2 * CPUFreq governor based on scheduler-provided CPU utilization data.
4 * Copyright (C) 2016, Intel Corporation
5 * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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.
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14 #include <linux/cpufreq.h>
15 #include <linux/slab.h>
16 #include <trace/events/power.h>
20 struct sugov_tunables
{
21 struct gov_attr_set attr_set
;
22 unsigned int rate_limit_us
;
26 struct cpufreq_policy
*policy
;
28 struct sugov_tunables
*tunables
;
29 struct list_head tunables_hook
;
31 raw_spinlock_t update_lock
; /* For shared policies */
32 u64 last_freq_update_time
;
33 s64 freq_update_delay_ns
;
34 unsigned int next_freq
;
36 /* The next fields are only needed if fast switch cannot be used. */
37 struct irq_work irq_work
;
38 struct work_struct work
;
39 struct mutex work_lock
;
40 bool work_in_progress
;
42 bool need_freq_update
;
46 struct update_util_data update_util
;
47 struct sugov_policy
*sg_policy
;
49 unsigned int cached_raw_freq
;
51 /* The fields below are only needed when sharing a policy. */
58 static DEFINE_PER_CPU(struct sugov_cpu
, sugov_cpu
);
60 /************************ Governor internals ***********************/
62 static bool sugov_should_update_freq(struct sugov_policy
*sg_policy
, u64 time
)
66 if (sg_policy
->work_in_progress
)
69 if (unlikely(sg_policy
->need_freq_update
)) {
70 sg_policy
->need_freq_update
= false;
72 * This happens when limits change, so forget the previous
73 * next_freq value and force an update.
75 sg_policy
->next_freq
= UINT_MAX
;
79 delta_ns
= time
- sg_policy
->last_freq_update_time
;
80 return delta_ns
>= sg_policy
->freq_update_delay_ns
;
83 static void sugov_update_commit(struct sugov_policy
*sg_policy
, u64 time
,
84 unsigned int next_freq
)
86 struct cpufreq_policy
*policy
= sg_policy
->policy
;
88 sg_policy
->last_freq_update_time
= time
;
90 if (policy
->fast_switch_enabled
) {
91 if (sg_policy
->next_freq
== next_freq
) {
92 trace_cpu_frequency(policy
->cur
, smp_processor_id());
95 sg_policy
->next_freq
= next_freq
;
96 next_freq
= cpufreq_driver_fast_switch(policy
, next_freq
);
97 if (next_freq
== CPUFREQ_ENTRY_INVALID
)
100 policy
->cur
= next_freq
;
101 trace_cpu_frequency(next_freq
, smp_processor_id());
102 } else if (sg_policy
->next_freq
!= next_freq
) {
103 sg_policy
->next_freq
= next_freq
;
104 sg_policy
->work_in_progress
= true;
105 irq_work_queue(&sg_policy
->irq_work
);
110 * get_next_freq - Compute a new frequency for a given cpufreq policy.
111 * @sg_cpu: schedutil cpu object to compute the new frequency for.
112 * @util: Current CPU utilization.
113 * @max: CPU capacity.
115 * If the utilization is frequency-invariant, choose the new frequency to be
116 * proportional to it, that is
118 * next_freq = C * max_freq * util / max
120 * Otherwise, approximate the would-be frequency-invariant utilization by
121 * util_raw * (curr_freq / max_freq) which leads to
123 * next_freq = C * curr_freq * util_raw / max
125 * Take C = 1.25 for the frequency tipping point at (util / max) = 0.8.
127 * The lowest driver-supported frequency which is equal or greater than the raw
128 * next_freq (as calculated above) is returned, subject to policy min/max and
129 * cpufreq driver limitations.
131 static unsigned int get_next_freq(struct sugov_cpu
*sg_cpu
, unsigned long util
,
134 struct sugov_policy
*sg_policy
= sg_cpu
->sg_policy
;
135 struct cpufreq_policy
*policy
= sg_policy
->policy
;
136 unsigned int freq
= arch_scale_freq_invariant() ?
137 policy
->cpuinfo
.max_freq
: policy
->cur
;
139 freq
= (freq
+ (freq
>> 2)) * util
/ max
;
141 if (freq
== sg_cpu
->cached_raw_freq
&& sg_policy
->next_freq
!= UINT_MAX
)
142 return sg_policy
->next_freq
;
143 sg_cpu
->cached_raw_freq
= freq
;
144 return cpufreq_driver_resolve_freq(policy
, freq
);
147 static void sugov_get_util(unsigned long *util
, unsigned long *max
)
149 struct rq
*rq
= this_rq();
150 unsigned long cfs_max
;
152 cfs_max
= arch_scale_cpu_capacity(NULL
, smp_processor_id());
154 *util
= min(rq
->cfs
.avg
.util_avg
, cfs_max
);
158 static void sugov_update_single(struct update_util_data
*hook
, u64 time
,
161 struct sugov_cpu
*sg_cpu
= container_of(hook
, struct sugov_cpu
, update_util
);
162 struct sugov_policy
*sg_policy
= sg_cpu
->sg_policy
;
163 struct cpufreq_policy
*policy
= sg_policy
->policy
;
164 unsigned long util
, max
;
167 if (!sugov_should_update_freq(sg_policy
, time
))
170 if (flags
& SCHED_CPUFREQ_RT_DL
) {
171 next_f
= policy
->cpuinfo
.max_freq
;
173 sugov_get_util(&util
, &max
);
174 next_f
= get_next_freq(sg_cpu
, util
, max
);
176 sugov_update_commit(sg_policy
, time
, next_f
);
179 static unsigned int sugov_next_freq_shared(struct sugov_cpu
*sg_cpu
,
180 unsigned long util
, unsigned long max
,
183 struct sugov_policy
*sg_policy
= sg_cpu
->sg_policy
;
184 struct cpufreq_policy
*policy
= sg_policy
->policy
;
185 unsigned int max_f
= policy
->cpuinfo
.max_freq
;
186 u64 last_freq_update_time
= sg_policy
->last_freq_update_time
;
189 if (flags
& SCHED_CPUFREQ_RT_DL
)
192 for_each_cpu(j
, policy
->cpus
) {
193 struct sugov_cpu
*j_sg_cpu
;
194 unsigned long j_util
, j_max
;
197 if (j
== smp_processor_id())
200 j_sg_cpu
= &per_cpu(sugov_cpu
, j
);
202 * If the CPU utilization was last updated before the previous
203 * frequency update and the time elapsed between the last update
204 * of the CPU utilization and the last frequency update is long
205 * enough, don't take the CPU into account as it probably is
208 delta_ns
= last_freq_update_time
- j_sg_cpu
->last_update
;
209 if (delta_ns
> TICK_NSEC
)
212 if (j_sg_cpu
->flags
& SCHED_CPUFREQ_RT_DL
)
215 j_util
= j_sg_cpu
->util
;
216 j_max
= j_sg_cpu
->max
;
217 if (j_util
* max
> j_max
* util
) {
223 return get_next_freq(sg_cpu
, util
, max
);
226 static void sugov_update_shared(struct update_util_data
*hook
, u64 time
,
229 struct sugov_cpu
*sg_cpu
= container_of(hook
, struct sugov_cpu
, update_util
);
230 struct sugov_policy
*sg_policy
= sg_cpu
->sg_policy
;
231 unsigned long util
, max
;
234 sugov_get_util(&util
, &max
);
236 raw_spin_lock(&sg_policy
->update_lock
);
240 sg_cpu
->flags
= flags
;
241 sg_cpu
->last_update
= time
;
243 if (sugov_should_update_freq(sg_policy
, time
)) {
244 next_f
= sugov_next_freq_shared(sg_cpu
, util
, max
, flags
);
245 sugov_update_commit(sg_policy
, time
, next_f
);
248 raw_spin_unlock(&sg_policy
->update_lock
);
251 static void sugov_work(struct work_struct
*work
)
253 struct sugov_policy
*sg_policy
= container_of(work
, struct sugov_policy
, work
);
255 mutex_lock(&sg_policy
->work_lock
);
256 __cpufreq_driver_target(sg_policy
->policy
, sg_policy
->next_freq
,
258 mutex_unlock(&sg_policy
->work_lock
);
260 sg_policy
->work_in_progress
= false;
263 static void sugov_irq_work(struct irq_work
*irq_work
)
265 struct sugov_policy
*sg_policy
;
267 sg_policy
= container_of(irq_work
, struct sugov_policy
, irq_work
);
268 schedule_work_on(smp_processor_id(), &sg_policy
->work
);
271 /************************** sysfs interface ************************/
273 static struct sugov_tunables
*global_tunables
;
274 static DEFINE_MUTEX(global_tunables_lock
);
276 static inline struct sugov_tunables
*to_sugov_tunables(struct gov_attr_set
*attr_set
)
278 return container_of(attr_set
, struct sugov_tunables
, attr_set
);
281 static ssize_t
rate_limit_us_show(struct gov_attr_set
*attr_set
, char *buf
)
283 struct sugov_tunables
*tunables
= to_sugov_tunables(attr_set
);
285 return sprintf(buf
, "%u\n", tunables
->rate_limit_us
);
288 static ssize_t
rate_limit_us_store(struct gov_attr_set
*attr_set
, const char *buf
,
291 struct sugov_tunables
*tunables
= to_sugov_tunables(attr_set
);
292 struct sugov_policy
*sg_policy
;
293 unsigned int rate_limit_us
;
295 if (kstrtouint(buf
, 10, &rate_limit_us
))
298 tunables
->rate_limit_us
= rate_limit_us
;
300 list_for_each_entry(sg_policy
, &attr_set
->policy_list
, tunables_hook
)
301 sg_policy
->freq_update_delay_ns
= rate_limit_us
* NSEC_PER_USEC
;
306 static struct governor_attr rate_limit_us
= __ATTR_RW(rate_limit_us
);
308 static struct attribute
*sugov_attributes
[] = {
313 static struct kobj_type sugov_tunables_ktype
= {
314 .default_attrs
= sugov_attributes
,
315 .sysfs_ops
= &governor_sysfs_ops
,
318 /********************** cpufreq governor interface *********************/
320 static struct cpufreq_governor schedutil_gov
;
322 static struct sugov_policy
*sugov_policy_alloc(struct cpufreq_policy
*policy
)
324 struct sugov_policy
*sg_policy
;
326 sg_policy
= kzalloc(sizeof(*sg_policy
), GFP_KERNEL
);
330 sg_policy
->policy
= policy
;
331 init_irq_work(&sg_policy
->irq_work
, sugov_irq_work
);
332 INIT_WORK(&sg_policy
->work
, sugov_work
);
333 mutex_init(&sg_policy
->work_lock
);
334 raw_spin_lock_init(&sg_policy
->update_lock
);
338 static void sugov_policy_free(struct sugov_policy
*sg_policy
)
340 mutex_destroy(&sg_policy
->work_lock
);
344 static struct sugov_tunables
*sugov_tunables_alloc(struct sugov_policy
*sg_policy
)
346 struct sugov_tunables
*tunables
;
348 tunables
= kzalloc(sizeof(*tunables
), GFP_KERNEL
);
350 gov_attr_set_init(&tunables
->attr_set
, &sg_policy
->tunables_hook
);
351 if (!have_governor_per_policy())
352 global_tunables
= tunables
;
357 static void sugov_tunables_free(struct sugov_tunables
*tunables
)
359 if (!have_governor_per_policy())
360 global_tunables
= NULL
;
365 static int sugov_init(struct cpufreq_policy
*policy
)
367 struct sugov_policy
*sg_policy
;
368 struct sugov_tunables
*tunables
;
372 /* State should be equivalent to EXIT */
373 if (policy
->governor_data
)
376 sg_policy
= sugov_policy_alloc(policy
);
380 mutex_lock(&global_tunables_lock
);
382 if (global_tunables
) {
383 if (WARN_ON(have_governor_per_policy())) {
387 policy
->governor_data
= sg_policy
;
388 sg_policy
->tunables
= global_tunables
;
390 gov_attr_set_get(&global_tunables
->attr_set
, &sg_policy
->tunables_hook
);
394 tunables
= sugov_tunables_alloc(sg_policy
);
400 tunables
->rate_limit_us
= LATENCY_MULTIPLIER
;
401 lat
= policy
->cpuinfo
.transition_latency
/ NSEC_PER_USEC
;
403 tunables
->rate_limit_us
*= lat
;
405 policy
->governor_data
= sg_policy
;
406 sg_policy
->tunables
= tunables
;
408 ret
= kobject_init_and_add(&tunables
->attr_set
.kobj
, &sugov_tunables_ktype
,
409 get_governor_parent_kobj(policy
), "%s",
415 mutex_unlock(&global_tunables_lock
);
417 cpufreq_enable_fast_switch(policy
);
421 policy
->governor_data
= NULL
;
422 sugov_tunables_free(tunables
);
425 mutex_unlock(&global_tunables_lock
);
427 sugov_policy_free(sg_policy
);
428 pr_err("initialization failed (error %d)\n", ret
);
432 static void sugov_exit(struct cpufreq_policy
*policy
)
434 struct sugov_policy
*sg_policy
= policy
->governor_data
;
435 struct sugov_tunables
*tunables
= sg_policy
->tunables
;
438 cpufreq_disable_fast_switch(policy
);
440 mutex_lock(&global_tunables_lock
);
442 count
= gov_attr_set_put(&tunables
->attr_set
, &sg_policy
->tunables_hook
);
443 policy
->governor_data
= NULL
;
445 sugov_tunables_free(tunables
);
447 mutex_unlock(&global_tunables_lock
);
449 sugov_policy_free(sg_policy
);
452 static int sugov_start(struct cpufreq_policy
*policy
)
454 struct sugov_policy
*sg_policy
= policy
->governor_data
;
457 sg_policy
->freq_update_delay_ns
= sg_policy
->tunables
->rate_limit_us
* NSEC_PER_USEC
;
458 sg_policy
->last_freq_update_time
= 0;
459 sg_policy
->next_freq
= UINT_MAX
;
460 sg_policy
->work_in_progress
= false;
461 sg_policy
->need_freq_update
= false;
463 for_each_cpu(cpu
, policy
->cpus
) {
464 struct sugov_cpu
*sg_cpu
= &per_cpu(sugov_cpu
, cpu
);
466 sg_cpu
->sg_policy
= sg_policy
;
467 if (policy_is_shared(policy
)) {
470 sg_cpu
->flags
= SCHED_CPUFREQ_RT
;
471 sg_cpu
->last_update
= 0;
472 sg_cpu
->cached_raw_freq
= 0;
473 cpufreq_add_update_util_hook(cpu
, &sg_cpu
->update_util
,
474 sugov_update_shared
);
476 cpufreq_add_update_util_hook(cpu
, &sg_cpu
->update_util
,
477 sugov_update_single
);
483 static void sugov_stop(struct cpufreq_policy
*policy
)
485 struct sugov_policy
*sg_policy
= policy
->governor_data
;
488 for_each_cpu(cpu
, policy
->cpus
)
489 cpufreq_remove_update_util_hook(cpu
);
493 irq_work_sync(&sg_policy
->irq_work
);
494 cancel_work_sync(&sg_policy
->work
);
497 static void sugov_limits(struct cpufreq_policy
*policy
)
499 struct sugov_policy
*sg_policy
= policy
->governor_data
;
501 if (!policy
->fast_switch_enabled
) {
502 mutex_lock(&sg_policy
->work_lock
);
503 cpufreq_policy_apply_limits(policy
);
504 mutex_unlock(&sg_policy
->work_lock
);
507 sg_policy
->need_freq_update
= true;
510 static struct cpufreq_governor schedutil_gov
= {
512 .owner
= THIS_MODULE
,
515 .start
= sugov_start
,
517 .limits
= sugov_limits
,
520 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
521 struct cpufreq_governor
*cpufreq_default_governor(void)
523 return &schedutil_gov
;
527 static int __init
sugov_register(void)
529 return cpufreq_register_governor(&schedutil_gov
);
531 fs_initcall(sugov_register
);