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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 14 15 #include <linux/cpu.h> 16 #include <linux/percpu-defs.h> 17 #include <linux/slab.h> 18 #include <linux/tick.h> 19 #include "cpufreq_governor.h" 20 21 /* On-demand governor macros */ 22 #define DEF_FREQUENCY_UP_THRESHOLD (80) 23 #define DEF_SAMPLING_DOWN_FACTOR (1) 24 #define MAX_SAMPLING_DOWN_FACTOR (100000) 25 #define MICRO_FREQUENCY_UP_THRESHOLD (95) 26 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE (10000) 27 #define MIN_FREQUENCY_UP_THRESHOLD (11) 28 #define MAX_FREQUENCY_UP_THRESHOLD (100) 29 30 static DEFINE_PER_CPU(struct od_cpu_dbs_info_s, od_cpu_dbs_info); 31 32 static struct od_ops od_ops; 33 34 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND 35 static struct cpufreq_governor cpufreq_gov_ondemand; 36 #endif 37 38 static unsigned int default_powersave_bias; 39 40 static void ondemand_powersave_bias_init_cpu(int cpu) 41 { 42 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu); 43 44 dbs_info->freq_table = cpufreq_frequency_get_table(cpu); 45 dbs_info->freq_lo = 0; 46 } 47 48 /* 49 * Not all CPUs want IO time to be accounted as busy; this depends on how 50 * efficient idling at a higher frequency/voltage is. 51 * Pavel Machek says this is not so for various generations of AMD and old 52 * Intel systems. 53 * Mike Chan (android.com) claims this is also not true for ARM. 54 * Because of this, whitelist specific known (series) of CPUs by default, and 55 * leave all others up to the user. 56 */ 57 static int should_io_be_busy(void) 58 { 59 #if defined(CONFIG_X86) 60 /* 61 * For Intel, Core 2 (model 15) and later have an efficient idle. 62 */ 63 if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL && 64 boot_cpu_data.x86 == 6 && 65 boot_cpu_data.x86_model >= 15) 66 return 1; 67 #endif 68 return 0; 69 } 70 71 /* 72 * Find right freq to be set now with powersave_bias on. 73 * Returns the freq_hi to be used right now and will set freq_hi_jiffies, 74 * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs. 75 */ 76 static unsigned int generic_powersave_bias_target(struct cpufreq_policy *policy, 77 unsigned int freq_next, unsigned int relation) 78 { 79 unsigned int freq_req, freq_reduc, freq_avg; 80 unsigned int freq_hi, freq_lo; 81 unsigned int index = 0; 82 unsigned int jiffies_total, jiffies_hi, jiffies_lo; 83 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, 84 policy->cpu); 85 struct dbs_data *dbs_data = policy->governor_data; 86 struct od_dbs_tuners *od_tuners = dbs_data->tuners; 87 88 if (!dbs_info->freq_table) { 89 dbs_info->freq_lo = 0; 90 dbs_info->freq_lo_jiffies = 0; 91 return freq_next; 92 } 93 94 cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next, 95 relation, &index); 96 freq_req = dbs_info->freq_table[index].frequency; 97 freq_reduc = freq_req * od_tuners->powersave_bias / 1000; 98 freq_avg = freq_req - freq_reduc; 99 100 /* Find freq bounds for freq_avg in freq_table */ 101 index = 0; 102 cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg, 103 CPUFREQ_RELATION_H, &index); 104 freq_lo = dbs_info->freq_table[index].frequency; 105 index = 0; 106 cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg, 107 CPUFREQ_RELATION_L, &index); 108 freq_hi = dbs_info->freq_table[index].frequency; 109 110 /* Find out how long we have to be in hi and lo freqs */ 111 if (freq_hi == freq_lo) { 112 dbs_info->freq_lo = 0; 113 dbs_info->freq_lo_jiffies = 0; 114 return freq_lo; 115 } 116 jiffies_total = usecs_to_jiffies(od_tuners->sampling_rate); 117 jiffies_hi = (freq_avg - freq_lo) * jiffies_total; 118 jiffies_hi += ((freq_hi - freq_lo) / 2); 119 jiffies_hi /= (freq_hi - freq_lo); 120 jiffies_lo = jiffies_total - jiffies_hi; 121 dbs_info->freq_lo = freq_lo; 122 dbs_info->freq_lo_jiffies = jiffies_lo; 123 dbs_info->freq_hi_jiffies = jiffies_hi; 124 return freq_hi; 125 } 126 127 static void ondemand_powersave_bias_init(void) 128 { 129 int i; 130 for_each_online_cpu(i) { 131 ondemand_powersave_bias_init_cpu(i); 132 } 133 } 134 135 static void dbs_freq_increase(struct cpufreq_policy *policy, unsigned int freq) 136 { 137 struct dbs_data *dbs_data = policy->governor_data; 138 struct od_dbs_tuners *od_tuners = dbs_data->tuners; 139 140 if (od_tuners->powersave_bias) 141 freq = od_ops.powersave_bias_target(policy, freq, 142 CPUFREQ_RELATION_H); 143 else if (policy->cur == policy->max) 144 return; 145 146 __cpufreq_driver_target(policy, freq, od_tuners->powersave_bias ? 147 CPUFREQ_RELATION_L : CPUFREQ_RELATION_H); 148 } 149 150 /* 151 * Every sampling_rate, we check, if current idle time is less than 20% 152 * (default), then we try to increase frequency. Else, we adjust the frequency 153 * proportional to load. 154 */ 155 static void od_check_cpu(int cpu, unsigned int load) 156 { 157 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu); 158 struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy; 159 struct dbs_data *dbs_data = policy->governor_data; 160 struct od_dbs_tuners *od_tuners = dbs_data->tuners; 161 162 dbs_info->freq_lo = 0; 163 164 /* Check for frequency increase */ 165 if (load > od_tuners->up_threshold) { 166 /* If switching to max speed, apply sampling_down_factor */ 167 if (policy->cur < policy->max) 168 dbs_info->rate_mult = 169 od_tuners->sampling_down_factor; 170 dbs_freq_increase(policy, policy->max); 171 return; 172 } else { 173 /* Calculate the next frequency proportional to load */ 174 unsigned int freq_next; 175 freq_next = load * policy->cpuinfo.max_freq / 100; 176 177 /* No longer fully busy, reset rate_mult */ 178 dbs_info->rate_mult = 1; 179 180 if (!od_tuners->powersave_bias) { 181 __cpufreq_driver_target(policy, freq_next, 182 CPUFREQ_RELATION_L); 183 return; 184 } 185 186 freq_next = od_ops.powersave_bias_target(policy, freq_next, 187 CPUFREQ_RELATION_L); 188 __cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_L); 189 } 190 } 191 192 static void od_dbs_timer(struct work_struct *work) 193 { 194 struct od_cpu_dbs_info_s *dbs_info = 195 container_of(work, struct od_cpu_dbs_info_s, cdbs.work.work); 196 unsigned int cpu = dbs_info->cdbs.cur_policy->cpu; 197 struct od_cpu_dbs_info_s *core_dbs_info = &per_cpu(od_cpu_dbs_info, 198 cpu); 199 struct dbs_data *dbs_data = dbs_info->cdbs.cur_policy->governor_data; 200 struct od_dbs_tuners *od_tuners = dbs_data->tuners; 201 int delay = 0, sample_type = core_dbs_info->sample_type; 202 bool modify_all = true; 203 204 mutex_lock(&core_dbs_info->cdbs.timer_mutex); 205 if (!need_load_eval(&core_dbs_info->cdbs, od_tuners->sampling_rate)) { 206 modify_all = false; 207 goto max_delay; 208 } 209 210 /* Common NORMAL_SAMPLE setup */ 211 core_dbs_info->sample_type = OD_NORMAL_SAMPLE; 212 if (sample_type == OD_SUB_SAMPLE) { 213 delay = core_dbs_info->freq_lo_jiffies; 214 __cpufreq_driver_target(core_dbs_info->cdbs.cur_policy, 215 core_dbs_info->freq_lo, CPUFREQ_RELATION_H); 216 } else { 217 dbs_check_cpu(dbs_data, cpu); 218 if (core_dbs_info->freq_lo) { 219 /* Setup timer for SUB_SAMPLE */ 220 core_dbs_info->sample_type = OD_SUB_SAMPLE; 221 delay = core_dbs_info->freq_hi_jiffies; 222 } 223 } 224 225 max_delay: 226 if (!delay) 227 delay = delay_for_sampling_rate(od_tuners->sampling_rate 228 * core_dbs_info->rate_mult); 229 230 gov_queue_work(dbs_data, dbs_info->cdbs.cur_policy, delay, modify_all); 231 mutex_unlock(&core_dbs_info->cdbs.timer_mutex); 232 } 233 234 /************************** sysfs interface ************************/ 235 static struct common_dbs_data od_dbs_cdata; 236 237 /** 238 * update_sampling_rate - update sampling rate effective immediately if needed. 239 * @new_rate: new sampling rate 240 * 241 * If new rate is smaller than the old, simply updating 242 * dbs_tuners_int.sampling_rate might not be appropriate. For example, if the 243 * original sampling_rate was 1 second and the requested new sampling rate is 10 244 * ms because the user needs immediate reaction from ondemand governor, but not 245 * sure if higher frequency will be required or not, then, the governor may 246 * change the sampling rate too late; up to 1 second later. Thus, if we are 247 * reducing the sampling rate, we need to make the new value effective 248 * immediately. 249 */ 250 static void update_sampling_rate(struct dbs_data *dbs_data, 251 unsigned int new_rate) 252 { 253 struct od_dbs_tuners *od_tuners = dbs_data->tuners; 254 int cpu; 255 256 od_tuners->sampling_rate = new_rate = max(new_rate, 257 dbs_data->min_sampling_rate); 258 259 for_each_online_cpu(cpu) { 260 struct cpufreq_policy *policy; 261 struct od_cpu_dbs_info_s *dbs_info; 262 unsigned long next_sampling, appointed_at; 263 264 policy = cpufreq_cpu_get(cpu); 265 if (!policy) 266 continue; 267 if (policy->governor != &cpufreq_gov_ondemand) { 268 cpufreq_cpu_put(policy); 269 continue; 270 } 271 dbs_info = &per_cpu(od_cpu_dbs_info, cpu); 272 cpufreq_cpu_put(policy); 273 274 mutex_lock(&dbs_info->cdbs.timer_mutex); 275 276 if (!delayed_work_pending(&dbs_info->cdbs.work)) { 277 mutex_unlock(&dbs_info->cdbs.timer_mutex); 278 continue; 279 } 280 281 next_sampling = jiffies + usecs_to_jiffies(new_rate); 282 appointed_at = dbs_info->cdbs.work.timer.expires; 283 284 if (time_before(next_sampling, appointed_at)) { 285 286 mutex_unlock(&dbs_info->cdbs.timer_mutex); 287 cancel_delayed_work_sync(&dbs_info->cdbs.work); 288 mutex_lock(&dbs_info->cdbs.timer_mutex); 289 290 gov_queue_work(dbs_data, dbs_info->cdbs.cur_policy, 291 usecs_to_jiffies(new_rate), true); 292 293 } 294 mutex_unlock(&dbs_info->cdbs.timer_mutex); 295 } 296 } 297 298 static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf, 299 size_t count) 300 { 301 unsigned int input; 302 int ret; 303 ret = sscanf(buf, "%u", &input); 304 if (ret != 1) 305 return -EINVAL; 306 307 update_sampling_rate(dbs_data, input); 308 return count; 309 } 310 311 static ssize_t store_io_is_busy(struct dbs_data *dbs_data, const char *buf, 312 size_t count) 313 { 314 struct od_dbs_tuners *od_tuners = dbs_data->tuners; 315 unsigned int input; 316 int ret; 317 unsigned int j; 318 319 ret = sscanf(buf, "%u", &input); 320 if (ret != 1) 321 return -EINVAL; 322 od_tuners->io_is_busy = !!input; 323 324 /* we need to re-evaluate prev_cpu_idle */ 325 for_each_online_cpu(j) { 326 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, 327 j); 328 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j, 329 &dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy); 330 } 331 return count; 332 } 333 334 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf, 335 size_t count) 336 { 337 struct od_dbs_tuners *od_tuners = dbs_data->tuners; 338 unsigned int input; 339 int ret; 340 ret = sscanf(buf, "%u", &input); 341 342 if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD || 343 input < MIN_FREQUENCY_UP_THRESHOLD) { 344 return -EINVAL; 345 } 346 347 od_tuners->up_threshold = input; 348 return count; 349 } 350 351 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data, 352 const char *buf, size_t count) 353 { 354 struct od_dbs_tuners *od_tuners = dbs_data->tuners; 355 unsigned int input, j; 356 int ret; 357 ret = sscanf(buf, "%u", &input); 358 359 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1) 360 return -EINVAL; 361 od_tuners->sampling_down_factor = input; 362 363 /* Reset down sampling multiplier in case it was active */ 364 for_each_online_cpu(j) { 365 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, 366 j); 367 dbs_info->rate_mult = 1; 368 } 369 return count; 370 } 371 372 static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data, 373 const char *buf, size_t count) 374 { 375 struct od_dbs_tuners *od_tuners = dbs_data->tuners; 376 unsigned int input; 377 int ret; 378 379 unsigned int j; 380 381 ret = sscanf(buf, "%u", &input); 382 if (ret != 1) 383 return -EINVAL; 384 385 if (input > 1) 386 input = 1; 387 388 if (input == od_tuners->ignore_nice_load) { /* nothing to do */ 389 return count; 390 } 391 od_tuners->ignore_nice_load = input; 392 393 /* we need to re-evaluate prev_cpu_idle */ 394 for_each_online_cpu(j) { 395 struct od_cpu_dbs_info_s *dbs_info; 396 dbs_info = &per_cpu(od_cpu_dbs_info, j); 397 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j, 398 &dbs_info->cdbs.prev_cpu_wall, od_tuners->io_is_busy); 399 if (od_tuners->ignore_nice_load) 400 dbs_info->cdbs.prev_cpu_nice = 401 kcpustat_cpu(j).cpustat[CPUTIME_NICE]; 402 403 } 404 return count; 405 } 406 407 static ssize_t store_powersave_bias(struct dbs_data *dbs_data, const char *buf, 408 size_t count) 409 { 410 struct od_dbs_tuners *od_tuners = dbs_data->tuners; 411 unsigned int input; 412 int ret; 413 ret = sscanf(buf, "%u", &input); 414 415 if (ret != 1) 416 return -EINVAL; 417 418 if (input > 1000) 419 input = 1000; 420 421 od_tuners->powersave_bias = input; 422 ondemand_powersave_bias_init(); 423 return count; 424 } 425 426 show_store_one(od, sampling_rate); 427 show_store_one(od, io_is_busy); 428 show_store_one(od, up_threshold); 429 show_store_one(od, sampling_down_factor); 430 show_store_one(od, ignore_nice_load); 431 show_store_one(od, powersave_bias); 432 declare_show_sampling_rate_min(od); 433 434 gov_sys_pol_attr_rw(sampling_rate); 435 gov_sys_pol_attr_rw(io_is_busy); 436 gov_sys_pol_attr_rw(up_threshold); 437 gov_sys_pol_attr_rw(sampling_down_factor); 438 gov_sys_pol_attr_rw(ignore_nice_load); 439 gov_sys_pol_attr_rw(powersave_bias); 440 gov_sys_pol_attr_ro(sampling_rate_min); 441 442 static struct attribute *dbs_attributes_gov_sys[] = { 443 &sampling_rate_min_gov_sys.attr, 444 &sampling_rate_gov_sys.attr, 445 &up_threshold_gov_sys.attr, 446 &sampling_down_factor_gov_sys.attr, 447 &ignore_nice_load_gov_sys.attr, 448 &powersave_bias_gov_sys.attr, 449 &io_is_busy_gov_sys.attr, 450 NULL 451 }; 452 453 static struct attribute_group od_attr_group_gov_sys = { 454 .attrs = dbs_attributes_gov_sys, 455 .name = "ondemand", 456 }; 457 458 static struct attribute *dbs_attributes_gov_pol[] = { 459 &sampling_rate_min_gov_pol.attr, 460 &sampling_rate_gov_pol.attr, 461 &up_threshold_gov_pol.attr, 462 &sampling_down_factor_gov_pol.attr, 463 &ignore_nice_load_gov_pol.attr, 464 &powersave_bias_gov_pol.attr, 465 &io_is_busy_gov_pol.attr, 466 NULL 467 }; 468 469 static struct attribute_group od_attr_group_gov_pol = { 470 .attrs = dbs_attributes_gov_pol, 471 .name = "ondemand", 472 }; 473 474 /************************** sysfs end ************************/ 475 476 static int od_init(struct dbs_data *dbs_data) 477 { 478 struct od_dbs_tuners *tuners; 479 u64 idle_time; 480 int cpu; 481 482 tuners = kzalloc(sizeof(*tuners), GFP_KERNEL); 483 if (!tuners) { 484 pr_err("%s: kzalloc failed\n", __func__); 485 return -ENOMEM; 486 } 487 488 cpu = get_cpu(); 489 idle_time = get_cpu_idle_time_us(cpu, NULL); 490 put_cpu(); 491 if (idle_time != -1ULL) { 492 /* Idle micro accounting is supported. Use finer thresholds */ 493 tuners->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD; 494 /* 495 * In nohz/micro accounting case we set the minimum frequency 496 * not depending on HZ, but fixed (very low). The deferred 497 * timer might skip some samples if idle/sleeping as needed. 498 */ 499 dbs_data->min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE; 500 } else { 501 tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD; 502 503 /* For correct statistics, we need 10 ticks for each measure */ 504 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO * 505 jiffies_to_usecs(10); 506 } 507 508 tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR; 509 tuners->ignore_nice_load = 0; 510 tuners->powersave_bias = default_powersave_bias; 511 tuners->io_is_busy = should_io_be_busy(); 512 513 dbs_data->tuners = tuners; 514 mutex_init(&dbs_data->mutex); 515 return 0; 516 } 517 518 static void od_exit(struct dbs_data *dbs_data) 519 { 520 kfree(dbs_data->tuners); 521 } 522 523 define_get_cpu_dbs_routines(od_cpu_dbs_info); 524 525 static struct od_ops od_ops = { 526 .powersave_bias_init_cpu = ondemand_powersave_bias_init_cpu, 527 .powersave_bias_target = generic_powersave_bias_target, 528 .freq_increase = dbs_freq_increase, 529 }; 530 531 static struct common_dbs_data od_dbs_cdata = { 532 .governor = GOV_ONDEMAND, 533 .attr_group_gov_sys = &od_attr_group_gov_sys, 534 .attr_group_gov_pol = &od_attr_group_gov_pol, 535 .get_cpu_cdbs = get_cpu_cdbs, 536 .get_cpu_dbs_info_s = get_cpu_dbs_info_s, 537 .gov_dbs_timer = od_dbs_timer, 538 .gov_check_cpu = od_check_cpu, 539 .gov_ops = &od_ops, 540 .init = od_init, 541 .exit = od_exit, 542 }; 543 544 static void od_set_powersave_bias(unsigned int powersave_bias) 545 { 546 struct cpufreq_policy *policy; 547 struct dbs_data *dbs_data; 548 struct od_dbs_tuners *od_tuners; 549 unsigned int cpu; 550 cpumask_t done; 551 552 default_powersave_bias = powersave_bias; 553 cpumask_clear(&done); 554 555 get_online_cpus(); 556 for_each_online_cpu(cpu) { 557 if (cpumask_test_cpu(cpu, &done)) 558 continue; 559 560 policy = per_cpu(od_cpu_dbs_info, cpu).cdbs.cur_policy; 561 if (!policy) 562 continue; 563 564 cpumask_or(&done, &done, policy->cpus); 565 566 if (policy->governor != &cpufreq_gov_ondemand) 567 continue; 568 569 dbs_data = policy->governor_data; 570 od_tuners = dbs_data->tuners; 571 od_tuners->powersave_bias = default_powersave_bias; 572 } 573 put_online_cpus(); 574 } 575 576 void od_register_powersave_bias_handler(unsigned int (*f) 577 (struct cpufreq_policy *, unsigned int, unsigned int), 578 unsigned int powersave_bias) 579 { 580 od_ops.powersave_bias_target = f; 581 od_set_powersave_bias(powersave_bias); 582 } 583 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler); 584 585 void od_unregister_powersave_bias_handler(void) 586 { 587 od_ops.powersave_bias_target = generic_powersave_bias_target; 588 od_set_powersave_bias(0); 589 } 590 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler); 591 592 static int od_cpufreq_governor_dbs(struct cpufreq_policy *policy, 593 unsigned int event) 594 { 595 return cpufreq_governor_dbs(policy, &od_dbs_cdata, event); 596 } 597 598 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND 599 static 600 #endif 601 struct cpufreq_governor cpufreq_gov_ondemand = { 602 .name = "ondemand", 603 .governor = od_cpufreq_governor_dbs, 604 .max_transition_latency = TRANSITION_LATENCY_LIMIT, 605 .owner = THIS_MODULE, 606 }; 607 608 static int __init cpufreq_gov_dbs_init(void) 609 { 610 return cpufreq_register_governor(&cpufreq_gov_ondemand); 611 } 612 613 static void __exit cpufreq_gov_dbs_exit(void) 614 { 615 cpufreq_unregister_governor(&cpufreq_gov_ondemand); 616 } 617 618 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>"); 619 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>"); 620 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for " 621 "Low Latency Frequency Transition capable processors"); 622 MODULE_LICENSE("GPL"); 623 624 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND 625 fs_initcall(cpufreq_gov_dbs_init); 626 #else 627 module_init(cpufreq_gov_dbs_init); 628 #endif 629 module_exit(cpufreq_gov_dbs_exit); 630