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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 = 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);