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 | |
11 | struct sugov_tunables { |
12 | struct gov_attr_set attr_set; |
13 | unsigned int rate_limit_us; |
14 | }; |
15 | |
16 | struct 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 | |
40 | struct 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 | |
58 | static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu); |
59 | |
60 | /************************ Governor internals ***********************/ |
61 | |
62 | static 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(policy: 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 | |
95 | static 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 | |
109 | static 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(work: &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 | */ |
125 | static __always_inline |
126 | unsigned long get_capacity_ref_freq(struct cpufreq_policy *policy) |
127 | { |
128 | unsigned int freq = arch_scale_freq_ref(cpu: 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 | */ |
165 | static 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, cap: 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, target_freq: freq); |
179 | } |
180 | |
181 | unsigned 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(util: 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 | |
198 | static void sugov_get_util(struct sugov_cpu *sg_cpu, unsigned long boost) |
199 | { |
200 | unsigned long min, max, util = cpu_util_cfs_boost(cpu: sg_cpu->cpu); |
201 | |
202 | util = effective_cpu_util(cpu: sg_cpu->cpu, util_cfs: util, min: &min, max: &max); |
203 | util = max(util, boost); |
204 | sg_cpu->bw_min = min; |
205 | sg_cpu->util = sugov_effective_cpu_perf(cpu: sg_cpu->cpu, actual: 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 | */ |
219 | static 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 | */ |
248 | static 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 | */ |
296 | static 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, set_iowait_boost: 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 |
328 | static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) |
329 | { |
330 | unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(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 |
337 | static 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 | */ |
344 | static 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 | |
350 | static 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_policy: 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 | |
370 | static 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(cpu: 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, util: sg_cpu->util, max: 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_freq: 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(policy: sg_policy->policy, target_freq: 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 | |
417 | static 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(cpu: 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(cpu: sg_cpu->cpu, min_perf: sg_cpu->bw_min, |
450 | target_perf: sg_cpu->util, capacity: max_cap); |
451 | |
452 | sg_cpu->sg_policy->last_freq_update_time = time; |
453 | } |
454 | |
455 | static 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(cpu: 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(sg_cpu: j_sg_cpu, time, max_cap); |
469 | sugov_get_util(sg_cpu: j_sg_cpu, boost); |
470 | |
471 | util = max(j_sg_cpu->util, util); |
472 | } |
473 | |
474 | return get_next_freq(sg_policy, util, max: max_cap); |
475 | } |
476 | |
477 | static void |
478 | sugov_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_freq: next_f)) |
495 | goto unlock; |
496 | |
497 | if (sg_policy->policy->fast_switch_enabled) |
498 | cpufreq_driver_fast_switch(policy: sg_policy->policy, target_freq: next_f); |
499 | else |
500 | sugov_deferred_update(sg_policy); |
501 | } |
502 | unlock: |
503 | raw_spin_unlock(&sg_policy->update_lock); |
504 | } |
505 | |
506 | static 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(policy: sg_policy->policy, target_freq: freq, CPUFREQ_RELATION_L); |
529 | mutex_unlock(lock: &sg_policy->work_lock); |
530 | } |
531 | |
532 | static 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(worker: &sg_policy->worker, work: &sg_policy->work); |
539 | } |
540 | |
541 | /************************** sysfs interface ************************/ |
542 | |
543 | static struct sugov_tunables *global_tunables; |
544 | static DEFINE_MUTEX(global_tunables_lock); |
545 | |
546 | static 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 | |
551 | static 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, fmt: "%u\n" , tunables->rate_limit_us); |
556 | } |
557 | |
558 | static ssize_t |
559 | rate_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(s: buf, base: 10, res: &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 | |
576 | static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us); |
577 | |
578 | static struct attribute *sugov_attrs[] = { |
579 | &rate_limit_us.attr, |
580 | NULL |
581 | }; |
582 | ATTRIBUTE_GROUPS(sugov); |
583 | |
584 | static void sugov_tunables_free(struct kobject *kobj) |
585 | { |
586 | struct gov_attr_set *attr_set = to_gov_attr_set(kobj); |
587 | |
588 | kfree(objp: to_sugov_tunables(attr_set)); |
589 | } |
590 | |
591 | static 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 |
600 | static void rebuild_sd_workfn(struct work_struct *work) |
601 | { |
602 | rebuild_sched_domains_energy(); |
603 | } |
604 | |
605 | static 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 | */ |
611 | static 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(work: &rebuild_sd_work); |
619 | } |
620 | #else |
621 | static inline void sugov_eas_rebuild_sd(void) { }; |
622 | #endif |
623 | |
624 | struct cpufreq_governor schedutil_gov; |
625 | |
626 | static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy) |
627 | { |
628 | struct sugov_policy *sg_policy; |
629 | |
630 | sg_policy = kzalloc(size: 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 | |
639 | static void sugov_policy_free(struct sugov_policy *sg_policy) |
640 | { |
641 | kfree(objp: sg_policy); |
642 | } |
643 | |
644 | static 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(ptr: thread)) { |
674 | pr_err("failed to create sugov thread: %ld\n" , PTR_ERR(thread)); |
675 | return PTR_ERR(ptr: thread); |
676 | } |
677 | |
678 | ret = sched_setattr_nocheck(thread, &attr); |
679 | if (ret) { |
680 | kthread_stop(k: 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(k: thread, mask: policy->related_cpus); |
687 | init_irq_work(work: &sg_policy->irq_work, func: sugov_irq_work); |
688 | mutex_init(&sg_policy->work_lock); |
689 | |
690 | wake_up_process(tsk: thread); |
691 | |
692 | return 0; |
693 | } |
694 | |
695 | static 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(worker: &sg_policy->worker); |
702 | kthread_stop(k: sg_policy->thread); |
703 | mutex_destroy(lock: &sg_policy->work_lock); |
704 | } |
705 | |
706 | static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy) |
707 | { |
708 | struct sugov_tunables *tunables; |
709 | |
710 | tunables = kzalloc(size: sizeof(*tunables), GFP_KERNEL); |
711 | if (tunables) { |
712 | gov_attr_set_init(attr_set: &tunables->attr_set, list_node: &sg_policy->tunables_hook); |
713 | if (!have_governor_per_policy()) |
714 | global_tunables = tunables; |
715 | } |
716 | return tunables; |
717 | } |
718 | |
719 | static void sugov_clear_global_tunables(void) |
720 | { |
721 | if (!have_governor_per_policy()) |
722 | global_tunables = NULL; |
723 | } |
724 | |
725 | static 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(attr_set: &global_tunables->attr_set, list_node: &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(kobj: &tunables->attr_set.kobj, ktype: &sugov_tunables_ktype, |
773 | parent: get_governor_parent_kobj(policy), fmt: "%s" , |
774 | schedutil_gov.name); |
775 | if (ret) |
776 | goto fail; |
777 | |
778 | sugov_eas_rebuild_sd(); |
779 | |
780 | out: |
781 | mutex_unlock(lock: &global_tunables_lock); |
782 | return 0; |
783 | |
784 | fail: |
785 | kobject_put(kobj: &tunables->attr_set.kobj); |
786 | policy->governor_data = NULL; |
787 | sugov_clear_global_tunables(); |
788 | |
789 | stop_kthread: |
790 | sugov_kthread_stop(sg_policy); |
791 | mutex_unlock(lock: &global_tunables_lock); |
792 | |
793 | free_sg_policy: |
794 | sugov_policy_free(sg_policy); |
795 | |
796 | disable_fast_switch: |
797 | cpufreq_disable_fast_switch(policy); |
798 | |
799 | pr_err("initialization failed (error %d)\n" , ret); |
800 | return ret; |
801 | } |
802 | |
803 | static 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(attr_set: &tunables->attr_set, list_node: &sg_policy->tunables_hook); |
812 | policy->governor_data = NULL; |
813 | if (!count) |
814 | sugov_clear_global_tunables(); |
815 | |
816 | mutex_unlock(lock: &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 | |
825 | static 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 | |
858 | static 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(work: &sg_policy->irq_work); |
870 | kthread_cancel_work_sync(work: &sg_policy->work); |
871 | } |
872 | } |
873 | |
874 | static 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(lock: &sg_policy->work_lock); |
882 | } |
883 | |
884 | sg_policy->limits_changed = true; |
885 | } |
886 | |
887 | struct 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 |
899 | struct cpufreq_governor *cpufreq_default_governor(void) |
900 | { |
901 | return &schedutil_gov; |
902 | } |
903 | #endif |
904 | |
905 | cpufreq_governor_init(schedutil_gov); |
906 | |