
1/*
2 * CPUFreq governor based on scheduler-provided CPU utilization data.
3 *
4 * Copyright (C) 2016, Intel Corporation
5 * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
6 *
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.
10 */
11
12#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14#include "sched.h"
15
16#include <trace/events/power.h>
17
18struct sugov_tunables {
19 struct gov_attr_set attr_set;
20 unsigned int rate_limit_us;
21};
22
23struct sugov_policy {
24 struct cpufreq_policy *policy;
25
26 struct sugov_tunables *tunables;
27 struct list_head tunables_hook;
28
29 raw_spinlock_t update_lock; /* For shared policies */
30 u64 last_freq_update_time;
31 s64 freq_update_delay_ns;
32 unsigned int next_freq;
33 unsigned int cached_raw_freq;
34
35 /* The next fields are only needed if fast switch cannot be used: */
36 struct irq_work irq_work;
37 struct kthread_work work;
38 struct mutex work_lock;
39 struct kthread_worker worker;
40 struct task_struct *thread;
41 bool work_in_progress;
42
43 bool need_freq_update;
44};
45
46struct sugov_cpu {
47 struct update_util_data update_util;
48 struct sugov_policy *sg_policy;
49 unsigned int cpu;
50
51 bool iowait_boost_pending;
52 unsigned int iowait_boost;
53 unsigned int iowait_boost_max;
54 u64 last_update;
55
56 /* The fields below are only needed when sharing a policy: */
57 unsigned long util_cfs;
58 unsigned long util_dl;
59 unsigned long max;
60
61 /* The field below is for single-CPU policies only: */
62#ifdef CONFIG_NO_HZ_COMMON
63 unsigned long saved_idle_calls;
64#endif
65};
66
67static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
68
69/************************ Governor internals ***********************/
70
71static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
72{
73 s64 delta_ns;
74
75 /*
76 * Since cpufreq_update_util() is called with rq->lock held for
77 * the @target_cpu, our per-CPU data is fully serialized.
78 *
79 * However, drivers cannot in general deal with cross-CPU
80 * requests, so while get_next_freq() will work, our
81 * sugov_update_commit() call may not for the fast switching platforms.
82 *
83 * Hence stop here for remote requests if they aren't supported
84 * by the hardware, as calculating the frequency is pointless if
85 * we cannot in fact act on it.
86 *
87 * For the slow switching platforms, the kthread is always scheduled on
88 * the right set of CPUs and any CPU can find the next frequency and
89 * schedule the kthread.
90 */
91 if (sg_policy->policy->fast_switch_enabled &&
92 !cpufreq_can_do_remote_dvfs(sg_policy->policy))
93 return false;
94
95 if (sg_policy->work_in_progress)
96 return false;
97
98 if (unlikely(sg_policy->need_freq_update)) {
99 sg_policy->need_freq_update = false;
100 /*
101 * This happens when limits change, so forget the previous
102 * next_freq value and force an update.
103 */
104 sg_policy->next_freq = UINT_MAX;
105 return true;
106 }
107
108 delta_ns = time - sg_policy->last_freq_update_time;
109
110 return delta_ns >= sg_policy->freq_update_delay_ns;
111}
112
113static void sugov_update_commit(struct sugov_policy *sg_policy, u64 time,
114 unsigned int next_freq)
115{
116 struct cpufreq_policy *policy = sg_policy->policy;
117
118 if (sg_policy->next_freq == next_freq)
119 return;
120
121 sg_policy->next_freq = next_freq;
122 sg_policy->last_freq_update_time = time;
123
124 if (policy->fast_switch_enabled) {
125 next_freq = cpufreq_driver_fast_switch(policy, next_freq);
126 if (!next_freq)
127 return;
128
129 policy->cur = next_freq;
130 trace_cpu_frequency(next_freq, smp_processor_id());
131 } else {
132 sg_policy->work_in_progress = true;
133 irq_work_queue(&sg_policy->irq_work);
134 }
135}
136
137/**
138 * get_next_freq - Compute a new frequency for a given cpufreq policy.
139 * @sg_policy: schedutil policy object to compute the new frequency for.
140 * @util: Current CPU utilization.
141 * @max: CPU capacity.
142 *
143 * If the utilization is frequency-invariant, choose the new frequency to be
144 * proportional to it, that is
145 *
146 * next_freq = C * max_freq * util / max
147 *
148 * Otherwise, approximate the would-be frequency-invariant utilization by
149 * util_raw * (curr_freq / max_freq) which leads to
150 *
151 * next_freq = C * curr_freq * util_raw / max
152 *
153 * Take C = 1.25 for the frequency tipping point at (util / max) = 0.8.
154 *
155 * The lowest driver-supported frequency which is equal or greater than the raw
156 * next_freq (as calculated above) is returned, subject to policy min/max and
157 * cpufreq driver limitations.
158 */
159static unsigned int get_next_freq(struct sugov_policy *sg_policy,
160 unsigned long util, unsigned long max)
161{
162 struct cpufreq_policy *policy = sg_policy->policy;
163 unsigned int freq = arch_scale_freq_invariant() ?
164 policy->cpuinfo.max_freq : policy->cur;
165
166 freq = (freq + (freq >> 2)) * util / max;
167
168 if (freq == sg_policy->cached_raw_freq && sg_policy->next_freq != UINT_MAX)
169 return sg_policy->next_freq;
170 sg_policy->cached_raw_freq = freq;
171 return cpufreq_driver_resolve_freq(policy, freq);
172}
173
174static void sugov_get_util(struct sugov_cpu *sg_cpu)
175{
176 struct rq *rq = cpu_rq(sg_cpu->cpu);
177
178 sg_cpu->max = arch_scale_cpu_capacity(NULL, sg_cpu->cpu);
179 sg_cpu->util_cfs = cpu_util_cfs(rq);
180 sg_cpu->util_dl = cpu_util_dl(rq);
181}
182
183static unsigned long sugov_aggregate_util(struct sugov_cpu *sg_cpu)
184{
185 struct rq *rq = cpu_rq(sg_cpu->cpu);
186 unsigned long util;
187
188 if (rq->rt.rt_nr_running) {
189 util = sg_cpu->max;
190 } else {
191 util = sg_cpu->util_dl;
192 if (rq->cfs.h_nr_running)
193 util += sg_cpu->util_cfs;
194 }
195
196 /*
197 * Ideally we would like to set util_dl as min/guaranteed freq and
198 * util_cfs + util_dl as requested freq. However, cpufreq is not yet
199 * ready for such an interface. So, we only do the latter for now.
200 */
201 return min(util, sg_cpu->max);
202}
203
204static void sugov_set_iowait_boost(struct sugov_cpu *sg_cpu, u64 time, unsigned int flags)
205{
206 if (flags & SCHED_CPUFREQ_IOWAIT) {
207 if (sg_cpu->iowait_boost_pending)
208 return;
209
210 sg_cpu->iowait_boost_pending = true;
211
212 if (sg_cpu->iowait_boost) {
213 sg_cpu->iowait_boost <<= 1;
214 if (sg_cpu->iowait_boost > sg_cpu->iowait_boost_max)
215 sg_cpu->iowait_boost = sg_cpu->iowait_boost_max;
216 } else {
217 sg_cpu->iowait_boost = sg_cpu->sg_policy->policy->min;
218 }
219 } else if (sg_cpu->iowait_boost) {
220 s64 delta_ns = time - sg_cpu->last_update;
221
222 /* Clear iowait_boost if the CPU apprears to have been idle. */
223 if (delta_ns > TICK_NSEC) {
224 sg_cpu->iowait_boost = 0;
225 sg_cpu->iowait_boost_pending = false;
226 }
227 }
228}
229
230static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, unsigned long *util,
231 unsigned long *max)
232{
233 unsigned int boost_util, boost_max;
234
235 if (!sg_cpu->iowait_boost)
236 return;
237
238 if (sg_cpu->iowait_boost_pending) {
239 sg_cpu->iowait_boost_pending = false;
240 } else {
241 sg_cpu->iowait_boost >>= 1;
242 if (sg_cpu->iowait_boost < sg_cpu->sg_policy->policy->min) {
243 sg_cpu->iowait_boost = 0;
244 return;
245 }
246 }
247
248 boost_util = sg_cpu->iowait_boost;
249 boost_max = sg_cpu->iowait_boost_max;
250
251 if (*util * boost_max < *max * boost_util) {
252 *util = boost_util;
253 *max = boost_max;
254 }
255}
256
257#ifdef CONFIG_NO_HZ_COMMON
258static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
259{
260 unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu);
261 bool ret = idle_calls == sg_cpu->saved_idle_calls;
262
263 sg_cpu->saved_idle_calls = idle_calls;
264 return ret;
265}
266#else
267static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
268#endif /* CONFIG_NO_HZ_COMMON */
269
270/*
271 * Make sugov_should_update_freq() ignore the rate limit when DL
272 * has increased the utilization.
273 */
274static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu, struct sugov_policy *sg_policy)
275{
276 if (cpu_util_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->util_dl)
277 sg_policy->need_freq_update = true;
278}
279
280static void sugov_update_single(struct update_util_data *hook, u64 time,
281 unsigned int flags)
282{
283 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
284 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
285 unsigned long util, max;
286 unsigned int next_f;
287 bool busy;
288
289 sugov_set_iowait_boost(sg_cpu, time, flags);
290 sg_cpu->last_update = time;
291
292 ignore_dl_rate_limit(sg_cpu, sg_policy);
293
294 if (!sugov_should_update_freq(sg_policy, time))
295 return;
296
297 busy = sugov_cpu_is_busy(sg_cpu);
298
299 sugov_get_util(sg_cpu);
300 max = sg_cpu->max;
301 util = sugov_aggregate_util(sg_cpu);
302 sugov_iowait_boost(sg_cpu, &util, &max);
303 next_f = get_next_freq(sg_policy, util, max);
304 /*
305 * Do not reduce the frequency if the CPU has not been idle
306 * recently, as the reduction is likely to be premature then.
307 */
308 if (busy && next_f < sg_policy->next_freq &&
309 sg_policy->next_freq != UINT_MAX) {
310 next_f = sg_policy->next_freq;
311
312 /* Reset cached freq as next_freq has changed */
313 sg_policy->cached_raw_freq = 0;
314 }
315
316 sugov_update_commit(sg_policy, time, next_f);
317}
318
319static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
320{
321 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
322 struct cpufreq_policy *policy = sg_policy->policy;
323 unsigned long util = 0, max = 1;
324 unsigned int j;
325
326 for_each_cpu(j, policy->cpus) {
327 struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
328 unsigned long j_util, j_max;
329 s64 delta_ns;
330
331 sugov_get_util(j_sg_cpu);
332
333 /*
334 * If the CFS CPU utilization was last updated before the
335 * previous frequency update and the time elapsed between the
336 * last update of the CPU utilization and the last frequency
337 * update is long enough, reset iowait_boost and util_cfs, as
338 * they are now probably stale. However, still consider the
339 * CPU contribution if it has some DEADLINE utilization
340 * (util_dl).
341 */
342 delta_ns = time - j_sg_cpu->last_update;
343 if (delta_ns > TICK_NSEC) {
344 j_sg_cpu->iowait_boost = 0;
345 j_sg_cpu->iowait_boost_pending = false;
346 }
347
348 j_max = j_sg_cpu->max;
349 j_util = sugov_aggregate_util(j_sg_cpu);
350 sugov_iowait_boost(j_sg_cpu, &j_util, &j_max);
351 if (j_util * max > j_max * util) {
352 util = j_util;
353 max = j_max;
354 }
355 }
356
357 return get_next_freq(sg_policy, util, max);
358}
359
360static void
361sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags)
362{
363 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
364 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
365 unsigned int next_f;
366
367 raw_spin_lock(&sg_policy->update_lock);
368
369 sugov_set_iowait_boost(sg_cpu, time, flags);
370 sg_cpu->last_update = time;
371
372 ignore_dl_rate_limit(sg_cpu, sg_policy);
373
374 if (sugov_should_update_freq(sg_policy, time)) {
375 next_f = sugov_next_freq_shared(sg_cpu, time);
376 sugov_update_commit(sg_policy, time, next_f);
377 }
378
379 raw_spin_unlock(&sg_policy->update_lock);
380}
381
382static void sugov_work(struct kthread_work *work)
383{
384 struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
385
386 mutex_lock(&sg_policy->work_lock);
387 __cpufreq_driver_target(sg_policy->policy, sg_policy->next_freq,
388 CPUFREQ_RELATION_L);
389 mutex_unlock(&sg_policy->work_lock);
390
391 sg_policy->work_in_progress = false;
392}
393
394static void sugov_irq_work(struct irq_work *irq_work)
395{
396 struct sugov_policy *sg_policy;
397
398 sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
399
400 kthread_queue_work(&sg_policy->worker, &sg_policy->work);
401}
402
403/************************** sysfs interface ************************/
404
405static struct sugov_tunables *global_tunables;
406static DEFINE_MUTEX(global_tunables_lock);
407
408static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
409{
410 return container_of(attr_set, struct sugov_tunables, attr_set);
411}
412
413static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
414{
415 struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
416
417 return sprintf(buf, "%u\n", tunables->rate_limit_us);
418}
419
420static ssize_t
421rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf, size_t count)
422{
423 struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
424 struct sugov_policy *sg_policy;
425 unsigned int rate_limit_us;
426
427 if (kstrtouint(buf, 10, &rate_limit_us))
428 return -EINVAL;
429
430 tunables->rate_limit_us = rate_limit_us;
431
432 list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
433 sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
434
435 return count;
436}
437
438static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
439
440static struct attribute *sugov_attributes[] = {
441 &rate_limit_us.attr,
442 NULL
443};
444
445static struct kobj_type sugov_tunables_ktype = {
446 .default_attrs = sugov_attributes,
447 .sysfs_ops = &governor_sysfs_ops,
448};
449
450/********************** cpufreq governor interface *********************/
451
452static struct cpufreq_governor schedutil_gov;
453
454static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
455{
456 struct sugov_policy *sg_policy;
457
458 sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
459 if (!sg_policy)
460 return NULL;
461
462 sg_policy->policy = policy;
463 raw_spin_lock_init(&sg_policy->update_lock);
464 return sg_policy;
465}
466
467static void sugov_policy_free(struct sugov_policy *sg_policy)
468{
469 kfree(sg_policy);
470}
471
472static int sugov_kthread_create(struct sugov_policy *sg_policy)
473{
474 struct task_struct *thread;
475 struct sched_attr attr = {
476 .size = sizeof(struct sched_attr),
477 .sched_policy = SCHED_DEADLINE,
478 .sched_flags = SCHED_FLAG_SUGOV,
479 .sched_nice = 0,
480 .sched_priority = 0,
481 /*
482 * Fake (unused) bandwidth; workaround to "fix"
483 * priority inheritance.
484 */
485 .sched_runtime = 1000000,
486 .sched_deadline = 10000000,
487 .sched_period = 10000000,
488 };
489 struct cpufreq_policy *policy = sg_policy->policy;
490 int ret;
491
492 /* kthread only required for slow path */
493 if (policy->fast_switch_enabled)
494 return 0;
495
496 kthread_init_work(&sg_policy->work, sugov_work);
497 kthread_init_worker(&sg_policy->worker);
498 thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
499 "sugov:%d",
500 cpumask_first(policy->related_cpus));
501 if (IS_ERR(thread)) {
502 pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread));
503 return PTR_ERR(thread);
504 }
505
506 ret = sched_setattr_nocheck(thread, &attr);
507 if (ret) {
508 kthread_stop(thread);
509 pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__);
510 return ret;
511 }
512
513 sg_policy->thread = thread;
514
515 /* Kthread is bound to all CPUs by default */
516 if (!policy->dvfs_possible_from_any_cpu)
517 kthread_bind_mask(thread, policy->related_cpus);
518
519 init_irq_work(&sg_policy->irq_work, sugov_irq_work);
520 mutex_init(&sg_policy->work_lock);
521
522 wake_up_process(thread);
523
524 return 0;
525}
526
527static void sugov_kthread_stop(struct sugov_policy *sg_policy)
528{
529 /* kthread only required for slow path */
530 if (sg_policy->policy->fast_switch_enabled)
531 return;
532
533 kthread_flush_worker(&sg_policy->worker);
534 kthread_stop(sg_policy->thread);
535 mutex_destroy(&sg_policy->work_lock);
536}
537
538static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
539{
540 struct sugov_tunables *tunables;
541
542 tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
543 if (tunables) {
544 gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
545 if (!have_governor_per_policy())
546 global_tunables = tunables;
547 }
548 return tunables;
549}
550
551static void sugov_tunables_free(struct sugov_tunables *tunables)
552{
553 if (!have_governor_per_policy())
554 global_tunables = NULL;
555
556 kfree(tunables);
557}
558
559static int sugov_init(struct cpufreq_policy *policy)
560{
561 struct sugov_policy *sg_policy;
562 struct sugov_tunables *tunables;
563 int ret = 0;
564
565 /* State should be equivalent to EXIT */
566 if (policy->governor_data)
567 return -EBUSY;
568
569 cpufreq_enable_fast_switch(policy);
570
571 sg_policy = sugov_policy_alloc(policy);
572 if (!sg_policy) {
573 ret = -ENOMEM;
574 goto disable_fast_switch;
575 }
576
577 ret = sugov_kthread_create(sg_policy);
578 if (ret)
579 goto free_sg_policy;
580
581 mutex_lock(&global_tunables_lock);
582
583 if (global_tunables) {
584 if (WARN_ON(have_governor_per_policy())) {
585 ret = -EINVAL;
586 goto stop_kthread;
587 }
588 policy->governor_data = sg_policy;
589 sg_policy->tunables = global_tunables;
590
591 gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
592 goto out;
593 }
594
595 tunables = sugov_tunables_alloc(sg_policy);
596 if (!tunables) {
597 ret = -ENOMEM;
598 goto stop_kthread;
599 }
600
601 tunables->rate_limit_us = cpufreq_policy_transition_delay_us(policy);
602
603 policy->governor_data = sg_policy;
604 sg_policy->tunables = tunables;
605
606 ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
607 get_governor_parent_kobj(policy), "%s",
608 schedutil_gov.name);
609 if (ret)
610 goto fail;
611
612out:
613 mutex_unlock(&global_tunables_lock);
614 return 0;
615
616fail:
617 policy->governor_data = NULL;
618 sugov_tunables_free(tunables);
619
620stop_kthread:
621 sugov_kthread_stop(sg_policy);
622 mutex_unlock(&global_tunables_lock);
623
624free_sg_policy:
625 sugov_policy_free(sg_policy);
626
627disable_fast_switch:
628 cpufreq_disable_fast_switch(policy);
629
630 pr_err("initialization failed (error %d)\n", ret);
631 return ret;
632}
633
634static void sugov_exit(struct cpufreq_policy *policy)
635{
636 struct sugov_policy *sg_policy = policy->governor_data;
637 struct sugov_tunables *tunables = sg_policy->tunables;
638 unsigned int count;
639
640 mutex_lock(&global_tunables_lock);
641
642 count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
643 policy->governor_data = NULL;
644 if (!count)
645 sugov_tunables_free(tunables);
646
647 mutex_unlock(&global_tunables_lock);
648
649 sugov_kthread_stop(sg_policy);
650 sugov_policy_free(sg_policy);
651 cpufreq_disable_fast_switch(policy);
652}
653
654static int sugov_start(struct cpufreq_policy *policy)
655{
656 struct sugov_policy *sg_policy = policy->governor_data;
657 unsigned int cpu;
658
659 sg_policy->freq_update_delay_ns = sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
660 sg_policy->last_freq_update_time = 0;
661 sg_policy->next_freq = UINT_MAX;
662 sg_policy->work_in_progress = false;
663 sg_policy->need_freq_update = false;
664 sg_policy->cached_raw_freq = 0;
665
666 for_each_cpu(cpu, policy->cpus) {
667 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
668
669 memset(sg_cpu, 0, sizeof(*sg_cpu));
670 sg_cpu->cpu = cpu;
671 sg_cpu->sg_policy = sg_policy;
672 sg_cpu->iowait_boost_max = policy->cpuinfo.max_freq;
673 }
674
675 for_each_cpu(cpu, policy->cpus) {
676 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
677
678 cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
679 policy_is_shared(policy) ?
680 sugov_update_shared :
681 sugov_update_single);
682 }
683 return 0;
684}
685
686static void sugov_stop(struct cpufreq_policy *policy)
687{
688 struct sugov_policy *sg_policy = policy->governor_data;
689 unsigned int cpu;
690
691 for_each_cpu(cpu, policy->cpus)
692 cpufreq_remove_update_util_hook(cpu);
693
694 synchronize_sched();
695
696 if (!policy->fast_switch_enabled) {
697 irq_work_sync(&sg_policy->irq_work);
698 kthread_cancel_work_sync(&sg_policy->work);
699 }
700}
701
702static void sugov_limits(struct cpufreq_policy *policy)
703{
704 struct sugov_policy *sg_policy = policy->governor_data;
705
706 if (!policy->fast_switch_enabled) {
707 mutex_lock(&sg_policy->work_lock);
708 cpufreq_policy_apply_limits(policy);
709 mutex_unlock(&sg_policy->work_lock);
710 }
711
712 sg_policy->need_freq_update = true;
713}
714
715static struct cpufreq_governor schedutil_gov = {
716 .name = "schedutil",
717 .owner = THIS_MODULE,
718 .dynamic_switching = true,
719 .init = sugov_init,
720 .exit = sugov_exit,
721 .start = sugov_start,
722 .stop = sugov_stop,
723 .limits = sugov_limits,
724};
725
726#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
727struct cpufreq_governor *cpufreq_default_governor(void)
728{
729 return &schedutil_gov;
730}
731#endif
732
733static int __init sugov_register(void)
734{
735 return cpufreq_register_governor(&schedutil_gov);
736}
737fs_initcall(sugov_register);