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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);
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 = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);
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 = false;
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 = scx_cpuperf_target(sg_cpu->cpu);
201
202 if (!scx_switched_all())
203 util += cpu_util_cfs_boost(sg_cpu->cpu);
204 util = effective_cpu_util(sg_cpu->cpu, util, &min, &max);
205 util = max(util, boost);
206 sg_cpu->bw_min = min;
207 sg_cpu->util = sugov_effective_cpu_perf(sg_cpu->cpu, util, min, max);
208}
209
210/**
211 * sugov_iowait_reset() - Reset the IO boost status of a CPU.
212 * @sg_cpu: the sugov data for the CPU to boost
213 * @time: the update time from the caller
214 * @set_iowait_boost: true if an IO boost has been requested
215 *
216 * The IO wait boost of a task is disabled after a tick since the last update
217 * of a CPU. If a new IO wait boost is requested after more then a tick, then
218 * we enable the boost starting from IOWAIT_BOOST_MIN, which improves energy
219 * efficiency by ignoring sporadic wakeups from IO.
220 */
221static bool sugov_iowait_reset(struct sugov_cpu *sg_cpu, u64 time,
222 bool set_iowait_boost)
223{
224 s64 delta_ns = time - sg_cpu->last_update;
225
226 /* Reset boost only if a tick has elapsed since last request */
227 if (delta_ns <= TICK_NSEC)
228 return false;
229
230 sg_cpu->iowait_boost = set_iowait_boost ? IOWAIT_BOOST_MIN : 0;
231 sg_cpu->iowait_boost_pending = set_iowait_boost;
232
233 return true;
234}
235
236/**
237 * sugov_iowait_boost() - Updates the IO boost status of a CPU.
238 * @sg_cpu: the sugov data for the CPU to boost
239 * @time: the update time from the caller
240 * @flags: SCHED_CPUFREQ_IOWAIT if the task is waking up after an IO wait
241 *
242 * Each time a task wakes up after an IO operation, the CPU utilization can be
243 * boosted to a certain utilization which doubles at each "frequent and
244 * successive" wakeup from IO, ranging from IOWAIT_BOOST_MIN to the utilization
245 * of the maximum OPP.
246 *
247 * To keep doubling, an IO boost has to be requested at least once per tick,
248 * otherwise we restart from the utilization of the minimum OPP.
249 */
250static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
251 unsigned int flags)
252{
253 bool set_iowait_boost = flags & SCHED_CPUFREQ_IOWAIT;
254
255 /* Reset boost if the CPU appears to have been idle enough */
256 if (sg_cpu->iowait_boost &&
257 sugov_iowait_reset(sg_cpu, time, set_iowait_boost))
258 return;
259
260 /* Boost only tasks waking up after IO */
261 if (!set_iowait_boost)
262 return;
263
264 /* Ensure boost doubles only one time at each request */
265 if (sg_cpu->iowait_boost_pending)
266 return;
267 sg_cpu->iowait_boost_pending = true;
268
269 /* Double the boost at each request */
270 if (sg_cpu->iowait_boost) {
271 sg_cpu->iowait_boost =
272 min_t(unsigned int, sg_cpu->iowait_boost << 1, SCHED_CAPACITY_SCALE);
273 return;
274 }
275
276 /* First wakeup after IO: start with minimum boost */
277 sg_cpu->iowait_boost = IOWAIT_BOOST_MIN;
278}
279
280/**
281 * sugov_iowait_apply() - Apply the IO boost to a CPU.
282 * @sg_cpu: the sugov data for the cpu to boost
283 * @time: the update time from the caller
284 * @max_cap: the max CPU capacity
285 *
286 * A CPU running a task which woken up after an IO operation can have its
287 * utilization boosted to speed up the completion of those IO operations.
288 * The IO boost value is increased each time a task wakes up from IO, in
289 * sugov_iowait_apply(), and it's instead decreased by this function,
290 * each time an increase has not been requested (!iowait_boost_pending).
291 *
292 * A CPU which also appears to have been idle for at least one tick has also
293 * its IO boost utilization reset.
294 *
295 * This mechanism is designed to boost high frequently IO waiting tasks, while
296 * being more conservative on tasks which does sporadic IO operations.
297 */
298static unsigned long sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time,
299 unsigned long max_cap)
300{
301 /* No boost currently required */
302 if (!sg_cpu->iowait_boost)
303 return 0;
304
305 /* Reset boost if the CPU appears to have been idle enough */
306 if (sugov_iowait_reset(sg_cpu, time, false))
307 return 0;
308
309 if (!sg_cpu->iowait_boost_pending) {
310 /*
311 * No boost pending; reduce the boost value.
312 */
313 sg_cpu->iowait_boost >>= 1;
314 if (sg_cpu->iowait_boost < IOWAIT_BOOST_MIN) {
315 sg_cpu->iowait_boost = 0;
316 return 0;
317 }
318 }
319
320 sg_cpu->iowait_boost_pending = false;
321
322 /*
323 * sg_cpu->util is already in capacity scale; convert iowait_boost
324 * into the same scale so we can compare.
325 */
326 return (sg_cpu->iowait_boost * max_cap) >> SCHED_CAPACITY_SHIFT;
327}
328
329#ifdef CONFIG_NO_HZ_COMMON
330static bool sugov_hold_freq(struct sugov_cpu *sg_cpu)
331{
332 unsigned long idle_calls;
333 bool ret;
334
335 /*
336 * The heuristics in this function is for the fair class. For SCX, the
337 * performance target comes directly from the BPF scheduler. Let's just
338 * follow it.
339 */
340 if (scx_switched_all())
341 return false;
342
343 /* if capped by uclamp_max, always update to be in compliance */
344 if (uclamp_rq_is_capped(cpu_rq(sg_cpu->cpu)))
345 return false;
346
347 /*
348 * Maintain the frequency if the CPU has not been idle recently, as
349 * reduction is likely to be premature.
350 */
351 idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu);
352 ret = idle_calls == sg_cpu->saved_idle_calls;
353
354 sg_cpu->saved_idle_calls = idle_calls;
355 return ret;
356}
357#else
358static inline bool sugov_hold_freq(struct sugov_cpu *sg_cpu) { return false; }
359#endif /* CONFIG_NO_HZ_COMMON */
360
361/*
362 * Make sugov_should_update_freq() ignore the rate limit when DL
363 * has increased the utilization.
364 */
365static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu)
366{
367 if (cpu_bw_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->bw_min)
368 sg_cpu->sg_policy->limits_changed = true;
369}
370
371static inline bool sugov_update_single_common(struct sugov_cpu *sg_cpu,
372 u64 time, unsigned long max_cap,
373 unsigned int flags)
374{
375 unsigned long boost;
376
377 sugov_iowait_boost(sg_cpu, time, flags);
378 sg_cpu->last_update = time;
379
380 ignore_dl_rate_limit(sg_cpu);
381
382 if (!sugov_should_update_freq(sg_cpu->sg_policy, time))
383 return false;
384
385 boost = sugov_iowait_apply(sg_cpu, time, max_cap);
386 sugov_get_util(sg_cpu, boost);
387
388 return true;
389}
390
391static void sugov_update_single_freq(struct update_util_data *hook, u64 time,
392 unsigned int flags)
393{
394 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
395 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
396 unsigned int cached_freq = sg_policy->cached_raw_freq;
397 unsigned long max_cap;
398 unsigned int next_f;
399
400 max_cap = arch_scale_cpu_capacity(sg_cpu->cpu);
401
402 if (!sugov_update_single_common(sg_cpu, time, max_cap, flags))
403 return;
404
405 next_f = get_next_freq(sg_policy, sg_cpu->util, max_cap);
406
407 if (sugov_hold_freq(sg_cpu) && next_f < sg_policy->next_freq &&
408 !sg_policy->need_freq_update) {
409 next_f = sg_policy->next_freq;
410
411 /* Restore cached freq as next_freq has changed */
412 sg_policy->cached_raw_freq = cached_freq;
413 }
414
415 if (!sugov_update_next_freq(sg_policy, time, next_f))
416 return;
417
418 /*
419 * This code runs under rq->lock for the target CPU, so it won't run
420 * concurrently on two different CPUs for the same target and it is not
421 * necessary to acquire the lock in the fast switch case.
422 */
423 if (sg_policy->policy->fast_switch_enabled) {
424 cpufreq_driver_fast_switch(sg_policy->policy, next_f);
425 } else {
426 raw_spin_lock(&sg_policy->update_lock);
427 sugov_deferred_update(sg_policy);
428 raw_spin_unlock(&sg_policy->update_lock);
429 }
430}
431
432static void sugov_update_single_perf(struct update_util_data *hook, u64 time,
433 unsigned int flags)
434{
435 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
436 unsigned long prev_util = sg_cpu->util;
437 unsigned long max_cap;
438
439 /*
440 * Fall back to the "frequency" path if frequency invariance is not
441 * supported, because the direct mapping between the utilization and
442 * the performance levels depends on the frequency invariance.
443 */
444 if (!arch_scale_freq_invariant()) {
445 sugov_update_single_freq(hook, time, flags);
446 return;
447 }
448
449 max_cap = arch_scale_cpu_capacity(sg_cpu->cpu);
450
451 if (!sugov_update_single_common(sg_cpu, time, max_cap, flags))
452 return;
453
454 if (sugov_hold_freq(sg_cpu) && sg_cpu->util < prev_util)
455 sg_cpu->util = prev_util;
456
457 cpufreq_driver_adjust_perf(sg_cpu->cpu, sg_cpu->bw_min,
458 sg_cpu->util, max_cap);
459
460 sg_cpu->sg_policy->last_freq_update_time = time;
461}
462
463static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
464{
465 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
466 struct cpufreq_policy *policy = sg_policy->policy;
467 unsigned long util = 0, max_cap;
468 unsigned int j;
469
470 max_cap = arch_scale_cpu_capacity(sg_cpu->cpu);
471
472 for_each_cpu(j, policy->cpus) {
473 struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
474 unsigned long boost;
475
476 boost = sugov_iowait_apply(j_sg_cpu, time, max_cap);
477 sugov_get_util(j_sg_cpu, boost);
478
479 util = max(j_sg_cpu->util, util);
480 }
481
482 return get_next_freq(sg_policy, util, max_cap);
483}
484
485static void
486sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags)
487{
488 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
489 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
490 unsigned int next_f;
491
492 raw_spin_lock(&sg_policy->update_lock);
493
494 sugov_iowait_boost(sg_cpu, time, flags);
495 sg_cpu->last_update = time;
496
497 ignore_dl_rate_limit(sg_cpu);
498
499 if (sugov_should_update_freq(sg_policy, time)) {
500 next_f = sugov_next_freq_shared(sg_cpu, time);
501
502 if (!sugov_update_next_freq(sg_policy, time, next_f))
503 goto unlock;
504
505 if (sg_policy->policy->fast_switch_enabled)
506 cpufreq_driver_fast_switch(sg_policy->policy, next_f);
507 else
508 sugov_deferred_update(sg_policy);
509 }
510unlock:
511 raw_spin_unlock(&sg_policy->update_lock);
512}
513
514static void sugov_work(struct kthread_work *work)
515{
516 struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
517 unsigned int freq;
518 unsigned long flags;
519
520 /*
521 * Hold sg_policy->update_lock shortly to handle the case where:
522 * in case sg_policy->next_freq is read here, and then updated by
523 * sugov_deferred_update() just before work_in_progress is set to false
524 * here, we may miss queueing the new update.
525 *
526 * Note: If a work was queued after the update_lock is released,
527 * sugov_work() will just be called again by kthread_work code; and the
528 * request will be proceed before the sugov thread sleeps.
529 */
530 raw_spin_lock_irqsave(&sg_policy->update_lock, flags);
531 freq = sg_policy->next_freq;
532 sg_policy->work_in_progress = false;
533 raw_spin_unlock_irqrestore(&sg_policy->update_lock, flags);
534
535 mutex_lock(&sg_policy->work_lock);
536 __cpufreq_driver_target(sg_policy->policy, freq, CPUFREQ_RELATION_L);
537 mutex_unlock(&sg_policy->work_lock);
538}
539
540static void sugov_irq_work(struct irq_work *irq_work)
541{
542 struct sugov_policy *sg_policy;
543
544 sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
545
546 kthread_queue_work(&sg_policy->worker, &sg_policy->work);
547}
548
549/************************** sysfs interface ************************/
550
551static struct sugov_tunables *global_tunables;
552static DEFINE_MUTEX(global_tunables_lock);
553
554static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
555{
556 return container_of(attr_set, struct sugov_tunables, attr_set);
557}
558
559static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
560{
561 struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
562
563 return sprintf(buf, "%u\n", tunables->rate_limit_us);
564}
565
566static ssize_t
567rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf, size_t count)
568{
569 struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
570 struct sugov_policy *sg_policy;
571 unsigned int rate_limit_us;
572
573 if (kstrtouint(buf, 10, &rate_limit_us))
574 return -EINVAL;
575
576 tunables->rate_limit_us = rate_limit_us;
577
578 list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
579 sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
580
581 return count;
582}
583
584static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
585
586static struct attribute *sugov_attrs[] = {
587 &rate_limit_us.attr,
588 NULL
589};
590ATTRIBUTE_GROUPS(sugov);
591
592static void sugov_tunables_free(struct kobject *kobj)
593{
594 struct gov_attr_set *attr_set = to_gov_attr_set(kobj);
595
596 kfree(to_sugov_tunables(attr_set));
597}
598
599static const struct kobj_type sugov_tunables_ktype = {
600 .default_groups = sugov_groups,
601 .sysfs_ops = &governor_sysfs_ops,
602 .release = &sugov_tunables_free,
603};
604
605/********************** cpufreq governor interface *********************/
606
607#ifdef CONFIG_ENERGY_MODEL
608static void rebuild_sd_workfn(struct work_struct *work)
609{
610 rebuild_sched_domains_energy();
611}
612
613static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);
614
615/*
616 * EAS shouldn't be attempted without sugov, so rebuild the sched_domains
617 * on governor changes to make sure the scheduler knows about it.
618 */
619static void sugov_eas_rebuild_sd(void)
620{
621 /*
622 * When called from the cpufreq_register_driver() path, the
623 * cpu_hotplug_lock is already held, so use a work item to
624 * avoid nested locking in rebuild_sched_domains().
625 */
626 schedule_work(&rebuild_sd_work);
627}
628#else
629static inline void sugov_eas_rebuild_sd(void) { };
630#endif
631
632struct cpufreq_governor schedutil_gov;
633
634static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
635{
636 struct sugov_policy *sg_policy;
637
638 sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
639 if (!sg_policy)
640 return NULL;
641
642 sg_policy->policy = policy;
643 raw_spin_lock_init(&sg_policy->update_lock);
644 return sg_policy;
645}
646
647static void sugov_policy_free(struct sugov_policy *sg_policy)
648{
649 kfree(sg_policy);
650}
651
652static int sugov_kthread_create(struct sugov_policy *sg_policy)
653{
654 struct task_struct *thread;
655 struct sched_attr attr = {
656 .size = sizeof(struct sched_attr),
657 .sched_policy = SCHED_DEADLINE,
658 .sched_flags = SCHED_FLAG_SUGOV,
659 .sched_nice = 0,
660 .sched_priority = 0,
661 /*
662 * Fake (unused) bandwidth; workaround to "fix"
663 * priority inheritance.
664 */
665 .sched_runtime = NSEC_PER_MSEC,
666 .sched_deadline = 10 * NSEC_PER_MSEC,
667 .sched_period = 10 * NSEC_PER_MSEC,
668 };
669 struct cpufreq_policy *policy = sg_policy->policy;
670 int ret;
671
672 /* kthread only required for slow path */
673 if (policy->fast_switch_enabled)
674 return 0;
675
676 kthread_init_work(&sg_policy->work, sugov_work);
677 kthread_init_worker(&sg_policy->worker);
678 thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
679 "sugov:%d",
680 cpumask_first(policy->related_cpus));
681 if (IS_ERR(thread)) {
682 pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread));
683 return PTR_ERR(thread);
684 }
685
686 ret = sched_setattr_nocheck(thread, &attr);
687 if (ret) {
688 kthread_stop(thread);
689 pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__);
690 return ret;
691 }
692
693 sg_policy->thread = thread;
694 kthread_bind_mask(thread, policy->related_cpus);
695 init_irq_work(&sg_policy->irq_work, sugov_irq_work);
696 mutex_init(&sg_policy->work_lock);
697
698 wake_up_process(thread);
699
700 return 0;
701}
702
703static void sugov_kthread_stop(struct sugov_policy *sg_policy)
704{
705 /* kthread only required for slow path */
706 if (sg_policy->policy->fast_switch_enabled)
707 return;
708
709 kthread_flush_worker(&sg_policy->worker);
710 kthread_stop(sg_policy->thread);
711 mutex_destroy(&sg_policy->work_lock);
712}
713
714static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
715{
716 struct sugov_tunables *tunables;
717
718 tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
719 if (tunables) {
720 gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
721 if (!have_governor_per_policy())
722 global_tunables = tunables;
723 }
724 return tunables;
725}
726
727static void sugov_clear_global_tunables(void)
728{
729 if (!have_governor_per_policy())
730 global_tunables = NULL;
731}
732
733static int sugov_init(struct cpufreq_policy *policy)
734{
735 struct sugov_policy *sg_policy;
736 struct sugov_tunables *tunables;
737 int ret = 0;
738
739 /* State should be equivalent to EXIT */
740 if (policy->governor_data)
741 return -EBUSY;
742
743 cpufreq_enable_fast_switch(policy);
744
745 sg_policy = sugov_policy_alloc(policy);
746 if (!sg_policy) {
747 ret = -ENOMEM;
748 goto disable_fast_switch;
749 }
750
751 ret = sugov_kthread_create(sg_policy);
752 if (ret)
753 goto free_sg_policy;
754
755 mutex_lock(&global_tunables_lock);
756
757 if (global_tunables) {
758 if (WARN_ON(have_governor_per_policy())) {
759 ret = -EINVAL;
760 goto stop_kthread;
761 }
762 policy->governor_data = sg_policy;
763 sg_policy->tunables = global_tunables;
764
765 gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
766 goto out;
767 }
768
769 tunables = sugov_tunables_alloc(sg_policy);
770 if (!tunables) {
771 ret = -ENOMEM;
772 goto stop_kthread;
773 }
774
775 tunables->rate_limit_us = cpufreq_policy_transition_delay_us(policy);
776
777 policy->governor_data = sg_policy;
778 sg_policy->tunables = tunables;
779
780 ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
781 get_governor_parent_kobj(policy), "%s",
782 schedutil_gov.name);
783 if (ret)
784 goto fail;
785
786out:
787 sugov_eas_rebuild_sd();
788 mutex_unlock(&global_tunables_lock);
789 return 0;
790
791fail:
792 kobject_put(&tunables->attr_set.kobj);
793 policy->governor_data = NULL;
794 sugov_clear_global_tunables();
795
796stop_kthread:
797 sugov_kthread_stop(sg_policy);
798 mutex_unlock(&global_tunables_lock);
799
800free_sg_policy:
801 sugov_policy_free(sg_policy);
802
803disable_fast_switch:
804 cpufreq_disable_fast_switch(policy);
805
806 pr_err("initialization failed (error %d)\n", ret);
807 return ret;
808}
809
810static void sugov_exit(struct cpufreq_policy *policy)
811{
812 struct sugov_policy *sg_policy = policy->governor_data;
813 struct sugov_tunables *tunables = sg_policy->tunables;
814 unsigned int count;
815
816 mutex_lock(&global_tunables_lock);
817
818 count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
819 policy->governor_data = NULL;
820 if (!count)
821 sugov_clear_global_tunables();
822
823 mutex_unlock(&global_tunables_lock);
824
825 sugov_kthread_stop(sg_policy);
826 sugov_policy_free(sg_policy);
827 cpufreq_disable_fast_switch(policy);
828
829 sugov_eas_rebuild_sd();
830}
831
832static int sugov_start(struct cpufreq_policy *policy)
833{
834 struct sugov_policy *sg_policy = policy->governor_data;
835 void (*uu)(struct update_util_data *data, u64 time, unsigned int flags);
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->cached_raw_freq = 0;
844
845 sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);
846
847 if (policy_is_shared(policy))
848 uu = sugov_update_shared;
849 else if (policy->fast_switch_enabled && cpufreq_driver_has_adjust_perf())
850 uu = sugov_update_single_perf;
851 else
852 uu = sugov_update_single_freq;
853
854 for_each_cpu(cpu, policy->cpus) {
855 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
856
857 memset(sg_cpu, 0, sizeof(*sg_cpu));
858 sg_cpu->cpu = cpu;
859 sg_cpu->sg_policy = sg_policy;
860 cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util, uu);
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 .flags = CPUFREQ_GOV_DYNAMIC_SWITCHING,
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);