2 * drivers/cpufreq/cpufreq_ondemand.c
4 * Copyright (C) 2001 Russell King
5 * (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
6 * Jun Nakajima <jun.nakajima@intel.com>
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.
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 #include <linux/hrtimer.h>
22 #include <linux/tick.h>
23 #include <linux/ktime.h>
24 #include <linux/sched.h>
27 * dbs is used in this file as a shortform for demandbased switching
28 * It helps to keep variable names smaller, simpler
31 #define DEF_FREQUENCY_DOWN_DIFFERENTIAL (10)
32 #define DEF_FREQUENCY_UP_THRESHOLD (80)
33 #define MICRO_FREQUENCY_DOWN_DIFFERENTIAL (3)
34 #define MICRO_FREQUENCY_UP_THRESHOLD (95)
35 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE (10000)
36 #define MIN_FREQUENCY_UP_THRESHOLD (11)
37 #define MAX_FREQUENCY_UP_THRESHOLD (100)
40 * The polling frequency of this governor depends on the capability of
41 * the processor. Default polling frequency is 1000 times the transition
42 * latency of the processor. The governor will work on any processor with
43 * transition latency <= 10mS, using appropriate sampling
45 * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
46 * this governor will not work.
47 * All times here are in uS.
49 #define MIN_SAMPLING_RATE_RATIO (2)
51 static unsigned int min_sampling_rate;
53 #define LATENCY_MULTIPLIER (1000)
54 #define MIN_LATENCY_MULTIPLIER (100)
55 #define TRANSITION_LATENCY_LIMIT (10 * 1000 * 1000)
57 static void do_dbs_timer(struct work_struct *work);
58 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
61 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
64 struct cpufreq_governor cpufreq_gov_ondemand = {
66 .governor = cpufreq_governor_dbs,
67 .max_transition_latency = TRANSITION_LATENCY_LIMIT,
72 enum {DBS_NORMAL_SAMPLE, DBS_SUB_SAMPLE};
74 struct cpu_dbs_info_s {
75 cputime64_t prev_cpu_idle;
76 cputime64_t prev_cpu_iowait;
77 cputime64_t prev_cpu_wall;
78 cputime64_t prev_cpu_nice;
79 struct cpufreq_policy *cur_policy;
80 struct delayed_work work;
81 struct cpufreq_frequency_table *freq_table;
83 unsigned int freq_lo_jiffies;
84 unsigned int freq_hi_jiffies;
86 unsigned int sample_type:1;
88 * percpu mutex that serializes governor limit change with
89 * do_dbs_timer invocation. We do not want do_dbs_timer to run
90 * when user is changing the governor or limits.
92 struct mutex timer_mutex;
94 static DEFINE_PER_CPU(struct cpu_dbs_info_s, od_cpu_dbs_info);
96 static unsigned int dbs_enable; /* number of CPUs using this policy */
99 * dbs_mutex protects data in dbs_tuners_ins from concurrent changes on
100 * different CPUs. It protects dbs_enable in governor start/stop.
102 static DEFINE_MUTEX(dbs_mutex);
104 static struct workqueue_struct *kondemand_wq;
106 static struct dbs_tuners {
107 unsigned int sampling_rate;
108 unsigned int up_threshold;
109 unsigned int down_differential;
110 unsigned int ignore_nice;
111 unsigned int powersave_bias;
112 unsigned int io_is_busy;
114 .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
115 .down_differential = DEF_FREQUENCY_DOWN_DIFFERENTIAL,
120 static inline cputime64_t get_cpu_idle_time_jiffy(unsigned int cpu,
123 cputime64_t idle_time;
124 cputime64_t cur_wall_time;
125 cputime64_t busy_time;
127 cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
128 busy_time = cputime64_add(kstat_cpu(cpu).cpustat.user,
129 kstat_cpu(cpu).cpustat.system);
131 busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.irq);
132 busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.softirq);
133 busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.steal);
134 busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.nice);
136 idle_time = cputime64_sub(cur_wall_time, busy_time);
138 *wall = (cputime64_t)jiffies_to_usecs(cur_wall_time);
140 return (cputime64_t)jiffies_to_usecs(idle_time);
143 static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
145 u64 idle_time = get_cpu_idle_time_us(cpu, wall);
147 if (idle_time == -1ULL)
148 return get_cpu_idle_time_jiffy(cpu, wall);
153 static inline cputime64_t get_cpu_iowait_time(unsigned int cpu, cputime64_t *wall)
155 u64 iowait_time = get_cpu_iowait_time_us(cpu, wall);
157 if (iowait_time == -1ULL)
164 * Find right freq to be set now with powersave_bias on.
165 * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
166 * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
168 static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
169 unsigned int freq_next,
170 unsigned int relation)
172 unsigned int freq_req, freq_reduc, freq_avg;
173 unsigned int freq_hi, freq_lo;
174 unsigned int index = 0;
175 unsigned int jiffies_total, jiffies_hi, jiffies_lo;
176 struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
179 if (!dbs_info->freq_table) {
180 dbs_info->freq_lo = 0;
181 dbs_info->freq_lo_jiffies = 0;
185 cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
187 freq_req = dbs_info->freq_table[index].frequency;
188 freq_reduc = freq_req * dbs_tuners_ins.powersave_bias / 1000;
189 freq_avg = freq_req - freq_reduc;
191 /* Find freq bounds for freq_avg in freq_table */
193 cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
194 CPUFREQ_RELATION_H, &index);
195 freq_lo = dbs_info->freq_table[index].frequency;
197 cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
198 CPUFREQ_RELATION_L, &index);
199 freq_hi = dbs_info->freq_table[index].frequency;
201 /* Find out how long we have to be in hi and lo freqs */
202 if (freq_hi == freq_lo) {
203 dbs_info->freq_lo = 0;
204 dbs_info->freq_lo_jiffies = 0;
207 jiffies_total = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
208 jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
209 jiffies_hi += ((freq_hi - freq_lo) / 2);
210 jiffies_hi /= (freq_hi - freq_lo);
211 jiffies_lo = jiffies_total - jiffies_hi;
212 dbs_info->freq_lo = freq_lo;
213 dbs_info->freq_lo_jiffies = jiffies_lo;
214 dbs_info->freq_hi_jiffies = jiffies_hi;
218 static void ondemand_powersave_bias_init_cpu(int cpu)
220 struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
221 dbs_info->freq_table = cpufreq_frequency_get_table(cpu);
222 dbs_info->freq_lo = 0;
225 static void ondemand_powersave_bias_init(void)
228 for_each_online_cpu(i) {
229 ondemand_powersave_bias_init_cpu(i);
233 /************************** sysfs interface ************************/
235 static ssize_t show_sampling_rate_max(struct kobject *kobj,
236 struct attribute *attr, char *buf)
238 printk_once(KERN_INFO "CPUFREQ: ondemand sampling_rate_max "
239 "sysfs file is deprecated - used by: %s\n", current->comm);
240 return sprintf(buf, "%u\n", -1U);
243 static ssize_t show_sampling_rate_min(struct kobject *kobj,
244 struct attribute *attr, char *buf)
246 return sprintf(buf, "%u\n", min_sampling_rate);
249 #define define_one_ro(_name) \
250 static struct global_attr _name = \
251 __ATTR(_name, 0444, show_##_name, NULL)
253 define_one_ro(sampling_rate_max);
254 define_one_ro(sampling_rate_min);
256 /* cpufreq_ondemand Governor Tunables */
257 #define show_one(file_name, object) \
258 static ssize_t show_##file_name \
259 (struct kobject *kobj, struct attribute *attr, char *buf) \
261 return sprintf(buf, "%u\n", dbs_tuners_ins.object); \
263 show_one(sampling_rate, sampling_rate);
264 show_one(io_is_busy, io_is_busy);
265 show_one(up_threshold, up_threshold);
266 show_one(ignore_nice_load, ignore_nice);
267 show_one(powersave_bias, powersave_bias);
269 /*** delete after deprecation time ***/
271 #define DEPRECATION_MSG(file_name) \
272 printk_once(KERN_INFO "CPUFREQ: Per core ondemand sysfs " \
273 "interface is deprecated - " #file_name "\n");
275 #define show_one_old(file_name) \
276 static ssize_t show_##file_name##_old \
277 (struct cpufreq_policy *unused, char *buf) \
279 printk_once(KERN_INFO "CPUFREQ: Per core ondemand sysfs " \
280 "interface is deprecated - " #file_name "\n"); \
281 return show_##file_name(NULL, NULL, buf); \
283 show_one_old(sampling_rate);
284 show_one_old(up_threshold);
285 show_one_old(ignore_nice_load);
286 show_one_old(powersave_bias);
287 show_one_old(sampling_rate_min);
288 show_one_old(sampling_rate_max);
290 #define define_one_ro_old(object, _name) \
291 static struct freq_attr object = \
292 __ATTR(_name, 0444, show_##_name##_old, NULL)
294 define_one_ro_old(sampling_rate_min_old, sampling_rate_min);
295 define_one_ro_old(sampling_rate_max_old, sampling_rate_max);
297 /*** delete after deprecation time ***/
299 static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
300 const char *buf, size_t count)
304 ret = sscanf(buf, "%u", &input);
308 mutex_lock(&dbs_mutex);
309 dbs_tuners_ins.sampling_rate = max(input, min_sampling_rate);
310 mutex_unlock(&dbs_mutex);
315 static ssize_t store_io_is_busy(struct kobject *a, struct attribute *b,
316 const char *buf, size_t count)
321 ret = sscanf(buf, "%u", &input);
325 mutex_lock(&dbs_mutex);
326 dbs_tuners_ins.io_is_busy = !!input;
327 mutex_unlock(&dbs_mutex);
332 static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
333 const char *buf, size_t count)
337 ret = sscanf(buf, "%u", &input);
339 if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
340 input < MIN_FREQUENCY_UP_THRESHOLD) {
344 mutex_lock(&dbs_mutex);
345 dbs_tuners_ins.up_threshold = input;
346 mutex_unlock(&dbs_mutex);
351 static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
352 const char *buf, size_t count)
359 ret = sscanf(buf, "%u", &input);
366 mutex_lock(&dbs_mutex);
367 if (input == dbs_tuners_ins.ignore_nice) { /* nothing to do */
368 mutex_unlock(&dbs_mutex);
371 dbs_tuners_ins.ignore_nice = input;
373 /* we need to re-evaluate prev_cpu_idle */
374 for_each_online_cpu(j) {
375 struct cpu_dbs_info_s *dbs_info;
376 dbs_info = &per_cpu(od_cpu_dbs_info, j);
377 dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
378 &dbs_info->prev_cpu_wall);
379 if (dbs_tuners_ins.ignore_nice)
380 dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
383 mutex_unlock(&dbs_mutex);
388 static ssize_t store_powersave_bias(struct kobject *a, struct attribute *b,
389 const char *buf, size_t count)
393 ret = sscanf(buf, "%u", &input);
401 mutex_lock(&dbs_mutex);
402 dbs_tuners_ins.powersave_bias = input;
403 ondemand_powersave_bias_init();
404 mutex_unlock(&dbs_mutex);
409 #define define_one_rw(_name) \
410 static struct global_attr _name = \
411 __ATTR(_name, 0644, show_##_name, store_##_name)
413 define_one_rw(sampling_rate);
414 define_one_rw(io_is_busy);
415 define_one_rw(up_threshold);
416 define_one_rw(ignore_nice_load);
417 define_one_rw(powersave_bias);
419 static struct attribute *dbs_attributes[] = {
420 &sampling_rate_max.attr,
421 &sampling_rate_min.attr,
424 &ignore_nice_load.attr,
425 &powersave_bias.attr,
430 static struct attribute_group dbs_attr_group = {
431 .attrs = dbs_attributes,
435 /*** delete after deprecation time ***/
437 #define write_one_old(file_name) \
438 static ssize_t store_##file_name##_old \
439 (struct cpufreq_policy *unused, const char *buf, size_t count) \
441 printk_once(KERN_INFO "CPUFREQ: Per core ondemand sysfs " \
442 "interface is deprecated - " #file_name "\n"); \
443 return store_##file_name(NULL, NULL, buf, count); \
445 write_one_old(sampling_rate);
446 write_one_old(up_threshold);
447 write_one_old(ignore_nice_load);
448 write_one_old(powersave_bias);
450 #define define_one_rw_old(object, _name) \
451 static struct freq_attr object = \
452 __ATTR(_name, 0644, show_##_name##_old, store_##_name##_old)
454 define_one_rw_old(sampling_rate_old, sampling_rate);
455 define_one_rw_old(up_threshold_old, up_threshold);
456 define_one_rw_old(ignore_nice_load_old, ignore_nice_load);
457 define_one_rw_old(powersave_bias_old, powersave_bias);
459 static struct attribute *dbs_attributes_old[] = {
460 &sampling_rate_max_old.attr,
461 &sampling_rate_min_old.attr,
462 &sampling_rate_old.attr,
463 &up_threshold_old.attr,
464 &ignore_nice_load_old.attr,
465 &powersave_bias_old.attr,
469 static struct attribute_group dbs_attr_group_old = {
470 .attrs = dbs_attributes_old,
474 /*** delete after deprecation time ***/
476 /************************** sysfs end ************************/
478 static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
480 unsigned int max_load_freq;
482 struct cpufreq_policy *policy;
485 this_dbs_info->freq_lo = 0;
486 policy = this_dbs_info->cur_policy;
489 * Every sampling_rate, we check, if current idle time is less
490 * than 20% (default), then we try to increase frequency
491 * Every sampling_rate, we look for a the lowest
492 * frequency which can sustain the load while keeping idle time over
493 * 30%. If such a frequency exist, we try to decrease to this frequency.
495 * Any frequency increase takes it to the maximum frequency.
496 * Frequency reduction happens at minimum steps of
497 * 5% (default) of current frequency
500 /* Get Absolute Load - in terms of freq */
503 for_each_cpu(j, policy->cpus) {
504 struct cpu_dbs_info_s *j_dbs_info;
505 cputime64_t cur_wall_time, cur_idle_time, cur_iowait_time;
506 unsigned int idle_time, wall_time, iowait_time;
507 unsigned int load, load_freq;
510 j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
512 cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
513 cur_iowait_time = get_cpu_iowait_time(j, &cur_wall_time);
515 wall_time = (unsigned int) cputime64_sub(cur_wall_time,
516 j_dbs_info->prev_cpu_wall);
517 j_dbs_info->prev_cpu_wall = cur_wall_time;
519 idle_time = (unsigned int) cputime64_sub(cur_idle_time,
520 j_dbs_info->prev_cpu_idle);
521 j_dbs_info->prev_cpu_idle = cur_idle_time;
523 iowait_time = (unsigned int) cputime64_sub(cur_iowait_time,
524 j_dbs_info->prev_cpu_iowait);
525 j_dbs_info->prev_cpu_iowait = cur_iowait_time;
527 if (dbs_tuners_ins.ignore_nice) {
528 cputime64_t cur_nice;
529 unsigned long cur_nice_jiffies;
531 cur_nice = cputime64_sub(kstat_cpu(j).cpustat.nice,
532 j_dbs_info->prev_cpu_nice);
534 * Assumption: nice time between sampling periods will
535 * be less than 2^32 jiffies for 32 bit sys
537 cur_nice_jiffies = (unsigned long)
538 cputime64_to_jiffies64(cur_nice);
540 j_dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
541 idle_time += jiffies_to_usecs(cur_nice_jiffies);
545 * For the purpose of ondemand, waiting for disk IO is an
546 * indication that you're performance critical, and not that
547 * the system is actually idle. So subtract the iowait time
548 * from the cpu idle time.
551 if (dbs_tuners_ins.io_is_busy && idle_time >= iowait_time)
552 idle_time -= iowait_time;
554 if (unlikely(!wall_time || wall_time < idle_time))
557 load = 100 * (wall_time - idle_time) / wall_time;
559 freq_avg = __cpufreq_driver_getavg(policy, j);
561 freq_avg = policy->cur;
563 load_freq = load * freq_avg;
564 if (load_freq > max_load_freq)
565 max_load_freq = load_freq;
568 /* Check for frequency increase */
569 if (max_load_freq > dbs_tuners_ins.up_threshold * policy->cur) {
570 /* if we are already at full speed then break out early */
571 if (!dbs_tuners_ins.powersave_bias) {
572 if (policy->cur == policy->max)
575 __cpufreq_driver_target(policy, policy->max,
578 int freq = powersave_bias_target(policy, policy->max,
580 __cpufreq_driver_target(policy, freq,
586 /* Check for frequency decrease */
587 /* if we cannot reduce the frequency anymore, break out early */
588 if (policy->cur == policy->min)
592 * The optimal frequency is the frequency that is the lowest that
593 * can support the current CPU usage without triggering the up
594 * policy. To be safe, we focus 10 points under the threshold.
597 (dbs_tuners_ins.up_threshold - dbs_tuners_ins.down_differential) *
599 unsigned int freq_next;
600 freq_next = max_load_freq /
601 (dbs_tuners_ins.up_threshold -
602 dbs_tuners_ins.down_differential);
604 if (freq_next < policy->min)
605 freq_next = policy->min;
607 if (!dbs_tuners_ins.powersave_bias) {
608 __cpufreq_driver_target(policy, freq_next,
611 int freq = powersave_bias_target(policy, freq_next,
613 __cpufreq_driver_target(policy, freq,
619 static void do_dbs_timer(struct work_struct *work)
621 struct cpu_dbs_info_s *dbs_info =
622 container_of(work, struct cpu_dbs_info_s, work.work);
623 unsigned int cpu = dbs_info->cpu;
624 int sample_type = dbs_info->sample_type;
626 /* We want all CPUs to do sampling nearly on same jiffy */
627 int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
629 delay -= jiffies % delay;
630 mutex_lock(&dbs_info->timer_mutex);
632 /* Common NORMAL_SAMPLE setup */
633 dbs_info->sample_type = DBS_NORMAL_SAMPLE;
634 if (!dbs_tuners_ins.powersave_bias ||
635 sample_type == DBS_NORMAL_SAMPLE) {
636 dbs_check_cpu(dbs_info);
637 if (dbs_info->freq_lo) {
638 /* Setup timer for SUB_SAMPLE */
639 dbs_info->sample_type = DBS_SUB_SAMPLE;
640 delay = dbs_info->freq_hi_jiffies;
643 __cpufreq_driver_target(dbs_info->cur_policy,
644 dbs_info->freq_lo, CPUFREQ_RELATION_H);
646 queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work, delay);
647 mutex_unlock(&dbs_info->timer_mutex);
650 static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
652 /* We want all CPUs to do sampling nearly on same jiffy */
653 int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
654 delay -= jiffies % delay;
656 dbs_info->sample_type = DBS_NORMAL_SAMPLE;
657 INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer);
658 queue_delayed_work_on(dbs_info->cpu, kondemand_wq, &dbs_info->work,
662 static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
664 cancel_delayed_work_sync(&dbs_info->work);
668 * Not all CPUs want IO time to be accounted as busy; this dependson how
669 * efficient idling at a higher frequency/voltage is.
670 * Pavel Machek says this is not so for various generations of AMD and old
672 * Mike Chan (androidlcom) calis this is also not true for ARM.
673 * Because of this, whitelist specific known (series) of CPUs by default, and
674 * leave all others up to the user.
676 static int should_io_be_busy(void)
678 #if defined(CONFIG_X86)
680 * For Intel, Core 2 (model 15) andl later have an efficient idle.
682 if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
683 boot_cpu_data.x86 == 6 &&
684 boot_cpu_data.x86_model >= 15)
690 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
693 unsigned int cpu = policy->cpu;
694 struct cpu_dbs_info_s *this_dbs_info;
698 this_dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
701 case CPUFREQ_GOV_START:
702 if ((!cpu_online(cpu)) || (!policy->cur))
705 mutex_lock(&dbs_mutex);
707 rc = sysfs_create_group(&policy->kobj, &dbs_attr_group_old);
709 mutex_unlock(&dbs_mutex);
714 for_each_cpu(j, policy->cpus) {
715 struct cpu_dbs_info_s *j_dbs_info;
716 j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
717 j_dbs_info->cur_policy = policy;
719 j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
720 &j_dbs_info->prev_cpu_wall);
721 if (dbs_tuners_ins.ignore_nice) {
722 j_dbs_info->prev_cpu_nice =
723 kstat_cpu(j).cpustat.nice;
726 this_dbs_info->cpu = cpu;
727 ondemand_powersave_bias_init_cpu(cpu);
729 * Start the timerschedule work, when this governor
730 * is used for first time
732 if (dbs_enable == 1) {
733 unsigned int latency;
735 rc = sysfs_create_group(cpufreq_global_kobject,
738 mutex_unlock(&dbs_mutex);
742 /* policy latency is in nS. Convert it to uS first */
743 latency = policy->cpuinfo.transition_latency / 1000;
746 /* Bring kernel and HW constraints together */
747 min_sampling_rate = max(min_sampling_rate,
748 MIN_LATENCY_MULTIPLIER * latency);
749 dbs_tuners_ins.sampling_rate =
750 max(min_sampling_rate,
751 latency * LATENCY_MULTIPLIER);
752 dbs_tuners_ins.io_is_busy = should_io_be_busy();
754 mutex_unlock(&dbs_mutex);
756 mutex_init(&this_dbs_info->timer_mutex);
757 dbs_timer_init(this_dbs_info);
760 case CPUFREQ_GOV_STOP:
761 dbs_timer_exit(this_dbs_info);
763 mutex_lock(&dbs_mutex);
764 sysfs_remove_group(&policy->kobj, &dbs_attr_group_old);
765 mutex_destroy(&this_dbs_info->timer_mutex);
767 mutex_unlock(&dbs_mutex);
769 sysfs_remove_group(cpufreq_global_kobject,
774 case CPUFREQ_GOV_LIMITS:
775 mutex_lock(&this_dbs_info->timer_mutex);
776 if (policy->max < this_dbs_info->cur_policy->cur)
777 __cpufreq_driver_target(this_dbs_info->cur_policy,
778 policy->max, CPUFREQ_RELATION_H);
779 else if (policy->min > this_dbs_info->cur_policy->cur)
780 __cpufreq_driver_target(this_dbs_info->cur_policy,
781 policy->min, CPUFREQ_RELATION_L);
782 mutex_unlock(&this_dbs_info->timer_mutex);
788 static int __init cpufreq_gov_dbs_init(void)
795 idle_time = get_cpu_idle_time_us(cpu, &wall);
797 if (idle_time != -1ULL) {
798 /* Idle micro accounting is supported. Use finer thresholds */
799 dbs_tuners_ins.up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
800 dbs_tuners_ins.down_differential =
801 MICRO_FREQUENCY_DOWN_DIFFERENTIAL;
803 * In no_hz/micro accounting case we set the minimum frequency
804 * not depending on HZ, but fixed (very low). The deferred
805 * timer might skip some samples if idle/sleeping as needed.
807 min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
809 /* For correct statistics, we need 10 ticks for each measure */
811 MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10);
814 kondemand_wq = create_workqueue("kondemand");
816 printk(KERN_ERR "Creation of kondemand failed\n");
819 err = cpufreq_register_governor(&cpufreq_gov_ondemand);
821 destroy_workqueue(kondemand_wq);
826 static void __exit cpufreq_gov_dbs_exit(void)
828 cpufreq_unregister_governor(&cpufreq_gov_ondemand);
829 destroy_workqueue(kondemand_wq);
833 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
834 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
835 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
836 "Low Latency Frequency Transition capable processors");
837 MODULE_LICENSE("GPL");
839 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
840 fs_initcall(cpufreq_gov_dbs_init);
842 module_init(cpufreq_gov_dbs_init);
844 module_exit(cpufreq_gov_dbs_exit);