cpufreq_ondemand.c 16.2 KB
Newer Older
L
Linus Torvalds 已提交
1 2 3 4 5 6 7 8 9 10 11 12
/*
 *  drivers/cpufreq/cpufreq_ondemand.c
 *
 *  Copyright (C)  2001 Russell King
 *            (C)  2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
 *                      Jun Nakajima <jun.nakajima@intel.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

13 14
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

L
Linus Torvalds 已提交
15
#include <linux/cpufreq.h>
16 17
#include <linux/init.h>
#include <linux/kernel.h>
L
Linus Torvalds 已提交
18
#include <linux/kernel_stat.h>
19 20
#include <linux/kobject.h>
#include <linux/module.h>
21
#include <linux/mutex.h>
22 23
#include <linux/percpu-defs.h>
#include <linux/sysfs.h>
24
#include <linux/tick.h>
25
#include <linux/types.h>
L
Linus Torvalds 已提交
26

27
#include "cpufreq_governor.h"
L
Linus Torvalds 已提交
28

29
/* On-demand governor macors */
30
#define DEF_FREQUENCY_DOWN_DIFFERENTIAL		(10)
L
Linus Torvalds 已提交
31
#define DEF_FREQUENCY_UP_THRESHOLD		(80)
32 33
#define DEF_SAMPLING_DOWN_FACTOR		(1)
#define MAX_SAMPLING_DOWN_FACTOR		(100000)
34 35
#define MICRO_FREQUENCY_DOWN_DIFFERENTIAL	(3)
#define MICRO_FREQUENCY_UP_THRESHOLD		(95)
36
#define MICRO_FREQUENCY_MIN_SAMPLE_RATE		(10000)
37
#define MIN_FREQUENCY_UP_THRESHOLD		(11)
L
Linus Torvalds 已提交
38 39
#define MAX_FREQUENCY_UP_THRESHOLD		(100)

40 41
static struct dbs_data od_dbs_data;
static DEFINE_PER_CPU(struct od_cpu_dbs_info_s, od_cpu_dbs_info);
L
Linus Torvalds 已提交
42

43 44 45 46
#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
static struct cpufreq_governor cpufreq_gov_ondemand;
#endif

47
static struct od_dbs_tuners od_tuners = {
48
	.up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
49
	.sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
50
	.down_differential = DEF_FREQUENCY_DOWN_DIFFERENTIAL,
51
	.ignore_nice = 0,
52
	.powersave_bias = 0,
L
Linus Torvalds 已提交
53 54
};

55
static void ondemand_powersave_bias_init_cpu(int cpu)
56
{
57
	struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
58

59 60 61
	dbs_info->freq_table = cpufreq_frequency_get_table(cpu);
	dbs_info->freq_lo = 0;
}
62

63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83
/*
 * Not all CPUs want IO time to be accounted as busy; this depends on how
 * efficient idling at a higher frequency/voltage is.
 * Pavel Machek says this is not so for various generations of AMD and old
 * Intel systems.
 * Mike Chan (androidlcom) calis this is also not true for ARM.
 * Because of this, whitelist specific known (series) of CPUs by default, and
 * leave all others up to the user.
 */
static int should_io_be_busy(void)
{
#if defined(CONFIG_X86)
	/*
	 * For Intel, Core 2 (model 15) andl later have an efficient idle.
	 */
	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
			boot_cpu_data.x86 == 6 &&
			boot_cpu_data.x86_model >= 15)
		return 1;
#endif
	return 0;
84 85
}

86 87 88 89 90
/*
 * Find right freq to be set now with powersave_bias on.
 * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
 * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
 */
91
static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
92
		unsigned int freq_next, unsigned int relation)
93 94 95 96 97
{
	unsigned int freq_req, freq_reduc, freq_avg;
	unsigned int freq_hi, freq_lo;
	unsigned int index = 0;
	unsigned int jiffies_total, jiffies_hi, jiffies_lo;
98
	struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
99
						   policy->cpu);
100 101 102 103 104 105 106 107 108 109

	if (!dbs_info->freq_table) {
		dbs_info->freq_lo = 0;
		dbs_info->freq_lo_jiffies = 0;
		return freq_next;
	}

	cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
			relation, &index);
	freq_req = dbs_info->freq_table[index].frequency;
110
	freq_reduc = freq_req * od_tuners.powersave_bias / 1000;
111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128
	freq_avg = freq_req - freq_reduc;

	/* Find freq bounds for freq_avg in freq_table */
	index = 0;
	cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
			CPUFREQ_RELATION_H, &index);
	freq_lo = dbs_info->freq_table[index].frequency;
	index = 0;
	cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
			CPUFREQ_RELATION_L, &index);
	freq_hi = dbs_info->freq_table[index].frequency;

	/* Find out how long we have to be in hi and lo freqs */
	if (freq_hi == freq_lo) {
		dbs_info->freq_lo = 0;
		dbs_info->freq_lo_jiffies = 0;
		return freq_lo;
	}
129
	jiffies_total = usecs_to_jiffies(od_tuners.sampling_rate);
130 131 132 133 134 135 136 137 138 139 140 141 142 143
	jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
	jiffies_hi += ((freq_hi - freq_lo) / 2);
	jiffies_hi /= (freq_hi - freq_lo);
	jiffies_lo = jiffies_total - jiffies_hi;
	dbs_info->freq_lo = freq_lo;
	dbs_info->freq_lo_jiffies = jiffies_lo;
	dbs_info->freq_hi_jiffies = jiffies_hi;
	return freq_hi;
}

static void ondemand_powersave_bias_init(void)
{
	int i;
	for_each_online_cpu(i) {
144
		ondemand_powersave_bias_init_cpu(i);
145 146 147
	}
}

148 149 150 151 152 153
static void dbs_freq_increase(struct cpufreq_policy *p, unsigned int freq)
{
	if (od_tuners.powersave_bias)
		freq = powersave_bias_target(p, freq, CPUFREQ_RELATION_H);
	else if (p->cur == p->max)
		return;
154

155 156 157 158 159 160 161 162 163 164 165 166 167 168
	__cpufreq_driver_target(p, freq, od_tuners.powersave_bias ?
			CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
}

/*
 * Every sampling_rate, we check, if current idle time is less than 20%
 * (default), then we try to increase frequency Every sampling_rate, we look for
 * a the lowest frequency which can sustain the load while keeping idle time
 * over 30%. If such a frequency exist, we try to decrease to this frequency.
 *
 * Any frequency increase takes it to the maximum frequency. Frequency reduction
 * happens at minimum steps of 5% (default) of current frequency
 */
static void od_check_cpu(int cpu, unsigned int load_freq)
L
Linus Torvalds 已提交
169
{
170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216
	struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
	struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy;

	dbs_info->freq_lo = 0;

	/* Check for frequency increase */
	if (load_freq > od_tuners.up_threshold * policy->cur) {
		/* If switching to max speed, apply sampling_down_factor */
		if (policy->cur < policy->max)
			dbs_info->rate_mult =
				od_tuners.sampling_down_factor;
		dbs_freq_increase(policy, policy->max);
		return;
	}

	/* Check for frequency decrease */
	/* if we cannot reduce the frequency anymore, break out early */
	if (policy->cur == policy->min)
		return;

	/*
	 * The optimal frequency is the frequency that is the lowest that can
	 * support the current CPU usage without triggering the up policy. To be
	 * safe, we focus 10 points under the threshold.
	 */
	if (load_freq < (od_tuners.up_threshold - od_tuners.down_differential) *
			policy->cur) {
		unsigned int freq_next;
		freq_next = load_freq / (od_tuners.up_threshold -
				od_tuners.down_differential);

		/* No longer fully busy, reset rate_mult */
		dbs_info->rate_mult = 1;

		if (freq_next < policy->min)
			freq_next = policy->min;

		if (!od_tuners.powersave_bias) {
			__cpufreq_driver_target(policy, freq_next,
					CPUFREQ_RELATION_L);
		} else {
			int freq = powersave_bias_target(policy, freq_next,
					CPUFREQ_RELATION_L);
			__cpufreq_driver_target(policy, freq,
					CPUFREQ_RELATION_L);
		}
	}
L
Linus Torvalds 已提交
217 218
}

219 220
static void od_timer_update(struct od_cpu_dbs_info_s *dbs_info, bool sample,
			    struct delayed_work *dw)
221 222 223
{
	unsigned int cpu = dbs_info->cdbs.cpu;
	int delay, sample_type = dbs_info->sample_type;
L
Linus Torvalds 已提交
224

225 226 227 228
	/* Common NORMAL_SAMPLE setup */
	dbs_info->sample_type = OD_NORMAL_SAMPLE;
	if (sample_type == OD_SUB_SAMPLE) {
		delay = dbs_info->freq_lo_jiffies;
229 230 231 232
		if (sample)
			__cpufreq_driver_target(dbs_info->cdbs.cur_policy,
						dbs_info->freq_lo,
						CPUFREQ_RELATION_H);
233
	} else {
234 235
		if (sample)
			dbs_check_cpu(&od_dbs_data, cpu);
236 237 238 239 240
		if (dbs_info->freq_lo) {
			/* Setup timer for SUB_SAMPLE */
			dbs_info->sample_type = OD_SUB_SAMPLE;
			delay = dbs_info->freq_hi_jiffies;
		} else {
241 242
			delay = delay_for_sampling_rate(od_tuners.sampling_rate
						* dbs_info->rate_mult);
243 244 245
		}
	}

246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270
	schedule_delayed_work_on(smp_processor_id(), dw, delay);
}

static void od_timer_coordinated(struct od_cpu_dbs_info_s *dbs_info_local,
				 struct delayed_work *dw)
{
	struct od_cpu_dbs_info_s *dbs_info;
	ktime_t time_now;
	s64 delta_us;
	bool sample = true;

	/* use leader CPU's dbs_info */
	dbs_info = &per_cpu(od_cpu_dbs_info, dbs_info_local->cdbs.cpu);
	mutex_lock(&dbs_info->cdbs.timer_mutex);

	time_now = ktime_get();
	delta_us = ktime_us_delta(time_now, dbs_info->cdbs.time_stamp);

	/* Do nothing if we recently have sampled */
	if (delta_us < (s64)(od_tuners.sampling_rate / 2))
		sample = false;
	else
		dbs_info->cdbs.time_stamp = time_now;

	od_timer_update(dbs_info, sample, dw);
271 272 273
	mutex_unlock(&dbs_info->cdbs.timer_mutex);
}

274 275 276 277 278 279 280 281 282 283 284 285 286 287 288
static void od_dbs_timer(struct work_struct *work)
{
	struct delayed_work *dw = to_delayed_work(work);
	struct od_cpu_dbs_info_s *dbs_info =
		container_of(work, struct od_cpu_dbs_info_s, cdbs.work.work);

	if (dbs_sw_coordinated_cpus(&dbs_info->cdbs)) {
		od_timer_coordinated(dbs_info, dw);
	} else {
		mutex_lock(&dbs_info->cdbs.timer_mutex);
		od_timer_update(dbs_info, true, dw);
		mutex_unlock(&dbs_info->cdbs.timer_mutex);
	}
}

289 290 291 292 293 294
/************************** sysfs interface ************************/

static ssize_t show_sampling_rate_min(struct kobject *kobj,
				      struct attribute *attr, char *buf)
{
	return sprintf(buf, "%u\n", od_dbs_data.min_sampling_rate);
L
Linus Torvalds 已提交
295 296
}

297 298 299 300 301
/**
 * update_sampling_rate - update sampling rate effective immediately if needed.
 * @new_rate: new sampling rate
 *
 * If new rate is smaller than the old, simply updaing
302 303 304 305 306 307 308
 * dbs_tuners_int.sampling_rate might not be appropriate. For example, if the
 * original sampling_rate was 1 second and the requested new sampling rate is 10
 * ms because the user needs immediate reaction from ondemand governor, but not
 * sure if higher frequency will be required or not, then, the governor may
 * change the sampling rate too late; up to 1 second later. Thus, if we are
 * reducing the sampling rate, we need to make the new value effective
 * immediately.
309 310 311 312 313
 */
static void update_sampling_rate(unsigned int new_rate)
{
	int cpu;

314 315
	od_tuners.sampling_rate = new_rate = max(new_rate,
			od_dbs_data.min_sampling_rate);
316 317 318

	for_each_online_cpu(cpu) {
		struct cpufreq_policy *policy;
319
		struct od_cpu_dbs_info_s *dbs_info;
320 321 322 323 324
		unsigned long next_sampling, appointed_at;

		policy = cpufreq_cpu_get(cpu);
		if (!policy)
			continue;
325 326 327 328
		if (policy->governor != &cpufreq_gov_ondemand) {
			cpufreq_cpu_put(policy);
			continue;
		}
329
		dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
330 331
		cpufreq_cpu_put(policy);

332
		mutex_lock(&dbs_info->cdbs.timer_mutex);
333

334 335
		if (!delayed_work_pending(&dbs_info->cdbs.work)) {
			mutex_unlock(&dbs_info->cdbs.timer_mutex);
336 337 338
			continue;
		}

339 340
		next_sampling = jiffies + usecs_to_jiffies(new_rate);
		appointed_at = dbs_info->cdbs.work.timer.expires;
341 342 343

		if (time_before(next_sampling, appointed_at)) {

344 345 346
			mutex_unlock(&dbs_info->cdbs.timer_mutex);
			cancel_delayed_work_sync(&dbs_info->cdbs.work);
			mutex_lock(&dbs_info->cdbs.timer_mutex);
347

348
			schedule_delayed_work_on(cpu, &dbs_info->cdbs.work,
349
					usecs_to_jiffies(new_rate));
350 351

		}
352
		mutex_unlock(&dbs_info->cdbs.timer_mutex);
353 354 355
	}
}

356 357
static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
				   const char *buf, size_t count)
L
Linus Torvalds 已提交
358 359 360
{
	unsigned int input;
	int ret;
361
	ret = sscanf(buf, "%u", &input);
362 363
	if (ret != 1)
		return -EINVAL;
364
	update_sampling_rate(input);
L
Linus Torvalds 已提交
365 366 367
	return count;
}

368 369 370 371 372 373 374 375 376
static ssize_t store_io_is_busy(struct kobject *a, struct attribute *b,
				   const char *buf, size_t count)
{
	unsigned int input;
	int ret;

	ret = sscanf(buf, "%u", &input);
	if (ret != 1)
		return -EINVAL;
377
	od_tuners.io_is_busy = !!input;
378 379 380
	return count;
}

381 382
static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
				  const char *buf, size_t count)
L
Linus Torvalds 已提交
383 384 385
{
	unsigned int input;
	int ret;
386
	ret = sscanf(buf, "%u", &input);
L
Linus Torvalds 已提交
387

388
	if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
389
			input < MIN_FREQUENCY_UP_THRESHOLD) {
L
Linus Torvalds 已提交
390 391
		return -EINVAL;
	}
392
	od_tuners.up_threshold = input;
L
Linus Torvalds 已提交
393 394 395
	return count;
}

396 397 398 399 400 401 402 403 404
static ssize_t store_sampling_down_factor(struct kobject *a,
			struct attribute *b, const char *buf, size_t count)
{
	unsigned int input, j;
	int ret;
	ret = sscanf(buf, "%u", &input);

	if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
		return -EINVAL;
405
	od_tuners.sampling_down_factor = input;
406 407 408

	/* Reset down sampling multiplier in case it was active */
	for_each_online_cpu(j) {
409 410
		struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
				j);
411 412 413 414 415
		dbs_info->rate_mult = 1;
	}
	return count;
}

416 417
static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
				      const char *buf, size_t count)
418 419 420 421 422
{
	unsigned int input;
	int ret;

	unsigned int j;
423

424
	ret = sscanf(buf, "%u", &input);
425
	if (ret != 1)
426 427
		return -EINVAL;

428
	if (input > 1)
429
		input = 1;
430

431
	if (input == od_tuners.ignore_nice) { /* nothing to do */
432 433
		return count;
	}
434
	od_tuners.ignore_nice = input;
435

436
	/* we need to re-evaluate prev_cpu_idle */
437
	for_each_online_cpu(j) {
438
		struct od_cpu_dbs_info_s *dbs_info;
439
		dbs_info = &per_cpu(od_cpu_dbs_info, j);
440 441 442 443 444
		dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
						&dbs_info->cdbs.prev_cpu_wall);
		if (od_tuners.ignore_nice)
			dbs_info->cdbs.prev_cpu_nice =
				kcpustat_cpu(j).cpustat[CPUTIME_NICE];
445

446 447 448 449
	}
	return count;
}

450 451
static ssize_t store_powersave_bias(struct kobject *a, struct attribute *b,
				    const char *buf, size_t count)
452 453 454 455 456 457 458 459 460 461 462
{
	unsigned int input;
	int ret;
	ret = sscanf(buf, "%u", &input);

	if (ret != 1)
		return -EINVAL;

	if (input > 1000)
		input = 1000;

463
	od_tuners.powersave_bias = input;
464 465 466 467
	ondemand_powersave_bias_init();
	return count;
}

468 469 470 471 472 473 474
show_one(od, sampling_rate, sampling_rate);
show_one(od, io_is_busy, io_is_busy);
show_one(od, up_threshold, up_threshold);
show_one(od, sampling_down_factor, sampling_down_factor);
show_one(od, ignore_nice_load, ignore_nice);
show_one(od, powersave_bias, powersave_bias);

475
define_one_global_rw(sampling_rate);
476
define_one_global_rw(io_is_busy);
477
define_one_global_rw(up_threshold);
478
define_one_global_rw(sampling_down_factor);
479 480
define_one_global_rw(ignore_nice_load);
define_one_global_rw(powersave_bias);
481
define_one_global_ro(sampling_rate_min);
L
Linus Torvalds 已提交
482

483
static struct attribute *dbs_attributes[] = {
L
Linus Torvalds 已提交
484 485 486
	&sampling_rate_min.attr,
	&sampling_rate.attr,
	&up_threshold.attr,
487
	&sampling_down_factor.attr,
488
	&ignore_nice_load.attr,
489
	&powersave_bias.attr,
490
	&io_is_busy.attr,
L
Linus Torvalds 已提交
491 492 493
	NULL
};

494
static struct attribute_group od_attr_group = {
L
Linus Torvalds 已提交
495 496 497 498 499 500
	.attrs = dbs_attributes,
	.name = "ondemand",
};

/************************** sysfs end ************************/

501
define_get_cpu_dbs_routines(od_cpu_dbs_info);
502

503 504 505 506 507 508
static struct od_ops od_ops = {
	.io_busy = should_io_be_busy,
	.powersave_bias_init_cpu = ondemand_powersave_bias_init_cpu,
	.powersave_bias_target = powersave_bias_target,
	.freq_increase = dbs_freq_increase,
};
509

510 511 512 513 514 515 516 517 518 519
static struct dbs_data od_dbs_data = {
	.governor = GOV_ONDEMAND,
	.attr_group = &od_attr_group,
	.tuners = &od_tuners,
	.get_cpu_cdbs = get_cpu_cdbs,
	.get_cpu_dbs_info_s = get_cpu_dbs_info_s,
	.gov_dbs_timer = od_dbs_timer,
	.gov_check_cpu = od_check_cpu,
	.gov_ops = &od_ops,
};
L
Linus Torvalds 已提交
520

521 522
static int od_cpufreq_governor_dbs(struct cpufreq_policy *policy,
		unsigned int event)
L
Linus Torvalds 已提交
523
{
524
	return cpufreq_governor_dbs(&od_dbs_data, policy, event);
L
Linus Torvalds 已提交
525 526
}

527 528
#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
static
529
#endif
530 531 532 533 534 535
struct cpufreq_governor cpufreq_gov_ondemand = {
	.name			= "ondemand",
	.governor		= od_cpufreq_governor_dbs,
	.max_transition_latency	= TRANSITION_LATENCY_LIMIT,
	.owner			= THIS_MODULE,
};
L
Linus Torvalds 已提交
536 537 538

static int __init cpufreq_gov_dbs_init(void)
{
539 540
	u64 idle_time;
	int cpu = get_cpu();
541

542
	mutex_init(&od_dbs_data.mutex);
543
	idle_time = get_cpu_idle_time_us(cpu, NULL);
544
	put_cpu();
545 546
	if (idle_time != -1ULL) {
		/* Idle micro accounting is supported. Use finer thresholds */
547 548
		od_tuners.up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
		od_tuners.down_differential = MICRO_FREQUENCY_DOWN_DIFFERENTIAL;
549
		/*
550
		 * In nohz/micro accounting case we set the minimum frequency
551 552 553
		 * not depending on HZ, but fixed (very low). The deferred
		 * timer might skip some samples if idle/sleeping as needed.
		*/
554
		od_dbs_data.min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
555 556
	} else {
		/* For correct statistics, we need 10 ticks for each measure */
557 558
		od_dbs_data.min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
			jiffies_to_usecs(10);
559
	}
560

561
	return cpufreq_register_governor(&cpufreq_gov_ondemand);
L
Linus Torvalds 已提交
562 563 564 565
}

static void __exit cpufreq_gov_dbs_exit(void)
{
566
	cpufreq_unregister_governor(&cpufreq_gov_ondemand);
L
Linus Torvalds 已提交
567 568
}

569 570 571
MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
572
	"Low Latency Frequency Transition capable processors");
573
MODULE_LICENSE("GPL");
L
Linus Torvalds 已提交
574

575 576 577
#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
fs_initcall(cpufreq_gov_dbs_init);
#else
L
Linus Torvalds 已提交
578
module_init(cpufreq_gov_dbs_init);
579
#endif
L
Linus Torvalds 已提交
580
module_exit(cpufreq_gov_dbs_exit);