drivers/cpufreq/cpufreq_interactive.c

   1 /*
   2  * drivers/cpufreq/cpufreq_interactive.c
   3  *
   4  * Copyright (C) 2010 Google, Inc.
   5  *
   6  * This software is licensed under the terms of the GNU General Public
   7  * License version 2, as published by the Free Software Foundation, and
   8  * may be copied, distributed, and modified under those terms.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * Author: Mike Chan (mike@android.com)
  16  *
  17  */
  18
  19 #include <linux/cpu.h>
  20 #include <linux/cpumask.h>
  21 #include <linux/cpufreq.h>
  22 #include <linux/module.h>
  23 #include <linux/mutex.h>
  24 #include <linux/sched.h>
  25 #include <linux/sched/rt.h>
  26 #include <linux/tick.h>
  27 #include <linux/time.h>
  28 #include <linux/timer.h>
  29 #include <linux/workqueue.h>
  30 #include <linux/kthread.h>
  31 #include <linux/mutex.h>
  32
  33 #define CREATE_TRACE_POINTS
  34 #include <trace/events/cpufreq_interactive.h>
  35
  36 #include <asm/cputime.h>
  37
  38 static atomic_t active_count = ATOMIC_INIT(0);
  39
  40 struct cpufreq_interactive_cpuinfo {
  41         struct timer_list cpu_timer;
  42         int timer_idlecancel;
  43         u64 time_in_idle;
  44         u64 idle_exit_time;
  45         u64 timer_run_time;
  46         int idling;
  47         u64 freq_change_time;
  48         u64 freq_change_time_in_idle;
  49         struct cpufreq_policy *policy;
  50         struct cpufreq_frequency_table *freq_table;
  51         unsigned int target_freq;
  52         int governor_enabled;
  53 };
  54
  55 static DEFINE_PER_CPU(struct cpufreq_interactive_cpuinfo, cpuinfo);
  56
  57 /* Workqueues handle frequency scaling */
  58 static struct task_struct *up_task;
  59 static struct workqueue_struct *down_wq;
  60 static struct work_struct freq_scale_down_work;
  61 static cpumask_t up_cpumask;
  62 static spinlock_t up_cpumask_lock;
  63 static cpumask_t down_cpumask;
  64 static spinlock_t down_cpumask_lock;
  65 static struct mutex set_speed_lock;
  66
  67 /* Hi speed to bump to from lo speed when load burst (default max) */
  68 static u64 hispeed_freq;
  69
  70 /* Go to hi speed when CPU load at or above this value. */
  71 #define DEFAULT_GO_HISPEED_LOAD 95
  72 static unsigned long go_hispeed_load;
  73
  74 /*
  75  * The minimum amount of time to spend at a frequency before we can ramp down.
  76  */
  77 #define DEFAULT_MIN_SAMPLE_TIME 20 * USEC_PER_MSEC
  78 static unsigned long min_sample_time;
  79
  80 /*
  81  * The sample rate of the timer used to increase frequency
  82  */
  83 #define DEFAULT_TIMER_RATE 20 * USEC_PER_MSEC
  84 static unsigned long timer_rate;
  85
  86 static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
  87                 unsigned int event);
  88
  89 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_INTERACTIVE
  90 static
  91 #endif
  92 struct cpufreq_governor cpufreq_gov_interactive = {
  93         .name = "interactive",
  94         .governor = cpufreq_governor_interactive,
  95         .max_transition_latency = 10000000,
  96         .owner = THIS_MODULE,
  97 };
  98
  99 static void cpufreq_interactive_timer(unsigned long data)
 100 {
 101         unsigned int delta_idle;
 102         unsigned int delta_time;
 103         int cpu_load;
 104         int load_since_change;
 105         u64 time_in_idle;
 106         u64 idle_exit_time;
 107         struct cpufreq_interactive_cpuinfo *pcpu =
 108                 &per_cpu(cpuinfo, data);
 109         u64 now_idle;
 110         unsigned int new_freq;
 111         unsigned int index;
 112         unsigned long flags;
 113
 114         smp_rmb();
 115
 116         if (!pcpu->governor_enabled)
 117                 goto exit;
 118
 119         /*
 120          * Once pcpu->timer_run_time is updated to >= pcpu->idle_exit_time,
 121          * this lets idle exit know the current idle time sample has
 122          * been processed, and idle exit can generate a new sample and
 123          * re-arm the timer.  This prevents a concurrent idle
 124          * exit on that CPU from writing a new set of info at the same time
 125          * the timer function runs (the timer function can't use that info
 126          * until more time passes).
 127          */
 128         time_in_idle = pcpu->time_in_idle;
 129         idle_exit_time = pcpu->idle_exit_time;
 130         now_idle = get_cpu_idle_time_us(data, &pcpu->timer_run_time);
 131         smp_wmb();
 132
 133         /* If we raced with cancelling a timer, skip. */
 134         if (!idle_exit_time)
 135                 goto exit;
 136
 137         delta_idle = (unsigned int)(now_idle - time_in_idle);
 138         delta_time = (unsigned int)(pcpu->timer_run_time - idle_exit_time);
 139
 140         /*
 141          * If timer ran less than 1ms after short-term sample started, retry.
 142          */
 143         if (delta_time < 1000)
 144                 goto rearm;
 145
 146         if (delta_idle > delta_time)
 147                 cpu_load = 0;
 148         else
 149                 cpu_load = 100 * (delta_time - delta_idle) / delta_time;
 150
 151         delta_idle = (unsigned int)(now_idle - pcpu->freq_change_time_in_idle);
 152         delta_time = (unsigned int)(pcpu->timer_run_time - pcpu->freq_change_time);
 153
 154         if ((delta_time == 0) || (delta_idle > delta_time))
 155                 load_since_change = 0;
 156         else
 157                 load_since_change =
 158                         100 * (delta_time - delta_idle) / delta_time;
 159
 160         /*
 161          * Choose greater of short-term load (since last idle timer
 162          * started or timer function re-armed itself) or long-term load
 163          * (since last frequency change).
 164          */
 165         if (load_since_change > cpu_load)
 166                 cpu_load = load_since_change;
 167
 168         if (cpu_load >= go_hispeed_load) {
 169                 if (pcpu->policy->cur == pcpu->policy->min)
 170                         new_freq = hispeed_freq;
 171                 else
 172                         new_freq = pcpu->policy->max * cpu_load / 100;
 173         } else {
 174                 new_freq = pcpu->policy->cur * cpu_load / 100;
 175         }
 176
 177         if (cpufreq_frequency_table_target(pcpu->policy, pcpu->freq_table,
 178                                            new_freq, CPUFREQ_RELATION_H,
 179                                            &index)) {
 180                 pr_warn_once("timer %d: cpufreq_frequency_table_target error\n",
 181                              (int) data);
 182                 goto rearm;
 183         }
 184
 185         new_freq = pcpu->freq_table[index].frequency;
 186
 187         if (pcpu->target_freq == new_freq)
 188         {
 189                 trace_cpufreq_interactive_already(data, cpu_load,
 190                                                   pcpu->target_freq, new_freq);
 191                 goto rearm_if_notmax;
 192         }
 193
 194         /*
 195          * Do not scale down unless we have been at this frequency for the
 196          * minimum sample time.
 197          */
 198         if (new_freq < pcpu->target_freq) {
 199                 if (pcpu->timer_run_time - pcpu->freq_change_time
 200                     < min_sample_time) {
 201                         trace_cpufreq_interactive_notyet(data, cpu_load,
 202                                          pcpu->target_freq, new_freq);
 203                         goto rearm;
 204                 }
 205         }
 206
 207         trace_cpufreq_interactive_target(data, cpu_load, pcpu->target_freq,
 208                                          new_freq);
 209
 210         if (new_freq < pcpu->target_freq) {
 211                 pcpu->target_freq = new_freq;
 212                 spin_lock_irqsave(&down_cpumask_lock, flags);
 213                 cpumask_set_cpu(data, &down_cpumask);
 214                 spin_unlock_irqrestore(&down_cpumask_lock, flags);
 215                 queue_work(down_wq, &freq_scale_down_work);
 216         } else {
 217                 pcpu->target_freq = new_freq;
 218                 spin_lock_irqsave(&up_cpumask_lock, flags);
 219                 cpumask_set_cpu(data, &up_cpumask);
 220                 spin_unlock_irqrestore(&up_cpumask_lock, flags);
 221                 wake_up_process(up_task);
 222         }
 223
 224 rearm_if_notmax:
 225         /*
 226          * Already set max speed and don't see a need to change that,
 227          * wait until next idle to re-evaluate, don't need timer.
 228          */
 229         if (pcpu->target_freq == pcpu->policy->max)
 230                 goto exit;
 231
 232 rearm:
 233         if (!timer_pending(&pcpu->cpu_timer)) {
 234                 /*
 235                  * If already at min: if that CPU is idle, don't set timer.
 236                  * Else cancel the timer if that CPU goes idle.  We don't
 237                  * need to re-evaluate speed until the next idle exit.
 238                  */
 239                 if (pcpu->target_freq == pcpu->policy->min) {
 240                         smp_rmb();
 241
 242                         if (pcpu->idling)
 243                                 goto exit;
 244
 245                         pcpu->timer_idlecancel = 1;
 246                 }
 247
 248                 pcpu->time_in_idle = get_cpu_idle_time_us(
 249                         data, &pcpu->idle_exit_time);
 250                 mod_timer(&pcpu->cpu_timer,
 251                           jiffies + usecs_to_jiffies(timer_rate));
 252         }
 253
 254 exit:
 255         return;
 256 }
 257
 258 static void cpufreq_interactive_idle_start(void)
 259 {
 260         struct cpufreq_interactive_cpuinfo *pcpu =
 261                 &per_cpu(cpuinfo, smp_processor_id());
 262         int pending;
 263
 264         if (!pcpu->governor_enabled)
 265                 return;
 266
 267         pcpu->idling = 1;
 268         smp_wmb();
 269         pending = timer_pending(&pcpu->cpu_timer);
 270
 271         if (pcpu->target_freq != pcpu->policy->min) {
 272 #ifdef CONFIG_SMP
 273                 /*
 274                  * Entering idle while not at lowest speed.  On some
 275                  * platforms this can hold the other CPU(s) at that speed
 276                  * even though the CPU is idle. Set a timer to re-evaluate
 277                  * speed so this idle CPU doesn't hold the other CPUs above
 278                  * min indefinitely.  This should probably be a quirk of
 279                  * the CPUFreq driver.
 280                  */
 281                 if (!pending) {
 282                         pcpu->time_in_idle = get_cpu_idle_time_us(
 283                                 smp_processor_id(), &pcpu->idle_exit_time);
 284                         pcpu->timer_idlecancel = 0;
 285                         mod_timer(&pcpu->cpu_timer,
 286                                   jiffies + usecs_to_jiffies(timer_rate));
 287                 }
 288 #endif
 289         } else {
 290                 /*
 291                  * If at min speed and entering idle after load has
 292                  * already been evaluated, and a timer has been set just in
 293                  * case the CPU suddenly goes busy, cancel that timer.  The
 294                  * CPU didn't go busy; we'll recheck things upon idle exit.
 295                  */
 296                 if (pending && pcpu->timer_idlecancel) {
 297                         del_timer(&pcpu->cpu_timer);
 298                         /*
 299                          * Ensure last timer run time is after current idle
 300                          * sample start time, so next idle exit will always
 301                          * start a new idle sampling period.
 302                          */
 303                         pcpu->idle_exit_time = 0;
 304                         pcpu->timer_idlecancel = 0;
 305                 }
 306         }
 307
 308 }
 309
 310 static void cpufreq_interactive_idle_end(void)
 311 {
 312         struct cpufreq_interactive_cpuinfo *pcpu =
 313                 &per_cpu(cpuinfo, smp_processor_id());
 314
 315         pcpu->idling = 0;
 316         smp_wmb();
 317
 318         /*
 319          * Arm the timer for 1-2 ticks later if not already, and if the timer
 320          * function has already processed the previous load sampling
 321          * interval.  (If the timer is not pending but has not processed
 322          * the previous interval, it is probably racing with us on another
 323          * CPU.  Let it compute load based on the previous sample and then
 324          * re-arm the timer for another interval when it's done, rather
 325          * than updating the interval start time to be "now", which doesn't
 326          * give the timer function enough time to make a decision on this
 327          * run.)
 328          */
 329         if (timer_pending(&pcpu->cpu_timer) == 0 &&
 330             pcpu->timer_run_time >= pcpu->idle_exit_time &&
 331             pcpu->governor_enabled) {
 332                 pcpu->time_in_idle =
 333                         get_cpu_idle_time_us(smp_processor_id(),
 334                                              &pcpu->idle_exit_time);
 335                 pcpu->timer_idlecancel = 0;
 336                 mod_timer(&pcpu->cpu_timer,
 337                           jiffies + usecs_to_jiffies(timer_rate));
 338         }
 339
 340 }
 341
 342 static int cpufreq_interactive_up_task(void *data)
 343 {
 344         unsigned int cpu;
 345         cpumask_t tmp_mask;
 346         unsigned long flags;
 347         struct cpufreq_interactive_cpuinfo *pcpu;
 348
 349         while (1) {
 350                 set_current_state(TASK_INTERRUPTIBLE);
 351                 spin_lock_irqsave(&up_cpumask_lock, flags);
 352
 353                 if (cpumask_empty(&up_cpumask)) {
 354                         spin_unlock_irqrestore(&up_cpumask_lock, flags);
 355                         schedule();
 356
 357                         if (kthread_should_stop())
 358                                 break;
 359
 360                         spin_lock_irqsave(&up_cpumask_lock, flags);
 361                 }
 362
 363                 set_current_state(TASK_RUNNING);
 364                 tmp_mask = up_cpumask;
 365                 cpumask_clear(&up_cpumask);
 366                 spin_unlock_irqrestore(&up_cpumask_lock, flags);
 367
 368                 for_each_cpu(cpu, &tmp_mask) {
 369                         unsigned int j;
 370                         unsigned int max_freq = 0;
 371
 372                         pcpu = &per_cpu(cpuinfo, cpu);
 373                         smp_rmb();
 374
 375                         if (!pcpu->governor_enabled)
 376                                 continue;
 377
 378                         mutex_lock(&set_speed_lock);
 379
 380                         for_each_cpu(j, pcpu->policy->cpus) {
 381                                 struct cpufreq_interactive_cpuinfo *pjcpu =
 382                                         &per_cpu(cpuinfo, j);
 383
 384                                 if (pjcpu->target_freq > max_freq)
 385                                         max_freq = pjcpu->target_freq;
 386                         }
 387
 388                         if (max_freq != pcpu->policy->cur)
 389                                 __cpufreq_driver_target(pcpu->policy,
 390                                                         max_freq,
 391                                                         CPUFREQ_RELATION_H);
 392                         mutex_unlock(&set_speed_lock);
 393
 394                         pcpu->freq_change_time_in_idle =
 395                                 get_cpu_idle_time_us(cpu,
 396                                                      &pcpu->freq_change_time);
 397                         trace_cpufreq_interactive_up(cpu, pcpu->target_freq,
 398                                                      pcpu->policy->cur);
 399                 }
 400         }
 401
 402         return 0;
 403 }
 404
 405 static void cpufreq_interactive_freq_down(struct work_struct *work)
 406 {
 407         unsigned int cpu;
 408         cpumask_t tmp_mask;
 409         unsigned long flags;
 410         struct cpufreq_interactive_cpuinfo *pcpu;
 411
 412         spin_lock_irqsave(&down_cpumask_lock, flags);
 413         tmp_mask = down_cpumask;
 414         cpumask_clear(&down_cpumask);
 415         spin_unlock_irqrestore(&down_cpumask_lock, flags);
 416
 417         for_each_cpu(cpu, &tmp_mask) {
 418                 unsigned int j;
 419                 unsigned int max_freq = 0;
 420
 421                 pcpu = &per_cpu(cpuinfo, cpu);
 422                 smp_rmb();
 423
 424                 if (!pcpu->governor_enabled)
 425                         continue;
 426
 427                 mutex_lock(&set_speed_lock);
 428
 429                 for_each_cpu(j, pcpu->policy->cpus) {
 430                         struct cpufreq_interactive_cpuinfo *pjcpu =
 431                                 &per_cpu(cpuinfo, j);
 432
 433                         if (pjcpu->target_freq > max_freq)
 434                                 max_freq = pjcpu->target_freq;
 435                 }
 436
 437                 if (max_freq != pcpu->policy->cur)
 438                         __cpufreq_driver_target(pcpu->policy, max_freq,
 439                                                 CPUFREQ_RELATION_H);
 440
 441                 mutex_unlock(&set_speed_lock);
 442                 pcpu->freq_change_time_in_idle =
 443                         get_cpu_idle_time_us(cpu,
 444                                              &pcpu->freq_change_time);
 445                 trace_cpufreq_interactive_down(cpu, pcpu->target_freq,
 446                                                pcpu->policy->cur);
 447         }
 448 }
 449
 450 static ssize_t show_hispeed_freq(struct kobject *kobj,
 451                                  struct attribute *attr, char *buf)
 452 {
 453         return sprintf(buf, "%llu\n", hispeed_freq);
 454 }
 455
 456 static ssize_t store_hispeed_freq(struct kobject *kobj,
 457                                   struct attribute *attr, const char *buf,
 458                                   size_t count)
 459 {
 460         int ret;
 461         u64 val;
 462
 463         ret = strict_strtoull(buf, 0, &val);
 464         if (ret < 0)
 465                 return ret;
 466         hispeed_freq = val;
 467         return count;
 468 }
 469
 470 static struct global_attr hispeed_freq_attr = __ATTR(hispeed_freq, 0644,
 471                 show_hispeed_freq, store_hispeed_freq);
 472
 473
 474 static ssize_t show_go_hispeed_load(struct kobject *kobj,
 475                                      struct attribute *attr, char *buf)
 476 {
 477         return sprintf(buf, "%lu\n", go_hispeed_load);
 478 }
 479
 480 static ssize_t store_go_hispeed_load(struct kobject *kobj,
 481                         struct attribute *attr, const char *buf, size_t count)
 482 {
 483         int ret;
 484         unsigned long val;
 485
 486         ret = strict_strtoul(buf, 0, &val);
 487         if (ret < 0)
 488                 return ret;
 489         go_hispeed_load = val;
 490         return count;
 491 }
 492
 493 static struct global_attr go_hispeed_load_attr = __ATTR(go_hispeed_load, 0644,
 494                 show_go_hispeed_load, store_go_hispeed_load);
 495
 496 static ssize_t show_min_sample_time(struct kobject *kobj,
 497                                 struct attribute *attr, char *buf)
 498 {
 499         return sprintf(buf, "%lu\n", min_sample_time);
 500 }
 501
 502 static ssize_t store_min_sample_time(struct kobject *kobj,
 503                         struct attribute *attr, const char *buf, size_t count)
 504 {
 505         int ret;
 506         unsigned long val;
 507
 508         ret = strict_strtoul(buf, 0, &val);
 509         if (ret < 0)
 510                 return ret;
 511         min_sample_time = val;
 512         return count;
 513 }
 514
 515 static struct global_attr min_sample_time_attr = __ATTR(min_sample_time, 0644,
 516                 show_min_sample_time, store_min_sample_time);
 517
 518 static ssize_t show_timer_rate(struct kobject *kobj,
 519                         struct attribute *attr, char *buf)
 520 {
 521         return sprintf(buf, "%lu\n", timer_rate);
 522 }
 523
 524 static ssize_t store_timer_rate(struct kobject *kobj,
 525                         struct attribute *attr, const char *buf, size_t count)
 526 {
 527         int ret;
 528         unsigned long val;
 529
 530         ret = strict_strtoul(buf, 0, &val);
 531         if (ret < 0)
 532                 return ret;
 533         timer_rate = val;
 534         return count;
 535 }
 536
 537 static struct global_attr timer_rate_attr = __ATTR(timer_rate, 0644,
 538                 show_timer_rate, store_timer_rate);
 539
 540 static struct attribute *interactive_attributes[] = {
 541         &hispeed_freq_attr.attr,
 542         &go_hispeed_load_attr.attr,
 543         &min_sample_time_attr.attr,
 544         &timer_rate_attr.attr,
 545         NULL,
 546 };
 547
 548 static struct attribute_group interactive_attr_group = {
 549         .attrs = interactive_attributes,
 550         .name = "interactive",
 551 };
 552
 553 static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
 554                 unsigned int event)
 555 {
 556         int rc;
 557         unsigned int j;
 558         struct cpufreq_interactive_cpuinfo *pcpu;
 559         struct cpufreq_frequency_table *freq_table;
 560
 561         switch (event) {
 562         case CPUFREQ_GOV_START:
 563                 if (!cpu_online(policy->cpu))
 564                         return -EINVAL;
 565
 566                 freq_table =
 567                         cpufreq_frequency_get_table(policy->cpu);
 568
 569                 for_each_cpu(j, policy->cpus) {
 570                         pcpu = &per_cpu(cpuinfo, j);
 571                         pcpu->policy = policy;
 572                         pcpu->target_freq = policy->cur;
 573                         pcpu->freq_table = freq_table;
 574                         pcpu->freq_change_time_in_idle =
 575                                 get_cpu_idle_time_us(j,
 576                                              &pcpu->freq_change_time);
 577                         pcpu->governor_enabled = 1;
 578                         smp_wmb();
 579                 }
 580
 581                 if (!hispeed_freq)
 582                         hispeed_freq = policy->max;
 583
 584                 /*
 585                  * Do not register the idle hook and create sysfs
 586                  * entries if we have already done so.
 587                  */
 588                 if (atomic_inc_return(&active_count) > 1)
 589                         return 0;
 590
 591                 rc = sysfs_create_group(cpufreq_global_kobject,
 592                                 &interactive_attr_group);
 593                 if (rc)
 594                         return rc;
 595
 596                 break;
 597
 598         case CPUFREQ_GOV_STOP:
 599                 for_each_cpu(j, policy->cpus) {
 600                         pcpu = &per_cpu(cpuinfo, j);
 601                         pcpu->governor_enabled = 0;
 602                         smp_wmb();
 603                         del_timer_sync(&pcpu->cpu_timer);
 604
 605                         /*
 606                          * Reset idle exit time since we may cancel the timer
 607                          * before it can run after the last idle exit time,
 608                          * to avoid tripping the check in idle exit for a timer
 609                          * that is trying to run.
 610                          */
 611                         pcpu->idle_exit_time = 0;
 612                 }
 613
 614                 flush_work(&freq_scale_down_work);
 615                 if (atomic_dec_return(&active_count) > 0)
 616                         return 0;
 617
 618                 sysfs_remove_group(cpufreq_global_kobject,
 619                                 &interactive_attr_group);
 620
 621                 break;
 622
 623         case CPUFREQ_GOV_LIMITS:
 624                 if (policy->max < policy->cur)
 625                         __cpufreq_driver_target(policy,
 626                                         policy->max, CPUFREQ_RELATION_H);
 627                 else if (policy->min > policy->cur)
 628                         __cpufreq_driver_target(policy,
 629                                         policy->min, CPUFREQ_RELATION_L);
 630                 break;
 631         }
 632         return 0;
 633 }
 634
 635 static int cpufreq_interactive_idle_notifier(struct notifier_block *nb,
 636                                              unsigned long val,
 637                                              void *data)
 638 {
 639         switch (val) {
 640         case IDLE_START:
 641                 cpufreq_interactive_idle_start();
 642                 break;
 643         case IDLE_END:
 644                 cpufreq_interactive_idle_end();
 645                 break;
 646         }
 647
 648         return 0;
 649 }
 650
 651 static struct notifier_block cpufreq_interactive_idle_nb = {
 652         .notifier_call = cpufreq_interactive_idle_notifier,
 653 };
 654
 655 static int __init cpufreq_interactive_init(void)
 656 {
 657         unsigned int i;
 658         struct cpufreq_interactive_cpuinfo *pcpu;
 659         struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
 660
 661         go_hispeed_load = DEFAULT_GO_HISPEED_LOAD;
 662         min_sample_time = DEFAULT_MIN_SAMPLE_TIME;
 663         timer_rate = DEFAULT_TIMER_RATE;
 664
 665         /* Initalize per-cpu timers */
 666         for_each_possible_cpu(i) {
 667                 pcpu = &per_cpu(cpuinfo, i);
 668                 init_timer(&pcpu->cpu_timer);
 669                 pcpu->cpu_timer.function = cpufreq_interactive_timer;
 670                 pcpu->cpu_timer.data = i;
 671         }
 672
 673         up_task = kthread_create(cpufreq_interactive_up_task, NULL,
 674                                  "kinteractiveup");
 675         if (IS_ERR(up_task))
 676                 return PTR_ERR(up_task);
 677
 678         sched_setscheduler_nocheck(up_task, SCHED_FIFO, &param);
 679         get_task_struct(up_task);
 680
 681         /* No rescuer thread, bind to CPU queuing the work for possibly
 682            warm cache (probably doesn't matter much). */
 683         down_wq = alloc_workqueue("knteractive_down", 0, 1);
 684
 685         if (!down_wq)
 686                 goto err_freeuptask;
 687
 688         INIT_WORK(&freq_scale_down_work,
 689                   cpufreq_interactive_freq_down);
 690
 691         spin_lock_init(&up_cpumask_lock);
 692         spin_lock_init(&down_cpumask_lock);
 693         mutex_init(&set_speed_lock);
 694
 695         idle_notifier_register(&cpufreq_interactive_idle_nb);
 696
 697         return cpufreq_register_governor(&cpufreq_gov_interactive);
 698
 699 err_freeuptask:
 700         put_task_struct(up_task);
 701         return -ENOMEM;
 702 }
 703
 704 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_INTERACTIVE
 705 fs_initcall(cpufreq_interactive_init);
 706 #else
 707 module_init(cpufreq_interactive_init);
 708 #endif
 709
 710 static void __exit cpufreq_interactive_exit(void)
 711 {
 712         cpufreq_unregister_governor(&cpufreq_gov_interactive);
 713         kthread_stop(up_task);
 714         put_task_struct(up_task);
 715         destroy_workqueue(down_wq);
 716 }
 717
 718 module_exit(cpufreq_interactive_exit);
 719
 720 MODULE_AUTHOR("Mike Chan <mike@android.com>");
 721 MODULE_DESCRIPTION("'cpufreq_interactive' - A cpufreq governor for "
 722         "Latency sensitive workloads");
 723 MODULE_LICENSE("GPL");