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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/*
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 <linux/cpufreq.h>
15#include <linux/kthread.h>
16#include <linux/slab.h>
17#include <trace/events/power.h>
18
19#include "sched.h"
20
21#define SUGOV_KTHREAD_PRIORITY 50
22
23struct sugov_tunables {
24 struct gov_attr_set attr_set;
25 unsigned int rate_limit_us;
26};
27
28struct sugov_policy {
29 struct cpufreq_policy *policy;
30
31 struct sugov_tunables *tunables;
32 struct list_head tunables_hook;
33
34 raw_spinlock_t update_lock; /* For shared policies */
35 u64 last_freq_update_time;
36 s64 freq_update_delay_ns;
37 unsigned int next_freq;
38
39 /* The next fields are only needed if fast switch cannot be used. */
40 struct irq_work irq_work;
41 struct kthread_work work;
42 struct mutex work_lock;
43 struct kthread_worker worker;
44 struct task_struct *thread;
45 bool work_in_progress;
46
47 bool need_freq_update;
48};
49
50struct sugov_cpu {
51 struct update_util_data update_util;
52 struct sugov_policy *sg_policy;
53
54 unsigned int cached_raw_freq;
55 unsigned long iowait_boost;
56 unsigned long iowait_boost_max;
57 u64 last_update;
58
59 /* The fields below are only needed when sharing a policy. */
60 unsigned long util;
61 unsigned long max;
62 unsigned int flags;
63};
64
65static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
66
67/************************ Governor internals ***********************/
68
69static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
70{
71 s64 delta_ns;
72
73 if (sg_policy->work_in_progress)
74 return false;
75
76 if (unlikely(sg_policy->need_freq_update)) {
77 sg_policy->need_freq_update = false;
78 /*
79 * This happens when limits change, so forget the previous
80 * next_freq value and force an update.
81 */
82 sg_policy->next_freq = UINT_MAX;
83 return true;
84 }
85
86 delta_ns = time - sg_policy->last_freq_update_time;
87 return delta_ns >= sg_policy->freq_update_delay_ns;
88}
89
90static void sugov_update_commit(struct sugov_policy *sg_policy, u64 time,
91 unsigned int next_freq)
92{
93 struct cpufreq_policy *policy = sg_policy->policy;
94
95 sg_policy->last_freq_update_time = time;
96
97 if (policy->fast_switch_enabled) {
98 if (sg_policy->next_freq == next_freq) {
99 trace_cpu_frequency(policy->cur, smp_processor_id());
100 return;
101 }
102 sg_policy->next_freq = next_freq;
103 next_freq = cpufreq_driver_fast_switch(policy, next_freq);
104 if (next_freq == CPUFREQ_ENTRY_INVALID)
105 return;
106
107 policy->cur = next_freq;
108 trace_cpu_frequency(next_freq, smp_processor_id());
109 } else if (sg_policy->next_freq != next_freq) {
110 sg_policy->next_freq = next_freq;
111 sg_policy->work_in_progress = true;
112 irq_work_queue(&sg_policy->irq_work);
113 }
114}
115
116/**
117 * get_next_freq - Compute a new frequency for a given cpufreq policy.
118 * @sg_cpu: schedutil cpu object to compute the new frequency for.
119 * @util: Current CPU utilization.
120 * @max: CPU capacity.
121 *
122 * If the utilization is frequency-invariant, choose the new frequency to be
123 * proportional to it, that is
124 *
125 * next_freq = C * max_freq * util / max
126 *
127 * Otherwise, approximate the would-be frequency-invariant utilization by
128 * util_raw * (curr_freq / max_freq) which leads to
129 *
130 * next_freq = C * curr_freq * util_raw / max
131 *
132 * Take C = 1.25 for the frequency tipping point at (util / max) = 0.8.
133 *
134 * The lowest driver-supported frequency which is equal or greater than the raw
135 * next_freq (as calculated above) is returned, subject to policy min/max and
136 * cpufreq driver limitations.
137 */
138static unsigned int get_next_freq(struct sugov_cpu *sg_cpu, unsigned long util,
139 unsigned long max)
140{
141 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
142 struct cpufreq_policy *policy = sg_policy->policy;
143 unsigned int freq = arch_scale_freq_invariant() ?
144 policy->cpuinfo.max_freq : policy->cur;
145
146 freq = (freq + (freq >> 2)) * util / max;
147
148 if (freq == sg_cpu->cached_raw_freq && sg_policy->next_freq != UINT_MAX)
149 return sg_policy->next_freq;
150 sg_cpu->cached_raw_freq = freq;
151 return cpufreq_driver_resolve_freq(policy, freq);
152}
153
154static void sugov_get_util(unsigned long *util, unsigned long *max)
155{
156 struct rq *rq = this_rq();
157 unsigned long cfs_max;
158
159 cfs_max = arch_scale_cpu_capacity(NULL, smp_processor_id());
160
161 *util = min(rq->cfs.avg.util_avg, cfs_max);
162 *max = cfs_max;
163}
164
165static void sugov_set_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
166 unsigned int flags)
167{
168 if (flags & SCHED_CPUFREQ_IOWAIT) {
169 sg_cpu->iowait_boost = sg_cpu->iowait_boost_max;
170 } else if (sg_cpu->iowait_boost) {
171 s64 delta_ns = time - sg_cpu->last_update;
172
173 /* Clear iowait_boost if the CPU apprears to have been idle. */
174 if (delta_ns > TICK_NSEC)
175 sg_cpu->iowait_boost = 0;
176 }
177}
178
179static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, unsigned long *util,
180 unsigned long *max)
181{
182 unsigned long boost_util = sg_cpu->iowait_boost;
183 unsigned long boost_max = sg_cpu->iowait_boost_max;
184
185 if (!boost_util)
186 return;
187
188 if (*util * boost_max < *max * boost_util) {
189 *util = boost_util;
190 *max = boost_max;
191 }
192 sg_cpu->iowait_boost >>= 1;
193}
194
195static void sugov_update_single(struct update_util_data *hook, u64 time,
196 unsigned int flags)
197{
198 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
199 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
200 struct cpufreq_policy *policy = sg_policy->policy;
201 unsigned long util, max;
202 unsigned int next_f;
203
204 sugov_set_iowait_boost(sg_cpu, time, flags);
205 sg_cpu->last_update = time;
206
207 if (!sugov_should_update_freq(sg_policy, time))
208 return;
209
210 if (flags & SCHED_CPUFREQ_RT_DL) {
211 next_f = policy->cpuinfo.max_freq;
212 } else {
213 sugov_get_util(&util, &max);
214 sugov_iowait_boost(sg_cpu, &util, &max);
215 next_f = get_next_freq(sg_cpu, util, max);
216 }
217 sugov_update_commit(sg_policy, time, next_f);
218}
219
220static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu,
221 unsigned long util, unsigned long max,
222 unsigned int flags)
223{
224 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
225 struct cpufreq_policy *policy = sg_policy->policy;
226 unsigned int max_f = policy->cpuinfo.max_freq;
227 u64 last_freq_update_time = sg_policy->last_freq_update_time;
228 unsigned int j;
229
230 if (flags & SCHED_CPUFREQ_RT_DL)
231 return max_f;
232
233 sugov_iowait_boost(sg_cpu, &util, &max);
234
235 for_each_cpu(j, policy->cpus) {
236 struct sugov_cpu *j_sg_cpu;
237 unsigned long j_util, j_max;
238 s64 delta_ns;
239
240 if (j == smp_processor_id())
241 continue;
242
243 j_sg_cpu = &per_cpu(sugov_cpu, j);
244 /*
245 * If the CPU utilization was last updated before the previous
246 * frequency update and the time elapsed between the last update
247 * of the CPU utilization and the last frequency update is long
248 * enough, don't take the CPU into account as it probably is
249 * idle now (and clear iowait_boost for it).
250 */
251 delta_ns = last_freq_update_time - j_sg_cpu->last_update;
252 if (delta_ns > TICK_NSEC) {
253 j_sg_cpu->iowait_boost = 0;
254 continue;
255 }
256 if (j_sg_cpu->flags & SCHED_CPUFREQ_RT_DL)
257 return max_f;
258
259 j_util = j_sg_cpu->util;
260 j_max = j_sg_cpu->max;
261 if (j_util * max > j_max * util) {
262 util = j_util;
263 max = j_max;
264 }
265
266 sugov_iowait_boost(j_sg_cpu, &util, &max);
267 }
268
269 return get_next_freq(sg_cpu, util, max);
270}
271
272static void sugov_update_shared(struct update_util_data *hook, u64 time,
273 unsigned int flags)
274{
275 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
276 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
277 unsigned long util, max;
278 unsigned int next_f;
279
280 sugov_get_util(&util, &max);
281
282 raw_spin_lock(&sg_policy->update_lock);
283
284 sg_cpu->util = util;
285 sg_cpu->max = max;
286 sg_cpu->flags = flags;
287
288 sugov_set_iowait_boost(sg_cpu, time, flags);
289 sg_cpu->last_update = time;
290
291 if (sugov_should_update_freq(sg_policy, time)) {
292 next_f = sugov_next_freq_shared(sg_cpu, util, max, flags);
293 sugov_update_commit(sg_policy, time, next_f);
294 }
295
296 raw_spin_unlock(&sg_policy->update_lock);
297}
298
299static void sugov_work(struct kthread_work *work)
300{
301 struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
302
303 mutex_lock(&sg_policy->work_lock);
304 __cpufreq_driver_target(sg_policy->policy, sg_policy->next_freq,
305 CPUFREQ_RELATION_L);
306 mutex_unlock(&sg_policy->work_lock);
307
308 sg_policy->work_in_progress = false;
309}
310
311static void sugov_irq_work(struct irq_work *irq_work)
312{
313 struct sugov_policy *sg_policy;
314
315 sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
316
317 /*
318 * For RT and deadline tasks, the schedutil governor shoots the
319 * frequency to maximum. Special care must be taken to ensure that this
320 * kthread doesn't result in the same behavior.
321 *
322 * This is (mostly) guaranteed by the work_in_progress flag. The flag is
323 * updated only at the end of the sugov_work() function and before that
324 * the schedutil governor rejects all other frequency scaling requests.
325 *
326 * There is a very rare case though, where the RT thread yields right
327 * after the work_in_progress flag is cleared. The effects of that are
328 * neglected for now.
329 */
330 kthread_queue_work(&sg_policy->worker, &sg_policy->work);
331}
332
333/************************** sysfs interface ************************/
334
335static struct sugov_tunables *global_tunables;
336static DEFINE_MUTEX(global_tunables_lock);
337
338static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
339{
340 return container_of(attr_set, struct sugov_tunables, attr_set);
341}
342
343static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
344{
345 struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
346
347 return sprintf(buf, "%u\n", tunables->rate_limit_us);
348}
349
350static ssize_t rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf,
351 size_t count)
352{
353 struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
354 struct sugov_policy *sg_policy;
355 unsigned int rate_limit_us;
356
357 if (kstrtouint(buf, 10, &rate_limit_us))
358 return -EINVAL;
359
360 tunables->rate_limit_us = rate_limit_us;
361
362 list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
363 sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
364
365 return count;
366}
367
368static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
369
370static struct attribute *sugov_attributes[] = {
371 &rate_limit_us.attr,
372 NULL
373};
374
375static struct kobj_type sugov_tunables_ktype = {
376 .default_attrs = sugov_attributes,
377 .sysfs_ops = &governor_sysfs_ops,
378};
379
380/********************** cpufreq governor interface *********************/
381
382static struct cpufreq_governor schedutil_gov;
383
384static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
385{
386 struct sugov_policy *sg_policy;
387
388 sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
389 if (!sg_policy)
390 return NULL;
391
392 sg_policy->policy = policy;
393 raw_spin_lock_init(&sg_policy->update_lock);
394 return sg_policy;
395}
396
397static void sugov_policy_free(struct sugov_policy *sg_policy)
398{
399 kfree(sg_policy);
400}
401
402static int sugov_kthread_create(struct sugov_policy *sg_policy)
403{
404 struct task_struct *thread;
405 struct sched_param param = { .sched_priority = MAX_USER_RT_PRIO / 2 };
406 struct cpufreq_policy *policy = sg_policy->policy;
407 int ret;
408
409 /* kthread only required for slow path */
410 if (policy->fast_switch_enabled)
411 return 0;
412
413 kthread_init_work(&sg_policy->work, sugov_work);
414 kthread_init_worker(&sg_policy->worker);
415 thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
416 "sugov:%d",
417 cpumask_first(policy->related_cpus));
418 if (IS_ERR(thread)) {
419 pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread));
420 return PTR_ERR(thread);
421 }
422
423 ret = sched_setscheduler_nocheck(thread, SCHED_FIFO, ¶m);
424 if (ret) {
425 kthread_stop(thread);
426 pr_warn("%s: failed to set SCHED_FIFO\n", __func__);
427 return ret;
428 }
429
430 sg_policy->thread = thread;
431 kthread_bind_mask(thread, policy->related_cpus);
432 init_irq_work(&sg_policy->irq_work, sugov_irq_work);
433 mutex_init(&sg_policy->work_lock);
434
435 wake_up_process(thread);
436
437 return 0;
438}
439
440static void sugov_kthread_stop(struct sugov_policy *sg_policy)
441{
442 /* kthread only required for slow path */
443 if (sg_policy->policy->fast_switch_enabled)
444 return;
445
446 kthread_flush_worker(&sg_policy->worker);
447 kthread_stop(sg_policy->thread);
448 mutex_destroy(&sg_policy->work_lock);
449}
450
451static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
452{
453 struct sugov_tunables *tunables;
454
455 tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
456 if (tunables) {
457 gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
458 if (!have_governor_per_policy())
459 global_tunables = tunables;
460 }
461 return tunables;
462}
463
464static void sugov_tunables_free(struct sugov_tunables *tunables)
465{
466 if (!have_governor_per_policy())
467 global_tunables = NULL;
468
469 kfree(tunables);
470}
471
472static int sugov_init(struct cpufreq_policy *policy)
473{
474 struct sugov_policy *sg_policy;
475 struct sugov_tunables *tunables;
476 unsigned int lat;
477 int ret = 0;
478
479 /* State should be equivalent to EXIT */
480 if (policy->governor_data)
481 return -EBUSY;
482
483 cpufreq_enable_fast_switch(policy);
484
485 sg_policy = sugov_policy_alloc(policy);
486 if (!sg_policy) {
487 ret = -ENOMEM;
488 goto disable_fast_switch;
489 }
490
491 ret = sugov_kthread_create(sg_policy);
492 if (ret)
493 goto free_sg_policy;
494
495 mutex_lock(&global_tunables_lock);
496
497 if (global_tunables) {
498 if (WARN_ON(have_governor_per_policy())) {
499 ret = -EINVAL;
500 goto stop_kthread;
501 }
502 policy->governor_data = sg_policy;
503 sg_policy->tunables = global_tunables;
504
505 gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
506 goto out;
507 }
508
509 tunables = sugov_tunables_alloc(sg_policy);
510 if (!tunables) {
511 ret = -ENOMEM;
512 goto stop_kthread;
513 }
514
515 tunables->rate_limit_us = LATENCY_MULTIPLIER;
516 lat = policy->cpuinfo.transition_latency / NSEC_PER_USEC;
517 if (lat)
518 tunables->rate_limit_us *= lat;
519
520 policy->governor_data = sg_policy;
521 sg_policy->tunables = tunables;
522
523 ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
524 get_governor_parent_kobj(policy), "%s",
525 schedutil_gov.name);
526 if (ret)
527 goto fail;
528
529out:
530 mutex_unlock(&global_tunables_lock);
531 return 0;
532
533fail:
534 policy->governor_data = NULL;
535 sugov_tunables_free(tunables);
536
537stop_kthread:
538 sugov_kthread_stop(sg_policy);
539
540free_sg_policy:
541 mutex_unlock(&global_tunables_lock);
542
543 sugov_policy_free(sg_policy);
544
545disable_fast_switch:
546 cpufreq_disable_fast_switch(policy);
547
548 pr_err("initialization failed (error %d)\n", ret);
549 return ret;
550}
551
552static void sugov_exit(struct cpufreq_policy *policy)
553{
554 struct sugov_policy *sg_policy = policy->governor_data;
555 struct sugov_tunables *tunables = sg_policy->tunables;
556 unsigned int count;
557
558 mutex_lock(&global_tunables_lock);
559
560 count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
561 policy->governor_data = NULL;
562 if (!count)
563 sugov_tunables_free(tunables);
564
565 mutex_unlock(&global_tunables_lock);
566
567 sugov_kthread_stop(sg_policy);
568 sugov_policy_free(sg_policy);
569 cpufreq_disable_fast_switch(policy);
570}
571
572static int sugov_start(struct cpufreq_policy *policy)
573{
574 struct sugov_policy *sg_policy = policy->governor_data;
575 unsigned int cpu;
576
577 sg_policy->freq_update_delay_ns = sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
578 sg_policy->last_freq_update_time = 0;
579 sg_policy->next_freq = UINT_MAX;
580 sg_policy->work_in_progress = false;
581 sg_policy->need_freq_update = false;
582
583 for_each_cpu(cpu, policy->cpus) {
584 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
585
586 sg_cpu->sg_policy = sg_policy;
587 if (policy_is_shared(policy)) {
588 sg_cpu->util = 0;
589 sg_cpu->max = 0;
590 sg_cpu->flags = SCHED_CPUFREQ_RT;
591 sg_cpu->last_update = 0;
592 sg_cpu->cached_raw_freq = 0;
593 sg_cpu->iowait_boost = 0;
594 sg_cpu->iowait_boost_max = policy->cpuinfo.max_freq;
595 cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
596 sugov_update_shared);
597 } else {
598 cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
599 sugov_update_single);
600 }
601 }
602 return 0;
603}
604
605static void sugov_stop(struct cpufreq_policy *policy)
606{
607 struct sugov_policy *sg_policy = policy->governor_data;
608 unsigned int cpu;
609
610 for_each_cpu(cpu, policy->cpus)
611 cpufreq_remove_update_util_hook(cpu);
612
613 synchronize_sched();
614
615 if (!policy->fast_switch_enabled) {
616 irq_work_sync(&sg_policy->irq_work);
617 kthread_cancel_work_sync(&sg_policy->work);
618 }
619}
620
621static void sugov_limits(struct cpufreq_policy *policy)
622{
623 struct sugov_policy *sg_policy = policy->governor_data;
624
625 if (!policy->fast_switch_enabled) {
626 mutex_lock(&sg_policy->work_lock);
627 cpufreq_policy_apply_limits(policy);
628 mutex_unlock(&sg_policy->work_lock);
629 }
630
631 sg_policy->need_freq_update = true;
632}
633
634static struct cpufreq_governor schedutil_gov = {
635 .name = "schedutil",
636 .owner = THIS_MODULE,
637 .init = sugov_init,
638 .exit = sugov_exit,
639 .start = sugov_start,
640 .stop = sugov_stop,
641 .limits = sugov_limits,
642};
643
644#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
645struct cpufreq_governor *cpufreq_default_governor(void)
646{
647 return &schedutil_gov;
648}
649#endif
650
651static int __init sugov_register(void)
652{
653 return cpufreq_register_governor(&schedutil_gov);
654}
655fs_initcall(sugov_register);