1// SPDX-License-Identifier: GPL-2.0
2/*
3 * CPUFreq governor based on scheduler-provided CPU utilization data.
4 *
5 * Copyright (C) 2016, Intel Corporation
6 * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
7 */
8
9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
11#include "sched.h"
12
13#include <linux/sched/cpufreq.h>
14#include <trace/events/power.h>
15
16struct sugov_tunables {
17 struct gov_attr_set attr_set;
18 unsigned int rate_limit_us;
19};
20
21struct sugov_policy {
22 struct cpufreq_policy *policy;
23
24 struct sugov_tunables *tunables;
25 struct list_head tunables_hook;
26
27 raw_spinlock_t update_lock; /* For shared policies */
28 u64 last_freq_update_time;
29 s64 freq_update_delay_ns;
30 unsigned int next_freq;
31 unsigned int cached_raw_freq;
32
33 /* The next fields are only needed if fast switch cannot be used: */
34 struct irq_work irq_work;
35 struct kthread_work work;
36 struct mutex work_lock;
37 struct kthread_worker worker;
38 struct task_struct *thread;
39 bool work_in_progress;
40
41 bool need_freq_update;
42};
43
44struct sugov_cpu {
45 struct update_util_data update_util;
46 struct sugov_policy *sg_policy;
47 unsigned int cpu;
48
49 bool iowait_boost_pending;
50 unsigned int iowait_boost;
51 u64 last_update;
52
53 unsigned long bw_dl;
54 unsigned long min;
55 unsigned long max;
56
57 /* The field below is for single-CPU policies only: */
58#ifdef CONFIG_NO_HZ_COMMON
59 unsigned long saved_idle_calls;
60#endif
61};
62
63static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
64
65/************************ Governor internals ***********************/
66
67static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
68{
69 s64 delta_ns;
70
71 /*
72 * Since cpufreq_update_util() is called with rq->lock held for
73 * the @target_cpu, our per-CPU data is fully serialized.
74 *
75 * However, drivers cannot in general deal with cross-CPU
76 * requests, so while get_next_freq() will work, our
77 * sugov_update_commit() call may not for the fast switching platforms.
78 *
79 * Hence stop here for remote requests if they aren't supported
80 * by the hardware, as calculating the frequency is pointless if
81 * we cannot in fact act on it.
82 *
83 * For the slow switching platforms, the kthread is always scheduled on
84 * the right set of CPUs and any CPU can find the next frequency and
85 * schedule the kthread.
86 */
87 if (sg_policy->policy->fast_switch_enabled &&
88 !cpufreq_this_cpu_can_update(sg_policy->policy))
89 return false;
90
91 if (unlikely(sg_policy->need_freq_update))
92 return true;
93
94 delta_ns = time - sg_policy->last_freq_update_time;
95
96 return delta_ns >= sg_policy->freq_update_delay_ns;
97}
98
99static bool sugov_update_next_freq(struct sugov_policy *sg_policy, u64 time,
100 unsigned int next_freq)
101{
102 if (sg_policy->next_freq == next_freq)
103 return false;
104
105 sg_policy->next_freq = next_freq;
106 sg_policy->last_freq_update_time = time;
107
108 return true;
109}
110
111static void sugov_fast_switch(struct sugov_policy *sg_policy, u64 time,
112 unsigned int next_freq)
113{
114 struct cpufreq_policy *policy = sg_policy->policy;
115
116 if (!sugov_update_next_freq(sg_policy, time, next_freq))
117 return;
118
119 next_freq = cpufreq_driver_fast_switch(policy, next_freq);
120 if (!next_freq)
121 return;
122
123 policy->cur = next_freq;
124 trace_cpu_frequency(next_freq, smp_processor_id());
125}
126
127static void sugov_deferred_update(struct sugov_policy *sg_policy, u64 time,
128 unsigned int next_freq)
129{
130 if (!sugov_update_next_freq(sg_policy, time, next_freq))
131 return;
132
133 if (!sg_policy->work_in_progress) {
134 sg_policy->work_in_progress = true;
135 irq_work_queue(&sg_policy->irq_work);
136 }
137}
138
139/**
140 * get_next_freq - Compute a new frequency for a given cpufreq policy.
141 * @sg_policy: schedutil policy object to compute the new frequency for.
142 * @util: Current CPU utilization.
143 * @max: CPU capacity.
144 *
145 * If the utilization is frequency-invariant, choose the new frequency to be
146 * proportional to it, that is
147 *
148 * next_freq = C * max_freq * util / max
149 *
150 * Otherwise, approximate the would-be frequency-invariant utilization by
151 * util_raw * (curr_freq / max_freq) which leads to
152 *
153 * next_freq = C * curr_freq * util_raw / max
154 *
155 * Take C = 1.25 for the frequency tipping point at (util / max) = 0.8.
156 *
157 * The lowest driver-supported frequency which is equal or greater than the raw
158 * next_freq (as calculated above) is returned, subject to policy min/max and
159 * cpufreq driver limitations.
160 */
161static unsigned int get_next_freq(struct sugov_policy *sg_policy,
162 unsigned long util, unsigned long max)
163{
164 struct cpufreq_policy *policy = sg_policy->policy;
165 unsigned int freq = arch_scale_freq_invariant() ?
166 policy->cpuinfo.max_freq : policy->cur;
167
168 freq = map_util_freq(util, freq, max);
169
170 if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)
171 return sg_policy->next_freq;
172
173 sg_policy->need_freq_update = false;
174 sg_policy->cached_raw_freq = freq;
175 return cpufreq_driver_resolve_freq(policy, freq);
176}
177
178/*
179 * This function computes an effective utilization for the given CPU, to be
180 * used for frequency selection given the linear relation: f = u * f_max.
181 *
182 * The scheduler tracks the following metrics:
183 *
184 * cpu_util_{cfs,rt,dl,irq}()
185 * cpu_bw_dl()
186 *
187 * Where the cfs,rt and dl util numbers are tracked with the same metric and
188 * synchronized windows and are thus directly comparable.
189 *
190 * The cfs,rt,dl utilization are the running times measured with rq->clock_task
191 * which excludes things like IRQ and steal-time. These latter are then accrued
192 * in the irq utilization.
193 *
194 * The DL bandwidth number otoh is not a measured metric but a value computed
195 * based on the task model parameters and gives the minimal utilization
196 * required to meet deadlines.
197 */
198unsigned long schedutil_freq_util(int cpu, unsigned long util_cfs,
199 unsigned long max, enum schedutil_type type)
200{
201 unsigned long dl_util, util, irq;
202 struct rq *rq = cpu_rq(cpu);
203
204 if (type == FREQUENCY_UTIL && rt_rq_is_runnable(&rq->rt))
205 return max;
206
207 /*
208 * Early check to see if IRQ/steal time saturates the CPU, can be
209 * because of inaccuracies in how we track these -- see
210 * update_irq_load_avg().
211 */
212 irq = cpu_util_irq(rq);
213 if (unlikely(irq >= max))
214 return max;
215
216 /*
217 * Because the time spend on RT/DL tasks is visible as 'lost' time to
218 * CFS tasks and we use the same metric to track the effective
219 * utilization (PELT windows are synchronized) we can directly add them
220 * to obtain the CPU's actual utilization.
221 */
222 util = util_cfs;
223 util += cpu_util_rt(rq);
224
225 dl_util = cpu_util_dl(rq);
226
227 /*
228 * For frequency selection we do not make cpu_util_dl() a permanent part
229 * of this sum because we want to use cpu_bw_dl() later on, but we need
230 * to check if the CFS+RT+DL sum is saturated (ie. no idle time) such
231 * that we select f_max when there is no idle time.
232 *
233 * NOTE: numerical errors or stop class might cause us to not quite hit
234 * saturation when we should -- something for later.
235 */
236 if (util + dl_util >= max)
237 return max;
238
239 /*
240 * OTOH, for energy computation we need the estimated running time, so
241 * include util_dl and ignore dl_bw.
242 */
243 if (type == ENERGY_UTIL)
244 util += dl_util;
245
246 /*
247 * There is still idle time; further improve the number by using the
248 * irq metric. Because IRQ/steal time is hidden from the task clock we
249 * need to scale the task numbers:
250 *
251 * 1 - irq
252 * U' = irq + ------- * U
253 * max
254 */
255 util = scale_irq_capacity(util, irq, max);
256 util += irq;
257
258 /*
259 * Bandwidth required by DEADLINE must always be granted while, for
260 * FAIR and RT, we use blocked utilization of IDLE CPUs as a mechanism
261 * to gracefully reduce the frequency when no tasks show up for longer
262 * periods of time.
263 *
264 * Ideally we would like to set bw_dl as min/guaranteed freq and util +
265 * bw_dl as requested freq. However, cpufreq is not yet ready for such
266 * an interface. So, we only do the latter for now.
267 */
268 if (type == FREQUENCY_UTIL)
269 util += cpu_bw_dl(rq);
270
271 return min(max, util);
272}
273
274static unsigned long sugov_get_util(struct sugov_cpu *sg_cpu)
275{
276 struct rq *rq = cpu_rq(sg_cpu->cpu);
277 unsigned long util = cpu_util_cfs(rq);
278 unsigned long max = arch_scale_cpu_capacity(NULL, sg_cpu->cpu);
279
280 sg_cpu->max = max;
281 sg_cpu->bw_dl = cpu_bw_dl(rq);
282
283 return schedutil_freq_util(sg_cpu->cpu, util, max, FREQUENCY_UTIL);
284}
285
286/**
287 * sugov_iowait_reset() - Reset the IO boost status of a CPU.
288 * @sg_cpu: the sugov data for the CPU to boost
289 * @time: the update time from the caller
290 * @set_iowait_boost: true if an IO boost has been requested
291 *
292 * The IO wait boost of a task is disabled after a tick since the last update
293 * of a CPU. If a new IO wait boost is requested after more then a tick, then
294 * we enable the boost starting from the minimum frequency, which improves
295 * energy efficiency by ignoring sporadic wakeups from IO.
296 */
297static bool sugov_iowait_reset(struct sugov_cpu *sg_cpu, u64 time,
298 bool set_iowait_boost)
299{
300 s64 delta_ns = time - sg_cpu->last_update;
301
302 /* Reset boost only if a tick has elapsed since last request */
303 if (delta_ns <= TICK_NSEC)
304 return false;
305
306 sg_cpu->iowait_boost = set_iowait_boost ? sg_cpu->min : 0;
307 sg_cpu->iowait_boost_pending = set_iowait_boost;
308
309 return true;
310}
311
312/**
313 * sugov_iowait_boost() - Updates the IO boost status of a CPU.
314 * @sg_cpu: the sugov data for the CPU to boost
315 * @time: the update time from the caller
316 * @flags: SCHED_CPUFREQ_IOWAIT if the task is waking up after an IO wait
317 *
318 * Each time a task wakes up after an IO operation, the CPU utilization can be
319 * boosted to a certain utilization which doubles at each "frequent and
320 * successive" wakeup from IO, ranging from the utilization of the minimum
321 * OPP to the utilization of the maximum OPP.
322 * To keep doubling, an IO boost has to be requested at least once per tick,
323 * otherwise we restart from the utilization of the minimum OPP.
324 */
325static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
326 unsigned int flags)
327{
328 bool set_iowait_boost = flags & SCHED_CPUFREQ_IOWAIT;
329
330 /* Reset boost if the CPU appears to have been idle enough */
331 if (sg_cpu->iowait_boost &&
332 sugov_iowait_reset(sg_cpu, time, set_iowait_boost))
333 return;
334
335 /* Boost only tasks waking up after IO */
336 if (!set_iowait_boost)
337 return;
338
339 /* Ensure boost doubles only one time at each request */
340 if (sg_cpu->iowait_boost_pending)
341 return;
342 sg_cpu->iowait_boost_pending = true;
343
344 /* Double the boost at each request */
345 if (sg_cpu->iowait_boost) {
346 sg_cpu->iowait_boost =
347 min_t(unsigned int, sg_cpu->iowait_boost << 1, SCHED_CAPACITY_SCALE);
348 return;
349 }
350
351 /* First wakeup after IO: start with minimum boost */
352 sg_cpu->iowait_boost = sg_cpu->min;
353}
354
355/**
356 * sugov_iowait_apply() - Apply the IO boost to a CPU.
357 * @sg_cpu: the sugov data for the cpu to boost
358 * @time: the update time from the caller
359 * @util: the utilization to (eventually) boost
360 * @max: the maximum value the utilization can be boosted to
361 *
362 * A CPU running a task which woken up after an IO operation can have its
363 * utilization boosted to speed up the completion of those IO operations.
364 * The IO boost value is increased each time a task wakes up from IO, in
365 * sugov_iowait_apply(), and it's instead decreased by this function,
366 * each time an increase has not been requested (!iowait_boost_pending).
367 *
368 * A CPU which also appears to have been idle for at least one tick has also
369 * its IO boost utilization reset.
370 *
371 * This mechanism is designed to boost high frequently IO waiting tasks, while
372 * being more conservative on tasks which does sporadic IO operations.
373 */
374static unsigned long sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time,
375 unsigned long util, unsigned long max)
376{
377 unsigned long boost;
378
379 /* No boost currently required */
380 if (!sg_cpu->iowait_boost)
381 return util;
382
383 /* Reset boost if the CPU appears to have been idle enough */
384 if (sugov_iowait_reset(sg_cpu, time, false))
385 return util;
386
387 if (!sg_cpu->iowait_boost_pending) {
388 /*
389 * No boost pending; reduce the boost value.
390 */
391 sg_cpu->iowait_boost >>= 1;
392 if (sg_cpu->iowait_boost < sg_cpu->min) {
393 sg_cpu->iowait_boost = 0;
394 return util;
395 }
396 }
397
398 sg_cpu->iowait_boost_pending = false;
399
400 /*
401 * @util is already in capacity scale; convert iowait_boost
402 * into the same scale so we can compare.
403 */
404 boost = (sg_cpu->iowait_boost * max) >> SCHED_CAPACITY_SHIFT;
405 return max(boost, util);
406}
407
408#ifdef CONFIG_NO_HZ_COMMON
409static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
410{
411 unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu);
412 bool ret = idle_calls == sg_cpu->saved_idle_calls;
413
414 sg_cpu->saved_idle_calls = idle_calls;
415 return ret;
416}
417#else
418static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
419#endif /* CONFIG_NO_HZ_COMMON */
420
421/*
422 * Make sugov_should_update_freq() ignore the rate limit when DL
423 * has increased the utilization.
424 */
425static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu, struct sugov_policy *sg_policy)
426{
427 if (cpu_bw_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->bw_dl)
428 sg_policy->need_freq_update = true;
429}
430
431static void sugov_update_single(struct update_util_data *hook, u64 time,
432 unsigned int flags)
433{
434 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
435 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
436 unsigned long util, max;
437 unsigned int next_f;
438 bool busy;
439
440 sugov_iowait_boost(sg_cpu, time, flags);
441 sg_cpu->last_update = time;
442
443 ignore_dl_rate_limit(sg_cpu, sg_policy);
444
445 if (!sugov_should_update_freq(sg_policy, time))
446 return;
447
448 busy = sugov_cpu_is_busy(sg_cpu);
449
450 util = sugov_get_util(sg_cpu);
451 max = sg_cpu->max;
452 util = sugov_iowait_apply(sg_cpu, time, util, max);
453 next_f = get_next_freq(sg_policy, util, max);
454 /*
455 * Do not reduce the frequency if the CPU has not been idle
456 * recently, as the reduction is likely to be premature then.
457 */
458 if (busy && next_f < sg_policy->next_freq) {
459 next_f = sg_policy->next_freq;
460
461 /* Reset cached freq as next_freq has changed */
462 sg_policy->cached_raw_freq = 0;
463 }
464
465 /*
466 * This code runs under rq->lock for the target CPU, so it won't run
467 * concurrently on two different CPUs for the same target and it is not
468 * necessary to acquire the lock in the fast switch case.
469 */
470 if (sg_policy->policy->fast_switch_enabled) {
471 sugov_fast_switch(sg_policy, time, next_f);
472 } else {
473 raw_spin_lock(&sg_policy->update_lock);
474 sugov_deferred_update(sg_policy, time, next_f);
475 raw_spin_unlock(&sg_policy->update_lock);
476 }
477}
478
479static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
480{
481 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
482 struct cpufreq_policy *policy = sg_policy->policy;
483 unsigned long util = 0, max = 1;
484 unsigned int j;
485
486 for_each_cpu(j, policy->cpus) {
487 struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
488 unsigned long j_util, j_max;
489
490 j_util = sugov_get_util(j_sg_cpu);
491 j_max = j_sg_cpu->max;
492 j_util = sugov_iowait_apply(j_sg_cpu, time, j_util, j_max);
493
494 if (j_util * max > j_max * util) {
495 util = j_util;
496 max = j_max;
497 }
498 }
499
500 return get_next_freq(sg_policy, util, max);
501}
502
503static void
504sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags)
505{
506 struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
507 struct sugov_policy *sg_policy = sg_cpu->sg_policy;
508 unsigned int next_f;
509
510 raw_spin_lock(&sg_policy->update_lock);
511
512 sugov_iowait_boost(sg_cpu, time, flags);
513 sg_cpu->last_update = time;
514
515 ignore_dl_rate_limit(sg_cpu, sg_policy);
516
517 if (sugov_should_update_freq(sg_policy, time)) {
518 next_f = sugov_next_freq_shared(sg_cpu, time);
519
520 if (sg_policy->policy->fast_switch_enabled)
521 sugov_fast_switch(sg_policy, time, next_f);
522 else
523 sugov_deferred_update(sg_policy, time, next_f);
524 }
525
526 raw_spin_unlock(&sg_policy->update_lock);
527}
528
529static void sugov_work(struct kthread_work *work)
530{
531 struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
532 unsigned int freq;
533 unsigned long flags;
534
535 /*
536 * Hold sg_policy->update_lock shortly to handle the case where:
537 * incase sg_policy->next_freq is read here, and then updated by
538 * sugov_deferred_update() just before work_in_progress is set to false
539 * here, we may miss queueing the new update.
540 *
541 * Note: If a work was queued after the update_lock is released,
542 * sugov_work() will just be called again by kthread_work code; and the
543 * request will be proceed before the sugov thread sleeps.
544 */
545 raw_spin_lock_irqsave(&sg_policy->update_lock, flags);
546 freq = sg_policy->next_freq;
547 sg_policy->work_in_progress = false;
548 raw_spin_unlock_irqrestore(&sg_policy->update_lock, flags);
549
550 mutex_lock(&sg_policy->work_lock);
551 __cpufreq_driver_target(sg_policy->policy, freq, CPUFREQ_RELATION_L);
552 mutex_unlock(&sg_policy->work_lock);
553}
554
555static void sugov_irq_work(struct irq_work *irq_work)
556{
557 struct sugov_policy *sg_policy;
558
559 sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
560
561 kthread_queue_work(&sg_policy->worker, &sg_policy->work);
562}
563
564/************************** sysfs interface ************************/
565
566static struct sugov_tunables *global_tunables;
567static DEFINE_MUTEX(global_tunables_lock);
568
569static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
570{
571 return container_of(attr_set, struct sugov_tunables, attr_set);
572}
573
574static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
575{
576 struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
577
578 return sprintf(buf, "%u\n", tunables->rate_limit_us);
579}
580
581static ssize_t
582rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf, size_t count)
583{
584 struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
585 struct sugov_policy *sg_policy;
586 unsigned int rate_limit_us;
587
588 if (kstrtouint(buf, 10, &rate_limit_us))
589 return -EINVAL;
590
591 tunables->rate_limit_us = rate_limit_us;
592
593 list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
594 sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
595
596 return count;
597}
598
599static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
600
601static struct attribute *sugov_attributes[] = {
602 &rate_limit_us.attr,
603 NULL
604};
605
606static struct kobj_type sugov_tunables_ktype = {
607 .default_attrs = sugov_attributes,
608 .sysfs_ops = &governor_sysfs_ops,
609};
610
611/********************** cpufreq governor interface *********************/
612
613struct cpufreq_governor schedutil_gov;
614
615static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
616{
617 struct sugov_policy *sg_policy;
618
619 sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
620 if (!sg_policy)
621 return NULL;
622
623 sg_policy->policy = policy;
624 raw_spin_lock_init(&sg_policy->update_lock);
625 return sg_policy;
626}
627
628static void sugov_policy_free(struct sugov_policy *sg_policy)
629{
630 kfree(sg_policy);
631}
632
633static int sugov_kthread_create(struct sugov_policy *sg_policy)
634{
635 struct task_struct *thread;
636 struct sched_attr attr = {
637 .size = sizeof(struct sched_attr),
638 .sched_policy = SCHED_DEADLINE,
639 .sched_flags = SCHED_FLAG_SUGOV,
640 .sched_nice = 0,
641 .sched_priority = 0,
642 /*
643 * Fake (unused) bandwidth; workaround to "fix"
644 * priority inheritance.
645 */
646 .sched_runtime = 1000000,
647 .sched_deadline = 10000000,
648 .sched_period = 10000000,
649 };
650 struct cpufreq_policy *policy = sg_policy->policy;
651 int ret;
652
653 /* kthread only required for slow path */
654 if (policy->fast_switch_enabled)
655 return 0;
656
657 kthread_init_work(&sg_policy->work, sugov_work);
658 kthread_init_worker(&sg_policy->worker);
659 thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
660 "sugov:%d",
661 cpumask_first(policy->related_cpus));
662 if (IS_ERR(thread)) {
663 pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread));
664 return PTR_ERR(thread);
665 }
666
667 ret = sched_setattr_nocheck(thread, &attr);
668 if (ret) {
669 kthread_stop(thread);
670 pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__);
671 return ret;
672 }
673
674 sg_policy->thread = thread;
675 kthread_bind_mask(thread, policy->related_cpus);
676 init_irq_work(&sg_policy->irq_work, sugov_irq_work);
677 mutex_init(&sg_policy->work_lock);
678
679 wake_up_process(thread);
680
681 return 0;
682}
683
684static void sugov_kthread_stop(struct sugov_policy *sg_policy)
685{
686 /* kthread only required for slow path */
687 if (sg_policy->policy->fast_switch_enabled)
688 return;
689
690 kthread_flush_worker(&sg_policy->worker);
691 kthread_stop(sg_policy->thread);
692 mutex_destroy(&sg_policy->work_lock);
693}
694
695static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
696{
697 struct sugov_tunables *tunables;
698
699 tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
700 if (tunables) {
701 gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
702 if (!have_governor_per_policy())
703 global_tunables = tunables;
704 }
705 return tunables;
706}
707
708static void sugov_tunables_free(struct sugov_tunables *tunables)
709{
710 if (!have_governor_per_policy())
711 global_tunables = NULL;
712
713 kfree(tunables);
714}
715
716static int sugov_init(struct cpufreq_policy *policy)
717{
718 struct sugov_policy *sg_policy;
719 struct sugov_tunables *tunables;
720 int ret = 0;
721
722 /* State should be equivalent to EXIT */
723 if (policy->governor_data)
724 return -EBUSY;
725
726 cpufreq_enable_fast_switch(policy);
727
728 sg_policy = sugov_policy_alloc(policy);
729 if (!sg_policy) {
730 ret = -ENOMEM;
731 goto disable_fast_switch;
732 }
733
734 ret = sugov_kthread_create(sg_policy);
735 if (ret)
736 goto free_sg_policy;
737
738 mutex_lock(&global_tunables_lock);
739
740 if (global_tunables) {
741 if (WARN_ON(have_governor_per_policy())) {
742 ret = -EINVAL;
743 goto stop_kthread;
744 }
745 policy->governor_data = sg_policy;
746 sg_policy->tunables = global_tunables;
747
748 gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
749 goto out;
750 }
751
752 tunables = sugov_tunables_alloc(sg_policy);
753 if (!tunables) {
754 ret = -ENOMEM;
755 goto stop_kthread;
756 }
757
758 tunables->rate_limit_us = cpufreq_policy_transition_delay_us(policy);
759
760 policy->governor_data = sg_policy;
761 sg_policy->tunables = tunables;
762
763 ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
764 get_governor_parent_kobj(policy), "%s",
765 schedutil_gov.name);
766 if (ret)
767 goto fail;
768
769out:
770 mutex_unlock(&global_tunables_lock);
771 return 0;
772
773fail:
774 policy->governor_data = NULL;
775 sugov_tunables_free(tunables);
776
777stop_kthread:
778 sugov_kthread_stop(sg_policy);
779 mutex_unlock(&global_tunables_lock);
780
781free_sg_policy:
782 sugov_policy_free(sg_policy);
783
784disable_fast_switch:
785 cpufreq_disable_fast_switch(policy);
786
787 pr_err("initialization failed (error %d)\n", ret);
788 return ret;
789}
790
791static void sugov_exit(struct cpufreq_policy *policy)
792{
793 struct sugov_policy *sg_policy = policy->governor_data;
794 struct sugov_tunables *tunables = sg_policy->tunables;
795 unsigned int count;
796
797 mutex_lock(&global_tunables_lock);
798
799 count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
800 policy->governor_data = NULL;
801 if (!count)
802 sugov_tunables_free(tunables);
803
804 mutex_unlock(&global_tunables_lock);
805
806 sugov_kthread_stop(sg_policy);
807 sugov_policy_free(sg_policy);
808 cpufreq_disable_fast_switch(policy);
809}
810
811static int sugov_start(struct cpufreq_policy *policy)
812{
813 struct sugov_policy *sg_policy = policy->governor_data;
814 unsigned int cpu;
815
816 sg_policy->freq_update_delay_ns = sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
817 sg_policy->last_freq_update_time = 0;
818 sg_policy->next_freq = 0;
819 sg_policy->work_in_progress = false;
820 sg_policy->need_freq_update = false;
821 sg_policy->cached_raw_freq = 0;
822
823 for_each_cpu(cpu, policy->cpus) {
824 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
825
826 memset(sg_cpu, 0, sizeof(*sg_cpu));
827 sg_cpu->cpu = cpu;
828 sg_cpu->sg_policy = sg_policy;
829 sg_cpu->min =
830 (SCHED_CAPACITY_SCALE * policy->cpuinfo.min_freq) /
831 policy->cpuinfo.max_freq;
832 }
833
834 for_each_cpu(cpu, policy->cpus) {
835 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
836
837 cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
838 policy_is_shared(policy) ?
839 sugov_update_shared :
840 sugov_update_single);
841 }
842 return 0;
843}
844
845static void sugov_stop(struct cpufreq_policy *policy)
846{
847 struct sugov_policy *sg_policy = policy->governor_data;
848 unsigned int cpu;
849
850 for_each_cpu(cpu, policy->cpus)
851 cpufreq_remove_update_util_hook(cpu);
852
853 synchronize_rcu();
854
855 if (!policy->fast_switch_enabled) {
856 irq_work_sync(&sg_policy->irq_work);
857 kthread_cancel_work_sync(&sg_policy->work);
858 }
859}
860
861static void sugov_limits(struct cpufreq_policy *policy)
862{
863 struct sugov_policy *sg_policy = policy->governor_data;
864
865 if (!policy->fast_switch_enabled) {
866 mutex_lock(&sg_policy->work_lock);
867 cpufreq_policy_apply_limits(policy);
868 mutex_unlock(&sg_policy->work_lock);
869 }
870
871 sg_policy->need_freq_update = true;
872}
873
874struct cpufreq_governor schedutil_gov = {
875 .name = "schedutil",
876 .owner = THIS_MODULE,
877 .dynamic_switching = true,
878 .init = sugov_init,
879 .exit = sugov_exit,
880 .start = sugov_start,
881 .stop = sugov_stop,
882 .limits = sugov_limits,
883};
884
885#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
886struct cpufreq_governor *cpufreq_default_governor(void)
887{
888 return &schedutil_gov;
889}
890#endif
891
892static int __init sugov_register(void)
893{
894 return cpufreq_register_governor(&schedutil_gov);
895}
896fs_initcall(sugov_register);
897
898#ifdef CONFIG_ENERGY_MODEL
899extern bool sched_energy_update;
900extern struct mutex sched_energy_mutex;
901
902static void rebuild_sd_workfn(struct work_struct *work)
903{
904 mutex_lock(&sched_energy_mutex);
905 sched_energy_update = true;
906 rebuild_sched_domains();
907 sched_energy_update = false;
908 mutex_unlock(&sched_energy_mutex);
909}
910static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);
911
912/*
913 * EAS shouldn't be attempted without sugov, so rebuild the sched_domains
914 * on governor changes to make sure the scheduler knows about it.
915 */
916void sched_cpufreq_governor_change(struct cpufreq_policy *policy,
917 struct cpufreq_governor *old_gov)
918{
919 if (old_gov == &schedutil_gov || policy->governor == &schedutil_gov) {
920 /*
921 * When called from the cpufreq_register_driver() path, the
922 * cpu_hotplug_lock is already held, so use a work item to
923 * avoid nested locking in rebuild_sched_domains().
924 */
925 schedule_work(&rebuild_sd_work);
926 }
927
928}
929#endif
930