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 "sched.h"
  15
  16 #include <trace/events/power.h>
  17
  18 struct sugov_tunables {
  19         struct gov_attr_set     attr_set;
  20         unsigned int            rate_limit_us;
  21 };
  22
  23 struct sugov_policy {
  24         struct cpufreq_policy   *policy;
  25
  26         struct sugov_tunables   *tunables;
  27         struct list_head        tunables_hook;
  28
  29         raw_spinlock_t          update_lock;    /* For shared policies */
  30         u64                     last_freq_update_time;
  31         s64                     freq_update_delay_ns;
  32         unsigned int            next_freq;
  33         unsigned int            cached_raw_freq;
  34
  35         /* The next fields are only needed if fast switch cannot be used: */
  36         struct                  irq_work irq_work;
  37         struct                  kthread_work work;
  38         struct                  mutex work_lock;
  39         struct                  kthread_worker worker;
  40         struct task_struct      *thread;
  41         bool                    work_in_progress;
  42
  43         bool                    need_freq_update;
  44 };
  45
  46 struct sugov_cpu {
  47         struct update_util_data update_util;
  48         struct sugov_policy     *sg_policy;
  49         unsigned int            cpu;
  50
  51         bool                    iowait_boost_pending;
  52         unsigned int            iowait_boost;
  53         unsigned int            iowait_boost_max;
  54         u64                     last_update;
  55
  56         /* The fields below are only needed when sharing a policy: */
  57         unsigned long           util_cfs;
  58         unsigned long           util_dl;
  59         unsigned long           max;
  60
  61         /* The field below is for single-CPU policies only: */
  62 #ifdef CONFIG_NO_HZ_COMMON
  63         unsigned long           saved_idle_calls;
  64 #endif
  65 };
  66
  67 static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
  68
  69 /************************ Governor internals ***********************/
  70
  71 static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
  72 {
  73         s64 delta_ns;
  74
  75         /*
  76          * Since cpufreq_update_util() is called with rq->lock held for
  77          * the @target_cpu, our per-CPU data is fully serialized.
  78          *
  79          * However, drivers cannot in general deal with cross-CPU
  80          * requests, so while get_next_freq() will work, our
  81          * sugov_update_commit() call may not for the fast switching platforms.
  82          *
  83          * Hence stop here for remote requests if they aren't supported
  84          * by the hardware, as calculating the frequency is pointless if
  85          * we cannot in fact act on it.
  86          *
  87          * For the slow switching platforms, the kthread is always scheduled on
  88          * the right set of CPUs and any CPU can find the next frequency and
  89          * schedule the kthread.
  90          */
  91         if (sg_policy->policy->fast_switch_enabled &&
  92             !cpufreq_this_cpu_can_update(sg_policy->policy))
  93                 return false;
  94
  95         if (unlikely(sg_policy->need_freq_update))
  96                 return true;
  97
  98         delta_ns = time - sg_policy->last_freq_update_time;
  99
 100         return delta_ns >= sg_policy->freq_update_delay_ns;
 101 }
 102
 103 static bool sugov_update_next_freq(struct sugov_policy *sg_policy, u64 time,
 104                                    unsigned int next_freq)
 105 {
 106         if (sg_policy->next_freq == next_freq)
 107                 return false;
 108
 109         sg_policy->next_freq = next_freq;
 110         sg_policy->last_freq_update_time = time;
 111
 112         return true;
 113 }
 114
 115 static void sugov_fast_switch(struct sugov_policy *sg_policy, u64 time,
 116                               unsigned int next_freq)
 117 {
 118         struct cpufreq_policy *policy = sg_policy->policy;
 119
 120         if (!sugov_update_next_freq(sg_policy, time, next_freq))
 121                 return;
 122
 123         next_freq = cpufreq_driver_fast_switch(policy, next_freq);
 124         if (!next_freq)
 125                 return;
 126
 127         policy->cur = next_freq;
 128         trace_cpu_frequency(next_freq, smp_processor_id());
 129 }
 130
 131 static void sugov_deferred_update(struct sugov_policy *sg_policy, u64 time,
 132                                   unsigned int next_freq)
 133 {
 134         if (!sugov_update_next_freq(sg_policy, time, next_freq))
 135                 return;
 136
 137         if (!sg_policy->work_in_progress) {
 138                 sg_policy->work_in_progress = true;
 139                 irq_work_queue(&sg_policy->irq_work);
 140         }
 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 = arch_scale_freq_invariant() ?
 170                                 policy->cpuinfo.max_freq : policy->cur;
 171
 172         freq = (freq + (freq >> 2)) * util / 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->need_freq_update = false;
 178         sg_policy->cached_raw_freq = freq;
 179         return cpufreq_driver_resolve_freq(policy, freq);
 180 }
 181
 182 static void sugov_get_util(struct sugov_cpu *sg_cpu)
 183 {
 184         struct rq *rq = cpu_rq(sg_cpu->cpu);
 185
 186         sg_cpu->max = arch_scale_cpu_capacity(NULL, sg_cpu->cpu);
 187         sg_cpu->util_cfs = cpu_util_cfs(rq);
 188         sg_cpu->util_dl  = cpu_util_dl(rq);
 189 }
 190
 191 static unsigned long sugov_aggregate_util(struct sugov_cpu *sg_cpu)
 192 {
 193         struct rq *rq = cpu_rq(sg_cpu->cpu);
 194
 195         if (rt_rq_is_runnable(&rq->rt))
 196                 return sg_cpu->max;
 197
 198         /*
 199          * Utilization required by DEADLINE must always be granted while, for
 200          * FAIR, we use blocked utilization of IDLE CPUs as a mechanism to
 201          * gracefully reduce the frequency when no tasks show up for longer
 202          * periods of time.
 203          *
 204          * Ideally we would like to set util_dl as min/guaranteed freq and
 205          * util_cfs + util_dl as requested freq. However, cpufreq is not yet
 206          * ready for such an interface. So, we only do the latter for now.
 207          */
 208         return min(sg_cpu->max, (sg_cpu->util_dl + sg_cpu->util_cfs));
 209 }
 210
 211 /**
 212  * sugov_iowait_reset() - Reset the IO boost status of a CPU.
 213  * @sg_cpu: the sugov data for the CPU to boost
 214  * @time: the update time from the caller
 215  * @set_iowait_boost: true if an IO boost has been requested
 216  *
 217  * The IO wait boost of a task is disabled after a tick since the last update
 218  * of a CPU. If a new IO wait boost is requested after more then a tick, then
 219  * we enable the boost starting from the minimum frequency, which improves
 220  * energy efficiency by ignoring sporadic wakeups from IO.
 221  */
 222 static bool sugov_iowait_reset(struct sugov_cpu *sg_cpu, u64 time,
 223                                bool set_iowait_boost)
 224 {
 225         s64 delta_ns = time - sg_cpu->last_update;
 226
 227         /* Reset boost only if a tick has elapsed since last request */
 228         if (delta_ns <= TICK_NSEC)
 229                 return false;
 230
 231         sg_cpu->iowait_boost = set_iowait_boost
 232                 ? sg_cpu->sg_policy->policy->min : 0;
 233         sg_cpu->iowait_boost_pending = set_iowait_boost;
 234
 235         return true;
 236 }
 237
 238 /**
 239  * sugov_iowait_boost() - Updates the IO boost status of a CPU.
 240  * @sg_cpu: the sugov data for the CPU to boost
 241  * @time: the update time from the caller
 242  * @flags: SCHED_CPUFREQ_IOWAIT if the task is waking up after an IO wait
 243  *
 244  * Each time a task wakes up after an IO operation, the CPU utilization can be
 245  * boosted to a certain utilization which doubles at each "frequent and
 246  * successive" wakeup from IO, ranging from the utilization of the minimum
 247  * OPP to the utilization of the maximum OPP.
 248  * To keep doubling, an IO boost has to be requested at least once per tick,
 249  * otherwise we restart from the utilization of the minimum OPP.
 250  */
 251 static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
 252                                unsigned int flags)
 253 {
 254         bool set_iowait_boost = flags & SCHED_CPUFREQ_IOWAIT;
 255
 256         /* Reset boost if the CPU appears to have been idle enough */
 257         if (sg_cpu->iowait_boost &&
 258             sugov_iowait_reset(sg_cpu, time, set_iowait_boost))
 259                 return;
 260
 261         /* Boost only tasks waking up after IO */
 262         if (!set_iowait_boost)
 263                 return;
 264
 265         /* Ensure boost doubles only one time at each request */
 266         if (sg_cpu->iowait_boost_pending)
 267                 return;
 268         sg_cpu->iowait_boost_pending = true;
 269
 270         /* Double the boost at each request */
 271         if (sg_cpu->iowait_boost) {
 272                 sg_cpu->iowait_boost <<= 1;
 273                 if (sg_cpu->iowait_boost > sg_cpu->iowait_boost_max)
 274                         sg_cpu->iowait_boost = sg_cpu->iowait_boost_max;
 275                 return;
 276         }
 277
 278         /* First wakeup after IO: start with minimum boost */
 279         sg_cpu->iowait_boost = sg_cpu->sg_policy->policy->min;
 280 }
 281
 282 /**
 283  * sugov_iowait_apply() - Apply the IO boost to a CPU.
 284  * @sg_cpu: the sugov data for the cpu to boost
 285  * @time: the update time from the caller
 286  * @util: the utilization to (eventually) boost
 287  * @max: the maximum value the utilization can be boosted to
 288  *
 289  * A CPU running a task which woken up after an IO operation can have its
 290  * utilization boosted to speed up the completion of those IO operations.
 291  * The IO boost value is increased each time a task wakes up from IO, in
 292  * sugov_iowait_apply(), and it's instead decreased by this function,
 293  * each time an increase has not been requested (!iowait_boost_pending).
 294  *
 295  * A CPU which also appears to have been idle for at least one tick has also
 296  * its IO boost utilization reset.
 297  *
 298  * This mechanism is designed to boost high frequently IO waiting tasks, while
 299  * being more conservative on tasks which does sporadic IO operations.
 300  */
 301 static void sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time,
 302                                unsigned long *util, unsigned long *max)
 303 {
 304         unsigned int boost_util, boost_max;
 305
 306         /* No boost currently required */
 307         if (!sg_cpu->iowait_boost)
 308                 return;
 309
 310         /* Reset boost if the CPU appears to have been idle enough */
 311         if (sugov_iowait_reset(sg_cpu, time, false))
 312                 return;
 313
 314         /*
 315          * An IO waiting task has just woken up:
 316          * allow to further double the boost value
 317          */
 318         if (sg_cpu->iowait_boost_pending) {
 319                 sg_cpu->iowait_boost_pending = false;
 320         } else {
 321                 /*
 322                  * Otherwise: reduce the boost value and disable it when we
 323                  * reach the minimum.
 324                  */
 325                 sg_cpu->iowait_boost >>= 1;
 326                 if (sg_cpu->iowait_boost < sg_cpu->sg_policy->policy->min) {
 327                         sg_cpu->iowait_boost = 0;
 328                         return;
 329                 }
 330         }
 331
 332         /*
 333          * Apply the current boost value: a CPU is boosted only if its current
 334          * utilization is smaller then the current IO boost level.
 335          */
 336         boost_util = sg_cpu->iowait_boost;
 337         boost_max = sg_cpu->iowait_boost_max;
 338         if (*util * boost_max < *max * boost_util) {
 339                 *util = boost_util;
 340                 *max = boost_max;
 341         }
 342 }
 343
 344 #ifdef CONFIG_NO_HZ_COMMON
 345 static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
 346 {
 347         unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu);
 348         bool ret = idle_calls == sg_cpu->saved_idle_calls;
 349
 350         sg_cpu->saved_idle_calls = idle_calls;
 351         return ret;
 352 }
 353 #else
 354 static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
 355 #endif /* CONFIG_NO_HZ_COMMON */
 356
 357 /*
 358  * Make sugov_should_update_freq() ignore the rate limit when DL
 359  * has increased the utilization.
 360  */
 361 static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu, struct sugov_policy *sg_policy)
 362 {
 363         if (cpu_util_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->util_dl)
 364                 sg_policy->need_freq_update = true;
 365 }
 366
 367 static void sugov_update_single(struct update_util_data *hook, u64 time,
 368                                 unsigned int flags)
 369 {
 370         struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
 371         struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 372         unsigned long util, max;
 373         unsigned int next_f;
 374         bool busy;
 375
 376         sugov_iowait_boost(sg_cpu, time, flags);
 377         sg_cpu->last_update = time;
 378
 379         ignore_dl_rate_limit(sg_cpu, sg_policy);
 380
 381         if (!sugov_should_update_freq(sg_policy, time))
 382                 return;
 383
 384         busy = sugov_cpu_is_busy(sg_cpu);
 385
 386         sugov_get_util(sg_cpu);
 387         max = sg_cpu->max;
 388         util = sugov_aggregate_util(sg_cpu);
 389         sugov_iowait_apply(sg_cpu, time, &util, &max);
 390         next_f = get_next_freq(sg_policy, util, max);
 391         /*
 392          * Do not reduce the frequency if the CPU has not been idle
 393          * recently, as the reduction is likely to be premature then.
 394          */
 395         if (busy && next_f < sg_policy->next_freq) {
 396                 next_f = sg_policy->next_freq;
 397
 398                 /* Reset cached freq as next_freq has changed */
 399                 sg_policy->cached_raw_freq = 0;
 400         }
 401
 402         /*
 403          * This code runs under rq->lock for the target CPU, so it won't run
 404          * concurrently on two different CPUs for the same target and it is not
 405          * necessary to acquire the lock in the fast switch case.
 406          */
 407         if (sg_policy->policy->fast_switch_enabled) {
 408                 sugov_fast_switch(sg_policy, time, next_f);
 409         } else {
 410                 raw_spin_lock(&sg_policy->update_lock);
 411                 sugov_deferred_update(sg_policy, time, next_f);
 412                 raw_spin_unlock(&sg_policy->update_lock);
 413         }
 414 }
 415
 416 static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
 417 {
 418         struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 419         struct cpufreq_policy *policy = sg_policy->policy;
 420         unsigned long util = 0, max = 1;
 421         unsigned int j;
 422
 423         for_each_cpu(j, policy->cpus) {
 424                 struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
 425                 unsigned long j_util, j_max;
 426
 427                 sugov_get_util(j_sg_cpu);
 428                 j_max = j_sg_cpu->max;
 429                 j_util = sugov_aggregate_util(j_sg_cpu);
 430                 sugov_iowait_apply(j_sg_cpu, time, &j_util, &j_max);
 431
 432                 if (j_util * max > j_max * util) {
 433                         util = j_util;
 434                         max = j_max;
 435                 }
 436         }
 437
 438         return get_next_freq(sg_policy, util, max);
 439 }
 440
 441 static void
 442 sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags)
 443 {
 444         struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
 445         struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 446         unsigned int next_f;
 447
 448         raw_spin_lock(&sg_policy->update_lock);
 449
 450         sugov_iowait_boost(sg_cpu, time, flags);
 451         sg_cpu->last_update = time;
 452
 453         ignore_dl_rate_limit(sg_cpu, sg_policy);
 454
 455         if (sugov_should_update_freq(sg_policy, time)) {
 456                 next_f = sugov_next_freq_shared(sg_cpu, time);
 457
 458                 if (sg_policy->policy->fast_switch_enabled)
 459                         sugov_fast_switch(sg_policy, time, next_f);
 460                 else
 461                         sugov_deferred_update(sg_policy, time, next_f);
 462         }
 463
 464         raw_spin_unlock(&sg_policy->update_lock);
 465 }
 466
 467 static void sugov_work(struct kthread_work *work)
 468 {
 469         struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
 470         unsigned int freq;
 471         unsigned long flags;
 472
 473         /*
 474          * Hold sg_policy->update_lock shortly to handle the case where:
 475          * incase sg_policy->next_freq is read here, and then updated by
 476          * sugov_deferred_update() just before work_in_progress is set to false
 477          * here, we may miss queueing the new update.
 478          *
 479          * Note: If a work was queued after the update_lock is released,
 480          * sugov_work() will just be called again by kthread_work code; and the
 481          * request will be proceed before the sugov thread sleeps.
 482          */
 483         raw_spin_lock_irqsave(&sg_policy->update_lock, flags);
 484         freq = sg_policy->next_freq;
 485         sg_policy->work_in_progress = false;
 486         raw_spin_unlock_irqrestore(&sg_policy->update_lock, flags);
 487
 488         mutex_lock(&sg_policy->work_lock);
 489         __cpufreq_driver_target(sg_policy->policy, freq, CPUFREQ_RELATION_L);
 490         mutex_unlock(&sg_policy->work_lock);
 491 }
 492
 493 static void sugov_irq_work(struct irq_work *irq_work)
 494 {
 495         struct sugov_policy *sg_policy;
 496
 497         sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
 498
 499         kthread_queue_work(&sg_policy->worker, &sg_policy->work);
 500 }
 501
 502 /************************** sysfs interface ************************/
 503
 504 static struct sugov_tunables *global_tunables;
 505 static DEFINE_MUTEX(global_tunables_lock);
 506
 507 static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
 508 {
 509         return container_of(attr_set, struct sugov_tunables, attr_set);
 510 }
 511
 512 static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
 513 {
 514         struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
 515
 516         return sprintf(buf, "%u\n", tunables->rate_limit_us);
 517 }
 518
 519 static ssize_t
 520 rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf, size_t count)
 521 {
 522         struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
 523         struct sugov_policy *sg_policy;
 524         unsigned int rate_limit_us;
 525
 526         if (kstrtouint(buf, 10, &rate_limit_us))
 527                 return -EINVAL;
 528
 529         tunables->rate_limit_us = rate_limit_us;
 530
 531         list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
 532                 sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
 533
 534         return count;
 535 }
 536
 537 static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
 538
 539 static struct attribute *sugov_attributes[] = {
 540         &rate_limit_us.attr,
 541         NULL
 542 };
 543
 544 static struct kobj_type sugov_tunables_ktype = {
 545         .default_attrs = sugov_attributes,
 546         .sysfs_ops = &governor_sysfs_ops,
 547 };
 548
 549 /********************** cpufreq governor interface *********************/
 550
 551 static struct cpufreq_governor schedutil_gov;
 552
 553 static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
 554 {
 555         struct sugov_policy *sg_policy;
 556
 557         sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
 558         if (!sg_policy)
 559                 return NULL;
 560
 561         sg_policy->policy = policy;
 562         raw_spin_lock_init(&sg_policy->update_lock);
 563         return sg_policy;
 564 }
 565
 566 static void sugov_policy_free(struct sugov_policy *sg_policy)
 567 {
 568         kfree(sg_policy);
 569 }
 570
 571 static int sugov_kthread_create(struct sugov_policy *sg_policy)
 572 {
 573         struct task_struct *thread;
 574         struct sched_attr attr = {
 575                 .size           = sizeof(struct sched_attr),
 576                 .sched_policy   = SCHED_DEADLINE,
 577                 .sched_flags    = SCHED_FLAG_SUGOV,
 578                 .sched_nice     = 0,
 579                 .sched_priority = 0,
 580                 /*
 581                  * Fake (unused) bandwidth; workaround to "fix"
 582                  * priority inheritance.
 583                  */
 584                 .sched_runtime  =  1000000,
 585                 .sched_deadline = 10000000,
 586                 .sched_period   = 10000000,
 587         };
 588         struct cpufreq_policy *policy = sg_policy->policy;
 589         int ret;
 590
 591         /* kthread only required for slow path */
 592         if (policy->fast_switch_enabled)
 593                 return 0;
 594
 595         kthread_init_work(&sg_policy->work, sugov_work);
 596         kthread_init_worker(&sg_policy->worker);
 597         thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
 598                                 "sugov:%d",
 599                                 cpumask_first(policy->related_cpus));
 600         if (IS_ERR(thread)) {
 601                 pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread));
 602                 return PTR_ERR(thread);
 603         }
 604
 605         ret = sched_setattr_nocheck(thread, &attr);
 606         if (ret) {
 607                 kthread_stop(thread);
 608                 pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__);
 609                 return ret;
 610         }
 611
 612         sg_policy->thread = thread;
 613         kthread_bind_mask(thread, policy->related_cpus);
 614         init_irq_work(&sg_policy->irq_work, sugov_irq_work);
 615         mutex_init(&sg_policy->work_lock);
 616
 617         wake_up_process(thread);
 618
 619         return 0;
 620 }
 621
 622 static void sugov_kthread_stop(struct sugov_policy *sg_policy)
 623 {
 624         /* kthread only required for slow path */
 625         if (sg_policy->policy->fast_switch_enabled)
 626                 return;
 627
 628         kthread_flush_worker(&sg_policy->worker);
 629         kthread_stop(sg_policy->thread);
 630         mutex_destroy(&sg_policy->work_lock);
 631 }
 632
 633 static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
 634 {
 635         struct sugov_tunables *tunables;
 636
 637         tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
 638         if (tunables) {
 639                 gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
 640                 if (!have_governor_per_policy())
 641                         global_tunables = tunables;
 642         }
 643         return tunables;
 644 }
 645
 646 static void sugov_tunables_free(struct sugov_tunables *tunables)
 647 {
 648         if (!have_governor_per_policy())
 649                 global_tunables = NULL;
 650
 651         kfree(tunables);
 652 }
 653
 654 static int sugov_init(struct cpufreq_policy *policy)
 655 {
 656         struct sugov_policy *sg_policy;
 657         struct sugov_tunables *tunables;
 658         int ret = 0;
 659
 660         /* State should be equivalent to EXIT */
 661         if (policy->governor_data)
 662                 return -EBUSY;
 663
 664         cpufreq_enable_fast_switch(policy);
 665
 666         sg_policy = sugov_policy_alloc(policy);
 667         if (!sg_policy) {
 668                 ret = -ENOMEM;
 669                 goto disable_fast_switch;
 670         }
 671
 672         ret = sugov_kthread_create(sg_policy);
 673         if (ret)
 674                 goto free_sg_policy;
 675
 676         mutex_lock(&global_tunables_lock);
 677
 678         if (global_tunables) {
 679                 if (WARN_ON(have_governor_per_policy())) {
 680                         ret = -EINVAL;
 681                         goto stop_kthread;
 682                 }
 683                 policy->governor_data = sg_policy;
 684                 sg_policy->tunables = global_tunables;
 685
 686                 gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
 687                 goto out;
 688         }
 689
 690         tunables = sugov_tunables_alloc(sg_policy);
 691         if (!tunables) {
 692                 ret = -ENOMEM;
 693                 goto stop_kthread;
 694         }
 695
 696         tunables->rate_limit_us = cpufreq_policy_transition_delay_us(policy);
 697
 698         policy->governor_data = sg_policy;
 699         sg_policy->tunables = tunables;
 700
 701         ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
 702                                    get_governor_parent_kobj(policy), "%s",
 703                                    schedutil_gov.name);
 704         if (ret)
 705                 goto fail;
 706
 707 out:
 708         mutex_unlock(&global_tunables_lock);
 709         return 0;
 710
 711 fail:
 712         policy->governor_data = NULL;
 713         sugov_tunables_free(tunables);
 714
 715 stop_kthread:
 716         sugov_kthread_stop(sg_policy);
 717         mutex_unlock(&global_tunables_lock);
 718
 719 free_sg_policy:
 720         sugov_policy_free(sg_policy);
 721
 722 disable_fast_switch:
 723         cpufreq_disable_fast_switch(policy);
 724
 725         pr_err("initialization failed (error %d)\n", ret);
 726         return ret;
 727 }
 728
 729 static void sugov_exit(struct cpufreq_policy *policy)
 730 {
 731         struct sugov_policy *sg_policy = policy->governor_data;
 732         struct sugov_tunables *tunables = sg_policy->tunables;
 733         unsigned int count;
 734
 735         mutex_lock(&global_tunables_lock);
 736
 737         count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
 738         policy->governor_data = NULL;
 739         if (!count)
 740                 sugov_tunables_free(tunables);
 741
 742         mutex_unlock(&global_tunables_lock);
 743
 744         sugov_kthread_stop(sg_policy);
 745         sugov_policy_free(sg_policy);
 746         cpufreq_disable_fast_switch(policy);
 747 }
 748
 749 static int sugov_start(struct cpufreq_policy *policy)
 750 {
 751         struct sugov_policy *sg_policy = policy->governor_data;
 752         unsigned int cpu;
 753
 754         sg_policy->freq_update_delay_ns = sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
 755         sg_policy->last_freq_update_time        = 0;
 756         sg_policy->next_freq                    = 0;
 757         sg_policy->work_in_progress             = false;
 758         sg_policy->need_freq_update             = false;
 759         sg_policy->cached_raw_freq              = 0;
 760
 761         for_each_cpu(cpu, policy->cpus) {
 762                 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
 763
 764                 memset(sg_cpu, 0, sizeof(*sg_cpu));
 765                 sg_cpu->cpu                     = cpu;
 766                 sg_cpu->sg_policy               = sg_policy;
 767                 sg_cpu->iowait_boost_max        = policy->cpuinfo.max_freq;
 768         }
 769
 770         for_each_cpu(cpu, policy->cpus) {
 771                 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
 772
 773                 cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
 774                                              policy_is_shared(policy) ?
 775                                                         sugov_update_shared :
 776                                                         sugov_update_single);
 777         }
 778         return 0;
 779 }
 780
 781 static void sugov_stop(struct cpufreq_policy *policy)
 782 {
 783         struct sugov_policy *sg_policy = policy->governor_data;
 784         unsigned int cpu;
 785
 786         for_each_cpu(cpu, policy->cpus)
 787                 cpufreq_remove_update_util_hook(cpu);
 788
 789         synchronize_sched();
 790
 791         if (!policy->fast_switch_enabled) {
 792                 irq_work_sync(&sg_policy->irq_work);
 793                 kthread_cancel_work_sync(&sg_policy->work);
 794         }
 795 }
 796
 797 static void sugov_limits(struct cpufreq_policy *policy)
 798 {
 799         struct sugov_policy *sg_policy = policy->governor_data;
 800
 801         if (!policy->fast_switch_enabled) {
 802                 mutex_lock(&sg_policy->work_lock);
 803                 cpufreq_policy_apply_limits(policy);
 804                 mutex_unlock(&sg_policy->work_lock);
 805         }
 806
 807         sg_policy->need_freq_update = true;
 808 }
 809
 810 static struct cpufreq_governor schedutil_gov = {
 811         .name                   = "schedutil",
 812         .owner                  = THIS_MODULE,
 813         .dynamic_switching      = true,
 814         .init                   = sugov_init,
 815         .exit                   = sugov_exit,
 816         .start                  = sugov_start,
 817         .stop                   = sugov_stop,
 818         .limits                 = sugov_limits,
 819 };
 820
 821 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
 822 struct cpufreq_governor *cpufreq_default_governor(void)
 823 {
 824         return &schedutil_gov;
 825 }
 826 #endif
 827
 828 static int __init sugov_register(void)
 829 {
 830         return cpufreq_register_governor(&schedutil_gov);
 831 }
 832 fs_initcall(sugov_register);