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          * For the slow switching platforms, the kthread is always scheduled on
  86          * the right set of CPUs and any CPU can find the next frequency and
  87          * schedule the kthread.
  88          */
  89         if (sg_policy->policy->fast_switch_enabled &&
  90             !cpufreq_this_cpu_can_update(sg_policy->policy))
  91                 return false;
  92
  93         if (unlikely(sg_policy->limits_changed)) {
  94                 sg_policy->limits_changed = false;
  95                 sg_policy->need_freq_update = true;
  96                 return true;
  97         }
  98
  99         delta_ns = time - sg_policy->last_freq_update_time;
 100
 101         return delta_ns >= sg_policy->freq_update_delay_ns;
 102 }
 103
 104 static bool sugov_update_next_freq(struct sugov_policy *sg_policy, u64 time,
 105                                    unsigned int next_freq)
 106 {
 107         if (sg_policy->next_freq == next_freq)
 108                 return false;
 109
 110         sg_policy->next_freq = next_freq;
 111         sg_policy->last_freq_update_time = time;
 112
 113         return true;
 114 }
 115
 116 static void sugov_fast_switch(struct sugov_policy *sg_policy, u64 time,
 117                               unsigned int next_freq)
 118 {
 119         struct cpufreq_policy *policy = sg_policy->policy;
 120         int cpu;
 121
 122         if (!sugov_update_next_freq(sg_policy, time, next_freq))
 123                 return;
 124
 125         next_freq = cpufreq_driver_fast_switch(policy, next_freq);
 126         if (!next_freq)
 127                 return;
 128
 129         policy->cur = next_freq;
 130
 131         if (trace_cpu_frequency_enabled()) {
 132                 for_each_cpu(cpu, policy->cpus)
 133                         trace_cpu_frequency(next_freq, cpu);
 134         }
 135 }
 136
 137 static void sugov_deferred_update(struct sugov_policy *sg_policy, u64 time,
 138                                   unsigned int next_freq)
 139 {
 140         if (!sugov_update_next_freq(sg_policy, time, next_freq))
 141                 return;
 142
 143         if (!sg_policy->work_in_progress) {
 144                 sg_policy->work_in_progress = true;
 145                 irq_work_queue(&sg_policy->irq_work);
 146         }
 147 }
 148
 149 /**
 150  * get_next_freq - Compute a new frequency for a given cpufreq policy.
 151  * @sg_policy: schedutil policy object to compute the new frequency for.
 152  * @util: Current CPU utilization.
 153  * @max: CPU capacity.
 154  *
 155  * If the utilization is frequency-invariant, choose the new frequency to be
 156  * proportional to it, that is
 157  *
 158  * next_freq = C * max_freq * util / max
 159  *
 160  * Otherwise, approximate the would-be frequency-invariant utilization by
 161  * util_raw * (curr_freq / max_freq) which leads to
 162  *
 163  * next_freq = C * curr_freq * util_raw / max
 164  *
 165  * Take C = 1.25 for the frequency tipping point at (util / max) = 0.8.
 166  *
 167  * The lowest driver-supported frequency which is equal or greater than the raw
 168  * next_freq (as calculated above) is returned, subject to policy min/max and
 169  * cpufreq driver limitations.
 170  */
 171 static unsigned int get_next_freq(struct sugov_policy *sg_policy,
 172                                   unsigned long util, unsigned long max)
 173 {
 174         struct cpufreq_policy *policy = sg_policy->policy;
 175         unsigned int freq = arch_scale_freq_invariant() ?
 176                                 policy->cpuinfo.max_freq : policy->cur;
 177
 178         freq = map_util_freq(util, freq, max);
 179
 180         if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)
 181                 return sg_policy->next_freq;
 182
 183         sg_policy->need_freq_update = false;
 184         sg_policy->cached_raw_freq = freq;
 185         return cpufreq_driver_resolve_freq(policy, freq);
 186 }
 187
 188 /*
 189  * This function computes an effective utilization for the given CPU, to be
 190  * used for frequency selection given the linear relation: f = u * f_max.
 191  *
 192  * The scheduler tracks the following metrics:
 193  *
 194  *   cpu_util_{cfs,rt,dl,irq}()
 195  *   cpu_bw_dl()
 196  *
 197  * Where the cfs,rt and dl util numbers are tracked with the same metric and
 198  * synchronized windows and are thus directly comparable.
 199  *
 200  * The cfs,rt,dl utilization are the running times measured with rq->clock_task
 201  * which excludes things like IRQ and steal-time. These latter are then accrued
 202  * in the irq utilization.
 203  *
 204  * The DL bandwidth number otoh is not a measured metric but a value computed
 205  * based on the task model parameters and gives the minimal utilization
 206  * required to meet deadlines.
 207  */
 208 unsigned long schedutil_cpu_util(int cpu, unsigned long util_cfs,
 209                                  unsigned long max, enum schedutil_type type,
 210                                  struct task_struct *p)
 211 {
 212         unsigned long dl_util, util, irq;
 213         struct rq *rq = cpu_rq(cpu);
 214
 215         if (!IS_BUILTIN(CONFIG_UCLAMP_TASK) &&
 216             type == FREQUENCY_UTIL && rt_rq_is_runnable(&rq->rt)) {
 217                 return max;
 218         }
 219
 220         /*
 221          * Early check to see if IRQ/steal time saturates the CPU, can be
 222          * because of inaccuracies in how we track these -- see
 223          * update_irq_load_avg().
 224          */
 225         irq = cpu_util_irq(rq);
 226         if (unlikely(irq >= max))
 227                 return max;
 228
 229         /*
 230          * Because the time spend on RT/DL tasks is visible as 'lost' time to
 231          * CFS tasks and we use the same metric to track the effective
 232          * utilization (PELT windows are synchronized) we can directly add them
 233          * to obtain the CPU's actual utilization.
 234          *
 235          * CFS and RT utilization can be boosted or capped, depending on
 236          * utilization clamp constraints requested by currently RUNNABLE
 237          * tasks.
 238          * When there are no CFS RUNNABLE tasks, clamps are released and
 239          * frequency will be gracefully reduced with the utilization decay.
 240          */
 241         util = util_cfs + cpu_util_rt(rq);
 242         if (type == FREQUENCY_UTIL)
 243                 util = uclamp_util_with(rq, util, p);
 244
 245         dl_util = cpu_util_dl(rq);
 246
 247         /*
 248          * For frequency selection we do not make cpu_util_dl() a permanent part
 249          * of this sum because we want to use cpu_bw_dl() later on, but we need
 250          * to check if the CFS+RT+DL sum is saturated (ie. no idle time) such
 251          * that we select f_max when there is no idle time.
 252          *
 253          * NOTE: numerical errors or stop class might cause us to not quite hit
 254          * saturation when we should -- something for later.
 255          */
 256         if (util + dl_util >= max)
 257                 return max;
 258
 259         /*
 260          * OTOH, for energy computation we need the estimated running time, so
 261          * include util_dl and ignore dl_bw.
 262          */
 263         if (type == ENERGY_UTIL)
 264                 util += dl_util;
 265
 266         /*
 267          * There is still idle time; further improve the number by using the
 268          * irq metric. Because IRQ/steal time is hidden from the task clock we
 269          * need to scale the task numbers:
 270          *
 271          *              max - irq
 272          *   U' = irq + --------- * U
 273          *                 max
 274          */
 275         util = scale_irq_capacity(util, irq, max);
 276         util += irq;
 277
 278         /*
 279          * Bandwidth required by DEADLINE must always be granted while, for
 280          * FAIR and RT, we use blocked utilization of IDLE CPUs as a mechanism
 281          * to gracefully reduce the frequency when no tasks show up for longer
 282          * periods of time.
 283          *
 284          * Ideally we would like to set bw_dl as min/guaranteed freq and util +
 285          * bw_dl as requested freq. However, cpufreq is not yet ready for such
 286          * an interface. So, we only do the latter for now.
 287          */
 288         if (type == FREQUENCY_UTIL)
 289                 util += cpu_bw_dl(rq);
 290
 291         return min(max, util);
 292 }
 293
 294 static unsigned long sugov_get_util(struct sugov_cpu *sg_cpu)
 295 {
 296         struct rq *rq = cpu_rq(sg_cpu->cpu);
 297         unsigned long util = cpu_util_cfs(rq);
 298         unsigned long max = arch_scale_cpu_capacity(sg_cpu->cpu);
 299
 300         sg_cpu->max = max;
 301         sg_cpu->bw_dl = cpu_bw_dl(rq);
 302
 303         return schedutil_cpu_util(sg_cpu->cpu, util, max, FREQUENCY_UTIL, NULL);
 304 }
 305
 306 /**
 307  * sugov_iowait_reset() - Reset the IO boost status of a CPU.
 308  * @sg_cpu: the sugov data for the CPU to boost
 309  * @time: the update time from the caller
 310  * @set_iowait_boost: true if an IO boost has been requested
 311  *
 312  * The IO wait boost of a task is disabled after a tick since the last update
 313  * of a CPU. If a new IO wait boost is requested after more then a tick, then
 314  * we enable the boost starting from IOWAIT_BOOST_MIN, which improves energy
 315  * efficiency by ignoring sporadic wakeups from IO.
 316  */
 317 static bool sugov_iowait_reset(struct sugov_cpu *sg_cpu, u64 time,
 318                                bool set_iowait_boost)
 319 {
 320         s64 delta_ns = time - sg_cpu->last_update;
 321
 322         /* Reset boost only if a tick has elapsed since last request */
 323         if (delta_ns <= TICK_NSEC)
 324                 return false;
 325
 326         sg_cpu->iowait_boost = set_iowait_boost ? IOWAIT_BOOST_MIN : 0;
 327         sg_cpu->iowait_boost_pending = set_iowait_boost;
 328
 329         return true;
 330 }
 331
 332 /**
 333  * sugov_iowait_boost() - Updates the IO boost status of a CPU.
 334  * @sg_cpu: the sugov data for the CPU to boost
 335  * @time: the update time from the caller
 336  * @flags: SCHED_CPUFREQ_IOWAIT if the task is waking up after an IO wait
 337  *
 338  * Each time a task wakes up after an IO operation, the CPU utilization can be
 339  * boosted to a certain utilization which doubles at each "frequent and
 340  * successive" wakeup from IO, ranging from IOWAIT_BOOST_MIN to the utilization
 341  * of the maximum OPP.
 342  *
 343  * To keep doubling, an IO boost has to be requested at least once per tick,
 344  * otherwise we restart from the utilization of the minimum OPP.
 345  */
 346 static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
 347                                unsigned int flags)
 348 {
 349         bool set_iowait_boost = flags & SCHED_CPUFREQ_IOWAIT;
 350
 351         /* Reset boost if the CPU appears to have been idle enough */
 352         if (sg_cpu->iowait_boost &&
 353             sugov_iowait_reset(sg_cpu, time, set_iowait_boost))
 354                 return;
 355
 356         /* Boost only tasks waking up after IO */
 357         if (!set_iowait_boost)
 358                 return;
 359
 360         /* Ensure boost doubles only one time at each request */
 361         if (sg_cpu->iowait_boost_pending)
 362                 return;
 363         sg_cpu->iowait_boost_pending = true;
 364
 365         /* Double the boost at each request */
 366         if (sg_cpu->iowait_boost) {
 367                 sg_cpu->iowait_boost =
 368                         min_t(unsigned int, sg_cpu->iowait_boost << 1, SCHED_CAPACITY_SCALE);
 369                 return;
 370         }
 371
 372         /* First wakeup after IO: start with minimum boost */
 373         sg_cpu->iowait_boost = IOWAIT_BOOST_MIN;
 374 }
 375
 376 /**
 377  * sugov_iowait_apply() - Apply the IO boost to a CPU.
 378  * @sg_cpu: the sugov data for the cpu to boost
 379  * @time: the update time from the caller
 380  * @util: the utilization to (eventually) boost
 381  * @max: the maximum value the utilization can be boosted to
 382  *
 383  * A CPU running a task which woken up after an IO operation can have its
 384  * utilization boosted to speed up the completion of those IO operations.
 385  * The IO boost value is increased each time a task wakes up from IO, in
 386  * sugov_iowait_apply(), and it's instead decreased by this function,
 387  * each time an increase has not been requested (!iowait_boost_pending).
 388  *
 389  * A CPU which also appears to have been idle for at least one tick has also
 390  * its IO boost utilization reset.
 391  *
 392  * This mechanism is designed to boost high frequently IO waiting tasks, while
 393  * being more conservative on tasks which does sporadic IO operations.
 394  */
 395 static unsigned long sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time,
 396                                         unsigned long util, unsigned long max)
 397 {
 398         unsigned long boost;
 399
 400         /* No boost currently required */
 401         if (!sg_cpu->iowait_boost)
 402                 return util;
 403
 404         /* Reset boost if the CPU appears to have been idle enough */
 405         if (sugov_iowait_reset(sg_cpu, time, false))
 406                 return util;
 407
 408         if (!sg_cpu->iowait_boost_pending) {
 409                 /*
 410                  * No boost pending; reduce the boost value.
 411                  */
 412                 sg_cpu->iowait_boost >>= 1;
 413                 if (sg_cpu->iowait_boost < IOWAIT_BOOST_MIN) {
 414                         sg_cpu->iowait_boost = 0;
 415                         return util;
 416                 }
 417         }
 418
 419         sg_cpu->iowait_boost_pending = false;
 420
 421         /*
 422          * @util is already in capacity scale; convert iowait_boost
 423          * into the same scale so we can compare.
 424          */
 425         boost = (sg_cpu->iowait_boost * max) >> SCHED_CAPACITY_SHIFT;
 426         return max(boost, util);
 427 }
 428
 429 #ifdef CONFIG_NO_HZ_COMMON
 430 static bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu)
 431 {
 432         unsigned long idle_calls = tick_nohz_get_idle_calls_cpu(sg_cpu->cpu);
 433         bool ret = idle_calls == sg_cpu->saved_idle_calls;
 434
 435         sg_cpu->saved_idle_calls = idle_calls;
 436         return ret;
 437 }
 438 #else
 439 static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
 440 #endif /* CONFIG_NO_HZ_COMMON */
 441
 442 /*
 443  * Make sugov_should_update_freq() ignore the rate limit when DL
 444  * has increased the utilization.
 445  */
 446 static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu, struct sugov_policy *sg_policy)
 447 {
 448         if (cpu_bw_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->bw_dl)
 449                 sg_policy->limits_changed = true;
 450 }
 451
 452 static void sugov_update_single(struct update_util_data *hook, u64 time,
 453                                 unsigned int flags)
 454 {
 455         struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
 456         struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 457         unsigned long util, max;
 458         unsigned int next_f;
 459         bool busy;
 460
 461         sugov_iowait_boost(sg_cpu, time, flags);
 462         sg_cpu->last_update = time;
 463
 464         ignore_dl_rate_limit(sg_cpu, sg_policy);
 465
 466         if (!sugov_should_update_freq(sg_policy, time))
 467                 return;
 468
 469         /* Limits may have changed, don't skip frequency update */
 470         busy = !sg_policy->need_freq_update && sugov_cpu_is_busy(sg_cpu);
 471
 472         util = sugov_get_util(sg_cpu);
 473         max = sg_cpu->max;
 474         util = sugov_iowait_apply(sg_cpu, time, util, max);
 475         next_f = get_next_freq(sg_policy, util, max);
 476         /*
 477          * Do not reduce the frequency if the CPU has not been idle
 478          * recently, as the reduction is likely to be premature then.
 479          */
 480         if (busy && next_f < sg_policy->next_freq) {
 481                 next_f = sg_policy->next_freq;
 482
 483                 /* Reset cached freq as next_freq has changed */
 484                 sg_policy->cached_raw_freq = 0;
 485         }
 486
 487         /*
 488          * This code runs under rq->lock for the target CPU, so it won't run
 489          * concurrently on two different CPUs for the same target and it is not
 490          * necessary to acquire the lock in the fast switch case.
 491          */
 492         if (sg_policy->policy->fast_switch_enabled) {
 493                 sugov_fast_switch(sg_policy, time, next_f);
 494         } else {
 495                 raw_spin_lock(&sg_policy->update_lock);
 496                 sugov_deferred_update(sg_policy, time, next_f);
 497                 raw_spin_unlock(&sg_policy->update_lock);
 498         }
 499 }
 500
 501 static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
 502 {
 503         struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 504         struct cpufreq_policy *policy = sg_policy->policy;
 505         unsigned long util = 0, max = 1;
 506         unsigned int j;
 507
 508         for_each_cpu(j, policy->cpus) {
 509                 struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
 510                 unsigned long j_util, j_max;
 511
 512                 j_util = sugov_get_util(j_sg_cpu);
 513                 j_max = j_sg_cpu->max;
 514                 j_util = sugov_iowait_apply(j_sg_cpu, time, j_util, j_max);
 515
 516                 if (j_util * max > j_max * util) {
 517                         util = j_util;
 518                         max = j_max;
 519                 }
 520         }
 521
 522         return get_next_freq(sg_policy, util, max);
 523 }
 524
 525 static void
 526 sugov_update_shared(struct update_util_data *hook, u64 time, unsigned int flags)
 527 {
 528         struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
 529         struct sugov_policy *sg_policy = sg_cpu->sg_policy;
 530         unsigned int next_f;
 531
 532         raw_spin_lock(&sg_policy->update_lock);
 533
 534         sugov_iowait_boost(sg_cpu, time, flags);
 535         sg_cpu->last_update = time;
 536
 537         ignore_dl_rate_limit(sg_cpu, sg_policy);
 538
 539         if (sugov_should_update_freq(sg_policy, time)) {
 540                 next_f = sugov_next_freq_shared(sg_cpu, time);
 541
 542                 if (sg_policy->policy->fast_switch_enabled)
 543                         sugov_fast_switch(sg_policy, time, next_f);
 544                 else
 545                         sugov_deferred_update(sg_policy, time, next_f);
 546         }
 547
 548         raw_spin_unlock(&sg_policy->update_lock);
 549 }
 550
 551 static void sugov_work(struct kthread_work *work)
 552 {
 553         struct sugov_policy *sg_policy = container_of(work, struct sugov_policy, work);
 554         unsigned int freq;
 555         unsigned long flags;
 556
 557         /*
 558          * Hold sg_policy->update_lock shortly to handle the case where:
 559          * incase sg_policy->next_freq is read here, and then updated by
 560          * sugov_deferred_update() just before work_in_progress is set to false
 561          * here, we may miss queueing the new update.
 562          *
 563          * Note: If a work was queued after the update_lock is released,
 564          * sugov_work() will just be called again by kthread_work code; and the
 565          * request will be proceed before the sugov thread sleeps.
 566          */
 567         raw_spin_lock_irqsave(&sg_policy->update_lock, flags);
 568         freq = sg_policy->next_freq;
 569         sg_policy->work_in_progress = false;
 570         raw_spin_unlock_irqrestore(&sg_policy->update_lock, flags);
 571
 572         mutex_lock(&sg_policy->work_lock);
 573         __cpufreq_driver_target(sg_policy->policy, freq, CPUFREQ_RELATION_L);
 574         mutex_unlock(&sg_policy->work_lock);
 575 }
 576
 577 static void sugov_irq_work(struct irq_work *irq_work)
 578 {
 579         struct sugov_policy *sg_policy;
 580
 581         sg_policy = container_of(irq_work, struct sugov_policy, irq_work);
 582
 583         kthread_queue_work(&sg_policy->worker, &sg_policy->work);
 584 }
 585
 586 /************************** sysfs interface ************************/
 587
 588 static struct sugov_tunables *global_tunables;
 589 static DEFINE_MUTEX(global_tunables_lock);
 590
 591 static inline struct sugov_tunables *to_sugov_tunables(struct gov_attr_set *attr_set)
 592 {
 593         return container_of(attr_set, struct sugov_tunables, attr_set);
 594 }
 595
 596 static ssize_t rate_limit_us_show(struct gov_attr_set *attr_set, char *buf)
 597 {
 598         struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
 599
 600         return sprintf(buf, "%u\n", tunables->rate_limit_us);
 601 }
 602
 603 static ssize_t
 604 rate_limit_us_store(struct gov_attr_set *attr_set, const char *buf, size_t count)
 605 {
 606         struct sugov_tunables *tunables = to_sugov_tunables(attr_set);
 607         struct sugov_policy *sg_policy;
 608         unsigned int rate_limit_us;
 609
 610         if (kstrtouint(buf, 10, &rate_limit_us))
 611                 return -EINVAL;
 612
 613         tunables->rate_limit_us = rate_limit_us;
 614
 615         list_for_each_entry(sg_policy, &attr_set->policy_list, tunables_hook)
 616                 sg_policy->freq_update_delay_ns = rate_limit_us * NSEC_PER_USEC;
 617
 618         return count;
 619 }
 620
 621 static struct governor_attr rate_limit_us = __ATTR_RW(rate_limit_us);
 622
 623 static struct attribute *sugov_attrs[] = {
 624         &rate_limit_us.attr,
 625         NULL
 626 };
 627 ATTRIBUTE_GROUPS(sugov);
 628
 629 static struct kobj_type sugov_tunables_ktype = {
 630         .default_groups = sugov_groups,
 631         .sysfs_ops = &governor_sysfs_ops,
 632 };
 633
 634 /********************** cpufreq governor interface *********************/
 635
 636 struct cpufreq_governor schedutil_gov;
 637
 638 static struct sugov_policy *sugov_policy_alloc(struct cpufreq_policy *policy)
 639 {
 640         struct sugov_policy *sg_policy;
 641
 642         sg_policy = kzalloc(sizeof(*sg_policy), GFP_KERNEL);
 643         if (!sg_policy)
 644                 return NULL;
 645
 646         sg_policy->policy = policy;
 647         raw_spin_lock_init(&sg_policy->update_lock);
 648         return sg_policy;
 649 }
 650
 651 static void sugov_policy_free(struct sugov_policy *sg_policy)
 652 {
 653         kfree(sg_policy);
 654 }
 655
 656 static int sugov_kthread_create(struct sugov_policy *sg_policy)
 657 {
 658         struct task_struct *thread;
 659         struct sched_attr attr = {
 660                 .size           = sizeof(struct sched_attr),
 661                 .sched_policy   = SCHED_DEADLINE,
 662                 .sched_flags    = SCHED_FLAG_SUGOV,
 663                 .sched_nice     = 0,
 664                 .sched_priority = 0,
 665                 /*
 666                  * Fake (unused) bandwidth; workaround to "fix"
 667                  * priority inheritance.
 668                  */
 669                 .sched_runtime  =  1000000,
 670                 .sched_deadline = 10000000,
 671                 .sched_period   = 10000000,
 672         };
 673         struct cpufreq_policy *policy = sg_policy->policy;
 674         int ret;
 675
 676         /* kthread only required for slow path */
 677         if (policy->fast_switch_enabled)
 678                 return 0;
 679
 680         kthread_init_work(&sg_policy->work, sugov_work);
 681         kthread_init_worker(&sg_policy->worker);
 682         thread = kthread_create(kthread_worker_fn, &sg_policy->worker,
 683                                 "sugov:%d",
 684                                 cpumask_first(policy->related_cpus));
 685         if (IS_ERR(thread)) {
 686                 pr_err("failed to create sugov thread: %ld\n", PTR_ERR(thread));
 687                 return PTR_ERR(thread);
 688         }
 689
 690         ret = sched_setattr_nocheck(thread, &attr);
 691         if (ret) {
 692                 kthread_stop(thread);
 693                 pr_warn("%s: failed to set SCHED_DEADLINE\n", __func__);
 694                 return ret;
 695         }
 696
 697         sg_policy->thread = thread;
 698         kthread_bind_mask(thread, policy->related_cpus);
 699         init_irq_work(&sg_policy->irq_work, sugov_irq_work);
 700         mutex_init(&sg_policy->work_lock);
 701
 702         wake_up_process(thread);
 703
 704         return 0;
 705 }
 706
 707 static void sugov_kthread_stop(struct sugov_policy *sg_policy)
 708 {
 709         /* kthread only required for slow path */
 710         if (sg_policy->policy->fast_switch_enabled)
 711                 return;
 712
 713         kthread_flush_worker(&sg_policy->worker);
 714         kthread_stop(sg_policy->thread);
 715         mutex_destroy(&sg_policy->work_lock);
 716 }
 717
 718 static struct sugov_tunables *sugov_tunables_alloc(struct sugov_policy *sg_policy)
 719 {
 720         struct sugov_tunables *tunables;
 721
 722         tunables = kzalloc(sizeof(*tunables), GFP_KERNEL);
 723         if (tunables) {
 724                 gov_attr_set_init(&tunables->attr_set, &sg_policy->tunables_hook);
 725                 if (!have_governor_per_policy())
 726                         global_tunables = tunables;
 727         }
 728         return tunables;
 729 }
 730
 731 static void sugov_tunables_free(struct sugov_tunables *tunables)
 732 {
 733         if (!have_governor_per_policy())
 734                 global_tunables = NULL;
 735
 736         kfree(tunables);
 737 }
 738
 739 static int sugov_init(struct cpufreq_policy *policy)
 740 {
 741         struct sugov_policy *sg_policy;
 742         struct sugov_tunables *tunables;
 743         int ret = 0;
 744
 745         /* State should be equivalent to EXIT */
 746         if (policy->governor_data)
 747                 return -EBUSY;
 748
 749         cpufreq_enable_fast_switch(policy);
 750
 751         sg_policy = sugov_policy_alloc(policy);
 752         if (!sg_policy) {
 753                 ret = -ENOMEM;
 754                 goto disable_fast_switch;
 755         }
 756
 757         ret = sugov_kthread_create(sg_policy);
 758         if (ret)
 759                 goto free_sg_policy;
 760
 761         mutex_lock(&global_tunables_lock);
 762
 763         if (global_tunables) {
 764                 if (WARN_ON(have_governor_per_policy())) {
 765                         ret = -EINVAL;
 766                         goto stop_kthread;
 767                 }
 768                 policy->governor_data = sg_policy;
 769                 sg_policy->tunables = global_tunables;
 770
 771                 gov_attr_set_get(&global_tunables->attr_set, &sg_policy->tunables_hook);
 772                 goto out;
 773         }
 774
 775         tunables = sugov_tunables_alloc(sg_policy);
 776         if (!tunables) {
 777                 ret = -ENOMEM;
 778                 goto stop_kthread;
 779         }
 780
 781         tunables->rate_limit_us = cpufreq_policy_transition_delay_us(policy);
 782
 783         policy->governor_data = sg_policy;
 784         sg_policy->tunables = tunables;
 785
 786         ret = kobject_init_and_add(&tunables->attr_set.kobj, &sugov_tunables_ktype,
 787                                    get_governor_parent_kobj(policy), "%s",
 788                                    schedutil_gov.name);
 789         if (ret)
 790                 goto fail;
 791
 792 out:
 793         mutex_unlock(&global_tunables_lock);
 794         return 0;
 795
 796 fail:
 797         kobject_put(&tunables->attr_set.kobj);
 798         policy->governor_data = NULL;
 799         sugov_tunables_free(tunables);
 800
 801 stop_kthread:
 802         sugov_kthread_stop(sg_policy);
 803         mutex_unlock(&global_tunables_lock);
 804
 805 free_sg_policy:
 806         sugov_policy_free(sg_policy);
 807
 808 disable_fast_switch:
 809         cpufreq_disable_fast_switch(policy);
 810
 811         pr_err("initialization failed (error %d)\n", ret);
 812         return ret;
 813 }
 814
 815 static void sugov_exit(struct cpufreq_policy *policy)
 816 {
 817         struct sugov_policy *sg_policy = policy->governor_data;
 818         struct sugov_tunables *tunables = sg_policy->tunables;
 819         unsigned int count;
 820
 821         mutex_lock(&global_tunables_lock);
 822
 823         count = gov_attr_set_put(&tunables->attr_set, &sg_policy->tunables_hook);
 824         policy->governor_data = NULL;
 825         if (!count)
 826                 sugov_tunables_free(tunables);
 827
 828         mutex_unlock(&global_tunables_lock);
 829
 830         sugov_kthread_stop(sg_policy);
 831         sugov_policy_free(sg_policy);
 832         cpufreq_disable_fast_switch(policy);
 833 }
 834
 835 static int sugov_start(struct cpufreq_policy *policy)
 836 {
 837         struct sugov_policy *sg_policy = policy->governor_data;
 838         unsigned int cpu;
 839
 840         sg_policy->freq_update_delay_ns = sg_policy->tunables->rate_limit_us * NSEC_PER_USEC;
 841         sg_policy->last_freq_update_time        = 0;
 842         sg_policy->next_freq                    = 0;
 843         sg_policy->work_in_progress             = false;
 844         sg_policy->limits_changed               = false;
 845         sg_policy->need_freq_update             = false;
 846         sg_policy->cached_raw_freq              = 0;
 847
 848         for_each_cpu(cpu, policy->cpus) {
 849                 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
 850
 851                 memset(sg_cpu, 0, sizeof(*sg_cpu));
 852                 sg_cpu->cpu                     = cpu;
 853                 sg_cpu->sg_policy               = sg_policy;
 854         }
 855
 856         for_each_cpu(cpu, policy->cpus) {
 857                 struct sugov_cpu *sg_cpu = &per_cpu(sugov_cpu, cpu);
 858
 859                 cpufreq_add_update_util_hook(cpu, &sg_cpu->update_util,
 860                                              policy_is_shared(policy) ?
 861                                                         sugov_update_shared :
 862                                                         sugov_update_single);
 863         }
 864         return 0;
 865 }
 866
 867 static void sugov_stop(struct cpufreq_policy *policy)
 868 {
 869         struct sugov_policy *sg_policy = policy->governor_data;
 870         unsigned int cpu;
 871
 872         for_each_cpu(cpu, policy->cpus)
 873                 cpufreq_remove_update_util_hook(cpu);
 874
 875         synchronize_rcu();
 876
 877         if (!policy->fast_switch_enabled) {
 878                 irq_work_sync(&sg_policy->irq_work);
 879                 kthread_cancel_work_sync(&sg_policy->work);
 880         }
 881 }
 882
 883 static void sugov_limits(struct cpufreq_policy *policy)
 884 {
 885         struct sugov_policy *sg_policy = policy->governor_data;
 886
 887         if (!policy->fast_switch_enabled) {
 888                 mutex_lock(&sg_policy->work_lock);
 889                 cpufreq_policy_apply_limits(policy);
 890                 mutex_unlock(&sg_policy->work_lock);
 891         }
 892
 893         sg_policy->limits_changed = true;
 894 }
 895
 896 struct cpufreq_governor schedutil_gov = {
 897         .name                   = "schedutil",
 898         .owner                  = THIS_MODULE,
 899         .dynamic_switching      = true,
 900         .init                   = sugov_init,
 901         .exit                   = sugov_exit,
 902         .start                  = sugov_start,
 903         .stop                   = sugov_stop,
 904         .limits                 = sugov_limits,
 905 };
 906
 907 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
 908 struct cpufreq_governor *cpufreq_default_governor(void)
 909 {
 910         return &schedutil_gov;
 911 }
 912 #endif
 913
 914 static int __init sugov_register(void)
 915 {
 916         return cpufreq_register_governor(&schedutil_gov);
 917 }
 918 core_initcall(sugov_register);
 919
 920 #ifdef CONFIG_ENERGY_MODEL
 921 extern bool sched_energy_update;
 922 extern struct mutex sched_energy_mutex;
 923
 924 static void rebuild_sd_workfn(struct work_struct *work)
 925 {
 926         mutex_lock(&sched_energy_mutex);
 927         sched_energy_update = true;
 928         rebuild_sched_domains();
 929         sched_energy_update = false;
 930         mutex_unlock(&sched_energy_mutex);
 931 }
 932 static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);
 933
 934 /*
 935  * EAS shouldn't be attempted without sugov, so rebuild the sched_domains
 936  * on governor changes to make sure the scheduler knows about it.
 937  */
 938 void sched_cpufreq_governor_change(struct cpufreq_policy *policy,
 939                                   struct cpufreq_governor *old_gov)
 940 {
 941         if (old_gov == &schedutil_gov || policy->governor == &schedutil_gov) {
 942                 /*
 943                  * When called from the cpufreq_register_driver() path, the
 944                  * cpu_hotplug_lock is already held, so use a work item to
 945                  * avoid nested locking in rebuild_sched_domains().
 946                  */
 947                 schedule_work(&rebuild_sd_work);
 948         }
 949
 950 }
 951 #endif