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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_min;
51
52 /* The field below is for single-CPU policies only: */
53#ifdef CONFIG_NO_HZ_COMMON
54 unsigned long saved_idle_calls;
55#endif
56};
57
58static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
59
60/************************ Governor internals ***********************/
61
62static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
63{
64 s64 delta_ns;
65
66 /*
67 * Since cpufreq_update_util() is called with rq->lock held for
68 * the @target_cpu, our per-CPU data is fully serialized.
69 *
70 * However, drivers cannot in general deal with cross-CPU
71 * requests, so while get_next_freq() will work, our
72 * sugov_update_commit() call may not for the fast switching platforms.
73 *
74 * Hence stop here for remote requests if they aren't supported
75 * by the hardware, as calculating the frequency is pointless if
76 * we cannot in fact act on it.
77 *
78 * This is needed on the slow switching platforms too to prevent CPUs
79 * going offline from leaving stale IRQ work items behind.
80 */
81 if (!cpufreq_this_cpu_can_update(sg_policy->policy))
82 return false;
83
84 if (unlikely(sg_policy->limits_changed)) {
85 sg_policy->limits_changed = false;
86 sg_policy->need_freq_update = true;
87 return true;
88 }
89
90 delta_ns = time - sg_policy->last_freq_update_time;
91
92 return delta_ns >= sg_policy->freq_update_delay_ns;
93}
94
95static bool sugov_update_next_freq(struct sugov_policy *sg_policy, u64 time,
96 unsigned int next_freq)
97{
98 if (sg_policy->need_freq_update)
99 sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);
100 else if (sg_policy->next_freq == next_freq)
101 return false;
102
103 sg_policy->next_freq = next_freq;
104 sg_policy->last_freq_update_time = time;
105
106 return true;
107}
108
109static void sugov_deferred_update(struct sugov_policy *sg_policy)
110{
111 if (!sg_policy->work_in_progress) {
112 sg_policy->work_in_progress = true;
113 irq_work_queue(&sg_policy->irq_work);
114 }
115}
116
117/**
118 * get_capacity_ref_freq - get the reference frequency that has been used to
119 * correlate frequency and compute capacity for a given cpufreq policy. We use
120 * the CPU managing it for the arch_scale_freq_ref() call in the function.
121 * @policy: the cpufreq policy of the CPU in question.
122 *
123 * Return: the reference CPU frequency to compute a capacity.
124 */
125static __always_inline
126unsigned long get_capacity_ref_freq(struct cpufreq_policy *policy)
127{
128 unsigned int freq = arch_scale_freq_ref(policy->cpu);
129
130 if (freq)
131 return freq;
132
133 if (arch_scale_freq_invariant())
134 return policy->cpuinfo.max_freq;
135
136 /*
137 * Apply a 25% margin so that we select a higher frequency than
138 * the current one before the CPU is fully busy:
139 */
140 return policy->cur + (policy->cur >> 2);
141}
142
143/**
144 * get_next_freq - Compute a new frequency for a given cpufreq policy.
145 * @sg_policy: schedutil policy object to compute the new frequency for.
146 * @util: Current CPU utilization.
147 * @max: CPU capacity.
148 *
149 * If the utilization is frequency-invariant, choose the new frequency to be
150 * proportional to it, that is
151 *
152 * next_freq = C * max_freq * util / max
153 *
154 * Otherwise, approximate the would-be frequency-invariant utilization by
155 * util_raw * (curr_freq / max_freq) which leads to
156 *
157 * next_freq = C * curr_freq * util_raw / max
158 *
159 * Take C = 1.25 for the frequency tipping point at (util / max) = 0.8.
160 *
161 * The lowest driver-supported frequency which is equal or greater than the raw
162 * next_freq (as calculated above) is returned, subject to policy min/max and
163 * cpufreq driver limitations.
164 */
165static unsigned int get_next_freq(struct sugov_policy *sg_policy,
166 unsigned long util, unsigned long max)
167{
168 struct cpufreq_policy *policy = sg_policy->policy;
169 unsigned int freq;
170
171 freq = get_capacity_ref_freq(policy);
172 freq = map_util_freq(util, freq, max);
173
174 if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)
175 return sg_policy->next_freq;
176
177 sg_policy->cached_raw_freq = freq;
178 return cpufreq_driver_resolve_freq(policy, freq);
179}
180
181unsigned long sugov_effective_cpu_perf(int cpu, unsigned long actual,
182 unsigned long min,
183 unsigned long max)
184{
185 /* Add dvfs headroom to actual utilization */
186 actual = map_util_perf(actual);
187 /* Actually we don't need to target the max performance */
188 if (actual < max)
189 max = actual;
190
191 /*
192 * Ensure at least minimum performance while providing more compute
193 * capacity when possible.
194 */
195 return max(min, max);
196}
197
198static void sugov_get_util(struct sugov_cpu *sg_cpu, unsigned long boost)
199{
200 unsigned long min, max, util = cpu_util_cfs_boost(sg_cpu->cpu);
201
202 util = effective_cpu_util(sg_cpu->cpu, util, &min, &max);
203 util = max(util, boost);
204 sg_cpu->bw_min = min;
205 sg_cpu->util = sugov_effective_cpu_perf(sg_cpu->cpu, util, min, max);
206}
207
208/**
209 * sugov_iowait_reset() - Reset the IO boost status of a CPU.
210 * @sg_cpu: the sugov data for the CPU to boost
211 * @time: the update time from the caller
212 * @set_iowait_boost: true if an IO boost has been requested
213 *
214 * The IO wait boost of a task is disabled after a tick since the last update
215 * of a CPU. If a new IO wait boost is requested after more then a tick, then
216 * we enable the boost starting from IOWAIT_BOOST_MIN, which improves energy
217 * efficiency by ignoring sporadic wakeups from IO.
218 */
219static bool sugov_iowait_reset(struct sugov_cpu *sg_cpu, u64 time,
220 bool set_iowait_boost)
221{
222 s64 delta_ns = time - sg_cpu->last_update;
223
224 /* Reset boost only if a tick has elapsed since last request */
225 if (delta_ns <= TICK_NSEC)
226 return false;
227
228 sg_cpu->iowait_boost = set_iowait_boost ? IOWAIT_BOOST_MIN : 0;
229 sg_cpu->iowait_boost_pending = set_iowait_boost;
230
231 return true;
232}
233
234/**
235 * sugov_iowait_boost() - Updates the IO boost status of a CPU.
236 * @sg_cpu: the sugov data for the CPU to boost
237 * @time: the update time from the caller
238 * @flags: SCHED_CPUFREQ_IOWAIT if the task is waking up after an IO wait
239 *
240 * Each time a task wakes up after an IO operation, the CPU utilization can be
241 * boosted to a certain utilization which doubles at each "frequent and
242 * successive" wakeup from IO, ranging from IOWAIT_BOOST_MIN to the utilization
243 * of the maximum OPP.
244 *
245 * To keep doubling, an IO boost has to be requested at least once per tick,
246 * otherwise we restart from the utilization of the minimum OPP.
247 */
248static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
249 unsigned int flags)
250{
251 bool set_iowait_boost = flags & SCHED_CPUFREQ_IOWAIT;
252
253 /* Reset boost if the CPU appears to have been idle enough */
254 if (sg_cpu->iowait_boost &&
255 sugov_iowait_reset(sg_cpu, time, set_iowait_boost))
256 return;
257
258 /* Boost only tasks waking up after IO */
259 if (!set_iowait_boost)
260 return;
261
262 /* Ensure boost doubles only one time at each request */
263 if (sg_cpu->iowait_boost_pending)
264 return;
265 sg_cpu->iowait_boost_pending = true;
266
267 /* Double the boost at each request */
268 if (sg_cpu->iowait_boost) {
269 sg_cpu->iowait_boost =
270 min_t(unsigned int, sg_cpu->iowait_boost << 1, SCHED_CAPACITY_SCALE);
271 return;
272 }
273
274 /* First wakeup after IO: start with minimum boost */
275 sg_cpu->iowait_boost = IOWAIT_BOOST_MIN;
276}
277
278/**
279 * sugov_iowait_apply() - Apply the IO boost to a CPU.
280 * @sg_cpu: the sugov data for the cpu to boost
281 * @time: the update time from the caller
282 * @max_cap: the max CPU capacity
283 *
284 * A CPU running a task which woken up after an IO operation can have its
285 * utilization boosted to speed up the completion of those IO operations.
286 * The IO boost value is increased each time a task wakes up from IO, in
287 * sugov_iowait_apply(), and it's instead decreased by this function,
288 * each time an increase has not been requested (!iowait_boost_pending).
289 *
290 * A CPU which also appears to have been idle for at least one tick has also
291 * its IO boost utilization reset.
292 *
293 * This mechanism is designed to boost high frequently IO waiting tasks, while
294 * being more conservative on tasks which does sporadic IO operations.
295 */
296static unsigned long sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time,
297 unsigned long max_cap)
298{
299 /* No boost currently required */
300 if (!sg_cpu->iowait_boost)
301 return 0;
302
303 /* Reset boost if the CPU appears to have been idle enough */
304 if (sugov_iowait_reset(sg_cpu, time, false))
305 return 0;
306
307 if (!sg_cpu->iowait_boost_pending) {
308 /*
309 * No boost pending; reduce the boost value.
310 */
311 sg_cpu->iowait_boost >>= 1;
312 if (sg_cpu->iowait_boost < IOWAIT_BOOST_MIN) {
313 sg_cpu->iowait_boost = 0;
314 return 0;
315 }
316 }
317
318 sg_cpu->iowait_boost_pending = false;
319
320 /*
321 * sg_cpu->util is already in capacity scale; convert iowait_boost
322 * into the same scale so we can compare.
323 */
324 return (sg_cpu->iowait_boost * max_cap) >> SCHED_CAPACITY_SHIFT;
325}
326
327#ifdef CONFIG_NO_HZ_COMMON
328static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
329{
330 unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu);
331 bool ret = idle_calls == sg_cpu->saved_idle_calls;
332
333 sg_cpu->saved_idle_calls = idle_calls;
334 return ret;
335}
336#else
337static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
338#endif /* CONFIG_NO_HZ_COMMON */
339
340/*
341 * Make sugov_should_update_freq() ignore the rate limit when DL
342 * has increased the utilization.
343 */
344static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu)
345{
346 if (cpu_bw_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->bw_min)
347 sg_cpu->sg_policy->limits_changed = true;
348}
349
350static inline bool sugov_update_single_common(struct sugov_cpu *sg_cpu,
351 u64 time, unsigned long max_cap,
352 unsigned int flags)
353{
354 unsigned long boost;
355
356 sugov_iowait_boost(sg_cpu, time, flags);
357 sg_cpu->last_update = time;
358
359 ignore_dl_rate_limit(sg_cpu);
360
361 if (!sugov_should_update_freq(sg_cpu->sg_policy, time))
362 return false;
363
364 boost = sugov_iowait_apply(sg_cpu, time, max_cap);
365 sugov_get_util(sg_cpu, boost);
366
367 return true;
368}
369
370static void sugov_update_single_freq(struct update_util_data *hook, u64 time,
371 unsigned int flags)
372{
373 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
374 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
375 unsigned int cached_freq = sg_policy->cached_raw_freq;
376 unsigned long max_cap;
377 unsigned int next_f;
378
379 max_cap = arch_scale_cpu_capacity(sg_cpu->cpu);
380
381 if (!sugov_update_single_common(sg_cpu, time, max_cap, flags))
382 return;
383
384 next_f = get_next_freq(sg_policy, sg_cpu->util, max_cap);
385 /*
386 * Do not reduce the frequency if the CPU has not been idle
387 * recently, as the reduction is likely to be premature then.
388 *
389 * Except when the rq is capped by uclamp_max.
390 */
391 if (!uclamp_rq_is_capped(cpu_rq(sg_cpu->cpu)) &&
392 sugov_cpu_is_busy(sg_cpu) && next_f < sg_policy->next_freq &&
393 !sg_policy->need_freq_update) {
394 next_f = sg_policy->next_freq;
395
396 /* Restore cached freq as next_freq has changed */
397 sg_policy->cached_raw_freq = cached_freq;
398 }
399
400 if (!sugov_update_next_freq(sg_policy, time, next_f))
401 return;
402
403 /*
404 * This code runs under rq->lock for the target CPU, so it won't run
405 * concurrently on two different CPUs for the same target and it is not
406 * necessary to acquire the lock in the fast switch case.
407 */
408 if (sg_policy->policy->fast_switch_enabled) {
409 cpufreq_driver_fast_switch(sg_policy->policy, next_f);
410 } else {
411 raw_spin_lock(&sg_policy->update_lock);
412 sugov_deferred_update(sg_policy);
413 raw_spin_unlock(&sg_policy->update_lock);
414 }
415}
416
417static void sugov_update_single_perf(struct update_util_data *hook, u64 time,
418 unsigned int flags)
419{
420 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
421 unsigned long prev_util = sg_cpu->util;
422 unsigned long max_cap;
423
424 /*
425 * Fall back to the "frequency" path if frequency invariance is not
426 * supported, because the direct mapping between the utilization and
427 * the performance levels depends on the frequency invariance.
428 */
429 if (!arch_scale_freq_invariant()) {
430 sugov_update_single_freq(hook, time, flags);
431 return;
432 }
433
434 max_cap = arch_scale_cpu_capacity(sg_cpu->cpu);
435
436 if (!sugov_update_single_common(sg_cpu, time, max_cap, flags))
437 return;
438
439 /*
440 * Do not reduce the target performance level if the CPU has not been
441 * idle recently, as the reduction is likely to be premature then.
442 *
443 * Except when the rq is capped by uclamp_max.
444 */
445 if (!uclamp_rq_is_capped(cpu_rq(sg_cpu->cpu)) &&
446 sugov_cpu_is_busy(sg_cpu) && sg_cpu->util < prev_util)
447 sg_cpu->util = prev_util;
448
449 cpufreq_driver_adjust_perf(sg_cpu->cpu, sg_cpu->bw_min,
450 sg_cpu->util, max_cap);
451
452 sg_cpu->sg_policy->last_freq_update_time = time;
453}
454
455static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
456{
457 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
458 struct cpufreq_policy *policy = sg_policy->policy;
459 unsigned long util = 0, max_cap;
460 unsigned int j;
461
462 max_cap = arch_scale_cpu_capacity(sg_cpu->cpu);
463
464 for_each_cpu(j, policy->cpus) {
465 struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
466 unsigned long boost;
467
468 boost = sugov_iowait_apply(j_sg_cpu, time, max_cap);
469 sugov_get_util(j_sg_cpu, boost);
470
471 util = max(j_sg_cpu->util, util);
472 }
473
474 return get_next_freq(sg_policy, util, max_cap);
475}
476
477static void
478sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags)
479{
480 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
481 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
482 unsigned int next_f;
483
484 raw_spin_lock(&sg_policy->update_lock);
485
486 sugov_iowait_boost(sg_cpu, time, flags);
487 sg_cpu->last_update = time;
488
489 ignore_dl_rate_limit(sg_cpu);
490
491 if (sugov_should_update_freq(sg_policy, time)) {
492 next_f = sugov_next_freq_shared(sg_cpu, time);
493
494 if (!sugov_update_next_freq(sg_policy, time, next_f))
495 goto unlock;
496
497 if (sg_policy->policy->fast_switch_enabled)
498 cpufreq_driver_fast_switch(sg_policy->policy, next_f);
499 else
500 sugov_deferred_update(sg_policy);
501 }
502unlock:
503 raw_spin_unlock(&sg_policy->update_lock);
504}
505
506static void sugov_work(struct kthread_work *work)
507{
508 struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
509 unsigned int freq;
510 unsigned long flags;
511
512 /*
513 * Hold sg_policy->update_lock shortly to handle the case where:
514 * in case sg_policy->next_freq is read here, and then updated by
515 * sugov_deferred_update() just before work_in_progress is set to false
516 * here, we may miss queueing the new update.
517 *
518 * Note: If a work was queued after the update_lock is released,
519 * sugov_work() will just be called again by kthread_work code; and the
520 * request will be proceed before the sugov thread sleeps.
521 */
522 raw_spin_lock_irqsave(&sg_policy->update_lock, flags);
523 freq = sg_policy->next_freq;
524 sg_policy->work_in_progress = false;
525 raw_spin_unlock_irqrestore(&sg_policy->update_lock, flags);
526
527 mutex_lock(&sg_policy->work_lock);
528 __cpufreq_driver_target(sg_policy->policy, freq, CPUFREQ_RELATION_L);
529 mutex_unlock(&sg_policy->work_lock);
530}
531
532static void sugov_irq_work(struct irq_work *irq_work)
533{
534 struct sugov_policy *sg_policy;
535
536 sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
537
538 kthread_queue_work(&sg_policy->worker, &sg_policy->work);
539}
540
541/************************** sysfs interface ************************/
542
543static struct sugov_tunables *global_tunables;
544static DEFINE_MUTEX(global_tunables_lock);
545
546static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
547{
548 return container_of(attr_set, struct sugov_tunables, attr_set);
549}
550
551static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
552{
553 struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
554
555 return sprintf(buf, "%u\n", tunables->rate_limit_us);
556}
557
558static ssize_t
559rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf, size_t count)
560{
561 struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
562 struct sugov_policy *sg_policy;
563 unsigned int rate_limit_us;
564
565 if (kstrtouint(buf, 10, &rate_limit_us))
566 return -EINVAL;
567
568 tunables->rate_limit_us = rate_limit_us;
569
570 list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
571 sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
572
573 return count;
574}
575
576static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
577
578static struct attribute *sugov_attrs[] = {
579 &rate_limit_us.attr,
580 NULL
581};
582ATTRIBUTE_GROUPS(sugov);
583
584static void sugov_tunables_free(struct kobject *kobj)
585{
586 struct gov_attr_set *attr_set = to_gov_attr_set(kobj);
587
588 kfree(to_sugov_tunables(attr_set));
589}
590
591static const struct kobj_type sugov_tunables_ktype = {
592 .default_groups = sugov_groups,
593 .sysfs_ops = &governor_sysfs_ops,
594 .release = &sugov_tunables_free,
595};
596
597/********************** cpufreq governor interface *********************/
598
599#ifdef CONFIG_ENERGY_MODEL
600static void rebuild_sd_workfn(struct work_struct *work)
601{
602 rebuild_sched_domains_energy();
603}
604
605static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);
606
607/*
608 * EAS shouldn't be attempted without sugov, so rebuild the sched_domains
609 * on governor changes to make sure the scheduler knows about it.
610 */
611static void sugov_eas_rebuild_sd(void)
612{
613 /*
614 * When called from the cpufreq_register_driver() path, the
615 * cpu_hotplug_lock is already held, so use a work item to
616 * avoid nested locking in rebuild_sched_domains().
617 */
618 schedule_work(&rebuild_sd_work);
619}
620#else
621static inline void sugov_eas_rebuild_sd(void) { };
622#endif
623
624struct cpufreq_governor schedutil_gov;
625
626static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
627{
628 struct sugov_policy *sg_policy;
629
630 sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
631 if (!sg_policy)
632 return NULL;
633
634 sg_policy->policy = policy;
635 raw_spin_lock_init(&sg_policy->update_lock);
636 return sg_policy;
637}
638
639static void sugov_policy_free(struct sugov_policy *sg_policy)
640{
641 kfree(sg_policy);
642}
643
644static int sugov_kthread_create(struct sugov_policy *sg_policy)
645{
646 struct task_struct *thread;
647 struct sched_attr attr = {
648 .size = sizeof(struct sched_attr),
649 .sched_policy = SCHED_DEADLINE,
650 .sched_flags = SCHED_FLAG_SUGOV,
651 .sched_nice = 0,
652 .sched_priority = 0,
653 /*
654 * Fake (unused) bandwidth; workaround to "fix"
655 * priority inheritance.
656 */
657 .sched_runtime = 1000000,
658 .sched_deadline = 10000000,
659 .sched_period = 10000000,
660 };
661 struct cpufreq_policy *policy = sg_policy->policy;
662 int ret;
663
664 /* kthread only required for slow path */
665 if (policy->fast_switch_enabled)
666 return 0;
667
668 kthread_init_work(&sg_policy->work, sugov_work);
669 kthread_init_worker(&sg_policy->worker);
670 thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
671 "sugov:%d",
672 cpumask_first(policy->related_cpus));
673 if (IS_ERR(thread)) {
674 pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread));
675 return PTR_ERR(thread);
676 }
677
678 ret = sched_setattr_nocheck(thread, &attr);
679 if (ret) {
680 kthread_stop(thread);
681 pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__);
682 return ret;
683 }
684
685 sg_policy->thread = thread;
686 kthread_bind_mask(thread, policy->related_cpus);
687 init_irq_work(&sg_policy->irq_work, sugov_irq_work);
688 mutex_init(&sg_policy->work_lock);
689
690 wake_up_process(thread);
691
692 return 0;
693}
694
695static void sugov_kthread_stop(struct sugov_policy *sg_policy)
696{
697 /* kthread only required for slow path */
698 if (sg_policy->policy->fast_switch_enabled)
699 return;
700
701 kthread_flush_worker(&sg_policy->worker);
702 kthread_stop(sg_policy->thread);
703 mutex_destroy(&sg_policy->work_lock);
704}
705
706static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
707{
708 struct sugov_tunables *tunables;
709
710 tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
711 if (tunables) {
712 gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
713 if (!have_governor_per_policy())
714 global_tunables = tunables;
715 }
716 return tunables;
717}
718
719static void sugov_clear_global_tunables(void)
720{
721 if (!have_governor_per_policy())
722 global_tunables = NULL;
723}
724
725static int sugov_init(struct cpufreq_policy *policy)
726{
727 struct sugov_policy *sg_policy;
728 struct sugov_tunables *tunables;
729 int ret = 0;
730
731 /* State should be equivalent to EXIT */
732 if (policy->governor_data)
733 return -EBUSY;
734
735 cpufreq_enable_fast_switch(policy);
736
737 sg_policy = sugov_policy_alloc(policy);
738 if (!sg_policy) {
739 ret = -ENOMEM;
740 goto disable_fast_switch;
741 }
742
743 ret = sugov_kthread_create(sg_policy);
744 if (ret)
745 goto free_sg_policy;
746
747 mutex_lock(&global_tunables_lock);
748
749 if (global_tunables) {
750 if (WARN_ON(have_governor_per_policy())) {
751 ret = -EINVAL;
752 goto stop_kthread;
753 }
754 policy->governor_data = sg_policy;
755 sg_policy->tunables = global_tunables;
756
757 gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
758 goto out;
759 }
760
761 tunables = sugov_tunables_alloc(sg_policy);
762 if (!tunables) {
763 ret = -ENOMEM;
764 goto stop_kthread;
765 }
766
767 tunables->rate_limit_us = cpufreq_policy_transition_delay_us(policy);
768
769 policy->governor_data = sg_policy;
770 sg_policy->tunables = tunables;
771
772 ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
773 get_governor_parent_kobj(policy), "%s",
774 schedutil_gov.name);
775 if (ret)
776 goto fail;
777
778 sugov_eas_rebuild_sd();
779
780out:
781 mutex_unlock(&global_tunables_lock);
782 return 0;
783
784fail:
785 kobject_put(&tunables->attr_set.kobj);
786 policy->governor_data = NULL;
787 sugov_clear_global_tunables();
788
789stop_kthread:
790 sugov_kthread_stop(sg_policy);
791 mutex_unlock(&global_tunables_lock);
792
793free_sg_policy:
794 sugov_policy_free(sg_policy);
795
796disable_fast_switch:
797 cpufreq_disable_fast_switch(policy);
798
799 pr_err("initialization failed (error %d)\n", ret);
800 return ret;
801}
802
803static void sugov_exit(struct cpufreq_policy *policy)
804{
805 struct sugov_policy *sg_policy = policy->governor_data;
806 struct sugov_tunables *tunables = sg_policy->tunables;
807 unsigned int count;
808
809 mutex_lock(&global_tunables_lock);
810
811 count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
812 policy->governor_data = NULL;
813 if (!count)
814 sugov_clear_global_tunables();
815
816 mutex_unlock(&global_tunables_lock);
817
818 sugov_kthread_stop(sg_policy);
819 sugov_policy_free(sg_policy);
820 cpufreq_disable_fast_switch(policy);
821
822 sugov_eas_rebuild_sd();
823}
824
825static int sugov_start(struct cpufreq_policy *policy)
826{
827 struct sugov_policy *sg_policy = policy->governor_data;
828 void (*uu)(struct update_util_data *data, u64 time, unsigned int flags);
829 unsigned int cpu;
830
831 sg_policy->freq_update_delay_ns = sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
832 sg_policy->last_freq_update_time = 0;
833 sg_policy->next_freq = 0;
834 sg_policy->work_in_progress = false;
835 sg_policy->limits_changed = false;
836 sg_policy->cached_raw_freq = 0;
837
838 sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);
839
840 if (policy_is_shared(policy))
841 uu = sugov_update_shared;
842 else if (policy->fast_switch_enabled && cpufreq_driver_has_adjust_perf())
843 uu = sugov_update_single_perf;
844 else
845 uu = sugov_update_single_freq;
846
847 for_each_cpu(cpu, policy->cpus) {
848 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
849
850 memset(sg_cpu, 0, sizeof(*sg_cpu));
851 sg_cpu->cpu = cpu;
852 sg_cpu->sg_policy = sg_policy;
853 cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util, uu);
854 }
855 return 0;
856}
857
858static void sugov_stop(struct cpufreq_policy *policy)
859{
860 struct sugov_policy *sg_policy = policy->governor_data;
861 unsigned int cpu;
862
863 for_each_cpu(cpu, policy->cpus)
864 cpufreq_remove_update_util_hook(cpu);
865
866 synchronize_rcu();
867
868 if (!policy->fast_switch_enabled) {
869 irq_work_sync(&sg_policy->irq_work);
870 kthread_cancel_work_sync(&sg_policy->work);
871 }
872}
873
874static void sugov_limits(struct cpufreq_policy *policy)
875{
876 struct sugov_policy *sg_policy = policy->governor_data;
877
878 if (!policy->fast_switch_enabled) {
879 mutex_lock(&sg_policy->work_lock);
880 cpufreq_policy_apply_limits(policy);
881 mutex_unlock(&sg_policy->work_lock);
882 }
883
884 sg_policy->limits_changed = true;
885}
886
887struct cpufreq_governor schedutil_gov = {
888 .name = "schedutil",
889 .owner = THIS_MODULE,
890 .flags = CPUFREQ_GOV_DYNAMIC_SWITCHING,
891 .init = sugov_init,
892 .exit = sugov_exit,
893 .start = sugov_start,
894 .stop = sugov_stop,
895 .limits = sugov_limits,
896};
897
898#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
899struct cpufreq_governor *cpufreq_default_governor(void)
900{
901 return &schedutil_gov;
902}
903#endif
904
905cpufreq_governor_init(schedutil_gov);
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 pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11#include "sched.h"
12
13#include <linux/sched/cpufreq.h>
14#include <trace/events/power.h>
15
16#define IOWAIT_BOOST_MIN (SCHED_CAPACITY_SCALE / 8)
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 limits_changed;
44 bool need_freq_update;
45};
46
47struct sugov_cpu {
48 struct update_util_data update_util;
49 struct sugov_policy *sg_policy;
50 unsigned int cpu;
51
52 bool iowait_boost_pending;
53 unsigned int iowait_boost;
54 u64 last_update;
55
56 unsigned long bw_dl;
57 unsigned long max;
58
59 /* The field below is for single-CPU policies only: */
60#ifdef CONFIG_NO_HZ_COMMON
61 unsigned long saved_idle_calls;
62#endif
63};
64
65static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
66
67/************************ Governor internals ***********************/
68
69static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
70{
71 s64 delta_ns;
72
73 /*
74 * Since cpufreq_update_util() is called with rq->lock held for
75 * the @target_cpu, our per-CPU data is fully serialized.
76 *
77 * However, drivers cannot in general deal with cross-CPU
78 * requests, so while get_next_freq() will work, our
79 * sugov_update_commit() call may not for the fast switching platforms.
80 *
81 * Hence stop here for remote requests if they aren't supported
82 * by the hardware, as calculating the frequency is pointless if
83 * we cannot in fact act on it.
84 *
85 * This is needed on the slow switching platforms too to prevent CPUs
86 * going offline from leaving stale IRQ work items behind.
87 */
88 if (!cpufreq_this_cpu_can_update(sg_policy->policy))
89 return false;
90
91 if (unlikely(sg_policy->limits_changed)) {
92 sg_policy->limits_changed = false;
93 sg_policy->need_freq_update = true;
94 return true;
95 }
96
97 delta_ns = time - sg_policy->last_freq_update_time;
98
99 return delta_ns >= sg_policy->freq_update_delay_ns;
100}
101
102static bool sugov_update_next_freq(struct sugov_policy *sg_policy, u64 time,
103 unsigned int next_freq)
104{
105 if (sg_policy->next_freq == next_freq)
106 return false;
107
108 sg_policy->next_freq = next_freq;
109 sg_policy->last_freq_update_time = time;
110
111 return true;
112}
113
114static void sugov_fast_switch(struct sugov_policy *sg_policy, u64 time,
115 unsigned int next_freq)
116{
117 struct cpufreq_policy *policy = sg_policy->policy;
118 int cpu;
119
120 if (!sugov_update_next_freq(sg_policy, time, next_freq))
121 return;
122
123 next_freq = cpufreq_driver_fast_switch(policy, next_freq);
124 if (!next_freq)
125 return;
126
127 policy->cur = next_freq;
128
129 if (trace_cpu_frequency_enabled()) {
130 for_each_cpu(cpu, policy->cpus)
131 trace_cpu_frequency(next_freq, cpu);
132 }
133}
134
135static void sugov_deferred_update(struct sugov_policy *sg_policy, u64 time,
136 unsigned int next_freq)
137{
138 if (!sugov_update_next_freq(sg_policy, time, next_freq))
139 return;
140
141 if (!sg_policy->work_in_progress) {
142 sg_policy->work_in_progress = true;
143 irq_work_queue(&sg_policy->irq_work);
144 }
145}
146
147/**
148 * get_next_freq - Compute a new frequency for a given cpufreq policy.
149 * @sg_policy: schedutil policy object to compute the new frequency for.
150 * @util: Current CPU utilization.
151 * @max: CPU capacity.
152 *
153 * If the utilization is frequency-invariant, choose the new frequency to be
154 * proportional to it, that is
155 *
156 * next_freq = C * max_freq * util / max
157 *
158 * Otherwise, approximate the would-be frequency-invariant utilization by
159 * util_raw * (curr_freq / max_freq) which leads to
160 *
161 * next_freq = C * curr_freq * util_raw / max
162 *
163 * Take C = 1.25 for the frequency tipping point at (util / max) = 0.8.
164 *
165 * The lowest driver-supported frequency which is equal or greater than the raw
166 * next_freq (as calculated above) is returned, subject to policy min/max and
167 * cpufreq driver limitations.
168 */
169static unsigned int get_next_freq(struct sugov_policy *sg_policy,
170 unsigned long util, unsigned long max)
171{
172 struct cpufreq_policy *policy = sg_policy->policy;
173 unsigned int freq = arch_scale_freq_invariant() ?
174 policy->cpuinfo.max_freq : policy->cur;
175
176 freq = map_util_freq(util, freq, max);
177
178 if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)
179 return sg_policy->next_freq;
180
181 sg_policy->need_freq_update = false;
182 sg_policy->cached_raw_freq = freq;
183 return cpufreq_driver_resolve_freq(policy, freq);
184}
185
186/*
187 * This function computes an effective utilization for the given CPU, to be
188 * used for frequency selection given the linear relation: f = u * f_max.
189 *
190 * The scheduler tracks the following metrics:
191 *
192 * cpu_util_{cfs,rt,dl,irq}()
193 * cpu_bw_dl()
194 *
195 * Where the cfs,rt and dl util numbers are tracked with the same metric and
196 * synchronized windows and are thus directly comparable.
197 *
198 * The cfs,rt,dl utilization are the running times measured with rq->clock_task
199 * which excludes things like IRQ and steal-time. These latter are then accrued
200 * in the irq utilization.
201 *
202 * The DL bandwidth number otoh is not a measured metric but a value computed
203 * based on the task model parameters and gives the minimal utilization
204 * required to meet deadlines.
205 */
206unsigned long schedutil_cpu_util(int cpu, unsigned long util_cfs,
207 unsigned long max, enum schedutil_type type,
208 struct task_struct *p)
209{
210 unsigned long dl_util, util, irq;
211 struct rq *rq = cpu_rq(cpu);
212
213 if (!uclamp_is_used() &&
214 type == FREQUENCY_UTIL && rt_rq_is_runnable(&rq->rt)) {
215 return max;
216 }
217
218 /*
219 * Early check to see if IRQ/steal time saturates the CPU, can be
220 * because of inaccuracies in how we track these -- see
221 * update_irq_load_avg().
222 */
223 irq = cpu_util_irq(rq);
224 if (unlikely(irq >= max))
225 return max;
226
227 /*
228 * Because the time spend on RT/DL tasks is visible as 'lost' time to
229 * CFS tasks and we use the same metric to track the effective
230 * utilization (PELT windows are synchronized) we can directly add them
231 * to obtain the CPU's actual utilization.
232 *
233 * CFS and RT utilization can be boosted or capped, depending on
234 * utilization clamp constraints requested by currently RUNNABLE
235 * tasks.
236 * When there are no CFS RUNNABLE tasks, clamps are released and
237 * frequency will be gracefully reduced with the utilization decay.
238 */
239 util = util_cfs + cpu_util_rt(rq);
240 if (type == FREQUENCY_UTIL)
241 util = uclamp_rq_util_with(rq, util, p);
242
243 dl_util = cpu_util_dl(rq);
244
245 /*
246 * For frequency selection we do not make cpu_util_dl() a permanent part
247 * of this sum because we want to use cpu_bw_dl() later on, but we need
248 * to check if the CFS+RT+DL sum is saturated (ie. no idle time) such
249 * that we select f_max when there is no idle time.
250 *
251 * NOTE: numerical errors or stop class might cause us to not quite hit
252 * saturation when we should -- something for later.
253 */
254 if (util + dl_util >= max)
255 return max;
256
257 /*
258 * OTOH, for energy computation we need the estimated running time, so
259 * include util_dl and ignore dl_bw.
260 */
261 if (type == ENERGY_UTIL)
262 util += dl_util;
263
264 /*
265 * There is still idle time; further improve the number by using the
266 * irq metric. Because IRQ/steal time is hidden from the task clock we
267 * need to scale the task numbers:
268 *
269 * max - irq
270 * U' = irq + --------- * U
271 * max
272 */
273 util = scale_irq_capacity(util, irq, max);
274 util += irq;
275
276 /*
277 * Bandwidth required by DEADLINE must always be granted while, for
278 * FAIR and RT, we use blocked utilization of IDLE CPUs as a mechanism
279 * to gracefully reduce the frequency when no tasks show up for longer
280 * periods of time.
281 *
282 * Ideally we would like to set bw_dl as min/guaranteed freq and util +
283 * bw_dl as requested freq. However, cpufreq is not yet ready for such
284 * an interface. So, we only do the latter for now.
285 */
286 if (type == FREQUENCY_UTIL)
287 util += cpu_bw_dl(rq);
288
289 return min(max, util);
290}
291
292static unsigned long sugov_get_util(struct sugov_cpu *sg_cpu)
293{
294 struct rq *rq = cpu_rq(sg_cpu->cpu);
295 unsigned long util = cpu_util_cfs(rq);
296 unsigned long max = arch_scale_cpu_capacity(sg_cpu->cpu);
297
298 sg_cpu->max = max;
299 sg_cpu->bw_dl = cpu_bw_dl(rq);
300
301 return schedutil_cpu_util(sg_cpu->cpu, util, max, FREQUENCY_UTIL, NULL);
302}
303
304/**
305 * sugov_iowait_reset() - Reset the IO boost status of a CPU.
306 * @sg_cpu: the sugov data for the CPU to boost
307 * @time: the update time from the caller
308 * @set_iowait_boost: true if an IO boost has been requested
309 *
310 * The IO wait boost of a task is disabled after a tick since the last update
311 * of a CPU. If a new IO wait boost is requested after more then a tick, then
312 * we enable the boost starting from IOWAIT_BOOST_MIN, which improves energy
313 * efficiency by ignoring sporadic wakeups from IO.
314 */
315static bool sugov_iowait_reset(struct sugov_cpu *sg_cpu, u64 time,
316 bool set_iowait_boost)
317{
318 s64 delta_ns = time - sg_cpu->last_update;
319
320 /* Reset boost only if a tick has elapsed since last request */
321 if (delta_ns <= TICK_NSEC)
322 return false;
323
324 sg_cpu->iowait_boost = set_iowait_boost ? IOWAIT_BOOST_MIN : 0;
325 sg_cpu->iowait_boost_pending = set_iowait_boost;
326
327 return true;
328}
329
330/**
331 * sugov_iowait_boost() - Updates the IO boost status of a CPU.
332 * @sg_cpu: the sugov data for the CPU to boost
333 * @time: the update time from the caller
334 * @flags: SCHED_CPUFREQ_IOWAIT if the task is waking up after an IO wait
335 *
336 * Each time a task wakes up after an IO operation, the CPU utilization can be
337 * boosted to a certain utilization which doubles at each "frequent and
338 * successive" wakeup from IO, ranging from IOWAIT_BOOST_MIN to the utilization
339 * of the maximum OPP.
340 *
341 * To keep doubling, an IO boost has to be requested at least once per tick,
342 * otherwise we restart from the utilization of the minimum OPP.
343 */
344static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
345 unsigned int flags)
346{
347 bool set_iowait_boost = flags & SCHED_CPUFREQ_IOWAIT;
348
349 /* Reset boost if the CPU appears to have been idle enough */
350 if (sg_cpu->iowait_boost &&
351 sugov_iowait_reset(sg_cpu, time, set_iowait_boost))
352 return;
353
354 /* Boost only tasks waking up after IO */
355 if (!set_iowait_boost)
356 return;
357
358 /* Ensure boost doubles only one time at each request */
359 if (sg_cpu->iowait_boost_pending)
360 return;
361 sg_cpu->iowait_boost_pending = true;
362
363 /* Double the boost at each request */
364 if (sg_cpu->iowait_boost) {
365 sg_cpu->iowait_boost =
366 min_t(unsigned int, sg_cpu->iowait_boost << 1, SCHED_CAPACITY_SCALE);
367 return;
368 }
369
370 /* First wakeup after IO: start with minimum boost */
371 sg_cpu->iowait_boost = IOWAIT_BOOST_MIN;
372}
373
374/**
375 * sugov_iowait_apply() - Apply the IO boost to a CPU.
376 * @sg_cpu: the sugov data for the cpu to boost
377 * @time: the update time from the caller
378 * @util: the utilization to (eventually) boost
379 * @max: the maximum value the utilization can be boosted to
380 *
381 * A CPU running a task which woken up after an IO operation can have its
382 * utilization boosted to speed up the completion of those IO operations.
383 * The IO boost value is increased each time a task wakes up from IO, in
384 * sugov_iowait_apply(), and it's instead decreased by this function,
385 * each time an increase has not been requested (!iowait_boost_pending).
386 *
387 * A CPU which also appears to have been idle for at least one tick has also
388 * its IO boost utilization reset.
389 *
390 * This mechanism is designed to boost high frequently IO waiting tasks, while
391 * being more conservative on tasks which does sporadic IO operations.
392 */
393static unsigned long sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time,
394 unsigned long util, unsigned long max)
395{
396 unsigned long boost;
397
398 /* No boost currently required */
399 if (!sg_cpu->iowait_boost)
400 return util;
401
402 /* Reset boost if the CPU appears to have been idle enough */
403 if (sugov_iowait_reset(sg_cpu, time, false))
404 return util;
405
406 if (!sg_cpu->iowait_boost_pending) {
407 /*
408 * No boost pending; reduce the boost value.
409 */
410 sg_cpu->iowait_boost >>= 1;
411 if (sg_cpu->iowait_boost < IOWAIT_BOOST_MIN) {
412 sg_cpu->iowait_boost = 0;
413 return util;
414 }
415 }
416
417 sg_cpu->iowait_boost_pending = false;
418
419 /*
420 * @util is already in capacity scale; convert iowait_boost
421 * into the same scale so we can compare.
422 */
423 boost = (sg_cpu->iowait_boost * max) >> SCHED_CAPACITY_SHIFT;
424 return max(boost, util);
425}
426
427#ifdef CONFIG_NO_HZ_COMMON
428static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
429{
430 unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu);
431 bool ret = idle_calls == sg_cpu->saved_idle_calls;
432
433 sg_cpu->saved_idle_calls = idle_calls;
434 return ret;
435}
436#else
437static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
438#endif /* CONFIG_NO_HZ_COMMON */
439
440/*
441 * Make sugov_should_update_freq() ignore the rate limit when DL
442 * has increased the utilization.
443 */
444static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu, struct sugov_policy *sg_policy)
445{
446 if (cpu_bw_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->bw_dl)
447 sg_policy->limits_changed = true;
448}
449
450static void sugov_update_single(struct update_util_data *hook, u64 time,
451 unsigned int flags)
452{
453 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
454 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
455 unsigned long util, max;
456 unsigned int next_f;
457 bool busy;
458
459 sugov_iowait_boost(sg_cpu, time, flags);
460 sg_cpu->last_update = time;
461
462 ignore_dl_rate_limit(sg_cpu, sg_policy);
463
464 if (!sugov_should_update_freq(sg_policy, time))
465 return;
466
467 /* Limits may have changed, don't skip frequency update */
468 busy = !sg_policy->need_freq_update && sugov_cpu_is_busy(sg_cpu);
469
470 util = sugov_get_util(sg_cpu);
471 max = sg_cpu->max;
472 util = sugov_iowait_apply(sg_cpu, time, util, max);
473 next_f = get_next_freq(sg_policy, util, max);
474 /*
475 * Do not reduce the frequency if the CPU has not been idle
476 * recently, as the reduction is likely to be premature then.
477 */
478 if (busy && next_f < sg_policy->next_freq) {
479 next_f = sg_policy->next_freq;
480
481 /* Reset cached freq as next_freq has changed */
482 sg_policy->cached_raw_freq = 0;
483 }
484
485 /*
486 * This code runs under rq->lock for the target CPU, so it won't run
487 * concurrently on two different CPUs for the same target and it is not
488 * necessary to acquire the lock in the fast switch case.
489 */
490 if (sg_policy->policy->fast_switch_enabled) {
491 sugov_fast_switch(sg_policy, time, next_f);
492 } else {
493 raw_spin_lock(&sg_policy->update_lock);
494 sugov_deferred_update(sg_policy, time, next_f);
495 raw_spin_unlock(&sg_policy->update_lock);
496 }
497}
498
499static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
500{
501 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
502 struct cpufreq_policy *policy = sg_policy->policy;
503 unsigned long util = 0, max = 1;
504 unsigned int j;
505
506 for_each_cpu(j, policy->cpus) {
507 struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
508 unsigned long j_util, j_max;
509
510 j_util = sugov_get_util(j_sg_cpu);
511 j_max = j_sg_cpu->max;
512 j_util = sugov_iowait_apply(j_sg_cpu, time, j_util, j_max);
513
514 if (j_util * max > j_max * util) {
515 util = j_util;
516 max = j_max;
517 }
518 }
519
520 return get_next_freq(sg_policy, util, max);
521}
522
523static void
524sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags)
525{
526 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
527 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
528 unsigned int next_f;
529
530 raw_spin_lock(&sg_policy->update_lock);
531
532 sugov_iowait_boost(sg_cpu, time, flags);
533 sg_cpu->last_update = time;
534
535 ignore_dl_rate_limit(sg_cpu, sg_policy);
536
537 if (sugov_should_update_freq(sg_policy, time)) {
538 next_f = sugov_next_freq_shared(sg_cpu, time);
539
540 if (sg_policy->policy->fast_switch_enabled)
541 sugov_fast_switch(sg_policy, time, next_f);
542 else
543 sugov_deferred_update(sg_policy, time, next_f);
544 }
545
546 raw_spin_unlock(&sg_policy->update_lock);
547}
548
549static void sugov_work(struct kthread_work *work)
550{
551 struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
552 unsigned int freq;
553 unsigned long flags;
554
555 /*
556 * Hold sg_policy->update_lock shortly to handle the case where:
557 * incase sg_policy->next_freq is read here, and then updated by
558 * sugov_deferred_update() just before work_in_progress is set to false
559 * here, we may miss queueing the new update.
560 *
561 * Note: If a work was queued after the update_lock is released,
562 * sugov_work() will just be called again by kthread_work code; and the
563 * request will be proceed before the sugov thread sleeps.
564 */
565 raw_spin_lock_irqsave(&sg_policy->update_lock, flags);
566 freq = sg_policy->next_freq;
567 sg_policy->work_in_progress = false;
568 raw_spin_unlock_irqrestore(&sg_policy->update_lock, flags);
569
570 mutex_lock(&sg_policy->work_lock);
571 __cpufreq_driver_target(sg_policy->policy, freq, CPUFREQ_RELATION_L);
572 mutex_unlock(&sg_policy->work_lock);
573}
574
575static void sugov_irq_work(struct irq_work *irq_work)
576{
577 struct sugov_policy *sg_policy;
578
579 sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
580
581 kthread_queue_work(&sg_policy->worker, &sg_policy->work);
582}
583
584/************************** sysfs interface ************************/
585
586static struct sugov_tunables *global_tunables;
587static DEFINE_MUTEX(global_tunables_lock);
588
589static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
590{
591 return container_of(attr_set, struct sugov_tunables, attr_set);
592}
593
594static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
595{
596 struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
597
598 return sprintf(buf, "%u\n", tunables->rate_limit_us);
599}
600
601static ssize_t
602rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf, size_t count)
603{
604 struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
605 struct sugov_policy *sg_policy;
606 unsigned int rate_limit_us;
607
608 if (kstrtouint(buf, 10, &rate_limit_us))
609 return -EINVAL;
610
611 tunables->rate_limit_us = rate_limit_us;
612
613 list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
614 sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
615
616 return count;
617}
618
619static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
620
621static struct attribute *sugov_attrs[] = {
622 &rate_limit_us.attr,
623 NULL
624};
625ATTRIBUTE_GROUPS(sugov);
626
627static struct kobj_type sugov_tunables_ktype = {
628 .default_groups = sugov_groups,
629 .sysfs_ops = &governor_sysfs_ops,
630};
631
632/********************** cpufreq governor interface *********************/
633
634struct cpufreq_governor schedutil_gov;
635
636static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
637{
638 struct sugov_policy *sg_policy;
639
640 sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
641 if (!sg_policy)
642 return NULL;
643
644 sg_policy->policy = policy;
645 raw_spin_lock_init(&sg_policy->update_lock);
646 return sg_policy;
647}
648
649static void sugov_policy_free(struct sugov_policy *sg_policy)
650{
651 kfree(sg_policy);
652}
653
654static int sugov_kthread_create(struct sugov_policy *sg_policy)
655{
656 struct task_struct *thread;
657 struct sched_attr attr = {
658 .size = sizeof(struct sched_attr),
659 .sched_policy = SCHED_DEADLINE,
660 .sched_flags = SCHED_FLAG_SUGOV,
661 .sched_nice = 0,
662 .sched_priority = 0,
663 /*
664 * Fake (unused) bandwidth; workaround to "fix"
665 * priority inheritance.
666 */
667 .sched_runtime = 1000000,
668 .sched_deadline = 10000000,
669 .sched_period = 10000000,
670 };
671 struct cpufreq_policy *policy = sg_policy->policy;
672 int ret;
673
674 /* kthread only required for slow path */
675 if (policy->fast_switch_enabled)
676 return 0;
677
678 kthread_init_work(&sg_policy->work, sugov_work);
679 kthread_init_worker(&sg_policy->worker);
680 thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
681 "sugov:%d",
682 cpumask_first(policy->related_cpus));
683 if (IS_ERR(thread)) {
684 pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread));
685 return PTR_ERR(thread);
686 }
687
688 ret = sched_setattr_nocheck(thread, &attr);
689 if (ret) {
690 kthread_stop(thread);
691 pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__);
692 return ret;
693 }
694
695 sg_policy->thread = thread;
696 kthread_bind_mask(thread, policy->related_cpus);
697 init_irq_work(&sg_policy->irq_work, sugov_irq_work);
698 mutex_init(&sg_policy->work_lock);
699
700 wake_up_process(thread);
701
702 return 0;
703}
704
705static void sugov_kthread_stop(struct sugov_policy *sg_policy)
706{
707 /* kthread only required for slow path */
708 if (sg_policy->policy->fast_switch_enabled)
709 return;
710
711 kthread_flush_worker(&sg_policy->worker);
712 kthread_stop(sg_policy->thread);
713 mutex_destroy(&sg_policy->work_lock);
714}
715
716static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
717{
718 struct sugov_tunables *tunables;
719
720 tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
721 if (tunables) {
722 gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
723 if (!have_governor_per_policy())
724 global_tunables = tunables;
725 }
726 return tunables;
727}
728
729static void sugov_tunables_free(struct sugov_tunables *tunables)
730{
731 if (!have_governor_per_policy())
732 global_tunables = NULL;
733
734 kfree(tunables);
735}
736
737static int sugov_init(struct cpufreq_policy *policy)
738{
739 struct sugov_policy *sg_policy;
740 struct sugov_tunables *tunables;
741 int ret = 0;
742
743 /* State should be equivalent to EXIT */
744 if (policy->governor_data)
745 return -EBUSY;
746
747 cpufreq_enable_fast_switch(policy);
748
749 sg_policy = sugov_policy_alloc(policy);
750 if (!sg_policy) {
751 ret = -ENOMEM;
752 goto disable_fast_switch;
753 }
754
755 ret = sugov_kthread_create(sg_policy);
756 if (ret)
757 goto free_sg_policy;
758
759 mutex_lock(&global_tunables_lock);
760
761 if (global_tunables) {
762 if (WARN_ON(have_governor_per_policy())) {
763 ret = -EINVAL;
764 goto stop_kthread;
765 }
766 policy->governor_data = sg_policy;
767 sg_policy->tunables = global_tunables;
768
769 gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
770 goto out;
771 }
772
773 tunables = sugov_tunables_alloc(sg_policy);
774 if (!tunables) {
775 ret = -ENOMEM;
776 goto stop_kthread;
777 }
778
779 tunables->rate_limit_us = cpufreq_policy_transition_delay_us(policy);
780
781 policy->governor_data = sg_policy;
782 sg_policy->tunables = tunables;
783
784 ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
785 get_governor_parent_kobj(policy), "%s",
786 schedutil_gov.name);
787 if (ret)
788 goto fail;
789
790out:
791 mutex_unlock(&global_tunables_lock);
792 return 0;
793
794fail:
795 kobject_put(&tunables->attr_set.kobj);
796 policy->governor_data = NULL;
797 sugov_tunables_free(tunables);
798
799stop_kthread:
800 sugov_kthread_stop(sg_policy);
801 mutex_unlock(&global_tunables_lock);
802
803free_sg_policy:
804 sugov_policy_free(sg_policy);
805
806disable_fast_switch:
807 cpufreq_disable_fast_switch(policy);
808
809 pr_err("initialization failed (error %d)\n", ret);
810 return ret;
811}
812
813static void sugov_exit(struct cpufreq_policy *policy)
814{
815 struct sugov_policy *sg_policy = policy->governor_data;
816 struct sugov_tunables *tunables = sg_policy->tunables;
817 unsigned int count;
818
819 mutex_lock(&global_tunables_lock);
820
821 count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
822 policy->governor_data = NULL;
823 if (!count)
824 sugov_tunables_free(tunables);
825
826 mutex_unlock(&global_tunables_lock);
827
828 sugov_kthread_stop(sg_policy);
829 sugov_policy_free(sg_policy);
830 cpufreq_disable_fast_switch(policy);
831}
832
833static int sugov_start(struct cpufreq_policy *policy)
834{
835 struct sugov_policy *sg_policy = policy->governor_data;
836 unsigned int cpu;
837
838 sg_policy->freq_update_delay_ns = sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
839 sg_policy->last_freq_update_time = 0;
840 sg_policy->next_freq = 0;
841 sg_policy->work_in_progress = false;
842 sg_policy->limits_changed = false;
843 sg_policy->need_freq_update = false;
844 sg_policy->cached_raw_freq = 0;
845
846 for_each_cpu(cpu, policy->cpus) {
847 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
848
849 memset(sg_cpu, 0, sizeof(*sg_cpu));
850 sg_cpu->cpu = cpu;
851 sg_cpu->sg_policy = sg_policy;
852 }
853
854 for_each_cpu(cpu, policy->cpus) {
855 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
856
857 cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
858 policy_is_shared(policy) ?
859 sugov_update_shared :
860 sugov_update_single);
861 }
862 return 0;
863}
864
865static void sugov_stop(struct cpufreq_policy *policy)
866{
867 struct sugov_policy *sg_policy = policy->governor_data;
868 unsigned int cpu;
869
870 for_each_cpu(cpu, policy->cpus)
871 cpufreq_remove_update_util_hook(cpu);
872
873 synchronize_rcu();
874
875 if (!policy->fast_switch_enabled) {
876 irq_work_sync(&sg_policy->irq_work);
877 kthread_cancel_work_sync(&sg_policy->work);
878 }
879}
880
881static void sugov_limits(struct cpufreq_policy *policy)
882{
883 struct sugov_policy *sg_policy = policy->governor_data;
884
885 if (!policy->fast_switch_enabled) {
886 mutex_lock(&sg_policy->work_lock);
887 cpufreq_policy_apply_limits(policy);
888 mutex_unlock(&sg_policy->work_lock);
889 }
890
891 sg_policy->limits_changed = true;
892}
893
894struct cpufreq_governor schedutil_gov = {
895 .name = "schedutil",
896 .owner = THIS_MODULE,
897 .dynamic_switching = true,
898 .init = sugov_init,
899 .exit = sugov_exit,
900 .start = sugov_start,
901 .stop = sugov_stop,
902 .limits = sugov_limits,
903};
904
905#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
906struct cpufreq_governor *cpufreq_default_governor(void)
907{
908 return &schedutil_gov;
909}
910#endif
911
912cpufreq_governor_init(schedutil_gov);
913
914#ifdef CONFIG_ENERGY_MODEL
915extern bool sched_energy_update;
916extern struct mutex sched_energy_mutex;
917
918static void rebuild_sd_workfn(struct work_struct *work)
919{
920 mutex_lock(&sched_energy_mutex);
921 sched_energy_update = true;
922 rebuild_sched_domains();
923 sched_energy_update = false;
924 mutex_unlock(&sched_energy_mutex);
925}
926static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);
927
928/*
929 * EAS shouldn't be attempted without sugov, so rebuild the sched_domains
930 * on governor changes to make sure the scheduler knows about it.
931 */
932void sched_cpufreq_governor_change(struct cpufreq_policy *policy,
933 struct cpufreq_governor *old_gov)
934{
935 if (old_gov == &schedutil_gov || policy->governor == &schedutil_gov) {
936 /*
937 * When called from the cpufreq_register_driver() path, the
938 * cpu_hotplug_lock is already held, so use a work item to
939 * avoid nested locking in rebuild_sched_domains().
940 */
941 schedule_work(&rebuild_sd_work);
942 }
943
944}
945#endif