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/moduleparam.h>
  24 #include <linux/mutex.h>
  25 #include <linux/sched.h>
  26 #include <linux/sched/rt.h>
  27 #include <linux/tick.h>
  28 #include <linux/time.h>
  29 #include <linux/timer.h>
  30 #include <linux/workqueue.h>
  31 #include <linux/kthread.h>
  32 #include <linux/mutex.h>
  33 #include <linux/slab.h>
  34 #include <asm/cputime.h>
  35
  36 #define CREATE_TRACE_POINTS
  37 #include <trace/events/cpufreq_interactive.h>
  38
  39 static atomic_t active_count = ATOMIC_INIT(0);
  40
  41 struct cpufreq_interactive_cpuinfo {
  42         struct timer_list cpu_timer;
  43         int timer_idlecancel;
  44         u64 time_in_idle;
  45         u64 time_in_idle_timestamp;
  46         u64 target_set_time;
  47         u64 target_set_time_in_idle;
  48         struct cpufreq_policy *policy;
  49         struct cpufreq_frequency_table *freq_table;
  50         unsigned int target_freq;
  51         unsigned int floor_freq;
  52         u64 floor_validate_time;
  53         u64 hispeed_validate_time;
  54         int governor_enabled;
  55 };
  56
  57 static DEFINE_PER_CPU(struct cpufreq_interactive_cpuinfo, cpuinfo);
  58
  59 /* realtime thread handles frequency scaling */
  60 static struct task_struct *speedchange_task;
  61 static cpumask_t speedchange_cpumask;
  62 static spinlock_t speedchange_cpumask_lock;
  63
  64 /* Hi speed to bump to from lo speed when load burst (default max) */
  65 static unsigned int hispeed_freq;
  66
  67 /* Go to hi speed when CPU load at or above this value. */
  68 #define DEFAULT_GO_HISPEED_LOAD 85
  69 static unsigned long go_hispeed_load;
  70
  71 /*
  72  * The minimum amount of time to spend at a frequency before we can ramp down.
  73  */
  74 #define DEFAULT_MIN_SAMPLE_TIME (80 * USEC_PER_MSEC)
  75 static unsigned long min_sample_time;
  76
  77 /*
  78  * The sample rate of the timer used to increase frequency
  79  */
  80 #define DEFAULT_TIMER_RATE (20 * USEC_PER_MSEC)
  81 static unsigned long timer_rate;
  82
  83 /*
  84  * Wait this long before raising speed above hispeed, by default a single
  85  * timer interval.
  86  */
  87 #define DEFAULT_ABOVE_HISPEED_DELAY DEFAULT_TIMER_RATE
  88 static unsigned long above_hispeed_delay_val;
  89
  90 /*
  91  * Non-zero means longer-term speed boost active.
  92  */
  93
  94 static int boost_val;
  95
  96 static bool governidle;
  97 module_param(governidle, bool, S_IWUSR | S_IRUGO);
  98 MODULE_PARM_DESC(governidle,
  99         "Set to 1 to wake up CPUs from idle to reduce speed (default 0)");
 100
 101 static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
 102                 unsigned int event);
 103
 104 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_INTERACTIVE
 105 static
 106 #endif
 107 struct cpufreq_governor cpufreq_gov_interactive = {
 108         .name = "interactive",
 109         .governor = cpufreq_governor_interactive,
 110         .max_transition_latency = 10000000,
 111         .owner = THIS_MODULE,
 112 };
 113
 114 static void cpufreq_interactive_timer_resched(
 115         struct cpufreq_interactive_cpuinfo *pcpu)
 116 {
 117         mod_timer_pinned(&pcpu->cpu_timer,
 118                          jiffies + usecs_to_jiffies(timer_rate));
 119         pcpu->time_in_idle =
 120                 get_cpu_idle_time_us(smp_processor_id(),
 121                                      &pcpu->time_in_idle_timestamp);
 122 }
 123
 124 static void cpufreq_interactive_timer(unsigned long data)
 125 {
 126         u64 now;
 127         unsigned int delta_idle;
 128         unsigned int delta_time;
 129         int cpu_load;
 130         int load_since_change;
 131         struct cpufreq_interactive_cpuinfo *pcpu =
 132                 &per_cpu(cpuinfo, data);
 133         u64 now_idle;
 134         unsigned int new_freq;
 135         unsigned int index;
 136         unsigned long flags;
 137
 138         smp_rmb();
 139
 140         if (!pcpu->governor_enabled)
 141                 goto exit;
 142
 143         now_idle = get_cpu_idle_time_us(data, &now);
 144         delta_idle = (unsigned int)(now_idle - pcpu->time_in_idle);
 145         delta_time = (unsigned int)(now - pcpu->time_in_idle_timestamp);
 146
 147         /*
 148          * If timer ran less than 1ms after short-term sample started, retry.
 149          */
 150         if (delta_time < 1000)
 151                 goto rearm;
 152
 153         if (delta_idle > delta_time)
 154                 cpu_load = 0;
 155         else
 156                 cpu_load = 100 * (delta_time - delta_idle) / delta_time;
 157
 158         delta_idle = (unsigned int)(now_idle - pcpu->target_set_time_in_idle);
 159         delta_time = (unsigned int)(now - pcpu->target_set_time);
 160
 161         if ((delta_time == 0) || (delta_idle > delta_time))
 162                 load_since_change = 0;
 163         else
 164                 load_since_change =
 165                         100 * (delta_time - delta_idle) / delta_time;
 166
 167         /*
 168          * Choose greater of short-term load (since last idle timer
 169          * started or timer function re-armed itself) or long-term load
 170          * (since last frequency change).
 171          */
 172         if (load_since_change > cpu_load)
 173                 cpu_load = load_since_change;
 174
 175         if (cpu_load >= go_hispeed_load || boost_val) {
 176                 if (pcpu->target_freq < hispeed_freq &&
 177                     hispeed_freq < pcpu->policy->max) {
 178                         new_freq = hispeed_freq;
 179                 } else {
 180                         new_freq = pcpu->policy->max * cpu_load / 100;
 181
 182                         if (new_freq < hispeed_freq)
 183                                 new_freq = hispeed_freq;
 184
 185                         if (pcpu->target_freq == hispeed_freq &&
 186                             new_freq > hispeed_freq &&
 187                             now - pcpu->hispeed_validate_time
 188                             < above_hispeed_delay_val) {
 189                                 trace_cpufreq_interactive_notyet(data, cpu_load,
 190                                                                  pcpu->target_freq,
 191                                                                  new_freq);
 192                                 goto rearm;
 193                         }
 194                 }
 195         } else {
 196                 new_freq = hispeed_freq * cpu_load / 100;
 197         }
 198
 199         if (new_freq <= hispeed_freq)
 200                 pcpu->hispeed_validate_time = now;
 201
 202         if (cpufreq_frequency_table_target(pcpu->policy, pcpu->freq_table,
 203                                            new_freq, CPUFREQ_RELATION_H,
 204                                            &index)) {
 205                 pr_warn_once("timer %d: cpufreq_frequency_table_target error\n",
 206                              (int) data);
 207                 goto rearm;
 208         }
 209
 210         new_freq = pcpu->freq_table[index].frequency;
 211
 212         /*
 213          * Do not scale below floor_freq unless we have been at or above the
 214          * floor frequency for the minimum sample time since last validated.
 215          */
 216         if (new_freq < pcpu->floor_freq) {
 217                 if (now - pcpu->floor_validate_time < min_sample_time) {
 218                         trace_cpufreq_interactive_notyet(data, cpu_load,
 219                                          pcpu->target_freq, new_freq);
 220                         goto rearm;
 221                 }
 222         }
 223
 224         pcpu->floor_freq = new_freq;
 225         pcpu->floor_validate_time = now;
 226
 227         if (pcpu->target_freq == new_freq) {
 228                 trace_cpufreq_interactive_already(data, cpu_load,
 229                                                   pcpu->target_freq, new_freq);
 230                 goto rearm_if_notmax;
 231         }
 232
 233         trace_cpufreq_interactive_target(data, cpu_load, pcpu->target_freq,
 234                                          new_freq);
 235         pcpu->target_set_time_in_idle = now_idle;
 236         pcpu->target_set_time = now;
 237
 238         pcpu->target_freq = new_freq;
 239         spin_lock_irqsave(&speedchange_cpumask_lock, flags);
 240         cpumask_set_cpu(data, &speedchange_cpumask);
 241         spin_unlock_irqrestore(&speedchange_cpumask_lock, flags);
 242         wake_up_process(speedchange_task);
 243
 244 rearm_if_notmax:
 245         /*
 246          * Already set max speed and don't see a need to change that,
 247          * wait until next idle to re-evaluate, don't need timer.
 248          */
 249         if (pcpu->target_freq == pcpu->policy->max)
 250                 goto exit;
 251
 252 rearm:
 253         if (!timer_pending(&pcpu->cpu_timer)) {
 254                 /*
 255                  * If governing speed in idle and already at min, cancel the
 256                  * timer if that CPU goes idle.  We don't need to re-evaluate
 257                  * speed until the next idle exit.
 258                  */
 259                 if (governidle && pcpu->target_freq == pcpu->policy->min)
 260                         pcpu->timer_idlecancel = 1;
 261
 262                 cpufreq_interactive_timer_resched(pcpu);
 263         }
 264
 265 exit:
 266         return;
 267 }
 268
 269 static void cpufreq_interactive_idle_start(void)
 270 {
 271         struct cpufreq_interactive_cpuinfo *pcpu =
 272                 &per_cpu(cpuinfo, smp_processor_id());
 273         int pending;
 274
 275         if (!pcpu->governor_enabled)
 276                 return;
 277
 278         pending = timer_pending(&pcpu->cpu_timer);
 279
 280         if (pcpu->target_freq != pcpu->policy->min) {
 281                 /*
 282                  * Entering idle while not at lowest speed.  On some
 283                  * platforms this can hold the other CPU(s) at that speed
 284                  * even though the CPU is idle. Set a timer to re-evaluate
 285                  * speed so this idle CPU doesn't hold the other CPUs above
 286                  * min indefinitely.  This should probably be a quirk of
 287                  * the CPUFreq driver.
 288                  */
 289                 if (!pending) {
 290                         pcpu->timer_idlecancel = 0;
 291                         cpufreq_interactive_timer_resched(pcpu);
 292                 }
 293         } else if (governidle) {
 294                 /*
 295                  * If at min speed and entering idle after load has
 296                  * already been evaluated, and a timer has been set just in
 297                  * case the CPU suddenly goes busy, cancel that timer.  The
 298                  * CPU didn't go busy; we'll recheck things upon idle exit.
 299                  */
 300                 if (pending && pcpu->timer_idlecancel) {
 301                         del_timer(&pcpu->cpu_timer);
 302                         pcpu->timer_idlecancel = 0;
 303                 }
 304         }
 305
 306 }
 307
 308 static void cpufreq_interactive_idle_end(void)
 309 {
 310         struct cpufreq_interactive_cpuinfo *pcpu =
 311                 &per_cpu(cpuinfo, smp_processor_id());
 312
 313         if (!pcpu->governor_enabled)
 314                 return;
 315
 316         /* Arm the timer for 1-2 ticks later if not already. */
 317         if (!timer_pending(&pcpu->cpu_timer)) {
 318                 pcpu->timer_idlecancel = 0;
 319                 cpufreq_interactive_timer_resched(pcpu);
 320         } else if (!governidle &&
 321                    time_after_eq(jiffies, pcpu->cpu_timer.expires)) {
 322                 del_timer(&pcpu->cpu_timer);
 323                 cpufreq_interactive_timer(smp_processor_id());
 324         }
 325 }
 326
 327 static int cpufreq_interactive_speedchange_task(void *data)
 328 {
 329         unsigned int cpu;
 330         cpumask_t tmp_mask;
 331         unsigned long flags;
 332         struct cpufreq_interactive_cpuinfo *pcpu;
 333
 334         while (1) {
 335                 set_current_state(TASK_INTERRUPTIBLE);
 336                 spin_lock_irqsave(&speedchange_cpumask_lock, flags);
 337
 338                 if (cpumask_empty(&speedchange_cpumask)) {
 339                         spin_unlock_irqrestore(&speedchange_cpumask_lock,
 340                                                flags);
 341                         schedule();
 342
 343                         if (kthread_should_stop())
 344                                 break;
 345
 346                         spin_lock_irqsave(&speedchange_cpumask_lock, flags);
 347                 }
 348
 349                 set_current_state(TASK_RUNNING);
 350                 tmp_mask = speedchange_cpumask;
 351                 cpumask_clear(&speedchange_cpumask);
 352                 spin_unlock_irqrestore(&speedchange_cpumask_lock, flags);
 353
 354                 for_each_cpu(cpu, &tmp_mask) {
 355                         unsigned int j;
 356                         unsigned int max_freq = 0;
 357
 358                         pcpu = &per_cpu(cpuinfo, cpu);
 359                         smp_rmb();
 360
 361                         if (!pcpu->governor_enabled)
 362                                 continue;
 363
 364                         for_each_cpu(j, pcpu->policy->cpus) {
 365                                 struct cpufreq_interactive_cpuinfo *pjcpu =
 366                                         &per_cpu(cpuinfo, j);
 367
 368                                 if (pjcpu->target_freq > max_freq)
 369                                         max_freq = pjcpu->target_freq;
 370                         }
 371
 372                         if (max_freq != pcpu->policy->cur)
 373                                 __cpufreq_driver_target(pcpu->policy,
 374                                                         max_freq,
 375                                                         CPUFREQ_RELATION_H);
 376                         trace_cpufreq_interactive_setspeed(cpu,
 377                                                      pcpu->target_freq,
 378                                                      pcpu->policy->cur);
 379                 }
 380         }
 381
 382         return 0;
 383 }
 384
 385 static void cpufreq_interactive_boost(void)
 386 {
 387         int i;
 388         int anyboost = 0;
 389         unsigned long flags;
 390         struct cpufreq_interactive_cpuinfo *pcpu;
 391
 392         spin_lock_irqsave(&speedchange_cpumask_lock, flags);
 393
 394         for_each_online_cpu(i) {
 395                 pcpu = &per_cpu(cpuinfo, i);
 396
 397                 if (pcpu->target_freq < hispeed_freq) {
 398                         pcpu->target_freq = hispeed_freq;
 399                         cpumask_set_cpu(i, &speedchange_cpumask);
 400                         pcpu->target_set_time_in_idle =
 401                                 get_cpu_idle_time_us(i, &pcpu->target_set_time);
 402                         pcpu->hispeed_validate_time = pcpu->target_set_time;
 403                         anyboost = 1;
 404                 }
 405
 406                 /*
 407                  * Set floor freq and (re)start timer for when last
 408                  * validated.
 409                  */
 410
 411                 pcpu->floor_freq = hispeed_freq;
 412                 pcpu->floor_validate_time = ktime_to_us(ktime_get());
 413         }
 414
 415         spin_unlock_irqrestore(&speedchange_cpumask_lock, flags);
 416
 417         if (anyboost)
 418                 wake_up_process(speedchange_task);
 419 }
 420
 421 static ssize_t show_hispeed_freq(struct kobject *kobj,
 422                                  struct attribute *attr, char *buf)
 423 {
 424         return sprintf(buf, "%u\n", hispeed_freq);
 425 }
 426
 427 static ssize_t store_hispeed_freq(struct kobject *kobj,
 428                                   struct attribute *attr, const char *buf,
 429                                   size_t count)
 430 {
 431         int ret;
 432         long unsigned int val;
 433
 434         ret = strict_strtoul(buf, 0, &val);
 435         if (ret < 0)
 436                 return ret;
 437         hispeed_freq = val;
 438         return count;
 439 }
 440
 441 static struct global_attr hispeed_freq_attr = __ATTR(hispeed_freq, 0644,
 442                 show_hispeed_freq, store_hispeed_freq);
 443
 444
 445 static ssize_t show_go_hispeed_load(struct kobject *kobj,
 446                                      struct attribute *attr, char *buf)
 447 {
 448         return sprintf(buf, "%lu\n", go_hispeed_load);
 449 }
 450
 451 static ssize_t store_go_hispeed_load(struct kobject *kobj,
 452                         struct attribute *attr, const char *buf, size_t count)
 453 {
 454         int ret;
 455         unsigned long val;
 456
 457         ret = strict_strtoul(buf, 0, &val);
 458         if (ret < 0)
 459                 return ret;
 460         go_hispeed_load = val;
 461         return count;
 462 }
 463
 464 static struct global_attr go_hispeed_load_attr = __ATTR(go_hispeed_load, 0644,
 465                 show_go_hispeed_load, store_go_hispeed_load);
 466
 467 static ssize_t show_min_sample_time(struct kobject *kobj,
 468                                 struct attribute *attr, char *buf)
 469 {
 470         return sprintf(buf, "%lu\n", min_sample_time);
 471 }
 472
 473 static ssize_t store_min_sample_time(struct kobject *kobj,
 474                         struct attribute *attr, const char *buf, size_t count)
 475 {
 476         int ret;
 477         unsigned long val;
 478
 479         ret = strict_strtoul(buf, 0, &val);
 480         if (ret < 0)
 481                 return ret;
 482         min_sample_time = val;
 483         return count;
 484 }
 485
 486 static struct global_attr min_sample_time_attr = __ATTR(min_sample_time, 0644,
 487                 show_min_sample_time, store_min_sample_time);
 488
 489 static ssize_t show_above_hispeed_delay(struct kobject *kobj,
 490                                         struct attribute *attr, char *buf)
 491 {
 492         return sprintf(buf, "%lu\n", above_hispeed_delay_val);
 493 }
 494
 495 static ssize_t store_above_hispeed_delay(struct kobject *kobj,
 496                                          struct attribute *attr,
 497                                          const char *buf, size_t count)
 498 {
 499         int ret;
 500         unsigned long val;
 501
 502         ret = strict_strtoul(buf, 0, &val);
 503         if (ret < 0)
 504                 return ret;
 505         above_hispeed_delay_val = val;
 506         return count;
 507 }
 508
 509 define_one_global_rw(above_hispeed_delay);
 510
 511 static ssize_t show_timer_rate(struct kobject *kobj,
 512                         struct attribute *attr, char *buf)
 513 {
 514         return sprintf(buf, "%lu\n", timer_rate);
 515 }
 516
 517 static ssize_t store_timer_rate(struct kobject *kobj,
 518                         struct attribute *attr, const char *buf, size_t count)
 519 {
 520         int ret;
 521         unsigned long val;
 522
 523         ret = strict_strtoul(buf, 0, &val);
 524         if (ret < 0)
 525                 return ret;
 526         timer_rate = val;
 527         return count;
 528 }
 529
 530 static struct global_attr timer_rate_attr = __ATTR(timer_rate, 0644,
 531                 show_timer_rate, store_timer_rate);
 532
 533 static ssize_t show_boost(struct kobject *kobj, struct attribute *attr,
 534                           char *buf)
 535 {
 536         return sprintf(buf, "%d\n", boost_val);
 537 }
 538
 539 static ssize_t store_boost(struct kobject *kobj, struct attribute *attr,
 540                            const char *buf, size_t count)
 541 {
 542         int ret;
 543         unsigned long val;
 544
 545         ret = kstrtoul(buf, 0, &val);
 546         if (ret < 0)
 547                 return ret;
 548
 549         boost_val = val;
 550
 551         if (boost_val) {
 552                 trace_cpufreq_interactive_boost("on");
 553                 cpufreq_interactive_boost();
 554         } else {
 555                 trace_cpufreq_interactive_unboost("off");
 556         }
 557
 558         return count;
 559 }
 560
 561 define_one_global_rw(boost);
 562
 563 static ssize_t store_boostpulse(struct kobject *kobj, struct attribute *attr,
 564                                 const char *buf, size_t count)
 565 {
 566         int ret;
 567         unsigned long val;
 568
 569         ret = kstrtoul(buf, 0, &val);
 570         if (ret < 0)
 571                 return ret;
 572
 573         trace_cpufreq_interactive_boost("pulse");
 574         cpufreq_interactive_boost();
 575         return count;
 576 }
 577
 578 static struct global_attr boostpulse =
 579         __ATTR(boostpulse, 0200, NULL, store_boostpulse);
 580
 581 static struct attribute *interactive_attributes[] = {
 582         &hispeed_freq_attr.attr,
 583         &go_hispeed_load_attr.attr,
 584         &above_hispeed_delay.attr,
 585         &min_sample_time_attr.attr,
 586         &timer_rate_attr.attr,
 587         &boost.attr,
 588         &boostpulse.attr,
 589         NULL,
 590 };
 591
 592 static struct attribute_group interactive_attr_group = {
 593         .attrs = interactive_attributes,
 594         .name = "interactive",
 595 };
 596
 597 static int cpufreq_interactive_idle_notifier(struct notifier_block *nb,
 598                                              unsigned long val,
 599                                              void *data)
 600 {
 601         switch (val) {
 602         case IDLE_START:
 603                 cpufreq_interactive_idle_start();
 604                 break;
 605         case IDLE_END:
 606                 cpufreq_interactive_idle_end();
 607                 break;
 608         }
 609
 610         return 0;
 611 }
 612
 613 static struct notifier_block cpufreq_interactive_idle_nb = {
 614         .notifier_call = cpufreq_interactive_idle_notifier,
 615 };
 616
 617 static int cpufreq_governor_interactive(struct cpufreq_policy *policy,
 618                 unsigned int event)
 619 {
 620         int rc;
 621         unsigned int j;
 622         struct cpufreq_interactive_cpuinfo *pcpu;
 623         struct cpufreq_frequency_table *freq_table;
 624
 625         switch (event) {
 626         case CPUFREQ_GOV_START:
 627                 if (!cpu_online(policy->cpu))
 628                         return -EINVAL;
 629
 630                 freq_table =
 631                         cpufreq_frequency_get_table(policy->cpu);
 632                 if (!hispeed_freq)
 633                         hispeed_freq = policy->max;
 634
 635                 for_each_cpu(j, policy->cpus) {
 636                         pcpu = &per_cpu(cpuinfo, j);
 637                         pcpu->policy = policy;
 638                         pcpu->target_freq = policy->cur;
 639                         pcpu->freq_table = freq_table;
 640                         pcpu->target_set_time_in_idle =
 641                                 get_cpu_idle_time_us(j,
 642                                              &pcpu->target_set_time);
 643                         pcpu->floor_freq = pcpu->target_freq;
 644                         pcpu->floor_validate_time =
 645                                 pcpu->target_set_time;
 646                         pcpu->hispeed_validate_time =
 647                                 pcpu->target_set_time;
 648                         pcpu->governor_enabled = 1;
 649                         smp_wmb();
 650                         pcpu->cpu_timer.expires =
 651                                 jiffies + usecs_to_jiffies(timer_rate);
 652                         add_timer_on(&pcpu->cpu_timer, j);
 653                 }
 654
 655                 /*
 656                  * Do not register the idle hook and create sysfs
 657                  * entries if we have already done so.
 658                  */
 659                 if (atomic_inc_return(&active_count) > 1)
 660                         return 0;
 661
 662                 rc = sysfs_create_group(cpufreq_global_kobject,
 663                                 &interactive_attr_group);
 664                 if (rc)
 665                         return rc;
 666
 667                 idle_notifier_register(&cpufreq_interactive_idle_nb);
 668                 break;
 669
 670         case CPUFREQ_GOV_STOP:
 671                 for_each_cpu(j, policy->cpus) {
 672                         pcpu = &per_cpu(cpuinfo, j);
 673                         pcpu->governor_enabled = 0;
 674                         smp_wmb();
 675                         del_timer_sync(&pcpu->cpu_timer);
 676                 }
 677
 678                 if (atomic_dec_return(&active_count) > 0)
 679                         return 0;
 680
 681                 idle_notifier_unregister(&cpufreq_interactive_idle_nb);
 682                 sysfs_remove_group(cpufreq_global_kobject,
 683                                 &interactive_attr_group);
 684
 685                 break;
 686
 687         case CPUFREQ_GOV_LIMITS:
 688                 if (policy->max < policy->cur)
 689                         __cpufreq_driver_target(policy,
 690                                         policy->max, CPUFREQ_RELATION_H);
 691                 else if (policy->min > policy->cur)
 692                         __cpufreq_driver_target(policy,
 693                                         policy->min, CPUFREQ_RELATION_L);
 694                 break;
 695         }
 696         return 0;
 697 }
 698
 699 static int __init cpufreq_interactive_init(void)
 700 {
 701         unsigned int i;
 702         struct cpufreq_interactive_cpuinfo *pcpu;
 703         struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
 704
 705         go_hispeed_load = DEFAULT_GO_HISPEED_LOAD;
 706         min_sample_time = DEFAULT_MIN_SAMPLE_TIME;
 707         above_hispeed_delay_val = DEFAULT_ABOVE_HISPEED_DELAY;
 708         timer_rate = DEFAULT_TIMER_RATE;
 709
 710         /* Initalize per-cpu timers */
 711         for_each_possible_cpu(i) {
 712                 pcpu = &per_cpu(cpuinfo, i);
 713                 if (governidle)
 714                         init_timer(&pcpu->cpu_timer);
 715                 else
 716                         init_timer_deferrable(&pcpu->cpu_timer);
 717                 pcpu->cpu_timer.function = cpufreq_interactive_timer;
 718                 pcpu->cpu_timer.data = i;
 719         }
 720
 721         spin_lock_init(&speedchange_cpumask_lock);
 722         speedchange_task =
 723                 kthread_create(cpufreq_interactive_speedchange_task, NULL,
 724                                "cfinteractive");
 725         if (IS_ERR(speedchange_task))
 726                 return PTR_ERR(speedchange_task);
 727
 728         sched_setscheduler_nocheck(speedchange_task, SCHED_FIFO, &param);
 729         get_task_struct(speedchange_task);
 730
 731         /* NB: wake up so the thread does not look hung to the freezer */
 732         wake_up_process(speedchange_task);
 733
 734         return cpufreq_register_governor(&cpufreq_gov_interactive);
 735 }
 736
 737 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_INTERACTIVE
 738 fs_initcall(cpufreq_interactive_init);
 739 #else
 740 module_init(cpufreq_interactive_init);
 741 #endif
 742
 743 static void __exit cpufreq_interactive_exit(void)
 744 {
 745         cpufreq_unregister_governor(&cpufreq_gov_interactive);
 746         kthread_stop(speedchange_task);
 747         put_task_struct(speedchange_task);
 748 }
 749
 750 module_exit(cpufreq_interactive_exit);
 751
 752 MODULE_AUTHOR("Mike Chan <mike@android.com>");
 753 MODULE_DESCRIPTION("'cpufreq_interactive' - A cpufreq governor for "
 754         "Latency sensitive workloads");
 755 MODULE_LICENSE("GPL");