SAFE public projects git trees. - safe/jmp/linux-2.6/blob - drivers/cpufreq/cpufreq_conservative.c

   1 /*
   2  *  drivers/cpufreq/cpufreq_conservative.c
   3  *
   4  *  Copyright (C)  2001 Russell King
   5  *            (C)  2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
   6  *                      Jun Nakajima <jun.nakajima@intel.com>
   7  *            (C)  2009 Alexander Clouter <alex@digriz.org.uk>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/smp.h>
  17 #include <linux/init.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/ctype.h>
  20 #include <linux/cpufreq.h>
  21 #include <linux/sysctl.h>
  22 #include <linux/types.h>
  23 #include <linux/fs.h>
  24 #include <linux/sysfs.h>
  25 #include <linux/cpu.h>
  26 #include <linux/kmod.h>
  27 #include <linux/workqueue.h>
  28 #include <linux/jiffies.h>
  29 #include <linux/kernel_stat.h>
  30 #include <linux/percpu.h>
  31 #include <linux/mutex.h>
  32 /*
  33  * dbs is used in this file as a shortform for demandbased switching
  34  * It helps to keep variable names smaller, simpler
  35  */
  36
  37 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
  38 #define DEF_FREQUENCY_DOWN_THRESHOLD            (20)
  39
  40 /*
  41  * The polling frequency of this governor depends on the capability of
  42  * the processor. Default polling frequency is 1000 times the transition
  43  * latency of the processor. The governor will work on any processor with
  44  * transition latency <= 10mS, using appropriate sampling
  45  * rate.
  46  * For CPUs with transition latency > 10mS (mostly drivers
  47  * with CPUFREQ_ETERNAL), this governor will not work.
  48  * All times here are in uS.
  49  */
  50 static unsigned int def_sampling_rate;
  51 #define MIN_SAMPLING_RATE_RATIO                 (2)
  52 /* for correct statistics, we need at least 10 ticks between each measure */
  53 #define MIN_STAT_SAMPLING_RATE                  \
  54                         (MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10))
  55 #define MIN_SAMPLING_RATE                       \
  56                         (def_sampling_rate / MIN_SAMPLING_RATE_RATIO)
  57 /* Above MIN_SAMPLING_RATE will vanish with its sysfs file soon
  58  * Define the minimal settable sampling rate to the greater of:
  59  *   - "HW transition latency" * 100 (same as default sampling / 10)
  60  *   - MIN_STAT_SAMPLING_RATE
  61  * To avoid that userspace shoots itself.
  62 */
  63 static unsigned int minimum_sampling_rate(void)
  64 {
  65         return max(def_sampling_rate / 10, MIN_STAT_SAMPLING_RATE);
  66 }
  67
  68 /* This will also vanish soon with removing sampling_rate_max */
  69 #define MAX_SAMPLING_RATE                       (500 * def_sampling_rate)
  70 #define LATENCY_MULTIPLIER                      (1000)
  71 #define DEF_SAMPLING_DOWN_FACTOR                (1)
  72 #define MAX_SAMPLING_DOWN_FACTOR                (10)
  73 #define TRANSITION_LATENCY_LIMIT                (10 * 1000 * 1000)
  74
  75 static void do_dbs_timer(struct work_struct *work);
  76
  77 struct cpu_dbs_info_s {
  78         struct cpufreq_policy *cur_policy;
  79         unsigned int prev_cpu_idle_up;
  80         unsigned int prev_cpu_idle_down;
  81         unsigned int enable;
  82         unsigned int down_skip;
  83         unsigned int requested_freq;
  84 };
  85 static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
  86
  87 static unsigned int dbs_enable; /* number of CPUs using this policy */
  88
  89 /*
  90  * DEADLOCK ALERT! There is a ordering requirement between cpu_hotplug
  91  * lock and dbs_mutex. cpu_hotplug lock should always be held before
  92  * dbs_mutex. If any function that can potentially take cpu_hotplug lock
  93  * (like __cpufreq_driver_target()) is being called with dbs_mutex taken, then
  94  * cpu_hotplug lock should be taken before that. Note that cpu_hotplug lock
  95  * is recursive for the same process. -Venki
  96  */
  97 static DEFINE_MUTEX(dbs_mutex);
  98 static DECLARE_DELAYED_WORK(dbs_work, do_dbs_timer);
  99
 100 struct dbs_tuners {
 101         unsigned int sampling_rate;
 102         unsigned int sampling_down_factor;
 103         unsigned int up_threshold;
 104         unsigned int down_threshold;
 105         unsigned int ignore_nice;
 106         unsigned int freq_step;
 107 };
 108
 109 static struct dbs_tuners dbs_tuners_ins = {
 110         .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
 111         .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD,
 112         .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
 113         .ignore_nice = 0,
 114         .freq_step = 5,
 115 };
 116
 117 static inline unsigned int get_cpu_idle_time(unsigned int cpu)
 118 {
 119         unsigned int add_nice = 0, ret;
 120
 121         if (dbs_tuners_ins.ignore_nice)
 122                 add_nice = kstat_cpu(cpu).cpustat.nice;
 123
 124         ret = kstat_cpu(cpu).cpustat.idle +
 125                 kstat_cpu(cpu).cpustat.iowait +
 126                 add_nice;
 127
 128         return ret;
 129 }
 130
 131 /* keep track of frequency transitions */
 132 static int
 133 dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 134                      void *data)
 135 {
 136         struct cpufreq_freqs *freq = data;
 137         struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cpu_dbs_info,
 138                                                         freq->cpu);
 139
 140         struct cpufreq_policy *policy;
 141
 142         if (!this_dbs_info->enable)
 143                 return 0;
 144
 145         policy = this_dbs_info->cur_policy;
 146
 147         /*
 148          * we only care if our internally tracked freq moves outside
 149          * the 'valid' ranges of freqency available to us otherwise
 150          * we do not change it
 151         */
 152         if (this_dbs_info->requested_freq > policy->max
 153                         || this_dbs_info->requested_freq < policy->min)
 154                 this_dbs_info->requested_freq = freq->new;
 155
 156         return 0;
 157 }
 158
 159 static struct notifier_block dbs_cpufreq_notifier_block = {
 160         .notifier_call = dbs_cpufreq_notifier
 161 };
 162
 163 /************************** sysfs interface ************************/
 164 static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
 165 {
 166         static int print_once;
 167
 168         if (!print_once) {
 169                 printk(KERN_INFO "CPUFREQ: conservative sampling_rate_max "
 170                        "sysfs file is deprecated - used by: %s\n",
 171                        current->comm);
 172                 print_once = 1;
 173         }
 174         return sprintf(buf, "%u\n", MAX_SAMPLING_RATE);
 175 }
 176
 177 static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf)
 178 {
 179         static int print_once;
 180
 181         if (!print_once) {
 182                 printk(KERN_INFO "CPUFREQ: conservative sampling_rate_max "
 183                        "sysfs file is deprecated - used by: %s\n", current->comm);
 184                 print_once = 1;
 185         }
 186         return sprintf(buf, "%u\n", MIN_SAMPLING_RATE);
 187 }
 188
 189 #define define_one_ro(_name)                            \
 190 static struct freq_attr _name =                         \
 191 __ATTR(_name, 0444, show_##_name, NULL)
 192
 193 define_one_ro(sampling_rate_max);
 194 define_one_ro(sampling_rate_min);
 195
 196 /* cpufreq_conservative Governor Tunables */
 197 #define show_one(file_name, object)                                     \
 198 static ssize_t show_##file_name                                         \
 199 (struct cpufreq_policy *unused, char *buf)                              \
 200 {                                                                       \
 201         return sprintf(buf, "%u\n", dbs_tuners_ins.object);             \
 202 }
 203 show_one(sampling_rate, sampling_rate);
 204 show_one(sampling_down_factor, sampling_down_factor);
 205 show_one(up_threshold, up_threshold);
 206 show_one(down_threshold, down_threshold);
 207 show_one(ignore_nice_load, ignore_nice);
 208 show_one(freq_step, freq_step);
 209
 210 static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
 211                 const char *buf, size_t count)
 212 {
 213         unsigned int input;
 214         int ret;
 215         ret = sscanf(buf, "%u", &input);
 216         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 217                 return -EINVAL;
 218
 219         mutex_lock(&dbs_mutex);
 220         dbs_tuners_ins.sampling_down_factor = input;
 221         mutex_unlock(&dbs_mutex);
 222
 223         return count;
 224 }
 225
 226 static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
 227                 const char *buf, size_t count)
 228 {
 229         unsigned int input;
 230         int ret;
 231         ret = sscanf(buf, "%u", &input);
 232
 233         mutex_lock(&dbs_mutex);
 234         if (ret != 1) {
 235                 mutex_unlock(&dbs_mutex);
 236                 return -EINVAL;
 237         }
 238         dbs_tuners_ins.sampling_rate = max(input, minimum_sampling_rate());
 239         mutex_unlock(&dbs_mutex);
 240
 241         return count;
 242 }
 243
 244 static ssize_t store_up_threshold(struct cpufreq_policy *unused,
 245                 const char *buf, size_t count)
 246 {
 247         unsigned int input;
 248         int ret;
 249         ret = sscanf(buf, "%u", &input);
 250
 251         mutex_lock(&dbs_mutex);
 252         if (ret != 1 || input > 100 ||
 253             input <= dbs_tuners_ins.down_threshold) {
 254                 mutex_unlock(&dbs_mutex);
 255                 return -EINVAL;
 256         }
 257
 258         dbs_tuners_ins.up_threshold = input;
 259         mutex_unlock(&dbs_mutex);
 260
 261         return count;
 262 }
 263
 264 static ssize_t store_down_threshold(struct cpufreq_policy *unused,
 265                 const char *buf, size_t count)
 266 {
 267         unsigned int input;
 268         int ret;
 269         ret = sscanf(buf, "%u", &input);
 270
 271         mutex_lock(&dbs_mutex);
 272         if (ret != 1 || input > 100 || input >= dbs_tuners_ins.up_threshold) {
 273                 mutex_unlock(&dbs_mutex);
 274                 return -EINVAL;
 275         }
 276
 277         dbs_tuners_ins.down_threshold = input;
 278         mutex_unlock(&dbs_mutex);
 279
 280         return count;
 281 }
 282
 283 static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
 284                 const char *buf, size_t count)
 285 {
 286         unsigned int input;
 287         int ret;
 288
 289         unsigned int j;
 290
 291         ret = sscanf(buf, "%u", &input);
 292         if (ret != 1)
 293                 return -EINVAL;
 294
 295         if (input > 1)
 296                 input = 1;
 297
 298         mutex_lock(&dbs_mutex);
 299         if (input == dbs_tuners_ins.ignore_nice) { /* nothing to do */
 300                 mutex_unlock(&dbs_mutex);
 301                 return count;
 302         }
 303         dbs_tuners_ins.ignore_nice = input;
 304
 305         /* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */
 306         for_each_online_cpu(j) {
 307                 struct cpu_dbs_info_s *j_dbs_info;
 308                 j_dbs_info = &per_cpu(cpu_dbs_info, j);
 309                 j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
 310                 j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up;
 311         }
 312         mutex_unlock(&dbs_mutex);
 313
 314         return count;
 315 }
 316
 317 static ssize_t store_freq_step(struct cpufreq_policy *policy,
 318                 const char *buf, size_t count)
 319 {
 320         unsigned int input;
 321         int ret;
 322
 323         ret = sscanf(buf, "%u", &input);
 324
 325         if (ret != 1)
 326                 return -EINVAL;
 327
 328         if (input > 100)
 329                 input = 100;
 330
 331         /* no need to test here if freq_step is zero as the user might actually
 332          * want this, they would be crazy though :) */
 333         mutex_lock(&dbs_mutex);
 334         dbs_tuners_ins.freq_step = input;
 335         mutex_unlock(&dbs_mutex);
 336
 337         return count;
 338 }
 339
 340 #define define_one_rw(_name) \
 341 static struct freq_attr _name = \
 342 __ATTR(_name, 0644, show_##_name, store_##_name)
 343
 344 define_one_rw(sampling_rate);
 345 define_one_rw(sampling_down_factor);
 346 define_one_rw(up_threshold);
 347 define_one_rw(down_threshold);
 348 define_one_rw(ignore_nice_load);
 349 define_one_rw(freq_step);
 350
 351 static struct attribute *dbs_attributes[] = {
 352         &sampling_rate_max.attr,
 353         &sampling_rate_min.attr,
 354         &sampling_rate.attr,
 355         &sampling_down_factor.attr,
 356         &up_threshold.attr,
 357         &down_threshold.attr,
 358         &ignore_nice_load.attr,
 359         &freq_step.attr,
 360         NULL
 361 };
 362
 363 static struct attribute_group dbs_attr_group = {
 364         .attrs = dbs_attributes,
 365         .name = "conservative",
 366 };
 367
 368 /************************** sysfs end ************************/
 369
 370 static void dbs_check_cpu(int cpu)
 371 {
 372         unsigned int idle_ticks, up_idle_ticks, down_idle_ticks;
 373         unsigned int tmp_idle_ticks, total_idle_ticks;
 374         unsigned int freq_target;
 375         unsigned int freq_down_sampling_rate;
 376         struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
 377         struct cpufreq_policy *policy;
 378
 379         if (!this_dbs_info->enable)
 380                 return;
 381
 382         policy = this_dbs_info->cur_policy;
 383
 384         /*
 385          * The default safe range is 20% to 80%
 386          * Every sampling_rate, we check
 387          *      - If current idle time is less than 20%, then we try to
 388          *        increase frequency
 389          * Every sampling_rate*sampling_down_factor, we check
 390          *      - If current idle time is more than 80%, then we try to
 391          *        decrease frequency
 392          *
 393          * Any frequency increase takes it to the maximum frequency.
 394          * Frequency reduction happens at minimum steps of
 395          * 5% (default) of max_frequency
 396          */
 397
 398         /* Check for frequency increase */
 399         idle_ticks = UINT_MAX;
 400
 401         /* Check for frequency increase */
 402         total_idle_ticks = get_cpu_idle_time(cpu);
 403         tmp_idle_ticks = total_idle_ticks -
 404                 this_dbs_info->prev_cpu_idle_up;
 405         this_dbs_info->prev_cpu_idle_up = total_idle_ticks;
 406
 407         if (tmp_idle_ticks < idle_ticks)
 408                 idle_ticks = tmp_idle_ticks;
 409
 410         /* Scale idle ticks by 100 and compare with up and down ticks */
 411         idle_ticks *= 100;
 412         up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) *
 413                         usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
 414
 415         if (idle_ticks < up_idle_ticks) {
 416                 this_dbs_info->down_skip = 0;
 417                 this_dbs_info->prev_cpu_idle_down =
 418                         this_dbs_info->prev_cpu_idle_up;
 419
 420                 /* if we are already at full speed then break out early */
 421                 if (this_dbs_info->requested_freq == policy->max)
 422                         return;
 423
 424                 freq_target = (dbs_tuners_ins.freq_step * policy->max) / 100;
 425
 426                 /* max freq cannot be less than 100. But who knows.... */
 427                 if (unlikely(freq_target == 0))
 428                         freq_target = 5;
 429
 430                 this_dbs_info->requested_freq += freq_target;
 431                 if (this_dbs_info->requested_freq > policy->max)
 432                         this_dbs_info->requested_freq = policy->max;
 433
 434                 __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
 435                         CPUFREQ_RELATION_H);
 436                 return;
 437         }
 438
 439         /* Check for frequency decrease */
 440         this_dbs_info->down_skip++;
 441         if (this_dbs_info->down_skip < dbs_tuners_ins.sampling_down_factor)
 442                 return;
 443
 444         /* Check for frequency decrease */
 445         total_idle_ticks = this_dbs_info->prev_cpu_idle_up;
 446         tmp_idle_ticks = total_idle_ticks -
 447                 this_dbs_info->prev_cpu_idle_down;
 448         this_dbs_info->prev_cpu_idle_down = total_idle_ticks;
 449
 450         if (tmp_idle_ticks < idle_ticks)
 451                 idle_ticks = tmp_idle_ticks;
 452
 453         /* Scale idle ticks by 100 and compare with up and down ticks */
 454         idle_ticks *= 100;
 455         this_dbs_info->down_skip = 0;
 456
 457         freq_down_sampling_rate = dbs_tuners_ins.sampling_rate *
 458                 dbs_tuners_ins.sampling_down_factor;
 459         down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) *
 460                 usecs_to_jiffies(freq_down_sampling_rate);
 461
 462         if (idle_ticks > down_idle_ticks) {
 463                 /*
 464                  * if we are already at the lowest speed then break out early
 465                  * or if we 'cannot' reduce the speed as the user might want
 466                  * freq_target to be zero
 467                  */
 468                 if (this_dbs_info->requested_freq == policy->min
 469                                 || dbs_tuners_ins.freq_step == 0)
 470                         return;
 471
 472                 freq_target = (dbs_tuners_ins.freq_step * policy->max) / 100;
 473
 474                 /* max freq cannot be less than 100. But who knows.... */
 475                 if (unlikely(freq_target == 0))
 476                         freq_target = 5;
 477
 478                 this_dbs_info->requested_freq -= freq_target;
 479                 if (this_dbs_info->requested_freq < policy->min)
 480                         this_dbs_info->requested_freq = policy->min;
 481
 482                 __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
 483                                 CPUFREQ_RELATION_H);
 484                 return;
 485         }
 486 }
 487
 488 static void do_dbs_timer(struct work_struct *work)
 489 {
 490         int i;
 491         mutex_lock(&dbs_mutex);
 492         for_each_online_cpu(i)
 493                 dbs_check_cpu(i);
 494         schedule_delayed_work(&dbs_work,
 495                         usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
 496         mutex_unlock(&dbs_mutex);
 497 }
 498
 499 static inline void dbs_timer_init(void)
 500 {
 501         init_timer_deferrable(&dbs_work.timer);
 502         schedule_delayed_work(&dbs_work,
 503                         usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
 504         return;
 505 }
 506
 507 static inline void dbs_timer_exit(void)
 508 {
 509         cancel_delayed_work(&dbs_work);
 510         return;
 511 }
 512
 513 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 514                                    unsigned int event)
 515 {
 516         unsigned int cpu = policy->cpu;
 517         struct cpu_dbs_info_s *this_dbs_info;
 518         unsigned int j;
 519         int rc;
 520
 521         this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
 522
 523         switch (event) {
 524         case CPUFREQ_GOV_START:
 525                 if ((!cpu_online(cpu)) || (!policy->cur))
 526                         return -EINVAL;
 527
 528                 if (this_dbs_info->enable) /* Already enabled */
 529                         break;
 530
 531                 mutex_lock(&dbs_mutex);
 532
 533                 rc = sysfs_create_group(&policy->kobj, &dbs_attr_group);
 534                 if (rc) {
 535                         mutex_unlock(&dbs_mutex);
 536                         return rc;
 537                 }
 538
 539                 for_each_cpu(j, policy->cpus) {
 540                         struct cpu_dbs_info_s *j_dbs_info;
 541                         j_dbs_info = &per_cpu(cpu_dbs_info, j);
 542                         j_dbs_info->cur_policy = policy;
 543
 544                         j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(cpu);
 545                         j_dbs_info->prev_cpu_idle_down
 546                                 = j_dbs_info->prev_cpu_idle_up;
 547                 }
 548                 this_dbs_info->enable = 1;
 549                 this_dbs_info->down_skip = 0;
 550                 this_dbs_info->requested_freq = policy->cur;
 551
 552                 dbs_enable++;
 553                 /*
 554                  * Start the timerschedule work, when this governor
 555                  * is used for first time
 556                  */
 557                 if (dbs_enable == 1) {
 558                         unsigned int latency;
 559                         /* policy latency is in nS. Convert it to uS first */
 560                         latency = policy->cpuinfo.transition_latency / 1000;
 561                         if (latency == 0)
 562                                 latency = 1;
 563
 564                         def_sampling_rate =
 565                                 max(10 * latency * LATENCY_MULTIPLIER,
 566                                     MIN_STAT_SAMPLING_RATE);
 567
 568                         dbs_tuners_ins.sampling_rate = def_sampling_rate;
 569
 570                         dbs_timer_init();
 571                         cpufreq_register_notifier(
 572                                         &dbs_cpufreq_notifier_block,
 573                                         CPUFREQ_TRANSITION_NOTIFIER);
 574                 }
 575
 576                 mutex_unlock(&dbs_mutex);
 577                 break;
 578
 579         case CPUFREQ_GOV_STOP:
 580                 mutex_lock(&dbs_mutex);
 581                 this_dbs_info->enable = 0;
 582                 sysfs_remove_group(&policy->kobj, &dbs_attr_group);
 583                 dbs_enable--;
 584                 /*
 585                  * Stop the timerschedule work, when this governor
 586                  * is used for first time
 587                  */
 588                 if (dbs_enable == 0) {
 589                         dbs_timer_exit();
 590                         cpufreq_unregister_notifier(
 591                                         &dbs_cpufreq_notifier_block,
 592                                         CPUFREQ_TRANSITION_NOTIFIER);
 593                 }
 594
 595                 mutex_unlock(&dbs_mutex);
 596
 597                 break;
 598
 599         case CPUFREQ_GOV_LIMITS:
 600                 mutex_lock(&dbs_mutex);
 601                 if (policy->max < this_dbs_info->cur_policy->cur)
 602                         __cpufreq_driver_target(
 603                                         this_dbs_info->cur_policy,
 604                                         policy->max, CPUFREQ_RELATION_H);
 605                 else if (policy->min > this_dbs_info->cur_policy->cur)
 606                         __cpufreq_driver_target(
 607                                         this_dbs_info->cur_policy,
 608                                         policy->min, CPUFREQ_RELATION_L);
 609                 mutex_unlock(&dbs_mutex);
 610                 break;
 611         }
 612         return 0;
 613 }
 614
 615 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 616 static
 617 #endif
 618 struct cpufreq_governor cpufreq_gov_conservative = {
 619         .name                   = "conservative",
 620         .governor               = cpufreq_governor_dbs,
 621         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 622         .owner                  = THIS_MODULE,
 623 };
 624
 625 static int __init cpufreq_gov_dbs_init(void)
 626 {
 627         return cpufreq_register_governor(&cpufreq_gov_conservative);
 628 }
 629
 630 static void __exit cpufreq_gov_dbs_exit(void)
 631 {
 632         /* Make sure that the scheduled work is indeed not running */
 633         flush_scheduled_work();
 634
 635         cpufreq_unregister_governor(&cpufreq_gov_conservative);
 636 }
 637
 638
 639 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
 640 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
 641                 "Low Latency Frequency Transition capable processors "
 642                 "optimised for use in a battery environment");
 643 MODULE_LICENSE("GPL");
 644
 645 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 646 fs_initcall(cpufreq_gov_dbs_init);
 647 #else
 648 module_init(cpufreq_gov_dbs_init);
 649 #endif
 650 module_exit(cpufreq_gov_dbs_exit);