[CPUFREQ] Resolve time unit thinko in ondemand/conservative govs
[linux-2.6.git] / 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/init.h>
17 #include <linux/cpufreq.h>
18 #include <linux/cpu.h>
19 #include <linux/jiffies.h>
20 #include <linux/kernel_stat.h>
21 #include <linux/mutex.h>
22 #include <linux/hrtimer.h>
23 #include <linux/tick.h>
24 #include <linux/ktime.h>
25 #include <linux/sched.h>
26
27 /*
28  * dbs is used in this file as a shortform for demandbased switching
29  * It helps to keep variable names smaller, simpler
30  */
31
32 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
33 #define DEF_FREQUENCY_DOWN_THRESHOLD            (20)
34
35 /*
36  * The polling frequency of this governor depends on the capability of
37  * the processor. Default polling frequency is 1000 times the transition
38  * latency of the processor. The governor will work on any processor with
39  * transition latency <= 10mS, using appropriate sampling
40  * rate.
41  * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
42  * this governor will not work.
43  * All times here are in uS.
44  */
45 #define MIN_SAMPLING_RATE_RATIO                 (2)
46
47 static unsigned int min_sampling_rate;
48
49 #define LATENCY_MULTIPLIER                      (1000)
50 #define MIN_LATENCY_MULTIPLIER                  (100)
51 #define DEF_SAMPLING_DOWN_FACTOR                (1)
52 #define MAX_SAMPLING_DOWN_FACTOR                (10)
53 #define TRANSITION_LATENCY_LIMIT                (10 * 1000 * 1000)
54
55 static void do_dbs_timer(struct work_struct *work);
56
57 struct cpu_dbs_info_s {
58         cputime64_t prev_cpu_idle;
59         cputime64_t prev_cpu_wall;
60         cputime64_t prev_cpu_nice;
61         struct cpufreq_policy *cur_policy;
62         struct delayed_work work;
63         unsigned int down_skip;
64         unsigned int requested_freq;
65         int cpu;
66         unsigned int enable:1;
67         /*
68          * percpu mutex that serializes governor limit change with
69          * do_dbs_timer invocation. We do not want do_dbs_timer to run
70          * when user is changing the governor or limits.
71          */
72         struct mutex timer_mutex;
73 };
74 static DEFINE_PER_CPU(struct cpu_dbs_info_s, cs_cpu_dbs_info);
75
76 static unsigned int dbs_enable; /* number of CPUs using this policy */
77
78 /*
79  * dbs_mutex protects data in dbs_tuners_ins from concurrent changes on
80  * different CPUs. It protects dbs_enable in governor start/stop.
81  */
82 static DEFINE_MUTEX(dbs_mutex);
83
84 static struct workqueue_struct  *kconservative_wq;
85
86 static struct dbs_tuners {
87         unsigned int sampling_rate;
88         unsigned int sampling_down_factor;
89         unsigned int up_threshold;
90         unsigned int down_threshold;
91         unsigned int ignore_nice;
92         unsigned int freq_step;
93 } dbs_tuners_ins = {
94         .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
95         .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD,
96         .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
97         .ignore_nice = 0,
98         .freq_step = 5,
99 };
100
101 static inline cputime64_t get_cpu_idle_time_jiffy(unsigned int cpu,
102                                                         cputime64_t *wall)
103 {
104         cputime64_t idle_time;
105         cputime64_t cur_wall_time;
106         cputime64_t busy_time;
107
108         cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
109         busy_time = cputime64_add(kstat_cpu(cpu).cpustat.user,
110                         kstat_cpu(cpu).cpustat.system);
111
112         busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.irq);
113         busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.softirq);
114         busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.steal);
115         busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.nice);
116
117         idle_time = cputime64_sub(cur_wall_time, busy_time);
118         if (wall)
119                 *wall = (cputime64_t)jiffies_to_usecs(cur_wall_time);
120
121         return (cputime64_t)jiffies_to_usecs(idle_time);;
122 }
123
124 static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
125 {
126         u64 idle_time = get_cpu_idle_time_us(cpu, wall);
127
128         if (idle_time == -1ULL)
129                 return get_cpu_idle_time_jiffy(cpu, wall);
130
131         return idle_time;
132 }
133
134 /* keep track of frequency transitions */
135 static int
136 dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
137                      void *data)
138 {
139         struct cpufreq_freqs *freq = data;
140         struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cs_cpu_dbs_info,
141                                                         freq->cpu);
142
143         struct cpufreq_policy *policy;
144
145         if (!this_dbs_info->enable)
146                 return 0;
147
148         policy = this_dbs_info->cur_policy;
149
150         /*
151          * we only care if our internally tracked freq moves outside
152          * the 'valid' ranges of freqency available to us otherwise
153          * we do not change it
154         */
155         if (this_dbs_info->requested_freq > policy->max
156                         || this_dbs_info->requested_freq < policy->min)
157                 this_dbs_info->requested_freq = freq->new;
158
159         return 0;
160 }
161
162 static struct notifier_block dbs_cpufreq_notifier_block = {
163         .notifier_call = dbs_cpufreq_notifier
164 };
165
166 /************************** sysfs interface ************************/
167 static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
168 {
169         printk_once(KERN_INFO "CPUFREQ: conservative sampling_rate_max "
170                     "sysfs file is deprecated - used by: %s\n", current->comm);
171         return sprintf(buf, "%u\n", -1U);
172 }
173
174 static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf)
175 {
176         return sprintf(buf, "%u\n", min_sampling_rate);
177 }
178
179 #define define_one_ro(_name)            \
180 static struct freq_attr _name =         \
181 __ATTR(_name, 0444, show_##_name, NULL)
182
183 define_one_ro(sampling_rate_max);
184 define_one_ro(sampling_rate_min);
185
186 /* cpufreq_conservative Governor Tunables */
187 #define show_one(file_name, object)                                     \
188 static ssize_t show_##file_name                                         \
189 (struct cpufreq_policy *unused, char *buf)                              \
190 {                                                                       \
191         return sprintf(buf, "%u\n", dbs_tuners_ins.object);             \
192 }
193 show_one(sampling_rate, sampling_rate);
194 show_one(sampling_down_factor, sampling_down_factor);
195 show_one(up_threshold, up_threshold);
196 show_one(down_threshold, down_threshold);
197 show_one(ignore_nice_load, ignore_nice);
198 show_one(freq_step, freq_step);
199
200 static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
201                 const char *buf, size_t count)
202 {
203         unsigned int input;
204         int ret;
205         ret = sscanf(buf, "%u", &input);
206
207         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
208                 return -EINVAL;
209
210         mutex_lock(&dbs_mutex);
211         dbs_tuners_ins.sampling_down_factor = input;
212         mutex_unlock(&dbs_mutex);
213
214         return count;
215 }
216
217 static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
218                 const char *buf, size_t count)
219 {
220         unsigned int input;
221         int ret;
222         ret = sscanf(buf, "%u", &input);
223
224         if (ret != 1)
225                 return -EINVAL;
226
227         mutex_lock(&dbs_mutex);
228         dbs_tuners_ins.sampling_rate = max(input, min_sampling_rate);
229         mutex_unlock(&dbs_mutex);
230
231         return count;
232 }
233
234 static ssize_t store_up_threshold(struct cpufreq_policy *unused,
235                 const char *buf, size_t count)
236 {
237         unsigned int input;
238         int ret;
239         ret = sscanf(buf, "%u", &input);
240
241         mutex_lock(&dbs_mutex);
242         if (ret != 1 || input > 100 ||
243                         input <= dbs_tuners_ins.down_threshold) {
244                 mutex_unlock(&dbs_mutex);
245                 return -EINVAL;
246         }
247
248         dbs_tuners_ins.up_threshold = input;
249         mutex_unlock(&dbs_mutex);
250
251         return count;
252 }
253
254 static ssize_t store_down_threshold(struct cpufreq_policy *unused,
255                 const char *buf, size_t count)
256 {
257         unsigned int input;
258         int ret;
259         ret = sscanf(buf, "%u", &input);
260
261         mutex_lock(&dbs_mutex);
262         /* cannot be lower than 11 otherwise freq will not fall */
263         if (ret != 1 || input < 11 || input > 100 ||
264                         input >= dbs_tuners_ins.up_threshold) {
265                 mutex_unlock(&dbs_mutex);
266                 return -EINVAL;
267         }
268
269         dbs_tuners_ins.down_threshold = input;
270         mutex_unlock(&dbs_mutex);
271
272         return count;
273 }
274
275 static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
276                 const char *buf, size_t count)
277 {
278         unsigned int input;
279         int ret;
280
281         unsigned int j;
282
283         ret = sscanf(buf, "%u", &input);
284         if (ret != 1)
285                 return -EINVAL;
286
287         if (input > 1)
288                 input = 1;
289
290         mutex_lock(&dbs_mutex);
291         if (input == dbs_tuners_ins.ignore_nice) { /* nothing to do */
292                 mutex_unlock(&dbs_mutex);
293                 return count;
294         }
295         dbs_tuners_ins.ignore_nice = input;
296
297         /* we need to re-evaluate prev_cpu_idle */
298         for_each_online_cpu(j) {
299                 struct cpu_dbs_info_s *dbs_info;
300                 dbs_info = &per_cpu(cs_cpu_dbs_info, j);
301                 dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
302                                                 &dbs_info->prev_cpu_wall);
303                 if (dbs_tuners_ins.ignore_nice)
304                         dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
305         }
306         mutex_unlock(&dbs_mutex);
307
308         return count;
309 }
310
311 static ssize_t store_freq_step(struct cpufreq_policy *policy,
312                 const char *buf, size_t count)
313 {
314         unsigned int input;
315         int ret;
316         ret = sscanf(buf, "%u", &input);
317
318         if (ret != 1)
319                 return -EINVAL;
320
321         if (input > 100)
322                 input = 100;
323
324         /* no need to test here if freq_step is zero as the user might actually
325          * want this, they would be crazy though :) */
326         mutex_lock(&dbs_mutex);
327         dbs_tuners_ins.freq_step = input;
328         mutex_unlock(&dbs_mutex);
329
330         return count;
331 }
332
333 #define define_one_rw(_name) \
334 static struct freq_attr _name = \
335 __ATTR(_name, 0644, show_##_name, store_##_name)
336
337 define_one_rw(sampling_rate);
338 define_one_rw(sampling_down_factor);
339 define_one_rw(up_threshold);
340 define_one_rw(down_threshold);
341 define_one_rw(ignore_nice_load);
342 define_one_rw(freq_step);
343
344 static struct attribute *dbs_attributes[] = {
345         &sampling_rate_max.attr,
346         &sampling_rate_min.attr,
347         &sampling_rate.attr,
348         &sampling_down_factor.attr,
349         &up_threshold.attr,
350         &down_threshold.attr,
351         &ignore_nice_load.attr,
352         &freq_step.attr,
353         NULL
354 };
355
356 static struct attribute_group dbs_attr_group = {
357         .attrs = dbs_attributes,
358         .name = "conservative",
359 };
360
361 /************************** sysfs end ************************/
362
363 static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
364 {
365         unsigned int load = 0;
366         unsigned int freq_target;
367
368         struct cpufreq_policy *policy;
369         unsigned int j;
370
371         policy = this_dbs_info->cur_policy;
372
373         /*
374          * Every sampling_rate, we check, if current idle time is less
375          * than 20% (default), then we try to increase frequency
376          * Every sampling_rate*sampling_down_factor, we check, if current
377          * idle time is more than 80%, then we try to decrease frequency
378          *
379          * Any frequency increase takes it to the maximum frequency.
380          * Frequency reduction happens at minimum steps of
381          * 5% (default) of maximum frequency
382          */
383
384         /* Get Absolute Load */
385         for_each_cpu(j, policy->cpus) {
386                 struct cpu_dbs_info_s *j_dbs_info;
387                 cputime64_t cur_wall_time, cur_idle_time;
388                 unsigned int idle_time, wall_time;
389
390                 j_dbs_info = &per_cpu(cs_cpu_dbs_info, j);
391
392                 cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
393
394                 wall_time = (unsigned int) cputime64_sub(cur_wall_time,
395                                 j_dbs_info->prev_cpu_wall);
396                 j_dbs_info->prev_cpu_wall = cur_wall_time;
397
398                 idle_time = (unsigned int) cputime64_sub(cur_idle_time,
399                                 j_dbs_info->prev_cpu_idle);
400                 j_dbs_info->prev_cpu_idle = cur_idle_time;
401
402                 if (dbs_tuners_ins.ignore_nice) {
403                         cputime64_t cur_nice;
404                         unsigned long cur_nice_jiffies;
405
406                         cur_nice = cputime64_sub(kstat_cpu(j).cpustat.nice,
407                                          j_dbs_info->prev_cpu_nice);
408                         /*
409                          * Assumption: nice time between sampling periods will
410                          * be less than 2^32 jiffies for 32 bit sys
411                          */
412                         cur_nice_jiffies = (unsigned long)
413                                         cputime64_to_jiffies64(cur_nice);
414
415                         j_dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
416                         idle_time += jiffies_to_usecs(cur_nice_jiffies);
417                 }
418
419                 if (unlikely(!wall_time || wall_time < idle_time))
420                         continue;
421
422                 load = 100 * (wall_time - idle_time) / wall_time;
423         }
424
425         /*
426          * break out if we 'cannot' reduce the speed as the user might
427          * want freq_step to be zero
428          */
429         if (dbs_tuners_ins.freq_step == 0)
430                 return;
431
432         /* Check for frequency increase */
433         if (load > dbs_tuners_ins.up_threshold) {
434                 this_dbs_info->down_skip = 0;
435
436                 /* if we are already at full speed then break out early */
437                 if (this_dbs_info->requested_freq == policy->max)
438                         return;
439
440                 freq_target = (dbs_tuners_ins.freq_step * policy->max) / 100;
441
442                 /* max freq cannot be less than 100. But who knows.... */
443                 if (unlikely(freq_target == 0))
444                         freq_target = 5;
445
446                 this_dbs_info->requested_freq += freq_target;
447                 if (this_dbs_info->requested_freq > policy->max)
448                         this_dbs_info->requested_freq = policy->max;
449
450                 __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
451                         CPUFREQ_RELATION_H);
452                 return;
453         }
454
455         /*
456          * The optimal frequency is the frequency that is the lowest that
457          * can support the current CPU usage without triggering the up
458          * policy. To be safe, we focus 10 points under the threshold.
459          */
460         if (load < (dbs_tuners_ins.down_threshold - 10)) {
461                 freq_target = (dbs_tuners_ins.freq_step * policy->max) / 100;
462
463                 this_dbs_info->requested_freq -= freq_target;
464                 if (this_dbs_info->requested_freq < policy->min)
465                         this_dbs_info->requested_freq = policy->min;
466
467                 /*
468                  * if we cannot reduce the frequency anymore, break out early
469                  */
470                 if (policy->cur == policy->min)
471                         return;
472
473                 __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
474                                 CPUFREQ_RELATION_H);
475                 return;
476         }
477 }
478
479 static void do_dbs_timer(struct work_struct *work)
480 {
481         struct cpu_dbs_info_s *dbs_info =
482                 container_of(work, struct cpu_dbs_info_s, work.work);
483         unsigned int cpu = dbs_info->cpu;
484
485         /* We want all CPUs to do sampling nearly on same jiffy */
486         int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
487
488         delay -= jiffies % delay;
489
490         mutex_lock(&dbs_info->timer_mutex);
491
492         dbs_check_cpu(dbs_info);
493
494         queue_delayed_work_on(cpu, kconservative_wq, &dbs_info->work, delay);
495         mutex_unlock(&dbs_info->timer_mutex);
496 }
497
498 static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
499 {
500         /* We want all CPUs to do sampling nearly on same jiffy */
501         int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
502         delay -= jiffies % delay;
503
504         dbs_info->enable = 1;
505         INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer);
506         queue_delayed_work_on(dbs_info->cpu, kconservative_wq, &dbs_info->work,
507                                 delay);
508 }
509
510 static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
511 {
512         dbs_info->enable = 0;
513         cancel_delayed_work_sync(&dbs_info->work);
514 }
515
516 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
517                                    unsigned int event)
518 {
519         unsigned int cpu = policy->cpu;
520         struct cpu_dbs_info_s *this_dbs_info;
521         unsigned int j;
522         int rc;
523
524         this_dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
525
526         switch (event) {
527         case CPUFREQ_GOV_START:
528                 if ((!cpu_online(cpu)) || (!policy->cur))
529                         return -EINVAL;
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(cs_cpu_dbs_info, j);
542                         j_dbs_info->cur_policy = policy;
543
544                         j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
545                                                 &j_dbs_info->prev_cpu_wall);
546                         if (dbs_tuners_ins.ignore_nice) {
547                                 j_dbs_info->prev_cpu_nice =
548                                                 kstat_cpu(j).cpustat.nice;
549                         }
550                 }
551                 this_dbs_info->down_skip = 0;
552                 this_dbs_info->requested_freq = policy->cur;
553
554                 mutex_init(&this_dbs_info->timer_mutex);
555                 dbs_enable++;
556                 /*
557                  * Start the timerschedule work, when this governor
558                  * is used for first time
559                  */
560                 if (dbs_enable == 1) {
561                         unsigned int latency;
562                         /* policy latency is in nS. Convert it to uS first */
563                         latency = policy->cpuinfo.transition_latency / 1000;
564                         if (latency == 0)
565                                 latency = 1;
566
567                         /*
568                          * conservative does not implement micro like ondemand
569                          * governor, thus we are bound to jiffes/HZ
570                          */
571                         min_sampling_rate =
572                                 MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10);
573                         /* Bring kernel and HW constraints together */
574                         min_sampling_rate = max(min_sampling_rate,
575                                         MIN_LATENCY_MULTIPLIER * latency);
576                         dbs_tuners_ins.sampling_rate =
577                                 max(min_sampling_rate,
578                                     latency * LATENCY_MULTIPLIER);
579
580                         cpufreq_register_notifier(
581                                         &dbs_cpufreq_notifier_block,
582                                         CPUFREQ_TRANSITION_NOTIFIER);
583                 }
584                 mutex_unlock(&dbs_mutex);
585
586                 dbs_timer_init(this_dbs_info);
587
588                 break;
589
590         case CPUFREQ_GOV_STOP:
591                 dbs_timer_exit(this_dbs_info);
592
593                 mutex_lock(&dbs_mutex);
594                 sysfs_remove_group(&policy->kobj, &dbs_attr_group);
595                 dbs_enable--;
596                 mutex_destroy(&this_dbs_info->timer_mutex);
597
598                 /*
599                  * Stop the timerschedule work, when this governor
600                  * is used for first time
601                  */
602                 if (dbs_enable == 0)
603                         cpufreq_unregister_notifier(
604                                         &dbs_cpufreq_notifier_block,
605                                         CPUFREQ_TRANSITION_NOTIFIER);
606
607                 mutex_unlock(&dbs_mutex);
608
609                 break;
610
611         case CPUFREQ_GOV_LIMITS:
612                 mutex_lock(&this_dbs_info->timer_mutex);
613                 if (policy->max < this_dbs_info->cur_policy->cur)
614                         __cpufreq_driver_target(
615                                         this_dbs_info->cur_policy,
616                                         policy->max, CPUFREQ_RELATION_H);
617                 else if (policy->min > this_dbs_info->cur_policy->cur)
618                         __cpufreq_driver_target(
619                                         this_dbs_info->cur_policy,
620                                         policy->min, CPUFREQ_RELATION_L);
621                 mutex_unlock(&this_dbs_info->timer_mutex);
622
623                 break;
624         }
625         return 0;
626 }
627
628 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
629 static
630 #endif
631 struct cpufreq_governor cpufreq_gov_conservative = {
632         .name                   = "conservative",
633         .governor               = cpufreq_governor_dbs,
634         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
635         .owner                  = THIS_MODULE,
636 };
637
638 static int __init cpufreq_gov_dbs_init(void)
639 {
640         int err;
641
642         kconservative_wq = create_workqueue("kconservative");
643         if (!kconservative_wq) {
644                 printk(KERN_ERR "Creation of kconservative failed\n");
645                 return -EFAULT;
646         }
647
648         err = cpufreq_register_governor(&cpufreq_gov_conservative);
649         if (err)
650                 destroy_workqueue(kconservative_wq);
651
652         return err;
653 }
654
655 static void __exit cpufreq_gov_dbs_exit(void)
656 {
657         cpufreq_unregister_governor(&cpufreq_gov_conservative);
658         destroy_workqueue(kconservative_wq);
659 }
660
661
662 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
663 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
664                 "Low Latency Frequency Transition capable processors "
665                 "optimised for use in a battery environment");
666 MODULE_LICENSE("GPL");
667
668 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
669 fs_initcall(cpufreq_gov_dbs_init);
670 #else
671 module_init(cpufreq_gov_dbs_init);
672 #endif
673 module_exit(cpufreq_gov_dbs_exit);