kernel/sched/cpufreq_schedutil.c

   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 <uapi/linux/sched/types.h>
  17 #include <linux/slab.h>
  18 #include <trace/events/power.h>
  19
  20 #include "sched.h"
  21
  22 #define SUGOV_KTHREAD_PRIORITY  50
  23
  24 struct sugov_tunables {
  25         struct gov_attr_set attr_set;
  26         unsigned int rate_limit_us;
  27 };
  28
  29 struct sugov_policy {
  30         struct cpufreq_policy *policy;
  31
  32         struct sugov_tunables *tunables;
  33         struct list_head tunables_hook;
  34
  35         raw_spinlock_t update_lock;  /* For shared policies */
  36         u64 last_freq_update_time;
  37         s64 freq_update_delay_ns;
  38         unsigned int next_freq;
  39         unsigned int cached_raw_freq;
  40
  41         /* The next fields are only needed if fast switch cannot be used. */
  42         struct irq_work irq_work;
  43         struct kthread_work work;
  44         struct mutex work_lock;
  45         struct kthread_worker worker;
  46         struct task_struct *thread;
  47         bool work_in_progress;
  48
  49         bool need_freq_update;
  50 };
  51
  52 struct sugov_cpu {
  53         struct update_util_data update_util;
  54         struct sugov_policy *sg_policy;
  55
  56         unsigned long iowait_boost;
  57         unsigned long iowait_boost_max;
  58         u64 last_update;
  59
  60         /* The fields below are only needed when sharing a policy. */
  61         unsigned long util;
  62         unsigned long max;
  63         unsigned int flags;
  64
  65         /* The field below is for single-CPU policies only. */
  66 #ifdef CONFIG_NO_HZ_COMMON
  67         unsigned long saved_idle_calls;
  68 #endif
  69 };
  70
  71 static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
  72
  73 /************************ Governor internals ***********************/
  74
  75 static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
  76 {
  77         s64 delta_ns;
  78
  79         if (sg_policy->work_in_progress)
  80                 return false;
  81
  82         if (unlikely(sg_policy->need_freq_update)) {
  83                 sg_policy->need_freq_update = false;
  84                 /*
  85                  * This happens when limits change, so forget the previous
  86                  * next_freq value and force an update.
  87                  */
  88                 sg_policy->next_freq = UINT_MAX;
  89                 return true;
  90         }
  91
  92         delta_ns = time - sg_policy->last_freq_update_time;
  93         return delta_ns >= sg_policy->freq_update_delay_ns;
  94 }
  95
  96 static void sugov_update_commit(struct sugov_policy *sg_policy, u64 time,
  97                                 unsigned int next_freq)
  98 {
  99         struct cpufreq_policy *policy = sg_policy->policy;
 100
 101         if (policy->fast_switch_enabled) {
 102                 if (sg_policy->next_freq == next_freq) {
 103                         trace_cpu_frequency(policy->cur, smp_processor_id());
 104                         return;
 105                 }
 106                 sg_policy->next_freq = next_freq;
 107                 sg_policy->last_freq_update_time = time;
 108                 next_freq = cpufreq_driver_fast_switch(policy, next_freq);
 109                 if (next_freq == CPUFREQ_ENTRY_INVALID)
 110                         return;
 111
 112                 policy->cur = next_freq;
 113                 trace_cpu_frequency(next_freq, smp_processor_id());
 114         } else if (sg_policy->next_freq != next_freq) {
 115                 sg_policy->next_freq = next_freq;
 116                 sg_policy->last_freq_update_time = time;
 117                 sg_policy->work_in_progress = true;
 118                 irq_work_queue(&sg_policy->irq_work);
 119         }
 120 }
 121
 122 /**
 123  * get_next_freq - Compute a new frequency for a given cpufreq policy.
 124  * @sg_policy: schedutil policy object to compute the new frequency for.
 125  * @util: Current CPU utilization.
 126  * @max: CPU capacity.
 127  *
 128  * If the utilization is frequency-invariant, choose the new frequency to be
 129  * proportional to it, that is
 130  *
 131  * next_freq = C * max_freq * util / max
 132  *
 133  * Otherwise, approximate the would-be frequency-invariant utilization by
 134  * util_raw * (curr_freq / max_freq) which leads to
 135  *
 136  * next_freq = C * curr_freq * util_raw / max
 137  *
 138  * Take C = 1.25 for the frequency tipping point at (util / max) = 0.8.
 139  *
 140  * The lowest driver-supported frequency which is equal or greater than the raw
 141  * next_freq (as calculated above) is returned, subject to policy min/max and
 142  * cpufreq driver limitations.
 143  */
 144 static unsigned int get_next_freq(struct sugov_policy *sg_policy,
 145                                   unsigned long util, unsigned long max)
 146 {
 147         struct cpufreq_policy *policy = sg_policy->policy;
 148         unsigned int freq = arch_scale_freq_invariant() ?
 149                                 policy->cpuinfo.max_freq : policy->cur;
 150
 151         freq = (freq + (freq >> 2)) * util / max;
 152
 153         if (freq == sg_policy->cached_raw_freq && sg_policy->next_freq != UINT_MAX)
 154                 return sg_policy->next_freq;
 155         sg_policy->cached_raw_freq = freq;
 156         return cpufreq_driver_resolve_freq(policy, freq);
 157 }
 158
 159 static void sugov_get_util(unsigned long *util, unsigned long *max)
 160 {
 161         struct rq *rq = this_rq();
 162         unsigned long cfs_max;
 163
 164         cfs_max = arch_scale_cpu_capacity(NULL, smp_processor_id());
 165
 166         *util = min(rq->cfs.avg.util_avg, cfs_max);
 167         *max = cfs_max;
 168 }
 169
 170 static void sugov_set_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
 171                                    unsigned int flags)
 172 {
 173         if (flags & SCHED_CPUFREQ_IOWAIT) {
 174                 sg_cpu->iowait_boost = sg_cpu->iowait_boost_max;
 175         } else if (sg_cpu->iowait_boost) {
 176                 s64 delta_ns = time - sg_cpu->last_update;
 177
 178                 /* Clear iowait_boost if the CPU apprears to have been idle. */
 179                 if (delta_ns > TICK_NSEC)
 180                         sg_cpu->iowait_boost = 0;
 181         }
 182 }
 183
 184 static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, unsigned long *util,
 185                                unsigned long *max)
 186 {
 187         unsigned long boost_util = sg_cpu->iowait_boost;
 188         unsigned long boost_max = sg_cpu->iowait_boost_max;
 189
 190         if (!boost_util)
 191                 return;
 192
 193         if (*util * boost_max < *max * boost_util) {
 194                 *util = boost_util;
 195                 *max = boost_max;
 196         }
 197         sg_cpu->iowait_boost >>= 1;
 198 }
 199
 200 #ifdef CONFIG_NO_HZ_COMMON
 201 static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
 202 {
 203         unsigned long idle_calls = tick_nohz_get_idle_calls();
 204         bool ret = idle_calls == sg_cpu->saved_idle_calls;
 205
 206         sg_cpu->saved_idle_calls = idle_calls;
 207         return ret;
 208 }
 209 #else
 210 static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
 211 #endif /* CONFIG_NO_HZ_COMMON */
 212
 213 static void sugov_update_single(struct update_util_data *hook, u64 time,
 214                                 unsigned int flags)
 215 {
 216         struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
 217         struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 218         struct cpufreq_policy *policy = sg_policy->policy;
 219         unsigned long util, max;
 220         unsigned int next_f;
 221         bool busy;
 222
 223         sugov_set_iowait_boost(sg_cpu, time, flags);
 224         sg_cpu->last_update = time;
 225
 226         if (!sugov_should_update_freq(sg_policy, time))
 227                 return;
 228
 229         busy = sugov_cpu_is_busy(sg_cpu);
 230
 231         if (flags & SCHED_CPUFREQ_RT_DL) {
 232                 next_f = policy->cpuinfo.max_freq;
 233         } else {
 234                 sugov_get_util(&util, &max);
 235                 sugov_iowait_boost(sg_cpu, &util, &max);
 236                 next_f = get_next_freq(sg_policy, util, max);
 237                 /*
 238                  * Do not reduce the frequency if the CPU has not been idle
 239                  * recently, as the reduction is likely to be premature then.
 240                  */
 241                 if (busy && next_f < sg_policy->next_freq)
 242                         next_f = sg_policy->next_freq;
 243         }
 244         sugov_update_commit(sg_policy, time, next_f);
 245 }
 246
 247 static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu)
 248 {
 249         struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 250         struct cpufreq_policy *policy = sg_policy->policy;
 251         u64 last_freq_update_time = sg_policy->last_freq_update_time;
 252         unsigned long util = 0, max = 1;
 253         unsigned int j;
 254
 255         for_each_cpu(j, policy->cpus) {
 256                 struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
 257                 unsigned long j_util, j_max;
 258                 s64 delta_ns;
 259
 260                 /*
 261                  * If the CPU utilization was last updated before the previous
 262                  * frequency update and the time elapsed between the last update
 263                  * of the CPU utilization and the last frequency update is long
 264                  * enough, don't take the CPU into account as it probably is
 265                  * idle now (and clear iowait_boost for it).
 266                  */
 267                 delta_ns = last_freq_update_time - j_sg_cpu->last_update;
 268                 if (delta_ns > TICK_NSEC) {
 269                         j_sg_cpu->iowait_boost = 0;
 270                         continue;
 271                 }
 272                 if (j_sg_cpu->flags & SCHED_CPUFREQ_RT_DL)
 273                         return policy->cpuinfo.max_freq;
 274
 275                 j_util = j_sg_cpu->util;
 276                 j_max = j_sg_cpu->max;
 277                 if (j_util * max > j_max * util) {
 278                         util = j_util;
 279                         max = j_max;
 280                 }
 281
 282                 sugov_iowait_boost(j_sg_cpu, &util, &max);
 283         }
 284
 285         return get_next_freq(sg_policy, util, max);
 286 }
 287
 288 static void sugov_update_shared(struct update_util_data *hook, u64 time,
 289                                 unsigned int flags)
 290 {
 291         struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
 292         struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 293         unsigned long util, max;
 294         unsigned int next_f;
 295
 296         sugov_get_util(&util, &max);
 297
 298         raw_spin_lock(&sg_policy->update_lock);
 299
 300         sg_cpu->util = util;
 301         sg_cpu->max = max;
 302         sg_cpu->flags = flags;
 303
 304         sugov_set_iowait_boost(sg_cpu, time, flags);
 305         sg_cpu->last_update = time;
 306
 307         if (sugov_should_update_freq(sg_policy, time)) {
 308                 if (flags & SCHED_CPUFREQ_RT_DL)
 309                         next_f = sg_policy->policy->cpuinfo.max_freq;
 310                 else
 311                         next_f = sugov_next_freq_shared(sg_cpu);
 312
 313                 sugov_update_commit(sg_policy, time, next_f);
 314         }
 315
 316         raw_spin_unlock(&sg_policy->update_lock);
 317 }
 318
 319 static void sugov_work(struct kthread_work *work)
 320 {
 321         struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
 322
 323         mutex_lock(&sg_policy->work_lock);
 324         __cpufreq_driver_target(sg_policy->policy, sg_policy->next_freq,
 325                                 CPUFREQ_RELATION_L);
 326         mutex_unlock(&sg_policy->work_lock);
 327
 328         sg_policy->work_in_progress = false;
 329 }
 330
 331 static void sugov_irq_work(struct irq_work *irq_work)
 332 {
 333         struct sugov_policy *sg_policy;
 334
 335         sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
 336
 337         /*
 338          * For RT and deadline tasks, the schedutil governor shoots the
 339          * frequency to maximum. Special care must be taken to ensure that this
 340          * kthread doesn't result in the same behavior.
 341          *
 342          * This is (mostly) guaranteed by the work_in_progress flag. The flag is
 343          * updated only at the end of the sugov_work() function and before that
 344          * the schedutil governor rejects all other frequency scaling requests.
 345          *
 346          * There is a very rare case though, where the RT thread yields right
 347          * after the work_in_progress flag is cleared. The effects of that are
 348          * neglected for now.
 349          */
 350         kthread_queue_work(&sg_policy->worker, &sg_policy->work);
 351 }
 352
 353 /************************** sysfs interface ************************/
 354
 355 static struct sugov_tunables *global_tunables;
 356 static DEFINE_MUTEX(global_tunables_lock);
 357
 358 static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
 359 {
 360         return container_of(attr_set, struct sugov_tunables, attr_set);
 361 }
 362
 363 static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
 364 {
 365         struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
 366
 367         return sprintf(buf, "%u\n", tunables->rate_limit_us);
 368 }
 369
 370 static ssize_t rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf,
 371                                    size_t count)
 372 {
 373         struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
 374         struct sugov_policy *sg_policy;
 375         unsigned int rate_limit_us;
 376
 377         if (kstrtouint(buf, 10, &rate_limit_us))
 378                 return -EINVAL;
 379
 380         tunables->rate_limit_us = rate_limit_us;
 381
 382         list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
 383                 sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
 384
 385         return count;
 386 }
 387
 388 static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
 389
 390 static struct attribute *sugov_attributes[] = {
 391         &rate_limit_us.attr,
 392         NULL
 393 };
 394
 395 static struct kobj_type sugov_tunables_ktype = {
 396         .default_attrs = sugov_attributes,
 397         .sysfs_ops = &governor_sysfs_ops,
 398 };
 399
 400 /********************** cpufreq governor interface *********************/
 401
 402 static struct cpufreq_governor schedutil_gov;
 403
 404 static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
 405 {
 406         struct sugov_policy *sg_policy;
 407
 408         sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
 409         if (!sg_policy)
 410                 return NULL;
 411
 412         sg_policy->policy = policy;
 413         raw_spin_lock_init(&sg_policy->update_lock);
 414         return sg_policy;
 415 }
 416
 417 static void sugov_policy_free(struct sugov_policy *sg_policy)
 418 {
 419         kfree(sg_policy);
 420 }
 421
 422 static int sugov_kthread_create(struct sugov_policy *sg_policy)
 423 {
 424         struct task_struct *thread;
 425         struct sched_param param = { .sched_priority = MAX_USER_RT_PRIO / 2 };
 426         struct cpufreq_policy *policy = sg_policy->policy;
 427         int ret;
 428
 429         /* kthread only required for slow path */
 430         if (policy->fast_switch_enabled)
 431                 return 0;
 432
 433         kthread_init_work(&sg_policy->work, sugov_work);
 434         kthread_init_worker(&sg_policy->worker);
 435         thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
 436                                 "sugov:%d",
 437                                 cpumask_first(policy->related_cpus));
 438         if (IS_ERR(thread)) {
 439                 pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread));
 440                 return PTR_ERR(thread);
 441         }
 442
 443         ret = sched_setscheduler_nocheck(thread, SCHED_FIFO, &param);
 444         if (ret) {
 445                 kthread_stop(thread);
 446                 pr_warn("%s: failed to set SCHED_FIFO\n", __func__);
 447                 return ret;
 448         }
 449
 450         sg_policy->thread = thread;
 451         kthread_bind_mask(thread, policy->related_cpus);
 452         init_irq_work(&sg_policy->irq_work, sugov_irq_work);
 453         mutex_init(&sg_policy->work_lock);
 454
 455         wake_up_process(thread);
 456
 457         return 0;
 458 }
 459
 460 static void sugov_kthread_stop(struct sugov_policy *sg_policy)
 461 {
 462         /* kthread only required for slow path */
 463         if (sg_policy->policy->fast_switch_enabled)
 464                 return;
 465
 466         kthread_flush_worker(&sg_policy->worker);
 467         kthread_stop(sg_policy->thread);
 468         mutex_destroy(&sg_policy->work_lock);
 469 }
 470
 471 static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
 472 {
 473         struct sugov_tunables *tunables;
 474
 475         tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
 476         if (tunables) {
 477                 gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
 478                 if (!have_governor_per_policy())
 479                         global_tunables = tunables;
 480         }
 481         return tunables;
 482 }
 483
 484 static void sugov_tunables_free(struct sugov_tunables *tunables)
 485 {
 486         if (!have_governor_per_policy())
 487                 global_tunables = NULL;
 488
 489         kfree(tunables);
 490 }
 491
 492 static int sugov_init(struct cpufreq_policy *policy)
 493 {
 494         struct sugov_policy *sg_policy;
 495         struct sugov_tunables *tunables;
 496         unsigned int lat;
 497         int ret = 0;
 498
 499         /* State should be equivalent to EXIT */
 500         if (policy->governor_data)
 501                 return -EBUSY;
 502
 503         cpufreq_enable_fast_switch(policy);
 504
 505         sg_policy = sugov_policy_alloc(policy);
 506         if (!sg_policy) {
 507                 ret = -ENOMEM;
 508                 goto disable_fast_switch;
 509         }
 510
 511         ret = sugov_kthread_create(sg_policy);
 512         if (ret)
 513                 goto free_sg_policy;
 514
 515         mutex_lock(&global_tunables_lock);
 516
 517         if (global_tunables) {
 518                 if (WARN_ON(have_governor_per_policy())) {
 519                         ret = -EINVAL;
 520                         goto stop_kthread;
 521                 }
 522                 policy->governor_data = sg_policy;
 523                 sg_policy->tunables = global_tunables;
 524
 525                 gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
 526                 goto out;
 527         }
 528
 529         tunables = sugov_tunables_alloc(sg_policy);
 530         if (!tunables) {
 531                 ret = -ENOMEM;
 532                 goto stop_kthread;
 533         }
 534
 535         tunables->rate_limit_us = LATENCY_MULTIPLIER;
 536         lat = policy->cpuinfo.transition_latency / NSEC_PER_USEC;
 537         if (lat)
 538                 tunables->rate_limit_us *= lat;
 539
 540         policy->governor_data = sg_policy;
 541         sg_policy->tunables = tunables;
 542
 543         ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
 544                                    get_governor_parent_kobj(policy), "%s",
 545                                    schedutil_gov.name);
 546         if (ret)
 547                 goto fail;
 548
 549 out:
 550         mutex_unlock(&global_tunables_lock);
 551         return 0;
 552
 553 fail:
 554         policy->governor_data = NULL;
 555         sugov_tunables_free(tunables);
 556
 557 stop_kthread:
 558         sugov_kthread_stop(sg_policy);
 559
 560 free_sg_policy:
 561         mutex_unlock(&global_tunables_lock);
 562
 563         sugov_policy_free(sg_policy);
 564
 565 disable_fast_switch:
 566         cpufreq_disable_fast_switch(policy);
 567
 568         pr_err("initialization failed (error %d)\n", ret);
 569         return ret;
 570 }
 571
 572 static void sugov_exit(struct cpufreq_policy *policy)
 573 {
 574         struct sugov_policy *sg_policy = policy->governor_data;
 575         struct sugov_tunables *tunables = sg_policy->tunables;
 576         unsigned int count;
 577
 578         mutex_lock(&global_tunables_lock);
 579
 580         count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
 581         policy->governor_data = NULL;
 582         if (!count)
 583                 sugov_tunables_free(tunables);
 584
 585         mutex_unlock(&global_tunables_lock);
 586
 587         sugov_kthread_stop(sg_policy);
 588         sugov_policy_free(sg_policy);
 589         cpufreq_disable_fast_switch(policy);
 590 }
 591
 592 static int sugov_start(struct cpufreq_policy *policy)
 593 {
 594         struct sugov_policy *sg_policy = policy->governor_data;
 595         unsigned int cpu;
 596
 597         sg_policy->freq_update_delay_ns = sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
 598         sg_policy->last_freq_update_time = 0;
 599         sg_policy->next_freq = UINT_MAX;
 600         sg_policy->work_in_progress = false;
 601         sg_policy->need_freq_update = false;
 602         sg_policy->cached_raw_freq = 0;
 603
 604         for_each_cpu(cpu, policy->cpus) {
 605                 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
 606
 607                 sg_cpu->sg_policy = sg_policy;
 608                 if (policy_is_shared(policy)) {
 609                         sg_cpu->util = 0;
 610                         sg_cpu->max = 0;
 611                         sg_cpu->flags = SCHED_CPUFREQ_RT;
 612                         sg_cpu->last_update = 0;
 613                         sg_cpu->iowait_boost = 0;
 614                         sg_cpu->iowait_boost_max = policy->cpuinfo.max_freq;
 615                         cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
 616                                                      sugov_update_shared);
 617                 } else {
 618                         cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
 619                                                      sugov_update_single);
 620                 }
 621         }
 622         return 0;
 623 }
 624
 625 static void sugov_stop(struct cpufreq_policy *policy)
 626 {
 627         struct sugov_policy *sg_policy = policy->governor_data;
 628         unsigned int cpu;
 629
 630         for_each_cpu(cpu, policy->cpus)
 631                 cpufreq_remove_update_util_hook(cpu);
 632
 633         synchronize_sched();
 634
 635         if (!policy->fast_switch_enabled) {
 636                 irq_work_sync(&sg_policy->irq_work);
 637                 kthread_cancel_work_sync(&sg_policy->work);
 638         }
 639 }
 640
 641 static void sugov_limits(struct cpufreq_policy *policy)
 642 {
 643         struct sugov_policy *sg_policy = policy->governor_data;
 644
 645         if (!policy->fast_switch_enabled) {
 646                 mutex_lock(&sg_policy->work_lock);
 647                 cpufreq_policy_apply_limits(policy);
 648                 mutex_unlock(&sg_policy->work_lock);
 649         }
 650
 651         sg_policy->need_freq_update = true;
 652 }
 653
 654 static struct cpufreq_governor schedutil_gov = {
 655         .name = "schedutil",
 656         .owner = THIS_MODULE,
 657         .init = sugov_init,
 658         .exit = sugov_exit,
 659         .start = sugov_start,
 660         .stop = sugov_stop,
 661         .limits = sugov_limits,
 662 };
 663
 664 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
 665 struct cpufreq_governor *cpufreq_default_governor(void)
 666 {
 667         return &schedutil_gov;
 668 }
 669 #endif
 670
 671 static int __init sugov_register(void)
 672 {
 673         return cpufreq_register_governor(&schedutil_gov);
 674 }
 675 fs_initcall(sugov_register);