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