git.oblomov.eu Git - linux-2.6/blob - drivers/cpufreq/cpufreq_ondemand.c

   1 /*
   2  *  drivers/cpufreq/cpufreq_ondemand.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  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/init.h>
  16 #include <linux/cpufreq.h>
  17 #include <linux/cpu.h>
  18 #include <linux/jiffies.h>
  19 #include <linux/kernel_stat.h>
  20 #include <linux/mutex.h>
  21
  22 /*
  23  * dbs is used in this file as a shortform for demandbased switching
  24  * It helps to keep variable names smaller, simpler
  25  */
  26
  27 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
  28 #define MIN_FREQUENCY_UP_THRESHOLD              (11)
  29 #define MAX_FREQUENCY_UP_THRESHOLD              (100)
  30
  31 /*
  32  * The polling frequency of this governor depends on the capability of
  33  * the processor. Default polling frequency is 1000 times the transition
  34  * latency of the processor. The governor will work on any processor with
  35  * transition latency <= 10mS, using appropriate sampling
  36  * rate.
  37  * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
  38  * this governor will not work.
  39  * All times here are in uS.
  40  */
  41 static unsigned int def_sampling_rate;
  42 #define MIN_SAMPLING_RATE_RATIO                 (2)
  43 /* for correct statistics, we need at least 10 ticks between each measure */
  44 #define MIN_STAT_SAMPLING_RATE                  \
  45                         (MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10))
  46 #define MIN_SAMPLING_RATE                       \
  47                         (def_sampling_rate / MIN_SAMPLING_RATE_RATIO)
  48 #define MAX_SAMPLING_RATE                       (500 * def_sampling_rate)
  49 #define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER    (1000)
  50 #define TRANSITION_LATENCY_LIMIT                (10 * 1000)
  51
  52 static void do_dbs_timer(struct work_struct *work);
  53
  54 /* Sampling types */
  55 enum dbs_sample {DBS_NORMAL_SAMPLE, DBS_SUB_SAMPLE};
  56
  57 struct cpu_dbs_info_s {
  58         cputime64_t prev_cpu_idle;
  59         cputime64_t prev_cpu_wall;
  60         struct cpufreq_policy *cur_policy;
  61         struct delayed_work work;
  62         enum dbs_sample sample_type;
  63         unsigned int enable;
  64         struct cpufreq_frequency_table *freq_table;
  65         unsigned int freq_lo;
  66         unsigned int freq_lo_jiffies;
  67         unsigned int freq_hi_jiffies;
  68 };
  69 static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
  70
  71 static unsigned int dbs_enable; /* number of CPUs using this policy */
  72
  73 /*
  74  * DEADLOCK ALERT! There is a ordering requirement between cpu_hotplug
  75  * lock and dbs_mutex. cpu_hotplug lock should always be held before
  76  * dbs_mutex. If any function that can potentially take cpu_hotplug lock
  77  * (like __cpufreq_driver_target()) is being called with dbs_mutex taken, then
  78  * cpu_hotplug lock should be taken before that. Note that cpu_hotplug lock
  79  * is recursive for the same process. -Venki
  80  */
  81 static DEFINE_MUTEX(dbs_mutex);
  82
  83 static struct workqueue_struct  *kondemand_wq;
  84
  85 static struct dbs_tuners {
  86         unsigned int sampling_rate;
  87         unsigned int up_threshold;
  88         unsigned int ignore_nice;
  89         unsigned int powersave_bias;
  90 } dbs_tuners_ins = {
  91         .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
  92         .ignore_nice = 0,
  93         .powersave_bias = 0,
  94 };
  95
  96 static inline cputime64_t get_cpu_idle_time(unsigned int cpu)
  97 {
  98         cputime64_t retval;
  99
 100         retval = cputime64_add(kstat_cpu(cpu).cpustat.idle,
 101                         kstat_cpu(cpu).cpustat.iowait);
 102
 103         if (dbs_tuners_ins.ignore_nice)
 104                 retval = cputime64_add(retval, kstat_cpu(cpu).cpustat.nice);
 105
 106         return retval;
 107 }
 108
 109 /*
 110  * Find right freq to be set now with powersave_bias on.
 111  * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
 112  * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
 113  */
 114 static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
 115                                           unsigned int freq_next,
 116                                           unsigned int relation)
 117 {
 118         unsigned int freq_req, freq_reduc, freq_avg;
 119         unsigned int freq_hi, freq_lo;
 120         unsigned int index = 0;
 121         unsigned int jiffies_total, jiffies_hi, jiffies_lo;
 122         struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, policy->cpu);
 123
 124         if (!dbs_info->freq_table) {
 125                 dbs_info->freq_lo = 0;
 126                 dbs_info->freq_lo_jiffies = 0;
 127                 return freq_next;
 128         }
 129
 130         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
 131                         relation, &index);
 132         freq_req = dbs_info->freq_table[index].frequency;
 133         freq_reduc = freq_req * dbs_tuners_ins.powersave_bias / 1000;
 134         freq_avg = freq_req - freq_reduc;
 135
 136         /* Find freq bounds for freq_avg in freq_table */
 137         index = 0;
 138         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
 139                         CPUFREQ_RELATION_H, &index);
 140         freq_lo = dbs_info->freq_table[index].frequency;
 141         index = 0;
 142         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
 143                         CPUFREQ_RELATION_L, &index);
 144         freq_hi = dbs_info->freq_table[index].frequency;
 145
 146         /* Find out how long we have to be in hi and lo freqs */
 147         if (freq_hi == freq_lo) {
 148                 dbs_info->freq_lo = 0;
 149                 dbs_info->freq_lo_jiffies = 0;
 150                 return freq_lo;
 151         }
 152         jiffies_total = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
 153         jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
 154         jiffies_hi += ((freq_hi - freq_lo) / 2);
 155         jiffies_hi /= (freq_hi - freq_lo);
 156         jiffies_lo = jiffies_total - jiffies_hi;
 157         dbs_info->freq_lo = freq_lo;
 158         dbs_info->freq_lo_jiffies = jiffies_lo;
 159         dbs_info->freq_hi_jiffies = jiffies_hi;
 160         return freq_hi;
 161 }
 162
 163 static void ondemand_powersave_bias_init(void)
 164 {
 165         int i;
 166         for_each_online_cpu(i) {
 167                 struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, i);
 168                 dbs_info->freq_table = cpufreq_frequency_get_table(i);
 169                 dbs_info->freq_lo = 0;
 170         }
 171 }
 172
 173 /************************** sysfs interface ************************/
 174 static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
 175 {
 176         return sprintf (buf, "%u\n", MAX_SAMPLING_RATE);
 177 }
 178
 179 static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf)
 180 {
 181         return sprintf (buf, "%u\n", MIN_SAMPLING_RATE);
 182 }
 183
 184 #define define_one_ro(_name)            \
 185 static struct freq_attr _name =         \
 186 __ATTR(_name, 0444, show_##_name, NULL)
 187
 188 define_one_ro(sampling_rate_max);
 189 define_one_ro(sampling_rate_min);
 190
 191 /* cpufreq_ondemand Governor Tunables */
 192 #define show_one(file_name, object)                                     \
 193 static ssize_t show_##file_name                                         \
 194 (struct cpufreq_policy *unused, char *buf)                              \
 195 {                                                                       \
 196         return sprintf(buf, "%u\n", dbs_tuners_ins.object);             \
 197 }
 198 show_one(sampling_rate, sampling_rate);
 199 show_one(up_threshold, up_threshold);
 200 show_one(ignore_nice_load, ignore_nice);
 201 show_one(powersave_bias, powersave_bias);
 202
 203 static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
 204                 const char *buf, size_t count)
 205 {
 206         unsigned int input;
 207         int ret;
 208         ret = sscanf(buf, "%u", &input);
 209
 210         mutex_lock(&dbs_mutex);
 211         if (ret != 1 || input > MAX_SAMPLING_RATE
 212                      || input < MIN_SAMPLING_RATE) {
 213                 mutex_unlock(&dbs_mutex);
 214                 return -EINVAL;
 215         }
 216
 217         dbs_tuners_ins.sampling_rate = input;
 218         mutex_unlock(&dbs_mutex);
 219
 220         return count;
 221 }
 222
 223 static ssize_t store_up_threshold(struct cpufreq_policy *unused,
 224                 const char *buf, size_t count)
 225 {
 226         unsigned int input;
 227         int ret;
 228         ret = sscanf(buf, "%u", &input);
 229
 230         mutex_lock(&dbs_mutex);
 231         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 232                         input < MIN_FREQUENCY_UP_THRESHOLD) {
 233                 mutex_unlock(&dbs_mutex);
 234                 return -EINVAL;
 235         }
 236
 237         dbs_tuners_ins.up_threshold = input;
 238         mutex_unlock(&dbs_mutex);
 239
 240         return count;
 241 }
 242
 243 static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
 244                 const char *buf, size_t count)
 245 {
 246         unsigned int input;
 247         int ret;
 248
 249         unsigned int j;
 250
 251         ret = sscanf(buf, "%u", &input);
 252         if ( ret != 1 )
 253                 return -EINVAL;
 254
 255         if ( input > 1 )
 256                 input = 1;
 257
 258         mutex_lock(&dbs_mutex);
 259         if ( input == dbs_tuners_ins.ignore_nice ) { /* nothing to do */
 260                 mutex_unlock(&dbs_mutex);
 261                 return count;
 262         }
 263         dbs_tuners_ins.ignore_nice = input;
 264
 265         /* we need to re-evaluate prev_cpu_idle */
 266         for_each_online_cpu(j) {
 267                 struct cpu_dbs_info_s *dbs_info;
 268                 dbs_info = &per_cpu(cpu_dbs_info, j);
 269                 dbs_info->prev_cpu_idle = get_cpu_idle_time(j);
 270                 dbs_info->prev_cpu_wall = get_jiffies_64();
 271         }
 272         mutex_unlock(&dbs_mutex);
 273
 274         return count;
 275 }
 276
 277 static ssize_t store_powersave_bias(struct cpufreq_policy *unused,
 278                 const char *buf, size_t count)
 279 {
 280         unsigned int input;
 281         int ret;
 282         ret = sscanf(buf, "%u", &input);
 283
 284         if (ret != 1)
 285                 return -EINVAL;
 286
 287         if (input > 1000)
 288                 input = 1000;
 289
 290         mutex_lock(&dbs_mutex);
 291         dbs_tuners_ins.powersave_bias = input;
 292         ondemand_powersave_bias_init();
 293         mutex_unlock(&dbs_mutex);
 294
 295         return count;
 296 }
 297
 298 #define define_one_rw(_name) \
 299 static struct freq_attr _name = \
 300 __ATTR(_name, 0644, show_##_name, store_##_name)
 301
 302 define_one_rw(sampling_rate);
 303 define_one_rw(up_threshold);
 304 define_one_rw(ignore_nice_load);
 305 define_one_rw(powersave_bias);
 306
 307 static struct attribute * dbs_attributes[] = {
 308         &sampling_rate_max.attr,
 309         &sampling_rate_min.attr,
 310         &sampling_rate.attr,
 311         &up_threshold.attr,
 312         &ignore_nice_load.attr,
 313         &powersave_bias.attr,
 314         NULL
 315 };
 316
 317 static struct attribute_group dbs_attr_group = {
 318         .attrs = dbs_attributes,
 319         .name = "ondemand",
 320 };
 321
 322 /************************** sysfs end ************************/
 323
 324 static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
 325 {
 326         unsigned int idle_ticks, total_ticks;
 327         unsigned int load;
 328         cputime64_t cur_jiffies;
 329
 330         struct cpufreq_policy *policy;
 331         unsigned int j;
 332
 333         if (!this_dbs_info->enable)
 334                 return;
 335
 336         this_dbs_info->freq_lo = 0;
 337         policy = this_dbs_info->cur_policy;
 338         cur_jiffies = jiffies64_to_cputime64(get_jiffies_64());
 339         total_ticks = (unsigned int) cputime64_sub(cur_jiffies,
 340                         this_dbs_info->prev_cpu_wall);
 341         this_dbs_info->prev_cpu_wall = cur_jiffies;
 342         if (!total_ticks)
 343                 return;
 344         /*
 345          * Every sampling_rate, we check, if current idle time is less
 346          * than 20% (default), then we try to increase frequency
 347          * Every sampling_rate, we look for a the lowest
 348          * frequency which can sustain the load while keeping idle time over
 349          * 30%. If such a frequency exist, we try to decrease to this frequency.
 350          *
 351          * Any frequency increase takes it to the maximum frequency.
 352          * Frequency reduction happens at minimum steps of
 353          * 5% (default) of current frequency
 354          */
 355
 356         /* Get Idle Time */
 357         idle_ticks = UINT_MAX;
 358         for_each_cpu_mask(j, policy->cpus) {
 359                 cputime64_t total_idle_ticks;
 360                 unsigned int tmp_idle_ticks;
 361                 struct cpu_dbs_info_s *j_dbs_info;
 362
 363                 j_dbs_info = &per_cpu(cpu_dbs_info, j);
 364                 total_idle_ticks = get_cpu_idle_time(j);
 365                 tmp_idle_ticks = (unsigned int) cputime64_sub(total_idle_ticks,
 366                                 j_dbs_info->prev_cpu_idle);
 367                 j_dbs_info->prev_cpu_idle = total_idle_ticks;
 368
 369                 if (tmp_idle_ticks < idle_ticks)
 370                         idle_ticks = tmp_idle_ticks;
 371         }
 372         load = (100 * (total_ticks - idle_ticks)) / total_ticks;
 373
 374         /* Check for frequency increase */
 375         if (load > dbs_tuners_ins.up_threshold) {
 376                 /* if we are already at full speed then break out early */
 377                 if (!dbs_tuners_ins.powersave_bias) {
 378                         if (policy->cur == policy->max)
 379                                 return;
 380
 381                         __cpufreq_driver_target(policy, policy->max,
 382                                 CPUFREQ_RELATION_H);
 383                 } else {
 384                         int freq = powersave_bias_target(policy, policy->max,
 385                                         CPUFREQ_RELATION_H);
 386                         __cpufreq_driver_target(policy, freq,
 387                                 CPUFREQ_RELATION_L);
 388                 }
 389                 return;
 390         }
 391
 392         /* Check for frequency decrease */
 393         /* if we cannot reduce the frequency anymore, break out early */
 394         if (policy->cur == policy->min)
 395                 return;
 396
 397         /*
 398          * The optimal frequency is the frequency that is the lowest that
 399          * can support the current CPU usage without triggering the up
 400          * policy. To be safe, we focus 10 points under the threshold.
 401          */
 402         if (load < (dbs_tuners_ins.up_threshold - 10)) {
 403                 unsigned int freq_next, freq_cur;
 404
 405                 freq_cur = cpufreq_driver_getavg(policy);
 406                 if (!freq_cur)
 407                         freq_cur = policy->cur;
 408
 409                 freq_next = (freq_cur * load) /
 410                         (dbs_tuners_ins.up_threshold - 10);
 411
 412                 if (!dbs_tuners_ins.powersave_bias) {
 413                         __cpufreq_driver_target(policy, freq_next,
 414                                         CPUFREQ_RELATION_L);
 415                 } else {
 416                         int freq = powersave_bias_target(policy, freq_next,
 417                                         CPUFREQ_RELATION_L);
 418                         __cpufreq_driver_target(policy, freq,
 419                                 CPUFREQ_RELATION_L);
 420                 }
 421         }
 422 }
 423
 424 static void do_dbs_timer(struct work_struct *work)
 425 {
 426         unsigned int cpu = smp_processor_id();
 427         struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, cpu);
 428         enum dbs_sample sample_type = dbs_info->sample_type;
 429         /* We want all CPUs to do sampling nearly on same jiffy */
 430         int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
 431
 432         /* Permit rescheduling of this work item */
 433         work_release(work);
 434
 435         delay -= jiffies % delay;
 436
 437         if (!dbs_info->enable)
 438                 return;
 439         /* Common NORMAL_SAMPLE setup */
 440         dbs_info->sample_type = DBS_NORMAL_SAMPLE;
 441         if (!dbs_tuners_ins.powersave_bias ||
 442             sample_type == DBS_NORMAL_SAMPLE) {
 443                 lock_cpu_hotplug();
 444                 dbs_check_cpu(dbs_info);
 445                 unlock_cpu_hotplug();
 446                 if (dbs_info->freq_lo) {
 447                         /* Setup timer for SUB_SAMPLE */
 448                         dbs_info->sample_type = DBS_SUB_SAMPLE;
 449                         delay = dbs_info->freq_hi_jiffies;
 450                 }
 451         } else {
 452                 __cpufreq_driver_target(dbs_info->cur_policy,
 453                                         dbs_info->freq_lo,
 454                                         CPUFREQ_RELATION_H);
 455         }
 456         queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work, delay);
 457 }
 458
 459 static inline void dbs_timer_init(unsigned int cpu)
 460 {
 461         struct cpu_dbs_info_s *dbs_info = &per_cpu(cpu_dbs_info, cpu);
 462         /* We want all CPUs to do sampling nearly on same jiffy */
 463         int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
 464         delay -= jiffies % delay;
 465
 466         ondemand_powersave_bias_init();
 467         INIT_DELAYED_WORK_NAR(&dbs_info->work, do_dbs_timer);
 468         dbs_info->sample_type = DBS_NORMAL_SAMPLE;
 469         queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work, delay);
 470 }
 471
 472 static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
 473 {
 474         dbs_info->enable = 0;
 475         cancel_delayed_work(&dbs_info->work);
 476         flush_workqueue(kondemand_wq);
 477 }
 478
 479 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 480                                    unsigned int event)
 481 {
 482         unsigned int cpu = policy->cpu;
 483         struct cpu_dbs_info_s *this_dbs_info;
 484         unsigned int j;
 485         int rc;
 486
 487         this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
 488
 489         switch (event) {
 490         case CPUFREQ_GOV_START:
 491                 if ((!cpu_online(cpu)) || (!policy->cur))
 492                         return -EINVAL;
 493
 494                 if (policy->cpuinfo.transition_latency >
 495                                 (TRANSITION_LATENCY_LIMIT * 1000)) {
 496                         printk(KERN_WARNING "ondemand governor failed to load "
 497                                "due to too long transition latency\n");
 498                         return -EINVAL;
 499                 }
 500                 if (this_dbs_info->enable) /* Already enabled */
 501                         break;
 502
 503                 mutex_lock(&dbs_mutex);
 504                 dbs_enable++;
 505                 if (dbs_enable == 1) {
 506                         kondemand_wq = create_workqueue("kondemand");
 507                         if (!kondemand_wq) {
 508                                 printk(KERN_ERR
 509                                          "Creation of kondemand failed\n");
 510                                 dbs_enable--;
 511                                 mutex_unlock(&dbs_mutex);
 512                                 return -ENOSPC;
 513                         }
 514                 }
 515
 516                 rc = sysfs_create_group(&policy->kobj, &dbs_attr_group);
 517                 if (rc) {
 518                         if (dbs_enable == 1)
 519                                 destroy_workqueue(kondemand_wq);
 520                         dbs_enable--;
 521                         mutex_unlock(&dbs_mutex);
 522                         return rc;
 523                 }
 524
 525                 for_each_cpu_mask(j, policy->cpus) {
 526                         struct cpu_dbs_info_s *j_dbs_info;
 527                         j_dbs_info = &per_cpu(cpu_dbs_info, j);
 528                         j_dbs_info->cur_policy = policy;
 529
 530                         j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j);
 531                         j_dbs_info->prev_cpu_wall = get_jiffies_64();
 532                 }
 533                 this_dbs_info->enable = 1;
 534                 /*
 535                  * Start the timerschedule work, when this governor
 536                  * is used for first time
 537                  */
 538                 if (dbs_enable == 1) {
 539                         unsigned int latency;
 540                         /* policy latency is in nS. Convert it to uS first */
 541                         latency = policy->cpuinfo.transition_latency / 1000;
 542                         if (latency == 0)
 543                                 latency = 1;
 544
 545                         def_sampling_rate = latency *
 546                                         DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
 547
 548                         if (def_sampling_rate < MIN_STAT_SAMPLING_RATE)
 549                                 def_sampling_rate = MIN_STAT_SAMPLING_RATE;
 550
 551                         dbs_tuners_ins.sampling_rate = def_sampling_rate;
 552                 }
 553                 dbs_timer_init(policy->cpu);
 554
 555                 mutex_unlock(&dbs_mutex);
 556                 break;
 557
 558         case CPUFREQ_GOV_STOP:
 559                 mutex_lock(&dbs_mutex);
 560                 dbs_timer_exit(this_dbs_info);
 561                 sysfs_remove_group(&policy->kobj, &dbs_attr_group);
 562                 dbs_enable--;
 563                 if (dbs_enable == 0)
 564                         destroy_workqueue(kondemand_wq);
 565
 566                 mutex_unlock(&dbs_mutex);
 567
 568                 break;
 569
 570         case CPUFREQ_GOV_LIMITS:
 571                 mutex_lock(&dbs_mutex);
 572                 if (policy->max < this_dbs_info->cur_policy->cur)
 573                         __cpufreq_driver_target(this_dbs_info->cur_policy,
 574                                                 policy->max,
 575                                                 CPUFREQ_RELATION_H);
 576                 else if (policy->min > this_dbs_info->cur_policy->cur)
 577                         __cpufreq_driver_target(this_dbs_info->cur_policy,
 578                                                 policy->min,
 579                                                 CPUFREQ_RELATION_L);
 580                 mutex_unlock(&dbs_mutex);
 581                 break;
 582         }
 583         return 0;
 584 }
 585
 586 static struct cpufreq_governor cpufreq_gov_dbs = {
 587         .name = "ondemand",
 588         .governor = cpufreq_governor_dbs,
 589         .owner = THIS_MODULE,
 590 };
 591
 592 static int __init cpufreq_gov_dbs_init(void)
 593 {
 594         return cpufreq_register_governor(&cpufreq_gov_dbs);
 595 }
 596
 597 static void __exit cpufreq_gov_dbs_exit(void)
 598 {
 599         cpufreq_unregister_governor(&cpufreq_gov_dbs);
 600 }
 601
 602
 603 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
 604 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
 605 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
 606                    "Low Latency Frequency Transition capable processors");
 607 MODULE_LICENSE("GPL");
 608
 609 module_init(cpufreq_gov_dbs_init);
 610 module_exit(cpufreq_gov_dbs_exit);