kernel/sched/cpufreq_schedutil.c

   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_dl;
  51         unsigned long           max;
  52
  53         /* The field below is for single-CPU policies only: */
  54 #ifdef CONFIG_NO_HZ_COMMON
  55         unsigned long           saved_idle_calls;
  56 #endif
  57 };
  58
  59 static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
  60
  61 /************************ Governor internals ***********************/
  62
  63 static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
  64 {
  65         s64 delta_ns;
  66
  67         /*
  68          * Since cpufreq_update_util() is called with rq->lock held for
  69          * the @target_cpu, our per-CPU data is fully serialized.
  70          *
  71          * However, drivers cannot in general deal with cross-CPU
  72          * requests, so while get_next_freq() will work, our
  73          * sugov_update_commit() call may not for the fast switching platforms.
  74          *
  75          * Hence stop here for remote requests if they aren't supported
  76          * by the hardware, as calculating the frequency is pointless if
  77          * we cannot in fact act on it.
  78          *
  79          * This is needed on the slow switching platforms too to prevent CPUs
  80          * going offline from leaving stale IRQ work items behind.
  81          */
  82         if (!cpufreq_this_cpu_can_update(sg_policy->policy))
  83                 return false;
  84
  85         if (unlikely(sg_policy->limits_changed)) {
  86                 sg_policy->limits_changed = false;
  87                 sg_policy->need_freq_update = true;
  88                 return true;
  89         }
  90
  91         delta_ns = time - sg_policy->last_freq_update_time;
  92
  93         return delta_ns >= sg_policy->freq_update_delay_ns;
  94 }
  95
  96 static bool sugov_update_next_freq(struct sugov_policy *sg_policy, u64 time,
  97                                    unsigned int next_freq)
  98 {
  99         if (sg_policy->need_freq_update)
 100                 sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);
 101         else if (sg_policy->next_freq == next_freq)
 102                 return false;
 103
 104         sg_policy->next_freq = next_freq;
 105         sg_policy->last_freq_update_time = time;
 106
 107         return true;
 108 }
 109
 110 static void sugov_deferred_update(struct sugov_policy *sg_policy)
 111 {
 112         if (!sg_policy->work_in_progress) {
 113                 sg_policy->work_in_progress = true;
 114                 irq_work_queue(&sg_policy->irq_work);
 115         }
 116 }
 117
 118 /**
 119  * get_next_freq - Compute a new frequency for a given cpufreq policy.
 120  * @sg_policy: schedutil policy object to compute the new frequency for.
 121  * @util: Current CPU utilization.
 122  * @max: CPU capacity.
 123  *
 124  * If the utilization is frequency-invariant, choose the new frequency to be
 125  * proportional to it, that is
 126  *
 127  * next_freq = C * max_freq * util / max
 128  *
 129  * Otherwise, approximate the would-be frequency-invariant utilization by
 130  * util_raw * (curr_freq / max_freq) which leads to
 131  *
 132  * next_freq = C * curr_freq * util_raw / max
 133  *
 134  * Take C = 1.25 for the frequency tipping point at (util / max) = 0.8.
 135  *
 136  * The lowest driver-supported frequency which is equal or greater than the raw
 137  * next_freq (as calculated above) is returned, subject to policy min/max and
 138  * cpufreq driver limitations.
 139  */
 140 static unsigned int get_next_freq(struct sugov_policy *sg_policy,
 141                                   unsigned long util, unsigned long max)
 142 {
 143         struct cpufreq_policy *policy = sg_policy->policy;
 144         unsigned int freq = arch_scale_freq_invariant() ?
 145                                 policy->cpuinfo.max_freq : policy->cur;
 146
 147         util = map_util_perf(util);
 148         freq = map_util_freq(util, freq, max);
 149
 150         if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)
 151                 return sg_policy->next_freq;
 152
 153         sg_policy->cached_raw_freq = freq;
 154         return cpufreq_driver_resolve_freq(policy, freq);
 155 }
 156
 157 static void sugov_get_util(struct sugov_cpu *sg_cpu)
 158 {
 159         struct rq *rq = cpu_rq(sg_cpu->cpu);
 160
 161         sg_cpu->max = arch_scale_cpu_capacity(sg_cpu->cpu);
 162         sg_cpu->bw_dl = cpu_bw_dl(rq);
 163         sg_cpu->util = effective_cpu_util(sg_cpu->cpu, cpu_util_cfs(sg_cpu->cpu),
 164                                           FREQUENCY_UTIL, NULL);
 165 }
 166
 167 /**
 168  * sugov_iowait_reset() - Reset the IO boost status of a CPU.
 169  * @sg_cpu: the sugov data for the CPU to boost
 170  * @time: the update time from the caller
 171  * @set_iowait_boost: true if an IO boost has been requested
 172  *
 173  * The IO wait boost of a task is disabled after a tick since the last update
 174  * of a CPU. If a new IO wait boost is requested after more then a tick, then
 175  * we enable the boost starting from IOWAIT_BOOST_MIN, which improves energy
 176  * efficiency by ignoring sporadic wakeups from IO.
 177  */
 178 static bool sugov_iowait_reset(struct sugov_cpu *sg_cpu, u64 time,
 179                                bool set_iowait_boost)
 180 {
 181         s64 delta_ns = time - sg_cpu->last_update;
 182
 183         /* Reset boost only if a tick has elapsed since last request */
 184         if (delta_ns <= TICK_NSEC)
 185                 return false;
 186
 187         sg_cpu->iowait_boost = set_iowait_boost ? IOWAIT_BOOST_MIN : 0;
 188         sg_cpu->iowait_boost_pending = set_iowait_boost;
 189
 190         return true;
 191 }
 192
 193 /**
 194  * sugov_iowait_boost() - Updates the IO boost status of a CPU.
 195  * @sg_cpu: the sugov data for the CPU to boost
 196  * @time: the update time from the caller
 197  * @flags: SCHED_CPUFREQ_IOWAIT if the task is waking up after an IO wait
 198  *
 199  * Each time a task wakes up after an IO operation, the CPU utilization can be
 200  * boosted to a certain utilization which doubles at each "frequent and
 201  * successive" wakeup from IO, ranging from IOWAIT_BOOST_MIN to the utilization
 202  * of the maximum OPP.
 203  *
 204  * To keep doubling, an IO boost has to be requested at least once per tick,
 205  * otherwise we restart from the utilization of the minimum OPP.
 206  */
 207 static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
 208                                unsigned int flags)
 209 {
 210         bool set_iowait_boost = flags & SCHED_CPUFREQ_IOWAIT;
 211
 212         /* Reset boost if the CPU appears to have been idle enough */
 213         if (sg_cpu->iowait_boost &&
 214             sugov_iowait_reset(sg_cpu, time, set_iowait_boost))
 215                 return;
 216
 217         /* Boost only tasks waking up after IO */
 218         if (!set_iowait_boost)
 219                 return;
 220
 221         /* Ensure boost doubles only one time at each request */
 222         if (sg_cpu->iowait_boost_pending)
 223                 return;
 224         sg_cpu->iowait_boost_pending = true;
 225
 226         /* Double the boost at each request */
 227         if (sg_cpu->iowait_boost) {
 228                 sg_cpu->iowait_boost =
 229                         min_t(unsigned int, sg_cpu->iowait_boost << 1, SCHED_CAPACITY_SCALE);
 230                 return;
 231         }
 232
 233         /* First wakeup after IO: start with minimum boost */
 234         sg_cpu->iowait_boost = IOWAIT_BOOST_MIN;
 235 }
 236
 237 /**
 238  * sugov_iowait_apply() - Apply the IO boost to a CPU.
 239  * @sg_cpu: the sugov data for the cpu to boost
 240  * @time: the update time from the caller
 241  *
 242  * A CPU running a task which woken up after an IO operation can have its
 243  * utilization boosted to speed up the completion of those IO operations.
 244  * The IO boost value is increased each time a task wakes up from IO, in
 245  * sugov_iowait_apply(), and it's instead decreased by this function,
 246  * each time an increase has not been requested (!iowait_boost_pending).
 247  *
 248  * A CPU which also appears to have been idle for at least one tick has also
 249  * its IO boost utilization reset.
 250  *
 251  * This mechanism is designed to boost high frequently IO waiting tasks, while
 252  * being more conservative on tasks which does sporadic IO operations.
 253  */
 254 static void sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time)
 255 {
 256         unsigned long boost;
 257
 258         /* No boost currently required */
 259         if (!sg_cpu->iowait_boost)
 260                 return;
 261
 262         /* Reset boost if the CPU appears to have been idle enough */
 263         if (sugov_iowait_reset(sg_cpu, time, false))
 264                 return;
 265
 266         if (!sg_cpu->iowait_boost_pending) {
 267                 /*
 268                  * No boost pending; reduce the boost value.
 269                  */
 270                 sg_cpu->iowait_boost >>= 1;
 271                 if (sg_cpu->iowait_boost < IOWAIT_BOOST_MIN) {
 272                         sg_cpu->iowait_boost = 0;
 273                         return;
 274                 }
 275         }
 276
 277         sg_cpu->iowait_boost_pending = false;
 278
 279         /*
 280          * sg_cpu->util is already in capacity scale; convert iowait_boost
 281          * into the same scale so we can compare.
 282          */
 283         boost = (sg_cpu->iowait_boost * sg_cpu->max) >> SCHED_CAPACITY_SHIFT;
 284         boost = uclamp_rq_util_with(cpu_rq(sg_cpu->cpu), boost, NULL);
 285         if (sg_cpu->util < boost)
 286                 sg_cpu->util = boost;
 287 }
 288
 289 #ifdef CONFIG_NO_HZ_COMMON
 290 static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
 291 {
 292         unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu);
 293         bool ret = idle_calls == sg_cpu->saved_idle_calls;
 294
 295         sg_cpu->saved_idle_calls = idle_calls;
 296         return ret;
 297 }
 298 #else
 299 static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
 300 #endif /* CONFIG_NO_HZ_COMMON */
 301
 302 /*
 303  * Make sugov_should_update_freq() ignore the rate limit when DL
 304  * has increased the utilization.
 305  */
 306 static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu)
 307 {
 308         if (cpu_bw_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->bw_dl)
 309                 sg_cpu->sg_policy->limits_changed = true;
 310 }
 311
 312 static inline bool sugov_update_single_common(struct sugov_cpu *sg_cpu,
 313                                               u64 time, unsigned int flags)
 314 {
 315         sugov_iowait_boost(sg_cpu, time, flags);
 316         sg_cpu->last_update = time;
 317
 318         ignore_dl_rate_limit(sg_cpu);
 319
 320         if (!sugov_should_update_freq(sg_cpu->sg_policy, time))
 321                 return false;
 322
 323         sugov_get_util(sg_cpu);
 324         sugov_iowait_apply(sg_cpu, time);
 325
 326         return true;
 327 }
 328
 329 static void sugov_update_single_freq(struct update_util_data *hook, u64 time,
 330                                      unsigned int flags)
 331 {
 332         struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
 333         struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 334         unsigned int cached_freq = sg_policy->cached_raw_freq;
 335         unsigned int next_f;
 336
 337         if (!sugov_update_single_common(sg_cpu, time, flags))
 338                 return;
 339
 340         next_f = get_next_freq(sg_policy, sg_cpu->util, sg_cpu->max);
 341         /*
 342          * Do not reduce the frequency if the CPU has not been idle
 343          * recently, as the reduction is likely to be premature then.
 344          *
 345          * Except when the rq is capped by uclamp_max.
 346          */
 347         if (!uclamp_rq_is_capped(cpu_rq(sg_cpu->cpu)) &&
 348             sugov_cpu_is_busy(sg_cpu) && next_f < sg_policy->next_freq) {
 349                 next_f = sg_policy->next_freq;
 350
 351                 /* Restore cached freq as next_freq has changed */
 352                 sg_policy->cached_raw_freq = cached_freq;
 353         }
 354
 355         if (!sugov_update_next_freq(sg_policy, time, next_f))
 356                 return;
 357
 358         /*
 359          * This code runs under rq->lock for the target CPU, so it won't run
 360          * concurrently on two different CPUs for the same target and it is not
 361          * necessary to acquire the lock in the fast switch case.
 362          */
 363         if (sg_policy->policy->fast_switch_enabled) {
 364                 cpufreq_driver_fast_switch(sg_policy->policy, next_f);
 365         } else {
 366                 raw_spin_lock(&sg_policy->update_lock);
 367                 sugov_deferred_update(sg_policy);
 368                 raw_spin_unlock(&sg_policy->update_lock);
 369         }
 370 }
 371
 372 static void sugov_update_single_perf(struct update_util_data *hook, u64 time,
 373                                      unsigned int flags)
 374 {
 375         struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
 376         unsigned long prev_util = sg_cpu->util;
 377
 378         /*
 379          * Fall back to the "frequency" path if frequency invariance is not
 380          * supported, because the direct mapping between the utilization and
 381          * the performance levels depends on the frequency invariance.
 382          */
 383         if (!arch_scale_freq_invariant()) {
 384                 sugov_update_single_freq(hook, time, flags);
 385                 return;
 386         }
 387
 388         if (!sugov_update_single_common(sg_cpu, time, flags))
 389                 return;
 390
 391         /*
 392          * Do not reduce the target performance level if the CPU has not been
 393          * idle recently, as the reduction is likely to be premature then.
 394          *
 395          * Except when the rq is capped by uclamp_max.
 396          */
 397         if (!uclamp_rq_is_capped(cpu_rq(sg_cpu->cpu)) &&
 398             sugov_cpu_is_busy(sg_cpu) && sg_cpu->util < prev_util)
 399                 sg_cpu->util = prev_util;
 400
 401         cpufreq_driver_adjust_perf(sg_cpu->cpu, map_util_perf(sg_cpu->bw_dl),
 402                                    map_util_perf(sg_cpu->util), sg_cpu->max);
 403
 404         sg_cpu->sg_policy->last_freq_update_time = time;
 405 }
 406
 407 static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
 408 {
 409         struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 410         struct cpufreq_policy *policy = sg_policy->policy;
 411         unsigned long util = 0, max = 1;
 412         unsigned int j;
 413
 414         for_each_cpu(j, policy->cpus) {
 415                 struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
 416                 unsigned long j_util, j_max;
 417
 418                 sugov_get_util(j_sg_cpu);
 419                 sugov_iowait_apply(j_sg_cpu, time);
 420                 j_util = j_sg_cpu->util;
 421                 j_max = j_sg_cpu->max;
 422
 423                 if (j_util * max > j_max * util) {
 424                         util = j_util;
 425                         max = j_max;
 426                 }
 427         }
 428
 429         return get_next_freq(sg_policy, util, max);
 430 }
 431
 432 static void
 433 sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags)
 434 {
 435         struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
 436         struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 437         unsigned int next_f;
 438
 439         raw_spin_lock(&sg_policy->update_lock);
 440
 441         sugov_iowait_boost(sg_cpu, time, flags);
 442         sg_cpu->last_update = time;
 443
 444         ignore_dl_rate_limit(sg_cpu);
 445
 446         if (sugov_should_update_freq(sg_policy, time)) {
 447                 next_f = sugov_next_freq_shared(sg_cpu, time);
 448
 449                 if (!sugov_update_next_freq(sg_policy, time, next_f))
 450                         goto unlock;
 451
 452                 if (sg_policy->policy->fast_switch_enabled)
 453                         cpufreq_driver_fast_switch(sg_policy->policy, next_f);
 454                 else
 455                         sugov_deferred_update(sg_policy);
 456         }
 457 unlock:
 458         raw_spin_unlock(&sg_policy->update_lock);
 459 }
 460
 461 static void sugov_work(struct kthread_work *work)
 462 {
 463         struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
 464         unsigned int freq;
 465         unsigned long flags;
 466
 467         /*
 468          * Hold sg_policy->update_lock shortly to handle the case where:
 469          * in case sg_policy->next_freq is read here, and then updated by
 470          * sugov_deferred_update() just before work_in_progress is set to false
 471          * here, we may miss queueing the new update.
 472          *
 473          * Note: If a work was queued after the update_lock is released,
 474          * sugov_work() will just be called again by kthread_work code; and the
 475          * request will be proceed before the sugov thread sleeps.
 476          */
 477         raw_spin_lock_irqsave(&sg_policy->update_lock, flags);
 478         freq = sg_policy->next_freq;
 479         sg_policy->work_in_progress = false;
 480         raw_spin_unlock_irqrestore(&sg_policy->update_lock, flags);
 481
 482         mutex_lock(&sg_policy->work_lock);
 483         __cpufreq_driver_target(sg_policy->policy, freq, CPUFREQ_RELATION_L);
 484         mutex_unlock(&sg_policy->work_lock);
 485 }
 486
 487 static void sugov_irq_work(struct irq_work *irq_work)
 488 {
 489         struct sugov_policy *sg_policy;
 490
 491         sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
 492
 493         kthread_queue_work(&sg_policy->worker, &sg_policy->work);
 494 }
 495
 496 /************************** sysfs interface ************************/
 497
 498 static struct sugov_tunables *global_tunables;
 499 static DEFINE_MUTEX(global_tunables_lock);
 500
 501 static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
 502 {
 503         return container_of(attr_set, struct sugov_tunables, attr_set);
 504 }
 505
 506 static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
 507 {
 508         struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
 509
 510         return sprintf(buf, "%u\n", tunables->rate_limit_us);
 511 }
 512
 513 static ssize_t
 514 rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf, size_t count)
 515 {
 516         struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
 517         struct sugov_policy *sg_policy;
 518         unsigned int rate_limit_us;
 519
 520         if (kstrtouint(buf, 10, &rate_limit_us))
 521                 return -EINVAL;
 522
 523         tunables->rate_limit_us = rate_limit_us;
 524
 525         list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
 526                 sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
 527
 528         return count;
 529 }
 530
 531 static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
 532
 533 static struct attribute *sugov_attrs[] = {
 534         &rate_limit_us.attr,
 535         NULL
 536 };
 537 ATTRIBUTE_GROUPS(sugov);
 538
 539 static void sugov_tunables_free(struct kobject *kobj)
 540 {
 541         struct gov_attr_set *attr_set = to_gov_attr_set(kobj);
 542
 543         kfree(to_sugov_tunables(attr_set));
 544 }
 545
 546 static struct kobj_type sugov_tunables_ktype = {
 547         .default_groups = sugov_groups,
 548         .sysfs_ops = &governor_sysfs_ops,
 549         .release = &sugov_tunables_free,
 550 };
 551
 552 /********************** cpufreq governor interface *********************/
 553
 554 struct cpufreq_governor schedutil_gov;
 555
 556 static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
 557 {
 558         struct sugov_policy *sg_policy;
 559
 560         sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
 561         if (!sg_policy)
 562                 return NULL;
 563
 564         sg_policy->policy = policy;
 565         raw_spin_lock_init(&sg_policy->update_lock);
 566         return sg_policy;
 567 }
 568
 569 static void sugov_policy_free(struct sugov_policy *sg_policy)
 570 {
 571         kfree(sg_policy);
 572 }
 573
 574 static int sugov_kthread_create(struct sugov_policy *sg_policy)
 575 {
 576         struct task_struct *thread;
 577         struct sched_attr attr = {
 578                 .size           = sizeof(struct sched_attr),
 579                 .sched_policy   = SCHED_DEADLINE,
 580                 .sched_flags    = SCHED_FLAG_SUGOV,
 581                 .sched_nice     = 0,
 582                 .sched_priority = 0,
 583                 /*
 584                  * Fake (unused) bandwidth; workaround to "fix"
 585                  * priority inheritance.
 586                  */
 587                 .sched_runtime  =  1000000,
 588                 .sched_deadline = 10000000,
 589                 .sched_period   = 10000000,
 590         };
 591         struct cpufreq_policy *policy = sg_policy->policy;
 592         int ret;
 593
 594         /* kthread only required for slow path */
 595         if (policy->fast_switch_enabled)
 596                 return 0;
 597
 598         kthread_init_work(&sg_policy->work, sugov_work);
 599         kthread_init_worker(&sg_policy->worker);
 600         thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
 601                                 "sugov:%d",
 602                                 cpumask_first(policy->related_cpus));
 603         if (IS_ERR(thread)) {
 604                 pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread));
 605                 return PTR_ERR(thread);
 606         }
 607
 608         ret = sched_setattr_nocheck(thread, &attr);
 609         if (ret) {
 610                 kthread_stop(thread);
 611                 pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__);
 612                 return ret;
 613         }
 614
 615         sg_policy->thread = thread;
 616         kthread_bind_mask(thread, policy->related_cpus);
 617         init_irq_work(&sg_policy->irq_work, sugov_irq_work);
 618         mutex_init(&sg_policy->work_lock);
 619
 620         wake_up_process(thread);
 621
 622         return 0;
 623 }
 624
 625 static void sugov_kthread_stop(struct sugov_policy *sg_policy)
 626 {
 627         /* kthread only required for slow path */
 628         if (sg_policy->policy->fast_switch_enabled)
 629                 return;
 630
 631         kthread_flush_worker(&sg_policy->worker);
 632         kthread_stop(sg_policy->thread);
 633         mutex_destroy(&sg_policy->work_lock);
 634 }
 635
 636 static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
 637 {
 638         struct sugov_tunables *tunables;
 639
 640         tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
 641         if (tunables) {
 642                 gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
 643                 if (!have_governor_per_policy())
 644                         global_tunables = tunables;
 645         }
 646         return tunables;
 647 }
 648
 649 static void sugov_clear_global_tunables(void)
 650 {
 651         if (!have_governor_per_policy())
 652                 global_tunables = NULL;
 653 }
 654
 655 static int sugov_init(struct cpufreq_policy *policy)
 656 {
 657         struct sugov_policy *sg_policy;
 658         struct sugov_tunables *tunables;
 659         int ret = 0;
 660
 661         /* State should be equivalent to EXIT */
 662         if (policy->governor_data)
 663                 return -EBUSY;
 664
 665         cpufreq_enable_fast_switch(policy);
 666
 667         sg_policy = sugov_policy_alloc(policy);
 668         if (!sg_policy) {
 669                 ret = -ENOMEM;
 670                 goto disable_fast_switch;
 671         }
 672
 673         ret = sugov_kthread_create(sg_policy);
 674         if (ret)
 675                 goto free_sg_policy;
 676
 677         mutex_lock(&global_tunables_lock);
 678
 679         if (global_tunables) {
 680                 if (WARN_ON(have_governor_per_policy())) {
 681                         ret = -EINVAL;
 682                         goto stop_kthread;
 683                 }
 684                 policy->governor_data = sg_policy;
 685                 sg_policy->tunables = global_tunables;
 686
 687                 gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
 688                 goto out;
 689         }
 690
 691         tunables = sugov_tunables_alloc(sg_policy);
 692         if (!tunables) {
 693                 ret = -ENOMEM;
 694                 goto stop_kthread;
 695         }
 696
 697         tunables->rate_limit_us = cpufreq_policy_transition_delay_us(policy);
 698
 699         policy->governor_data = sg_policy;
 700         sg_policy->tunables = tunables;
 701
 702         ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
 703                                    get_governor_parent_kobj(policy), "%s",
 704                                    schedutil_gov.name);
 705         if (ret)
 706                 goto fail;
 707
 708 out:
 709         mutex_unlock(&global_tunables_lock);
 710         return 0;
 711
 712 fail:
 713         kobject_put(&tunables->attr_set.kobj);
 714         policy->governor_data = NULL;
 715         sugov_clear_global_tunables();
 716
 717 stop_kthread:
 718         sugov_kthread_stop(sg_policy);
 719         mutex_unlock(&global_tunables_lock);
 720
 721 free_sg_policy:
 722         sugov_policy_free(sg_policy);
 723
 724 disable_fast_switch:
 725         cpufreq_disable_fast_switch(policy);
 726
 727         pr_err("initialization failed (error %d)\n", ret);
 728         return ret;
 729 }
 730
 731 static void sugov_exit(struct cpufreq_policy *policy)
 732 {
 733         struct sugov_policy *sg_policy = policy->governor_data;
 734         struct sugov_tunables *tunables = sg_policy->tunables;
 735         unsigned int count;
 736
 737         mutex_lock(&global_tunables_lock);
 738
 739         count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
 740         policy->governor_data = NULL;
 741         if (!count)
 742                 sugov_clear_global_tunables();
 743
 744         mutex_unlock(&global_tunables_lock);
 745
 746         sugov_kthread_stop(sg_policy);
 747         sugov_policy_free(sg_policy);
 748         cpufreq_disable_fast_switch(policy);
 749 }
 750
 751 static int sugov_start(struct cpufreq_policy *policy)
 752 {
 753         struct sugov_policy *sg_policy = policy->governor_data;
 754         void (*uu)(struct update_util_data *data, u64 time, unsigned int flags);
 755         unsigned int cpu;
 756
 757         sg_policy->freq_update_delay_ns = sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
 758         sg_policy->last_freq_update_time        = 0;
 759         sg_policy->next_freq                    = 0;
 760         sg_policy->work_in_progress             = false;
 761         sg_policy->limits_changed               = false;
 762         sg_policy->cached_raw_freq              = 0;
 763
 764         sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);
 765
 766         for_each_cpu(cpu, policy->cpus) {
 767                 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
 768
 769                 memset(sg_cpu, 0, sizeof(*sg_cpu));
 770                 sg_cpu->cpu                     = cpu;
 771                 sg_cpu->sg_policy               = sg_policy;
 772         }
 773
 774         if (policy_is_shared(policy))
 775                 uu = sugov_update_shared;
 776         else if (policy->fast_switch_enabled && cpufreq_driver_has_adjust_perf())
 777                 uu = sugov_update_single_perf;
 778         else
 779                 uu = sugov_update_single_freq;
 780
 781         for_each_cpu(cpu, policy->cpus) {
 782                 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
 783
 784                 cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util, uu);
 785         }
 786         return 0;
 787 }
 788
 789 static void sugov_stop(struct cpufreq_policy *policy)
 790 {
 791         struct sugov_policy *sg_policy = policy->governor_data;
 792         unsigned int cpu;
 793
 794         for_each_cpu(cpu, policy->cpus)
 795                 cpufreq_remove_update_util_hook(cpu);
 796
 797         synchronize_rcu();
 798
 799         if (!policy->fast_switch_enabled) {
 800                 irq_work_sync(&sg_policy->irq_work);
 801                 kthread_cancel_work_sync(&sg_policy->work);
 802         }
 803 }
 804
 805 static void sugov_limits(struct cpufreq_policy *policy)
 806 {
 807         struct sugov_policy *sg_policy = policy->governor_data;
 808
 809         if (!policy->fast_switch_enabled) {
 810                 mutex_lock(&sg_policy->work_lock);
 811                 cpufreq_policy_apply_limits(policy);
 812                 mutex_unlock(&sg_policy->work_lock);
 813         }
 814
 815         sg_policy->limits_changed = true;
 816 }
 817
 818 struct cpufreq_governor schedutil_gov = {
 819         .name                   = "schedutil",
 820         .owner                  = THIS_MODULE,
 821         .flags                  = CPUFREQ_GOV_DYNAMIC_SWITCHING,
 822         .init                   = sugov_init,
 823         .exit                   = sugov_exit,
 824         .start                  = sugov_start,
 825         .stop                   = sugov_stop,
 826         .limits                 = sugov_limits,
 827 };
 828
 829 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
 830 struct cpufreq_governor *cpufreq_default_governor(void)
 831 {
 832         return &schedutil_gov;
 833 }
 834 #endif
 835
 836 cpufreq_governor_init(schedutil_gov);
 837
 838 #ifdef CONFIG_ENERGY_MODEL
 839 static void rebuild_sd_workfn(struct work_struct *work)
 840 {
 841         rebuild_sched_domains_energy();
 842 }
 843 static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);
 844
 845 /*
 846  * EAS shouldn't be attempted without sugov, so rebuild the sched_domains
 847  * on governor changes to make sure the scheduler knows about it.
 848  */
 849 void sched_cpufreq_governor_change(struct cpufreq_policy *policy,
 850                                   struct cpufreq_governor *old_gov)
 851 {
 852         if (old_gov == &schedutil_gov || policy->governor == &schedutil_gov) {
 853                 /*
 854                  * When called from the cpufreq_register_driver() path, the
 855                  * cpu_hotplug_lock is already held, so use a work item to
 856                  * avoid nested locking in rebuild_sched_domains().
 857                  */
 858                 schedule_work(&rebuild_sd_work);
 859         }
 860
 861 }
 862 #endif