root/kernel/sched/cpufreq_schedutil.c

DEFINITIONS

1. sugov_should_update_freq
2. sugov_update_next_freq
3. sugov_fast_switch
4. sugov_deferred_update
5. get_next_freq
6. schedutil_cpu_util
7. sugov_get_util
8. sugov_iowait_reset
9. sugov_iowait_boost
10. sugov_iowait_apply
11. sugov_cpu_is_busy
12. sugov_cpu_is_busy
13. ignore_dl_rate_limit
14. sugov_update_single
15. sugov_next_freq_shared
16. sugov_update_shared
17. sugov_work
18. sugov_irq_work
19. to_sugov_tunables
20. rate_limit_us_show
21. rate_limit_us_store
22. sugov_policy_alloc
23. sugov_policy_free
24. sugov_kthread_create
25. sugov_kthread_stop
26. sugov_tunables_alloc
27. sugov_tunables_free
28. sugov_init
29. sugov_exit
30. sugov_start
31. sugov_stop
32. sugov_limits
33. cpufreq_default_governor
34. sugov_register
35. rebuild_sd_workfn
36. sched_cpufreq_governor_change

   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 pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  10 
  11 #include "sched.h"
  12 
  13 #include <linux/sched/cpufreq.h>
  14 #include <trace/events/power.h>
  15 
  16 #define IOWAIT_BOOST_MIN        (SCHED_CAPACITY_SCALE / 8)
  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                    limits_changed;
  44         bool                    need_freq_update;
  45 };
  46 
  47 struct sugov_cpu {
  48         struct update_util_data update_util;
  49         struct sugov_policy     *sg_policy;
  50         unsigned int            cpu;
  51 
  52         bool                    iowait_boost_pending;
  53         unsigned int            iowait_boost;
  54         u64                     last_update;
  55 
  56         unsigned long           bw_dl;
  57         unsigned long           max;
  58 
  59         /* The field below is for single-CPU policies only: */
  60 #ifdef CONFIG_NO_HZ_COMMON
  61         unsigned long           saved_idle_calls;
  62 #endif
  63 };
  64 
  65 static DEFINE_PER_CPU(struct sugov_cpu, sugov_cpu);
  66 
  67 /************************ Governor internals ***********************/
  68 
  69 static bool sugov_should_update_freq(struct sugov_policy *sg_policy, u64 time)
  70 {
  71         s64 delta_ns;
  72 
  73         /*
  74          * Since cpufreq_update_util() is called with rq->lock held for
  75          * the @target_cpu, our per-CPU data is fully serialized.
  76          *
  77          * However, drivers cannot in general deal with cross-CPU
  78          * requests, so while get_next_freq() will work, our
  79          * sugov_update_commit() call may not for the fast switching platforms.
  80          *
  81          * Hence stop here for remote requests if they aren't supported
  82          * by the hardware, as calculating the frequency is pointless if
  83          * we cannot in fact act on it.
  84          *
  85          * This is needed on the slow switching platforms too to prevent CPUs
  86          * going offline from leaving stale IRQ work items behind.
  87          */
  88         if (!cpufreq_this_cpu_can_update(sg_policy->policy))
  89                 return false;
  90 
  91         if (unlikely(sg_policy->limits_changed)) {
  92                 sg_policy->limits_changed = false;
  93                 sg_policy->need_freq_update = true;
  94                 return true;
  95         }
  96 
  97         delta_ns = time - sg_policy->last_freq_update_time;
  98 
  99         return delta_ns >= sg_policy->freq_update_delay_ns;
 100 }
 101 
 102 static bool sugov_update_next_freq(struct sugov_policy *sg_policy, u64 time,
 103                                    unsigned int next_freq)
 104 {
 105         if (sg_policy->next_freq == next_freq)
 106                 return false;
 107 
 108         sg_policy->next_freq = next_freq;
 109         sg_policy->last_freq_update_time = time;
 110 
 111         return true;
 112 }
 113 
 114 static void sugov_fast_switch(struct sugov_policy *sg_policy, u64 time,
 115                               unsigned int next_freq)
 116 {
 117         struct cpufreq_policy *policy = sg_policy->policy;
 118         int cpu;
 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 
 129         if (trace_cpu_frequency_enabled()) {
 130                 for_each_cpu(cpu, policy->cpus)
 131                         trace_cpu_frequency(next_freq, cpu);
 132         }
 133 }
 134 
 135 static void sugov_deferred_update(struct sugov_policy *sg_policy, u64 time,
 136                                   unsigned int next_freq)
 137 {
 138         if (!sugov_update_next_freq(sg_policy, time, next_freq))
 139                 return;
 140 
 141         if (!sg_policy->work_in_progress) {
 142                 sg_policy->work_in_progress = true;
 143                 irq_work_queue(&sg_policy->irq_work);
 144         }
 145 }
 146 
 147 /**
 148  * get_next_freq - Compute a new frequency for a given cpufreq policy.
 149  * @sg_policy: schedutil policy object to compute the new frequency for.
 150  * @util: Current CPU utilization.
 151  * @max: CPU capacity.
 152  *
 153  * If the utilization is frequency-invariant, choose the new frequency to be
 154  * proportional to it, that is
 155  *
 156  * next_freq = C * max_freq * util / max
 157  *
 158  * Otherwise, approximate the would-be frequency-invariant utilization by
 159  * util_raw * (curr_freq / max_freq) which leads to
 160  *
 161  * next_freq = C * curr_freq * util_raw / max
 162  *
 163  * Take C = 1.25 for the frequency tipping point at (util / max) = 0.8.
 164  *
 165  * The lowest driver-supported frequency which is equal or greater than the raw
 166  * next_freq (as calculated above) is returned, subject to policy min/max and
 167  * cpufreq driver limitations.
 168  */
 169 static unsigned int get_next_freq(struct sugov_policy *sg_policy,
 170                                   unsigned long util, unsigned long max)
 171 {
 172         struct cpufreq_policy *policy = sg_policy->policy;
 173         unsigned int freq = arch_scale_freq_invariant() ?
 174                                 policy->cpuinfo.max_freq : policy->cur;
 175 
 176         freq = map_util_freq(util, freq, max);
 177 
 178         if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)
 179                 return sg_policy->next_freq;
 180 
 181         sg_policy->need_freq_update = false;
 182         sg_policy->cached_raw_freq = freq;
 183         return cpufreq_driver_resolve_freq(policy, freq);
 184 }
 185 
 186 /*
 187  * This function computes an effective utilization for the given CPU, to be
 188  * used for frequency selection given the linear relation: f = u * f_max.
 189  *
 190  * The scheduler tracks the following metrics:
 191  *
 192  *   cpu_util_{cfs,rt,dl,irq}()
 193  *   cpu_bw_dl()
 194  *
 195  * Where the cfs,rt and dl util numbers are tracked with the same metric and
 196  * synchronized windows and are thus directly comparable.
 197  *
 198  * The cfs,rt,dl utilization are the running times measured with rq->clock_task
 199  * which excludes things like IRQ and steal-time. These latter are then accrued
 200  * in the irq utilization.
 201  *
 202  * The DL bandwidth number otoh is not a measured metric but a value computed
 203  * based on the task model parameters and gives the minimal utilization
 204  * required to meet deadlines.
 205  */
 206 unsigned long schedutil_cpu_util(int cpu, unsigned long util_cfs,
 207                                  unsigned long max, enum schedutil_type type,
 208                                  struct task_struct *p)
 209 {
 210         unsigned long dl_util, util, irq;
 211         struct rq *rq = cpu_rq(cpu);
 212 
 213         if (!IS_BUILTIN(CONFIG_UCLAMP_TASK) &&
 214             type == FREQUENCY_UTIL && rt_rq_is_runnable(&rq->rt)) {
 215                 return max;
 216         }
 217 
 218         /*
 219          * Early check to see if IRQ/steal time saturates the CPU, can be
 220          * because of inaccuracies in how we track these -- see
 221          * update_irq_load_avg().
 222          */
 223         irq = cpu_util_irq(rq);
 224         if (unlikely(irq >= max))
 225                 return max;
 226 
 227         /*
 228          * Because the time spend on RT/DL tasks is visible as 'lost' time to
 229          * CFS tasks and we use the same metric to track the effective
 230          * utilization (PELT windows are synchronized) we can directly add them
 231          * to obtain the CPU's actual utilization.
 232          *
 233          * CFS and RT utilization can be boosted or capped, depending on
 234          * utilization clamp constraints requested by currently RUNNABLE
 235          * tasks.
 236          * When there are no CFS RUNNABLE tasks, clamps are released and
 237          * frequency will be gracefully reduced with the utilization decay.
 238          */
 239         util = util_cfs + cpu_util_rt(rq);
 240         if (type == FREQUENCY_UTIL)
 241                 util = uclamp_util_with(rq, util, p);
 242 
 243         dl_util = cpu_util_dl(rq);
 244 
 245         /*
 246          * For frequency selection we do not make cpu_util_dl() a permanent part
 247          * of this sum because we want to use cpu_bw_dl() later on, but we need
 248          * to check if the CFS+RT+DL sum is saturated (ie. no idle time) such
 249          * that we select f_max when there is no idle time.
 250          *
 251          * NOTE: numerical errors or stop class might cause us to not quite hit
 252          * saturation when we should -- something for later.
 253          */
 254         if (util + dl_util >= max)
 255                 return max;
 256 
 257         /*
 258          * OTOH, for energy computation we need the estimated running time, so
 259          * include util_dl and ignore dl_bw.
 260          */
 261         if (type == ENERGY_UTIL)
 262                 util += dl_util;
 263 
 264         /*
 265          * There is still idle time; further improve the number by using the
 266          * irq metric. Because IRQ/steal time is hidden from the task clock we
 267          * need to scale the task numbers:
 268          *
 269          *              max - irq
 270          *   U' = irq + --------- * U
 271          *                 max
 272          */
 273         util = scale_irq_capacity(util, irq, max);
 274         util += irq;
 275 
 276         /*
 277          * Bandwidth required by DEADLINE must always be granted while, for
 278          * FAIR and RT, we use blocked utilization of IDLE CPUs as a mechanism
 279          * to gracefully reduce the frequency when no tasks show up for longer
 280          * periods of time.
 281          *
 282          * Ideally we would like to set bw_dl as min/guaranteed freq and util +
 283          * bw_dl as requested freq. However, cpufreq is not yet ready for such
 284          * an interface. So, we only do the latter for now.
 285          */
 286         if (type == FREQUENCY_UTIL)
 287                 util += cpu_bw_dl(rq);
 288 
 289         return min(max, util);
 290 }
 291 
 292 static unsigned long sugov_get_util(struct sugov_cpu *sg_cpu)
 293 {
 294         struct rq *rq = cpu_rq(sg_cpu->cpu);
 295         unsigned long util = cpu_util_cfs(rq);
 296         unsigned long max = arch_scale_cpu_capacity(sg_cpu->cpu);
 297 
 298         sg_cpu->max = max;
 299         sg_cpu->bw_dl = cpu_bw_dl(rq);
 300 
 301         return schedutil_cpu_util(sg_cpu->cpu, util, max, FREQUENCY_UTIL, NULL);
 302 }
 303 
 304 /**
 305  * sugov_iowait_reset() - Reset the IO boost status of a CPU.
 306  * @sg_cpu: the sugov data for the CPU to boost
 307  * @time: the update time from the caller
 308  * @set_iowait_boost: true if an IO boost has been requested
 309  *
 310  * The IO wait boost of a task is disabled after a tick since the last update
 311  * of a CPU. If a new IO wait boost is requested after more then a tick, then
 312  * we enable the boost starting from IOWAIT_BOOST_MIN, which improves energy
 313  * efficiency by ignoring sporadic wakeups from IO.
 314  */
 315 static bool sugov_iowait_reset(struct sugov_cpu *sg_cpu, u64 time,
 316                                bool set_iowait_boost)
 317 {
 318         s64 delta_ns = time - sg_cpu->last_update;
 319 
 320         /* Reset boost only if a tick has elapsed since last request */
 321         if (delta_ns <= TICK_NSEC)
 322                 return false;
 323 
 324         sg_cpu->iowait_boost = set_iowait_boost ? IOWAIT_BOOST_MIN : 0;
 325         sg_cpu->iowait_boost_pending = set_iowait_boost;
 326 
 327         return true;
 328 }
 329 
 330 /**
 331  * sugov_iowait_boost() - Updates the IO boost status of a CPU.
 332  * @sg_cpu: the sugov data for the CPU to boost
 333  * @time: the update time from the caller
 334  * @flags: SCHED_CPUFREQ_IOWAIT if the task is waking up after an IO wait
 335  *
 336  * Each time a task wakes up after an IO operation, the CPU utilization can be
 337  * boosted to a certain utilization which doubles at each "frequent and
 338  * successive" wakeup from IO, ranging from IOWAIT_BOOST_MIN to the utilization
 339  * of the maximum OPP.
 340  *
 341  * To keep doubling, an IO boost has to be requested at least once per tick,
 342  * otherwise we restart from the utilization of the minimum OPP.
 343  */
 344 static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
 345                                unsigned int flags)
 346 {
 347         bool set_iowait_boost = flags & SCHED_CPUFREQ_IOWAIT;
 348 
 349         /* Reset boost if the CPU appears to have been idle enough */
 350         if (sg_cpu->iowait_boost &&
 351             sugov_iowait_reset(sg_cpu, time, set_iowait_boost))
 352                 return;
 353 
 354         /* Boost only tasks waking up after IO */
 355         if (!set_iowait_boost)
 356                 return;
 357 
 358         /* Ensure boost doubles only one time at each request */
 359         if (sg_cpu->iowait_boost_pending)
 360                 return;
 361         sg_cpu->iowait_boost_pending = true;
 362 
 363         /* Double the boost at each request */
 364         if (sg_cpu->iowait_boost) {
 365                 sg_cpu->iowait_boost =
 366                         min_t(unsigned int, sg_cpu->iowait_boost << 1, SCHED_CAPACITY_SCALE);
 367                 return;
 368         }
 369 
 370         /* First wakeup after IO: start with minimum boost */
 371         sg_cpu->iowait_boost = IOWAIT_BOOST_MIN;
 372 }
 373 
 374 /**
 375  * sugov_iowait_apply() - Apply the IO boost to a CPU.
 376  * @sg_cpu: the sugov data for the cpu to boost
 377  * @time: the update time from the caller
 378  * @util: the utilization to (eventually) boost
 379  * @max: the maximum value the utilization can be boosted to
 380  *
 381  * A CPU running a task which woken up after an IO operation can have its
 382  * utilization boosted to speed up the completion of those IO operations.
 383  * The IO boost value is increased each time a task wakes up from IO, in
 384  * sugov_iowait_apply(), and it's instead decreased by this function,
 385  * each time an increase has not been requested (!iowait_boost_pending).
 386  *
 387  * A CPU which also appears to have been idle for at least one tick has also
 388  * its IO boost utilization reset.
 389  *
 390  * This mechanism is designed to boost high frequently IO waiting tasks, while
 391  * being more conservative on tasks which does sporadic IO operations.
 392  */
 393 static unsigned long sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time,
 394                                         unsigned long util, unsigned long max)
 395 {
 396         unsigned long boost;
 397 
 398         /* No boost currently required */
 399         if (!sg_cpu->iowait_boost)
 400                 return util;
 401 
 402         /* Reset boost if the CPU appears to have been idle enough */
 403         if (sugov_iowait_reset(sg_cpu, time, false))
 404                 return util;
 405 
 406         if (!sg_cpu->iowait_boost_pending) {
 407                 /*
 408                  * No boost pending; reduce the boost value.
 409                  */
 410                 sg_cpu->iowait_boost >>= 1;
 411                 if (sg_cpu->iowait_boost < IOWAIT_BOOST_MIN) {
 412                         sg_cpu->iowait_boost = 0;
 413                         return util;
 414                 }
 415         }
 416 
 417         sg_cpu->iowait_boost_pending = false;
 418 
 419         /*
 420          * @util is already in capacity scale; convert iowait_boost
 421          * into the same scale so we can compare.
 422          */
 423         boost = (sg_cpu->iowait_boost * max) >> SCHED_CAPACITY_SHIFT;
 424         return max(boost, util);
 425 }
 426 
 427 #ifdef CONFIG_NO_HZ_COMMON
 428 static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
 429 {
 430         unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu);
 431         bool ret = idle_calls == sg_cpu->saved_idle_calls;
 432 
 433         sg_cpu->saved_idle_calls = idle_calls;
 434         return ret;
 435 }
 436 #else
 437 static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
 438 #endif /* CONFIG_NO_HZ_COMMON */
 439 
 440 /*
 441  * Make sugov_should_update_freq() ignore the rate limit when DL
 442  * has increased the utilization.
 443  */
 444 static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu, struct sugov_policy *sg_policy)
 445 {
 446         if (cpu_bw_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->bw_dl)
 447                 sg_policy->limits_changed = true;
 448 }
 449 
 450 static void sugov_update_single(struct update_util_data *hook, u64 time,
 451                                 unsigned int flags)
 452 {
 453         struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
 454         struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 455         unsigned long util, max;
 456         unsigned int next_f;
 457         bool busy;
 458 
 459         sugov_iowait_boost(sg_cpu, time, flags);
 460         sg_cpu->last_update = time;
 461 
 462         ignore_dl_rate_limit(sg_cpu, sg_policy);
 463 
 464         if (!sugov_should_update_freq(sg_policy, time))
 465                 return;
 466 
 467         /* Limits may have changed, don't skip frequency update */
 468         busy = !sg_policy->need_freq_update && sugov_cpu_is_busy(sg_cpu);
 469 
 470         util = sugov_get_util(sg_cpu);
 471         max = sg_cpu->max;
 472         util = sugov_iowait_apply(sg_cpu, time, util, max);
 473         next_f = get_next_freq(sg_policy, util, max);
 474         /*
 475          * Do not reduce the frequency if the CPU has not been idle
 476          * recently, as the reduction is likely to be premature then.
 477          */
 478         if (busy && next_f < sg_policy->next_freq) {
 479                 next_f = sg_policy->next_freq;
 480 
 481                 /* Reset cached freq as next_freq has changed */
 482                 sg_policy->cached_raw_freq = 0;
 483         }
 484 
 485         /*
 486          * This code runs under rq->lock for the target CPU, so it won't run
 487          * concurrently on two different CPUs for the same target and it is not
 488          * necessary to acquire the lock in the fast switch case.
 489          */
 490         if (sg_policy->policy->fast_switch_enabled) {
 491                 sugov_fast_switch(sg_policy, time, next_f);
 492         } else {
 493                 raw_spin_lock(&sg_policy->update_lock);
 494                 sugov_deferred_update(sg_policy, time, next_f);
 495                 raw_spin_unlock(&sg_policy->update_lock);
 496         }
 497 }
 498 
 499 static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
 500 {
 501         struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 502         struct cpufreq_policy *policy = sg_policy->policy;
 503         unsigned long util = 0, max = 1;
 504         unsigned int j;
 505 
 506         for_each_cpu(j, policy->cpus) {
 507                 struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
 508                 unsigned long j_util, j_max;
 509 
 510                 j_util = sugov_get_util(j_sg_cpu);
 511                 j_max = j_sg_cpu->max;
 512                 j_util = sugov_iowait_apply(j_sg_cpu, time, j_util, j_max);
 513 
 514                 if (j_util * max > j_max * util) {
 515                         util = j_util;
 516                         max = j_max;
 517                 }
 518         }
 519 
 520         return get_next_freq(sg_policy, util, max);
 521 }
 522 
 523 static void
 524 sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags)
 525 {
 526         struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
 527         struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 528         unsigned int next_f;
 529 
 530         raw_spin_lock(&sg_policy->update_lock);
 531 
 532         sugov_iowait_boost(sg_cpu, time, flags);
 533         sg_cpu->last_update = time;
 534 
 535         ignore_dl_rate_limit(sg_cpu, sg_policy);
 536 
 537         if (sugov_should_update_freq(sg_policy, time)) {
 538                 next_f = sugov_next_freq_shared(sg_cpu, time);
 539 
 540                 if (sg_policy->policy->fast_switch_enabled)
 541                         sugov_fast_switch(sg_policy, time, next_f);
 542                 else
 543                         sugov_deferred_update(sg_policy, time, next_f);
 544         }
 545 
 546         raw_spin_unlock(&sg_policy->update_lock);
 547 }
 548 
 549 static void sugov_work(struct kthread_work *work)
 550 {
 551         struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
 552         unsigned int freq;
 553         unsigned long flags;
 554 
 555         /*
 556          * Hold sg_policy->update_lock shortly to handle the case where:
 557          * incase sg_policy->next_freq is read here, and then updated by
 558          * sugov_deferred_update() just before work_in_progress is set to false
 559          * here, we may miss queueing the new update.
 560          *
 561          * Note: If a work was queued after the update_lock is released,
 562          * sugov_work() will just be called again by kthread_work code; and the
 563          * request will be proceed before the sugov thread sleeps.
 564          */
 565         raw_spin_lock_irqsave(&sg_policy->update_lock, flags);
 566         freq = sg_policy->next_freq;
 567         sg_policy->work_in_progress = false;
 568         raw_spin_unlock_irqrestore(&sg_policy->update_lock, flags);
 569 
 570         mutex_lock(&sg_policy->work_lock);
 571         __cpufreq_driver_target(sg_policy->policy, freq, CPUFREQ_RELATION_L);
 572         mutex_unlock(&sg_policy->work_lock);
 573 }
 574 
 575 static void sugov_irq_work(struct irq_work *irq_work)
 576 {
 577         struct sugov_policy *sg_policy;
 578 
 579         sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
 580 
 581         kthread_queue_work(&sg_policy->worker, &sg_policy->work);
 582 }
 583 
 584 /************************** sysfs interface ************************/
 585 
 586 static struct sugov_tunables *global_tunables;
 587 static DEFINE_MUTEX(global_tunables_lock);
 588 
 589 static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
 590 {
 591         return container_of(attr_set, struct sugov_tunables, attr_set);
 592 }
 593 
 594 static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
 595 {
 596         struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
 597 
 598         return sprintf(buf, "%u\n", tunables->rate_limit_us);
 599 }
 600 
 601 static ssize_t
 602 rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf, size_t count)
 603 {
 604         struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
 605         struct sugov_policy *sg_policy;
 606         unsigned int rate_limit_us;
 607 
 608         if (kstrtouint(buf, 10, &rate_limit_us))
 609                 return -EINVAL;
 610 
 611         tunables->rate_limit_us = rate_limit_us;
 612 
 613         list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
 614                 sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
 615 
 616         return count;
 617 }
 618 
 619 static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
 620 
 621 static struct attribute *sugov_attrs[] = {
 622         &rate_limit_us.attr,
 623         NULL
 624 };
 625 ATTRIBUTE_GROUPS(sugov);
 626 
 627 static struct kobj_type sugov_tunables_ktype = {
 628         .default_groups = sugov_groups,
 629         .sysfs_ops = &governor_sysfs_ops,
 630 };
 631 
 632 /********************** cpufreq governor interface *********************/
 633 
 634 struct cpufreq_governor schedutil_gov;
 635 
 636 static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
 637 {
 638         struct sugov_policy *sg_policy;
 639 
 640         sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
 641         if (!sg_policy)
 642                 return NULL;
 643 
 644         sg_policy->policy = policy;
 645         raw_spin_lock_init(&sg_policy->update_lock);
 646         return sg_policy;
 647 }
 648 
 649 static void sugov_policy_free(struct sugov_policy *sg_policy)
 650 {
 651         kfree(sg_policy);
 652 }
 653 
 654 static int sugov_kthread_create(struct sugov_policy *sg_policy)
 655 {
 656         struct task_struct *thread;
 657         struct sched_attr attr = {
 658                 .size           = sizeof(struct sched_attr),
 659                 .sched_policy   = SCHED_DEADLINE,
 660                 .sched_flags    = SCHED_FLAG_SUGOV,
 661                 .sched_nice     = 0,
 662                 .sched_priority = 0,
 663                 /*
 664                  * Fake (unused) bandwidth; workaround to "fix"
 665                  * priority inheritance.
 666                  */
 667                 .sched_runtime  =  1000000,
 668                 .sched_deadline = 10000000,
 669                 .sched_period   = 10000000,
 670         };
 671         struct cpufreq_policy *policy = sg_policy->policy;
 672         int ret;
 673 
 674         /* kthread only required for slow path */
 675         if (policy->fast_switch_enabled)
 676                 return 0;
 677 
 678         kthread_init_work(&sg_policy->work, sugov_work);
 679         kthread_init_worker(&sg_policy->worker);
 680         thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
 681                                 "sugov:%d",
 682                                 cpumask_first(policy->related_cpus));
 683         if (IS_ERR(thread)) {
 684                 pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread));
 685                 return PTR_ERR(thread);
 686         }
 687 
 688         ret = sched_setattr_nocheck(thread, &attr);
 689         if (ret) {
 690                 kthread_stop(thread);
 691                 pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__);
 692                 return ret;
 693         }
 694 
 695         sg_policy->thread = thread;
 696         kthread_bind_mask(thread, policy->related_cpus);
 697         init_irq_work(&sg_policy->irq_work, sugov_irq_work);
 698         mutex_init(&sg_policy->work_lock);
 699 
 700         wake_up_process(thread);
 701 
 702         return 0;
 703 }
 704 
 705 static void sugov_kthread_stop(struct sugov_policy *sg_policy)
 706 {
 707         /* kthread only required for slow path */
 708         if (sg_policy->policy->fast_switch_enabled)
 709                 return;
 710 
 711         kthread_flush_worker(&sg_policy->worker);
 712         kthread_stop(sg_policy->thread);
 713         mutex_destroy(&sg_policy->work_lock);
 714 }
 715 
 716 static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
 717 {
 718         struct sugov_tunables *tunables;
 719 
 720         tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
 721         if (tunables) {
 722                 gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
 723                 if (!have_governor_per_policy())
 724                         global_tunables = tunables;
 725         }
 726         return tunables;
 727 }
 728 
 729 static void sugov_tunables_free(struct sugov_tunables *tunables)
 730 {
 731         if (!have_governor_per_policy())
 732                 global_tunables = NULL;
 733 
 734         kfree(tunables);
 735 }
 736 
 737 static int sugov_init(struct cpufreq_policy *policy)
 738 {
 739         struct sugov_policy *sg_policy;
 740         struct sugov_tunables *tunables;
 741         int ret = 0;
 742 
 743         /* State should be equivalent to EXIT */
 744         if (policy->governor_data)
 745                 return -EBUSY;
 746 
 747         cpufreq_enable_fast_switch(policy);
 748 
 749         sg_policy = sugov_policy_alloc(policy);
 750         if (!sg_policy) {
 751                 ret = -ENOMEM;
 752                 goto disable_fast_switch;
 753         }
 754 
 755         ret = sugov_kthread_create(sg_policy);
 756         if (ret)
 757                 goto free_sg_policy;
 758 
 759         mutex_lock(&global_tunables_lock);
 760 
 761         if (global_tunables) {
 762                 if (WARN_ON(have_governor_per_policy())) {
 763                         ret = -EINVAL;
 764                         goto stop_kthread;
 765                 }
 766                 policy->governor_data = sg_policy;
 767                 sg_policy->tunables = global_tunables;
 768 
 769                 gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
 770                 goto out;
 771         }
 772 
 773         tunables = sugov_tunables_alloc(sg_policy);
 774         if (!tunables) {
 775                 ret = -ENOMEM;
 776                 goto stop_kthread;
 777         }
 778 
 779         tunables->rate_limit_us = cpufreq_policy_transition_delay_us(policy);
 780 
 781         policy->governor_data = sg_policy;
 782         sg_policy->tunables = tunables;
 783 
 784         ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
 785                                    get_governor_parent_kobj(policy), "%s",
 786                                    schedutil_gov.name);
 787         if (ret)
 788                 goto fail;
 789 
 790 out:
 791         mutex_unlock(&global_tunables_lock);
 792         return 0;
 793 
 794 fail:
 795         kobject_put(&tunables->attr_set.kobj);
 796         policy->governor_data = NULL;
 797         sugov_tunables_free(tunables);
 798 
 799 stop_kthread:
 800         sugov_kthread_stop(sg_policy);
 801         mutex_unlock(&global_tunables_lock);
 802 
 803 free_sg_policy:
 804         sugov_policy_free(sg_policy);
 805 
 806 disable_fast_switch:
 807         cpufreq_disable_fast_switch(policy);
 808 
 809         pr_err("initialization failed (error %d)\n", ret);
 810         return ret;
 811 }
 812 
 813 static void sugov_exit(struct cpufreq_policy *policy)
 814 {
 815         struct sugov_policy *sg_policy = policy->governor_data;
 816         struct sugov_tunables *tunables = sg_policy->tunables;
 817         unsigned int count;
 818 
 819         mutex_lock(&global_tunables_lock);
 820 
 821         count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
 822         policy->governor_data = NULL;
 823         if (!count)
 824                 sugov_tunables_free(tunables);
 825 
 826         mutex_unlock(&global_tunables_lock);
 827 
 828         sugov_kthread_stop(sg_policy);
 829         sugov_policy_free(sg_policy);
 830         cpufreq_disable_fast_switch(policy);
 831 }
 832 
 833 static int sugov_start(struct cpufreq_policy *policy)
 834 {
 835         struct sugov_policy *sg_policy = policy->governor_data;
 836         unsigned int cpu;
 837 
 838         sg_policy->freq_update_delay_ns = sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
 839         sg_policy->last_freq_update_time        = 0;
 840         sg_policy->next_freq                    = 0;
 841         sg_policy->work_in_progress             = false;
 842         sg_policy->limits_changed               = false;
 843         sg_policy->need_freq_update             = false;
 844         sg_policy->cached_raw_freq              = 0;
 845 
 846         for_each_cpu(cpu, policy->cpus) {
 847                 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
 848 
 849                 memset(sg_cpu, 0, sizeof(*sg_cpu));
 850                 sg_cpu->cpu                     = cpu;
 851                 sg_cpu->sg_policy               = sg_policy;
 852         }
 853 
 854         for_each_cpu(cpu, policy->cpus) {
 855                 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
 856 
 857                 cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
 858                                              policy_is_shared(policy) ?
 859                                                         sugov_update_shared :
 860                                                         sugov_update_single);
 861         }
 862         return 0;
 863 }
 864 
 865 static void sugov_stop(struct cpufreq_policy *policy)
 866 {
 867         struct sugov_policy *sg_policy = policy->governor_data;
 868         unsigned int cpu;
 869 
 870         for_each_cpu(cpu, policy->cpus)
 871                 cpufreq_remove_update_util_hook(cpu);
 872 
 873         synchronize_rcu();
 874 
 875         if (!policy->fast_switch_enabled) {
 876                 irq_work_sync(&sg_policy->irq_work);
 877                 kthread_cancel_work_sync(&sg_policy->work);
 878         }
 879 }
 880 
 881 static void sugov_limits(struct cpufreq_policy *policy)
 882 {
 883         struct sugov_policy *sg_policy = policy->governor_data;
 884 
 885         if (!policy->fast_switch_enabled) {
 886                 mutex_lock(&sg_policy->work_lock);
 887                 cpufreq_policy_apply_limits(policy);
 888                 mutex_unlock(&sg_policy->work_lock);
 889         }
 890 
 891         sg_policy->limits_changed = true;
 892 }
 893 
 894 struct cpufreq_governor schedutil_gov = {
 895         .name                   = "schedutil",
 896         .owner                  = THIS_MODULE,
 897         .dynamic_switching      = true,
 898         .init                   = sugov_init,
 899         .exit                   = sugov_exit,
 900         .start                  = sugov_start,
 901         .stop                   = sugov_stop,
 902         .limits                 = sugov_limits,
 903 };
 904 
 905 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
 906 struct cpufreq_governor *cpufreq_default_governor(void)
 907 {
 908         return &schedutil_gov;
 909 }
 910 #endif
 911 
 912 static int __init sugov_register(void)
 913 {
 914         return cpufreq_register_governor(&schedutil_gov);
 915 }
 916 fs_initcall(sugov_register);
 917 
 918 #ifdef CONFIG_ENERGY_MODEL
 919 extern bool sched_energy_update;
 920 extern struct mutex sched_energy_mutex;
 921 
 922 static void rebuild_sd_workfn(struct work_struct *work)
 923 {
 924         mutex_lock(&sched_energy_mutex);
 925         sched_energy_update = true;
 926         rebuild_sched_domains();
 927         sched_energy_update = false;
 928         mutex_unlock(&sched_energy_mutex);
 929 }
 930 static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);
 931 
 932 /*
 933  * EAS shouldn't be attempted without sugov, so rebuild the sched_domains
 934  * on governor changes to make sure the scheduler knows about it.
 935  */
 936 void sched_cpufreq_governor_change(struct cpufreq_policy *policy,
 937                                   struct cpufreq_governor *old_gov)
 938 {
 939         if (old_gov == &schedutil_gov || policy->governor == &schedutil_gov) {
 940                 /*
 941                  * When called from the cpufreq_register_driver() path, the
 942                  * cpu_hotplug_lock is already held, so use a work item to
 943                  * avoid nested locking in rebuild_sched_domains().
 944                  */
 945                 schedule_work(&rebuild_sd_work);
 946         }
 947 
 948 }
 949 #endif