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 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->need_freq_update) {
 106                 if (sg_policy->next_freq == next_freq)
 107                         return false;
 108         } else {
 109                 sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);
 110         }
 111
 112         sg_policy->next_freq = next_freq;
 113         sg_policy->last_freq_update_time = time;
 114
 115         return true;
 116 }
 117
 118 static void sugov_fast_switch(struct sugov_policy *sg_policy, u64 time,
 119                               unsigned int next_freq)
 120 {
 121         if (sugov_update_next_freq(sg_policy, time, next_freq))
 122                 cpufreq_driver_fast_switch(sg_policy->policy, next_freq);
 123 }
 124
 125 static void sugov_deferred_update(struct sugov_policy *sg_policy, u64 time,
 126                                   unsigned int next_freq)
 127 {
 128         if (!sugov_update_next_freq(sg_policy, time, next_freq))
 129                 return;
 130
 131         if (!sg_policy->work_in_progress) {
 132                 sg_policy->work_in_progress = true;
 133                 irq_work_queue(&sg_policy->irq_work);
 134         }
 135 }
 136
 137 /**
 138  * get_next_freq - Compute a new frequency for a given cpufreq policy.
 139  * @sg_policy: schedutil policy object to compute the new frequency for.
 140  * @util: Current CPU utilization.
 141  * @max: CPU capacity.
 142  *
 143  * If the utilization is frequency-invariant, choose the new frequency to be
 144  * proportional to it, that is
 145  *
 146  * next_freq = C * max_freq * util / max
 147  *
 148  * Otherwise, approximate the would-be frequency-invariant utilization by
 149  * util_raw * (curr_freq / max_freq) which leads to
 150  *
 151  * next_freq = C * curr_freq * util_raw / max
 152  *
 153  * Take C = 1.25 for the frequency tipping point at (util / max) = 0.8.
 154  *
 155  * The lowest driver-supported frequency which is equal or greater than the raw
 156  * next_freq (as calculated above) is returned, subject to policy min/max and
 157  * cpufreq driver limitations.
 158  */
 159 static unsigned int get_next_freq(struct sugov_policy *sg_policy,
 160                                   unsigned long util, unsigned long max)
 161 {
 162         struct cpufreq_policy *policy = sg_policy->policy;
 163         unsigned int freq = arch_scale_freq_invariant() ?
 164                                 policy->cpuinfo.max_freq : policy->cur;
 165
 166         freq = map_util_freq(util, freq, max);
 167
 168         if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)
 169                 return sg_policy->next_freq;
 170
 171         sg_policy->cached_raw_freq = freq;
 172         return cpufreq_driver_resolve_freq(policy, freq);
 173 }
 174
 175 /*
 176  * This function computes an effective utilization for the given CPU, to be
 177  * used for frequency selection given the linear relation: f = u * f_max.
 178  *
 179  * The scheduler tracks the following metrics:
 180  *
 181  *   cpu_util_{cfs,rt,dl,irq}()
 182  *   cpu_bw_dl()
 183  *
 184  * Where the cfs,rt and dl util numbers are tracked with the same metric and
 185  * synchronized windows and are thus directly comparable.
 186  *
 187  * The cfs,rt,dl utilization are the running times measured with rq->clock_task
 188  * which excludes things like IRQ and steal-time. These latter are then accrued
 189  * in the irq utilization.
 190  *
 191  * The DL bandwidth number otoh is not a measured metric but a value computed
 192  * based on the task model parameters and gives the minimal utilization
 193  * required to meet deadlines.
 194  */
 195 unsigned long schedutil_cpu_util(int cpu, unsigned long util_cfs,
 196                                  unsigned long max, enum schedutil_type type,
 197                                  struct task_struct *p)
 198 {
 199         unsigned long dl_util, util, irq;
 200         struct rq *rq = cpu_rq(cpu);
 201
 202         if (!uclamp_is_used() &&
 203             type == FREQUENCY_UTIL && rt_rq_is_runnable(&rq->rt)) {
 204                 return max;
 205         }
 206
 207         /*
 208          * Early check to see if IRQ/steal time saturates the CPU, can be
 209          * because of inaccuracies in how we track these -- see
 210          * update_irq_load_avg().
 211          */
 212         irq = cpu_util_irq(rq);
 213         if (unlikely(irq >= max))
 214                 return max;
 215
 216         /*
 217          * Because the time spend on RT/DL tasks is visible as 'lost' time to
 218          * CFS tasks and we use the same metric to track the effective
 219          * utilization (PELT windows are synchronized) we can directly add them
 220          * to obtain the CPU's actual utilization.
 221          *
 222          * CFS and RT utilization can be boosted or capped, depending on
 223          * utilization clamp constraints requested by currently RUNNABLE
 224          * tasks.
 225          * When there are no CFS RUNNABLE tasks, clamps are released and
 226          * frequency will be gracefully reduced with the utilization decay.
 227          */
 228         util = util_cfs + cpu_util_rt(rq);
 229         if (type == FREQUENCY_UTIL)
 230                 util = uclamp_rq_util_with(rq, util, p);
 231
 232         dl_util = cpu_util_dl(rq);
 233
 234         /*
 235          * For frequency selection we do not make cpu_util_dl() a permanent part
 236          * of this sum because we want to use cpu_bw_dl() later on, but we need
 237          * to check if the CFS+RT+DL sum is saturated (ie. no idle time) such
 238          * that we select f_max when there is no idle time.
 239          *
 240          * NOTE: numerical errors or stop class might cause us to not quite hit
 241          * saturation when we should -- something for later.
 242          */
 243         if (util + dl_util >= max)
 244                 return max;
 245
 246         /*
 247          * OTOH, for energy computation we need the estimated running time, so
 248          * include util_dl and ignore dl_bw.
 249          */
 250         if (type == ENERGY_UTIL)
 251                 util += dl_util;
 252
 253         /*
 254          * There is still idle time; further improve the number by using the
 255          * irq metric. Because IRQ/steal time is hidden from the task clock we
 256          * need to scale the task numbers:
 257          *
 258          *              max - irq
 259          *   U' = irq + --------- * U
 260          *                 max
 261          */
 262         util = scale_irq_capacity(util, irq, max);
 263         util += irq;
 264
 265         /*
 266          * Bandwidth required by DEADLINE must always be granted while, for
 267          * FAIR and RT, we use blocked utilization of IDLE CPUs as a mechanism
 268          * to gracefully reduce the frequency when no tasks show up for longer
 269          * periods of time.
 270          *
 271          * Ideally we would like to set bw_dl as min/guaranteed freq and util +
 272          * bw_dl as requested freq. However, cpufreq is not yet ready for such
 273          * an interface. So, we only do the latter for now.
 274          */
 275         if (type == FREQUENCY_UTIL)
 276                 util += cpu_bw_dl(rq);
 277
 278         return min(max, util);
 279 }
 280
 281 static unsigned long sugov_get_util(struct sugov_cpu *sg_cpu)
 282 {
 283         struct rq *rq = cpu_rq(sg_cpu->cpu);
 284         unsigned long util = cpu_util_cfs(rq);
 285         unsigned long max = arch_scale_cpu_capacity(sg_cpu->cpu);
 286
 287         sg_cpu->max = max;
 288         sg_cpu->bw_dl = cpu_bw_dl(rq);
 289
 290         return schedutil_cpu_util(sg_cpu->cpu, util, max, FREQUENCY_UTIL, NULL);
 291 }
 292
 293 /**
 294  * sugov_iowait_reset() - Reset the IO boost status of a CPU.
 295  * @sg_cpu: the sugov data for the CPU to boost
 296  * @time: the update time from the caller
 297  * @set_iowait_boost: true if an IO boost has been requested
 298  *
 299  * The IO wait boost of a task is disabled after a tick since the last update
 300  * of a CPU. If a new IO wait boost is requested after more then a tick, then
 301  * we enable the boost starting from IOWAIT_BOOST_MIN, which improves energy
 302  * efficiency by ignoring sporadic wakeups from IO.
 303  */
 304 static bool sugov_iowait_reset(struct sugov_cpu *sg_cpu, u64 time,
 305                                bool set_iowait_boost)
 306 {
 307         s64 delta_ns = time - sg_cpu->last_update;
 308
 309         /* Reset boost only if a tick has elapsed since last request */
 310         if (delta_ns <= TICK_NSEC)
 311                 return false;
 312
 313         sg_cpu->iowait_boost = set_iowait_boost ? IOWAIT_BOOST_MIN : 0;
 314         sg_cpu->iowait_boost_pending = set_iowait_boost;
 315
 316         return true;
 317 }
 318
 319 /**
 320  * sugov_iowait_boost() - Updates the IO boost status of a CPU.
 321  * @sg_cpu: the sugov data for the CPU to boost
 322  * @time: the update time from the caller
 323  * @flags: SCHED_CPUFREQ_IOWAIT if the task is waking up after an IO wait
 324  *
 325  * Each time a task wakes up after an IO operation, the CPU utilization can be
 326  * boosted to a certain utilization which doubles at each "frequent and
 327  * successive" wakeup from IO, ranging from IOWAIT_BOOST_MIN to the utilization
 328  * of the maximum OPP.
 329  *
 330  * To keep doubling, an IO boost has to be requested at least once per tick,
 331  * otherwise we restart from the utilization of the minimum OPP.
 332  */
 333 static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
 334                                unsigned int flags)
 335 {
 336         bool set_iowait_boost = flags & SCHED_CPUFREQ_IOWAIT;
 337
 338         /* Reset boost if the CPU appears to have been idle enough */
 339         if (sg_cpu->iowait_boost &&
 340             sugov_iowait_reset(sg_cpu, time, set_iowait_boost))
 341                 return;
 342
 343         /* Boost only tasks waking up after IO */
 344         if (!set_iowait_boost)
 345                 return;
 346
 347         /* Ensure boost doubles only one time at each request */
 348         if (sg_cpu->iowait_boost_pending)
 349                 return;
 350         sg_cpu->iowait_boost_pending = true;
 351
 352         /* Double the boost at each request */
 353         if (sg_cpu->iowait_boost) {
 354                 sg_cpu->iowait_boost =
 355                         min_t(unsigned int, sg_cpu->iowait_boost << 1, SCHED_CAPACITY_SCALE);
 356                 return;
 357         }
 358
 359         /* First wakeup after IO: start with minimum boost */
 360         sg_cpu->iowait_boost = IOWAIT_BOOST_MIN;
 361 }
 362
 363 /**
 364  * sugov_iowait_apply() - Apply the IO boost to a CPU.
 365  * @sg_cpu: the sugov data for the cpu to boost
 366  * @time: the update time from the caller
 367  * @util: the utilization to (eventually) boost
 368  * @max: the maximum value the utilization can be boosted to
 369  *
 370  * A CPU running a task which woken up after an IO operation can have its
 371  * utilization boosted to speed up the completion of those IO operations.
 372  * The IO boost value is increased each time a task wakes up from IO, in
 373  * sugov_iowait_apply(), and it's instead decreased by this function,
 374  * each time an increase has not been requested (!iowait_boost_pending).
 375  *
 376  * A CPU which also appears to have been idle for at least one tick has also
 377  * its IO boost utilization reset.
 378  *
 379  * This mechanism is designed to boost high frequently IO waiting tasks, while
 380  * being more conservative on tasks which does sporadic IO operations.
 381  */
 382 static unsigned long sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time,
 383                                         unsigned long util, unsigned long max)
 384 {
 385         unsigned long boost;
 386
 387         /* No boost currently required */
 388         if (!sg_cpu->iowait_boost)
 389                 return util;
 390
 391         /* Reset boost if the CPU appears to have been idle enough */
 392         if (sugov_iowait_reset(sg_cpu, time, false))
 393                 return util;
 394
 395         if (!sg_cpu->iowait_boost_pending) {
 396                 /*
 397                  * No boost pending; reduce the boost value.
 398                  */
 399                 sg_cpu->iowait_boost >>= 1;
 400                 if (sg_cpu->iowait_boost < IOWAIT_BOOST_MIN) {
 401                         sg_cpu->iowait_boost = 0;
 402                         return util;
 403                 }
 404         }
 405
 406         sg_cpu->iowait_boost_pending = false;
 407
 408         /*
 409          * @util is already in capacity scale; convert iowait_boost
 410          * into the same scale so we can compare.
 411          */
 412         boost = (sg_cpu->iowait_boost * max) >> SCHED_CAPACITY_SHIFT;
 413         return max(boost, util);
 414 }
 415
 416 #ifdef CONFIG_NO_HZ_COMMON
 417 static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
 418 {
 419         unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu);
 420         bool ret = idle_calls == sg_cpu->saved_idle_calls;
 421
 422         sg_cpu->saved_idle_calls = idle_calls;
 423         return ret;
 424 }
 425 #else
 426 static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
 427 #endif /* CONFIG_NO_HZ_COMMON */
 428
 429 /*
 430  * Make sugov_should_update_freq() ignore the rate limit when DL
 431  * has increased the utilization.
 432  */
 433 static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu, struct sugov_policy *sg_policy)
 434 {
 435         if (cpu_bw_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->bw_dl)
 436                 sg_policy->limits_changed = true;
 437 }
 438
 439 static void sugov_update_single(struct update_util_data *hook, u64 time,
 440                                 unsigned int flags)
 441 {
 442         struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
 443         struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 444         unsigned long util, max;
 445         unsigned int next_f;
 446         unsigned int cached_freq = sg_policy->cached_raw_freq;
 447
 448         sugov_iowait_boost(sg_cpu, time, flags);
 449         sg_cpu->last_update = time;
 450
 451         ignore_dl_rate_limit(sg_cpu, sg_policy);
 452
 453         if (!sugov_should_update_freq(sg_policy, time))
 454                 return;
 455
 456         util = sugov_get_util(sg_cpu);
 457         max = sg_cpu->max;
 458         util = sugov_iowait_apply(sg_cpu, time, util, max);
 459         next_f = get_next_freq(sg_policy, util, max);
 460         /*
 461          * Do not reduce the frequency if the CPU has not been idle
 462          * recently, as the reduction is likely to be premature then.
 463          */
 464         if (sugov_cpu_is_busy(sg_cpu) && next_f < sg_policy->next_freq) {
 465                 next_f = sg_policy->next_freq;
 466
 467                 /* Restore cached freq as next_freq has changed */
 468                 sg_policy->cached_raw_freq = cached_freq;
 469         }
 470
 471         /*
 472          * This code runs under rq->lock for the target CPU, so it won't run
 473          * concurrently on two different CPUs for the same target and it is not
 474          * necessary to acquire the lock in the fast switch case.
 475          */
 476         if (sg_policy->policy->fast_switch_enabled) {
 477                 sugov_fast_switch(sg_policy, time, next_f);
 478         } else {
 479                 raw_spin_lock(&sg_policy->update_lock);
 480                 sugov_deferred_update(sg_policy, time, next_f);
 481                 raw_spin_unlock(&sg_policy->update_lock);
 482         }
 483 }
 484
 485 static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
 486 {
 487         struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 488         struct cpufreq_policy *policy = sg_policy->policy;
 489         unsigned long util = 0, max = 1;
 490         unsigned int j;
 491
 492         for_each_cpu(j, policy->cpus) {
 493                 struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
 494                 unsigned long j_util, j_max;
 495
 496                 j_util = sugov_get_util(j_sg_cpu);
 497                 j_max = j_sg_cpu->max;
 498                 j_util = sugov_iowait_apply(j_sg_cpu, time, j_util, j_max);
 499
 500                 if (j_util * max > j_max * util) {
 501                         util = j_util;
 502                         max = j_max;
 503                 }
 504         }
 505
 506         return get_next_freq(sg_policy, util, max);
 507 }
 508
 509 static void
 510 sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags)
 511 {
 512         struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
 513         struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 514         unsigned int next_f;
 515
 516         raw_spin_lock(&sg_policy->update_lock);
 517
 518         sugov_iowait_boost(sg_cpu, time, flags);
 519         sg_cpu->last_update = time;
 520
 521         ignore_dl_rate_limit(sg_cpu, sg_policy);
 522
 523         if (sugov_should_update_freq(sg_policy, time)) {
 524                 next_f = sugov_next_freq_shared(sg_cpu, time);
 525
 526                 if (sg_policy->policy->fast_switch_enabled)
 527                         sugov_fast_switch(sg_policy, time, next_f);
 528                 else
 529                         sugov_deferred_update(sg_policy, time, next_f);
 530         }
 531
 532         raw_spin_unlock(&sg_policy->update_lock);
 533 }
 534
 535 static void sugov_work(struct kthread_work *work)
 536 {
 537         struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
 538         unsigned int freq;
 539         unsigned long flags;
 540
 541         /*
 542          * Hold sg_policy->update_lock shortly to handle the case where:
 543          * incase sg_policy->next_freq is read here, and then updated by
 544          * sugov_deferred_update() just before work_in_progress is set to false
 545          * here, we may miss queueing the new update.
 546          *
 547          * Note: If a work was queued after the update_lock is released,
 548          * sugov_work() will just be called again by kthread_work code; and the
 549          * request will be proceed before the sugov thread sleeps.
 550          */
 551         raw_spin_lock_irqsave(&sg_policy->update_lock, flags);
 552         freq = sg_policy->next_freq;
 553         sg_policy->work_in_progress = false;
 554         raw_spin_unlock_irqrestore(&sg_policy->update_lock, flags);
 555
 556         mutex_lock(&sg_policy->work_lock);
 557         __cpufreq_driver_target(sg_policy->policy, freq, CPUFREQ_RELATION_L);
 558         mutex_unlock(&sg_policy->work_lock);
 559 }
 560
 561 static void sugov_irq_work(struct irq_work *irq_work)
 562 {
 563         struct sugov_policy *sg_policy;
 564
 565         sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
 566
 567         kthread_queue_work(&sg_policy->worker, &sg_policy->work);
 568 }
 569
 570 /************************** sysfs interface ************************/
 571
 572 static struct sugov_tunables *global_tunables;
 573 static DEFINE_MUTEX(global_tunables_lock);
 574
 575 static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
 576 {
 577         return container_of(attr_set, struct sugov_tunables, attr_set);
 578 }
 579
 580 static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
 581 {
 582         struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
 583
 584         return sprintf(buf, "%u\n", tunables->rate_limit_us);
 585 }
 586
 587 static ssize_t
 588 rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf, size_t count)
 589 {
 590         struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
 591         struct sugov_policy *sg_policy;
 592         unsigned int rate_limit_us;
 593
 594         if (kstrtouint(buf, 10, &rate_limit_us))
 595                 return -EINVAL;
 596
 597         tunables->rate_limit_us = rate_limit_us;
 598
 599         list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
 600                 sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
 601
 602         return count;
 603 }
 604
 605 static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
 606
 607 static struct attribute *sugov_attrs[] = {
 608         &rate_limit_us.attr,
 609         NULL
 610 };
 611 ATTRIBUTE_GROUPS(sugov);
 612
 613 static struct kobj_type sugov_tunables_ktype = {
 614         .default_groups = sugov_groups,
 615         .sysfs_ops = &governor_sysfs_ops,
 616 };
 617
 618 /********************** cpufreq governor interface *********************/
 619
 620 struct cpufreq_governor schedutil_gov;
 621
 622 static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
 623 {
 624         struct sugov_policy *sg_policy;
 625
 626         sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
 627         if (!sg_policy)
 628                 return NULL;
 629
 630         sg_policy->policy = policy;
 631         raw_spin_lock_init(&sg_policy->update_lock);
 632         return sg_policy;
 633 }
 634
 635 static void sugov_policy_free(struct sugov_policy *sg_policy)
 636 {
 637         kfree(sg_policy);
 638 }
 639
 640 static int sugov_kthread_create(struct sugov_policy *sg_policy)
 641 {
 642         struct task_struct *thread;
 643         struct sched_attr attr = {
 644                 .size           = sizeof(struct sched_attr),
 645                 .sched_policy   = SCHED_DEADLINE,
 646                 .sched_flags    = SCHED_FLAG_SUGOV,
 647                 .sched_nice     = 0,
 648                 .sched_priority = 0,
 649                 /*
 650                  * Fake (unused) bandwidth; workaround to "fix"
 651                  * priority inheritance.
 652                  */
 653                 .sched_runtime  =  1000000,
 654                 .sched_deadline = 10000000,
 655                 .sched_period   = 10000000,
 656         };
 657         struct cpufreq_policy *policy = sg_policy->policy;
 658         int ret;
 659
 660         /* kthread only required for slow path */
 661         if (policy->fast_switch_enabled)
 662                 return 0;
 663
 664         kthread_init_work(&sg_policy->work, sugov_work);
 665         kthread_init_worker(&sg_policy->worker);
 666         thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
 667                                 "sugov:%d",
 668                                 cpumask_first(policy->related_cpus));
 669         if (IS_ERR(thread)) {
 670                 pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread));
 671                 return PTR_ERR(thread);
 672         }
 673
 674         ret = sched_setattr_nocheck(thread, &attr);
 675         if (ret) {
 676                 kthread_stop(thread);
 677                 pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__);
 678                 return ret;
 679         }
 680
 681         sg_policy->thread = thread;
 682         kthread_bind_mask(thread, policy->related_cpus);
 683         init_irq_work(&sg_policy->irq_work, sugov_irq_work);
 684         mutex_init(&sg_policy->work_lock);
 685
 686         wake_up_process(thread);
 687
 688         return 0;
 689 }
 690
 691 static void sugov_kthread_stop(struct sugov_policy *sg_policy)
 692 {
 693         /* kthread only required for slow path */
 694         if (sg_policy->policy->fast_switch_enabled)
 695                 return;
 696
 697         kthread_flush_worker(&sg_policy->worker);
 698         kthread_stop(sg_policy->thread);
 699         mutex_destroy(&sg_policy->work_lock);
 700 }
 701
 702 static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
 703 {
 704         struct sugov_tunables *tunables;
 705
 706         tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
 707         if (tunables) {
 708                 gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
 709                 if (!have_governor_per_policy())
 710                         global_tunables = tunables;
 711         }
 712         return tunables;
 713 }
 714
 715 static void sugov_tunables_free(struct sugov_tunables *tunables)
 716 {
 717         if (!have_governor_per_policy())
 718                 global_tunables = NULL;
 719
 720         kfree(tunables);
 721 }
 722
 723 static int sugov_init(struct cpufreq_policy *policy)
 724 {
 725         struct sugov_policy *sg_policy;
 726         struct sugov_tunables *tunables;
 727         int ret = 0;
 728
 729         /* State should be equivalent to EXIT */
 730         if (policy->governor_data)
 731                 return -EBUSY;
 732
 733         cpufreq_enable_fast_switch(policy);
 734
 735         sg_policy = sugov_policy_alloc(policy);
 736         if (!sg_policy) {
 737                 ret = -ENOMEM;
 738                 goto disable_fast_switch;
 739         }
 740
 741         ret = sugov_kthread_create(sg_policy);
 742         if (ret)
 743                 goto free_sg_policy;
 744
 745         mutex_lock(&global_tunables_lock);
 746
 747         if (global_tunables) {
 748                 if (WARN_ON(have_governor_per_policy())) {
 749                         ret = -EINVAL;
 750                         goto stop_kthread;
 751                 }
 752                 policy->governor_data = sg_policy;
 753                 sg_policy->tunables = global_tunables;
 754
 755                 gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
 756                 goto out;
 757         }
 758
 759         tunables = sugov_tunables_alloc(sg_policy);
 760         if (!tunables) {
 761                 ret = -ENOMEM;
 762                 goto stop_kthread;
 763         }
 764
 765         tunables->rate_limit_us = cpufreq_policy_transition_delay_us(policy);
 766
 767         policy->governor_data = sg_policy;
 768         sg_policy->tunables = tunables;
 769
 770         ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
 771                                    get_governor_parent_kobj(policy), "%s",
 772                                    schedutil_gov.name);
 773         if (ret)
 774                 goto fail;
 775
 776 out:
 777         mutex_unlock(&global_tunables_lock);
 778         return 0;
 779
 780 fail:
 781         kobject_put(&tunables->attr_set.kobj);
 782         policy->governor_data = NULL;
 783         sugov_tunables_free(tunables);
 784
 785 stop_kthread:
 786         sugov_kthread_stop(sg_policy);
 787         mutex_unlock(&global_tunables_lock);
 788
 789 free_sg_policy:
 790         sugov_policy_free(sg_policy);
 791
 792 disable_fast_switch:
 793         cpufreq_disable_fast_switch(policy);
 794
 795         pr_err("initialization failed (error %d)\n", ret);
 796         return ret;
 797 }
 798
 799 static void sugov_exit(struct cpufreq_policy *policy)
 800 {
 801         struct sugov_policy *sg_policy = policy->governor_data;
 802         struct sugov_tunables *tunables = sg_policy->tunables;
 803         unsigned int count;
 804
 805         mutex_lock(&global_tunables_lock);
 806
 807         count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
 808         policy->governor_data = NULL;
 809         if (!count)
 810                 sugov_tunables_free(tunables);
 811
 812         mutex_unlock(&global_tunables_lock);
 813
 814         sugov_kthread_stop(sg_policy);
 815         sugov_policy_free(sg_policy);
 816         cpufreq_disable_fast_switch(policy);
 817 }
 818
 819 static int sugov_start(struct cpufreq_policy *policy)
 820 {
 821         struct sugov_policy *sg_policy = policy->governor_data;
 822         unsigned int cpu;
 823
 824         sg_policy->freq_update_delay_ns = sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
 825         sg_policy->last_freq_update_time        = 0;
 826         sg_policy->next_freq                    = 0;
 827         sg_policy->work_in_progress             = false;
 828         sg_policy->limits_changed               = false;
 829         sg_policy->cached_raw_freq              = 0;
 830
 831         sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);
 832
 833         for_each_cpu(cpu, policy->cpus) {
 834                 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
 835
 836                 memset(sg_cpu, 0, sizeof(*sg_cpu));
 837                 sg_cpu->cpu                     = cpu;
 838                 sg_cpu->sg_policy               = sg_policy;
 839         }
 840
 841         for_each_cpu(cpu, policy->cpus) {
 842                 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
 843
 844                 cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
 845                                              policy_is_shared(policy) ?
 846                                                         sugov_update_shared :
 847                                                         sugov_update_single);
 848         }
 849         return 0;
 850 }
 851
 852 static void sugov_stop(struct cpufreq_policy *policy)
 853 {
 854         struct sugov_policy *sg_policy = policy->governor_data;
 855         unsigned int cpu;
 856
 857         for_each_cpu(cpu, policy->cpus)
 858                 cpufreq_remove_update_util_hook(cpu);
 859
 860         synchronize_rcu();
 861
 862         if (!policy->fast_switch_enabled) {
 863                 irq_work_sync(&sg_policy->irq_work);
 864                 kthread_cancel_work_sync(&sg_policy->work);
 865         }
 866 }
 867
 868 static void sugov_limits(struct cpufreq_policy *policy)
 869 {
 870         struct sugov_policy *sg_policy = policy->governor_data;
 871
 872         if (!policy->fast_switch_enabled) {
 873                 mutex_lock(&sg_policy->work_lock);
 874                 cpufreq_policy_apply_limits(policy);
 875                 mutex_unlock(&sg_policy->work_lock);
 876         }
 877
 878         sg_policy->limits_changed = true;
 879 }
 880
 881 struct cpufreq_governor schedutil_gov = {
 882         .name                   = "schedutil",
 883         .owner                  = THIS_MODULE,
 884         .flags                  = CPUFREQ_GOV_DYNAMIC_SWITCHING,
 885         .init                   = sugov_init,
 886         .exit                   = sugov_exit,
 887         .start                  = sugov_start,
 888         .stop                   = sugov_stop,
 889         .limits                 = sugov_limits,
 890 };
 891
 892 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
 893 struct cpufreq_governor *cpufreq_default_governor(void)
 894 {
 895         return &schedutil_gov;
 896 }
 897 #endif
 898
 899 cpufreq_governor_init(schedutil_gov);
 900
 901 #ifdef CONFIG_ENERGY_MODEL
 902 extern bool sched_energy_update;
 903 extern struct mutex sched_energy_mutex;
 904
 905 static void rebuild_sd_workfn(struct work_struct *work)
 906 {
 907         mutex_lock(&sched_energy_mutex);
 908         sched_energy_update = true;
 909         rebuild_sched_domains();
 910         sched_energy_update = false;
 911         mutex_unlock(&sched_energy_mutex);
 912 }
 913 static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);
 914
 915 /*
 916  * EAS shouldn't be attempted without sugov, so rebuild the sched_domains
 917  * on governor changes to make sure the scheduler knows about it.
 918  */
 919 void sched_cpufreq_governor_change(struct cpufreq_policy *policy,
 920                                   struct cpufreq_governor *old_gov)
 921 {
 922         if (old_gov == &schedutil_gov || policy->governor == &schedutil_gov) {
 923                 /*
 924                  * When called from the cpufreq_register_driver() path, the
 925                  * cpu_hotplug_lock is already held, so use a work item to
 926                  * avoid nested locking in rebuild_sched_domains().
 927                  */
 928                 schedule_work(&rebuild_sd_work);
 929         }
 930
 931 }
 932 #endif