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Root/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	#include <linux/hrtimer.h>
22	#include <linux/tick.h>
23	#include <linux/ktime.h>
24	#include <linux/sched.h>
25
26	/*
27	* dbs is used in this file as a shortform for demandbased switching
28	* It helps to keep variable names smaller, simpler
29	*/
30
31	#define DEF_FREQUENCY_DOWN_DIFFERENTIAL (10)
32	#define DEF_FREQUENCY_UP_THRESHOLD (80)
33	#define DEF_SAMPLING_DOWN_FACTOR (1)
34	#define MAX_SAMPLING_DOWN_FACTOR (100000)
35	#define MICRO_FREQUENCY_DOWN_DIFFERENTIAL (3)
36	#define MICRO_FREQUENCY_UP_THRESHOLD (95)
37	#define MICRO_FREQUENCY_MIN_SAMPLE_RATE (10000)
38	#define MIN_FREQUENCY_UP_THRESHOLD (11)
39	#define MAX_FREQUENCY_UP_THRESHOLD (100)
40
41	/*
42	* The polling frequency of this governor depends on the capability of
43	* the processor. Default polling frequency is 1000 times the transition
44	* latency of the processor. The governor will work on any processor with
45	* transition latency <= 10mS, using appropriate sampling
46	* rate.
47	* For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
48	* this governor will not work.
49	* All times here are in uS.
50	*/
51	#define MIN_SAMPLING_RATE_RATIO (2)
52
53	static unsigned int min_sampling_rate;
54
55	#define LATENCY_MULTIPLIER (1000)
56	#define MIN_LATENCY_MULTIPLIER (100)
57	#define TRANSITION_LATENCY_LIMIT (10 * 1000 * 1000)
58
59	static void do_dbs_timer(struct work_struct *work);
60	static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
61	unsigned int event);
62
63	#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
64	static
65	#endif
66	struct cpufreq_governor cpufreq_gov_ondemand = {
67	.name = "ondemand",
68	.governor = cpufreq_governor_dbs,
69	.max_transition_latency = TRANSITION_LATENCY_LIMIT,
70	.owner = THIS_MODULE,
71	};
72
73	/* Sampling types */
74	enum {DBS_NORMAL_SAMPLE, DBS_SUB_SAMPLE};
75
76	struct cpu_dbs_info_s {
77	cputime64_t prev_cpu_idle;
78	cputime64_t prev_cpu_iowait;
79	cputime64_t prev_cpu_wall;
80	cputime64_t prev_cpu_nice;
81	struct cpufreq_policy *cur_policy;
82	struct delayed_work work;
83	struct cpufreq_frequency_table *freq_table;
84	unsigned int freq_lo;
85	unsigned int freq_lo_jiffies;
86	unsigned int freq_hi_jiffies;
87	unsigned int rate_mult;
88	int cpu;
89	unsigned int sample_type:1;
90	/*
91	* percpu mutex that serializes governor limit change with
92	* do_dbs_timer invocation. We do not want do_dbs_timer to run
93	* when user is changing the governor or limits.
94	*/
95	struct mutex timer_mutex;
96	};
97	static DEFINE_PER_CPU(struct cpu_dbs_info_s, od_cpu_dbs_info);
98
99	static unsigned int dbs_enable; /* number of CPUs using this policy */
100
101	/*
102	* dbs_mutex protects dbs_enable in governor start/stop.
103	*/
104	static DEFINE_MUTEX(dbs_mutex);
105
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 sampling_down_factor;
112	unsigned int powersave_bias;
113	unsigned int io_is_busy;
114	} dbs_tuners_ins = {
115	.up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
116	.sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
117	.down_differential = DEF_FREQUENCY_DOWN_DIFFERENTIAL,
118	.ignore_nice = 0,
119	.powersave_bias = 0,
120	};
121
122	static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall)
123	{
124	u64 idle_time;
125	u64 cur_wall_time;
126	u64 busy_time;
127
128	cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
129
130	busy_time = kcpustat_cpu(cpu).cpustat[CPUTIME_USER];
131	busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SYSTEM];
132	busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_IRQ];
133	busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SOFTIRQ];
134	busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_STEAL];
135	busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_NICE];
136
137	idle_time = cur_wall_time - busy_time;
138	if (wall)
139	*wall = jiffies_to_usecs(cur_wall_time);
140
141	return jiffies_to_usecs(idle_time);
142	}
143
144	static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
145	{
146	u64 idle_time = get_cpu_idle_time_us(cpu, NULL);
147
148	if (idle_time == -1ULL)
149	return get_cpu_idle_time_jiffy(cpu, wall);
150	else
151	idle_time += get_cpu_iowait_time_us(cpu, wall);
152
153	return idle_time;
154	}
155
156	static inline cputime64_t get_cpu_iowait_time(unsigned int cpu, cputime64_t *wall)
157	{
158	u64 iowait_time = get_cpu_iowait_time_us(cpu, wall);
159
160	if (iowait_time == -1ULL)
161	return 0;
162
163	return iowait_time;
164	}
165
166	/*
167	* Find right freq to be set now with powersave_bias on.
168	* Returns the freq_hi to be used right now and will set freq_hi_jiffies,
169	* freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
170	*/
171	static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
172	unsigned int freq_next,
173	unsigned int relation)
174	{
175	unsigned int freq_req, freq_reduc, freq_avg;
176	unsigned int freq_hi, freq_lo;
177	unsigned int index = 0;
178	unsigned int jiffies_total, jiffies_hi, jiffies_lo;
179	struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
180	policy->cpu);
181
182	if (!dbs_info->freq_table) {
183	dbs_info->freq_lo = 0;
184	dbs_info->freq_lo_jiffies = 0;
185	return freq_next;
186	}
187
188	cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
189	relation, &index);
190	freq_req = dbs_info->freq_table[index].frequency;
191	freq_reduc = freq_req * dbs_tuners_ins.powersave_bias / 1000;
192	freq_avg = freq_req - freq_reduc;
193
194	/* Find freq bounds for freq_avg in freq_table */
195	index = 0;
196	cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
197	CPUFREQ_RELATION_H, &index);
198	freq_lo = dbs_info->freq_table[index].frequency;
199	index = 0;
200	cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
201	CPUFREQ_RELATION_L, &index);
202	freq_hi = dbs_info->freq_table[index].frequency;
203
204	/* Find out how long we have to be in hi and lo freqs */
205	if (freq_hi == freq_lo) {
206	dbs_info->freq_lo = 0;
207	dbs_info->freq_lo_jiffies = 0;
208	return freq_lo;
209	}
210	jiffies_total = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
211	jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
212	jiffies_hi += ((freq_hi - freq_lo) / 2);
213	jiffies_hi /= (freq_hi - freq_lo);
214	jiffies_lo = jiffies_total - jiffies_hi;
215	dbs_info->freq_lo = freq_lo;
216	dbs_info->freq_lo_jiffies = jiffies_lo;
217	dbs_info->freq_hi_jiffies = jiffies_hi;
218	return freq_hi;
219	}
220
221	static void ondemand_powersave_bias_init_cpu(int cpu)
222	{
223	struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
224	dbs_info->freq_table = cpufreq_frequency_get_table(cpu);
225	dbs_info->freq_lo = 0;
226	}
227
228	static void ondemand_powersave_bias_init(void)
229	{
230	int i;
231	for_each_online_cpu(i) {
232	ondemand_powersave_bias_init_cpu(i);
233	}
234	}
235
236	/************************ sysfs interface **********************/
237
238	static ssize_t show_sampling_rate_min(struct kobject *kobj,
239	struct attribute attr, char buf)
240	{
241	return sprintf(buf, "%u\n", min_sampling_rate);
242	}
243
244	define_one_global_ro(sampling_rate_min);
245
246	/* cpufreq_ondemand Governor Tunables */
247	#define show_one(file_name, object) \
248	static ssize_t show_##file_name \
249	(struct kobject kobj, struct attribute attr, char *buf) \
250	{ \
251	return sprintf(buf, "%u\n", dbs_tuners_ins.object); \
252	}
253	show_one(sampling_rate, sampling_rate);
254	show_one(io_is_busy, io_is_busy);
255	show_one(up_threshold, up_threshold);
256	show_one(sampling_down_factor, sampling_down_factor);
257	show_one(ignore_nice_load, ignore_nice);
258	show_one(powersave_bias, powersave_bias);
259
260	/**
261	* update_sampling_rate - update sampling rate effective immediately if needed.
262	* @new_rate: new sampling rate
263	*
264	* If new rate is smaller than the old, simply updaing
265	* dbs_tuners_int.sampling_rate might not be appropriate. For example,
266	* if the original sampling_rate was 1 second and the requested new sampling
267	* rate is 10 ms because the user needs immediate reaction from ondemand
268	* governor, but not sure if higher frequency will be required or not,
269	* then, the governor may change the sampling rate too late; up to 1 second
270	* later. Thus, if we are reducing the sampling rate, we need to make the
271	* new value effective immediately.
272	*/
273	static void update_sampling_rate(unsigned int new_rate)
274	{
275	int cpu;
276
277	dbs_tuners_ins.sampling_rate = new_rate
278	= max(new_rate, min_sampling_rate);
279
280	for_each_online_cpu(cpu) {
281	struct cpufreq_policy *policy;
282	struct cpu_dbs_info_s *dbs_info;
283	unsigned long next_sampling, appointed_at;
284
285	policy = cpufreq_cpu_get(cpu);
286	if (!policy)
287	continue;
288	dbs_info = &per_cpu(od_cpu_dbs_info, policy->cpu);
289	cpufreq_cpu_put(policy);
290
291	mutex_lock(&dbs_info->timer_mutex);
292
293	if (!delayed_work_pending(&dbs_info->work)) {
294	mutex_unlock(&dbs_info->timer_mutex);
295	continue;
296	}
297
298	next_sampling = jiffies + usecs_to_jiffies(new_rate);
299	appointed_at = dbs_info->work.timer.expires;
300
301
302	if (time_before(next_sampling, appointed_at)) {
303
304	mutex_unlock(&dbs_info->timer_mutex);
305	cancel_delayed_work_sync(&dbs_info->work);
306	mutex_lock(&dbs_info->timer_mutex);
307
308	schedule_delayed_work_on(dbs_info->cpu, &dbs_info->work,
309	usecs_to_jiffies(new_rate));
310
311	}
312	mutex_unlock(&dbs_info->timer_mutex);
313	}
314	}
315
316	static ssize_t store_sampling_rate(struct kobject a, struct attribute b,
317	const char *buf, size_t count)
318	{
319	unsigned int input;
320	int ret;
321	ret = sscanf(buf, "%u", &input);
322	if (ret != 1)
323	return -EINVAL;
324	update_sampling_rate(input);
325	return count;
326	}
327
328	static ssize_t store_io_is_busy(struct kobject a, struct attribute b,
329	const char *buf, size_t count)
330	{
331	unsigned int input;
332	int ret;
333
334	ret = sscanf(buf, "%u", &input);
335	if (ret != 1)
336	return -EINVAL;
337	dbs_tuners_ins.io_is_busy = !!input;
338	return count;
339	}
340
341	static ssize_t store_up_threshold(struct kobject a, struct attribute b,
342	const char *buf, size_t count)
343	{
344	unsigned int input;
345	int ret;
346	ret = sscanf(buf, "%u", &input);
347
348	if (ret != 1 \|\| input > MAX_FREQUENCY_UP_THRESHOLD \|\|
349	input < MIN_FREQUENCY_UP_THRESHOLD) {
350	return -EINVAL;
351	}
352	dbs_tuners_ins.up_threshold = input;
353	return count;
354	}
355
356	static ssize_t store_sampling_down_factor(struct kobject *a,
357	struct attribute b, const char buf, size_t count)
358	{
359	unsigned int input, j;
360	int ret;
361	ret = sscanf(buf, "%u", &input);
362
363	if (ret != 1 \|\| input > MAX_SAMPLING_DOWN_FACTOR \|\| input < 1)
364	return -EINVAL;
365	dbs_tuners_ins.sampling_down_factor = input;
366
367	/* Reset down sampling multiplier in case it was active */
368	for_each_online_cpu(j) {
369	struct cpu_dbs_info_s *dbs_info;
370	dbs_info = &per_cpu(od_cpu_dbs_info, j);
371	dbs_info->rate_mult = 1;
372	}
373	return count;
374	}
375
376	static ssize_t store_ignore_nice_load(struct kobject a, struct attribute b,
377	const char *buf, size_t count)
378	{
379	unsigned int input;
380	int ret;
381
382	unsigned int j;
383
384	ret = sscanf(buf, "%u", &input);
385	if (ret != 1)
386	return -EINVAL;
387
388	if (input > 1)
389	input = 1;
390
391	if (input == dbs_tuners_ins.ignore_nice) { /* nothing to do */
392	return count;
393	}
394	dbs_tuners_ins.ignore_nice = input;
395
396	/* we need to re-evaluate prev_cpu_idle */
397	for_each_online_cpu(j) {
398	struct cpu_dbs_info_s *dbs_info;
399	dbs_info = &per_cpu(od_cpu_dbs_info, j);
400	dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
401	&dbs_info->prev_cpu_wall);
402	if (dbs_tuners_ins.ignore_nice)
403	dbs_info->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE];
404
405	}
406	return count;
407	}
408
409	static ssize_t store_powersave_bias(struct kobject a, struct attribute b,
410	const char *buf, size_t count)
411	{
412	unsigned int input;
413	int ret;
414	ret = sscanf(buf, "%u", &input);
415
416	if (ret != 1)
417	return -EINVAL;
418
419	if (input > 1000)
420	input = 1000;
421
422	dbs_tuners_ins.powersave_bias = input;
423	ondemand_powersave_bias_init();
424	return count;
425	}
426
427	define_one_global_rw(sampling_rate);
428	define_one_global_rw(io_is_busy);
429	define_one_global_rw(up_threshold);
430	define_one_global_rw(sampling_down_factor);
431	define_one_global_rw(ignore_nice_load);
432	define_one_global_rw(powersave_bias);
433
434	static struct attribute *dbs_attributes[] = {
435	&sampling_rate_min.attr,
436	&sampling_rate.attr,
437	&up_threshold.attr,
438	&sampling_down_factor.attr,
439	&ignore_nice_load.attr,
440	&powersave_bias.attr,
441	&io_is_busy.attr,
442	NULL
443	};
444
445	static struct attribute_group dbs_attr_group = {
446	.attrs = dbs_attributes,
447	.name = "ondemand",
448	};
449
450	/************************ sysfs end **********************/
451
452	static void dbs_freq_increase(struct cpufreq_policy *p, unsigned int freq)
453	{
454	if (dbs_tuners_ins.powersave_bias)
455	freq = powersave_bias_target(p, freq, CPUFREQ_RELATION_H);
456	else if (p->cur == p->max)
457	return;
458
459	__cpufreq_driver_target(p, freq, dbs_tuners_ins.powersave_bias ?
460	CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
461	}
462
463	static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
464	{
465	unsigned int max_load_freq;
466
467	struct cpufreq_policy *policy;
468	unsigned int j;
469
470	this_dbs_info->freq_lo = 0;
471	policy = this_dbs_info->cur_policy;
472
473	/*
474	* Every sampling_rate, we check, if current idle time is less
475	* than 20% (default), then we try to increase frequency
476	* Every sampling_rate, we look for a the lowest
477	* frequency which can sustain the load while keeping idle time over
478	* 30%. If such a frequency exist, we try to decrease to this frequency.
479	*
480	* Any frequency increase takes it to the maximum frequency.
481	* Frequency reduction happens at minimum steps of
482	* 5% (default) of current frequency
483	*/
484
485	/* Get Absolute Load - in terms of freq */
486	max_load_freq = 0;
487
488	for_each_cpu(j, policy->cpus) {
489	struct cpu_dbs_info_s *j_dbs_info;
490	cputime64_t cur_wall_time, cur_idle_time, cur_iowait_time;
491	unsigned int idle_time, wall_time, iowait_time;
492	unsigned int load, load_freq;
493	int freq_avg;
494
495	j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
496
497	cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
498	cur_iowait_time = get_cpu_iowait_time(j, &cur_wall_time);
499
500	wall_time = (unsigned int)
501	(cur_wall_time - j_dbs_info->prev_cpu_wall);
502	j_dbs_info->prev_cpu_wall = cur_wall_time;
503
504	idle_time = (unsigned int)
505	(cur_idle_time - j_dbs_info->prev_cpu_idle);
506	j_dbs_info->prev_cpu_idle = cur_idle_time;
507
508	iowait_time = (unsigned int)
509	(cur_iowait_time - j_dbs_info->prev_cpu_iowait);
510	j_dbs_info->prev_cpu_iowait = cur_iowait_time;
511
512	if (dbs_tuners_ins.ignore_nice) {
513	u64 cur_nice;
514	unsigned long cur_nice_jiffies;
515
516	cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE] -
517	j_dbs_info->prev_cpu_nice;
518	/*
519	* Assumption: nice time between sampling periods will
520	* be less than 2^32 jiffies for 32 bit sys
521	*/
522	cur_nice_jiffies = (unsigned long)
523	cputime64_to_jiffies64(cur_nice);
524
525	j_dbs_info->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE];
526	idle_time += jiffies_to_usecs(cur_nice_jiffies);
527	}
528
529	/*
530	* For the purpose of ondemand, waiting for disk IO is an
531	* indication that you're performance critical, and not that
532	* the system is actually idle. So subtract the iowait time
533	* from the cpu idle time.
534	*/
535
536	if (dbs_tuners_ins.io_is_busy && idle_time >= iowait_time)
537	idle_time -= iowait_time;
538
539	if (unlikely(!wall_time \|\| wall_time < idle_time))
540	continue;
541
542	load = 100 * (wall_time - idle_time) / wall_time;
543
544	freq_avg = __cpufreq_driver_getavg(policy, j);
545	if (freq_avg <= 0)
546	freq_avg = policy->cur;
547
548	load_freq = load * freq_avg;
549	if (load_freq > max_load_freq)
550	max_load_freq = load_freq;
551	}
552
553	/* Check for frequency increase */
554	if (max_load_freq > dbs_tuners_ins.up_threshold * policy->cur) {
555	/* If switching to max speed, apply sampling_down_factor */
556	if (policy->cur < policy->max)
557	this_dbs_info->rate_mult =
558	dbs_tuners_ins.sampling_down_factor;
559	dbs_freq_increase(policy, policy->max);
560	return;
561	}
562
563	/* Check for frequency decrease */
564	/* if we cannot reduce the frequency anymore, break out early */
565	if (policy->cur == policy->min)
566	return;
567
568	/*
569	* The optimal frequency is the frequency that is the lowest that
570	* can support the current CPU usage without triggering the up
571	* policy. To be safe, we focus 10 points under the threshold.
572	*/
573	if (max_load_freq <
574	(dbs_tuners_ins.up_threshold - dbs_tuners_ins.down_differential) *
575	policy->cur) {
576	unsigned int freq_next;
577	freq_next = max_load_freq /
578	(dbs_tuners_ins.up_threshold -
579	dbs_tuners_ins.down_differential);
580
581	/* No longer fully busy, reset rate_mult */
582	this_dbs_info->rate_mult = 1;
583
584	if (freq_next < policy->min)
585	freq_next = policy->min;
586
587	if (!dbs_tuners_ins.powersave_bias) {
588	__cpufreq_driver_target(policy, freq_next,
589	CPUFREQ_RELATION_L);
590	} else {
591	int freq = powersave_bias_target(policy, freq_next,
592	CPUFREQ_RELATION_L);
593	__cpufreq_driver_target(policy, freq,
594	CPUFREQ_RELATION_L);
595	}
596	}
597	}
598
599	static void do_dbs_timer(struct work_struct *work)
600	{
601	struct cpu_dbs_info_s *dbs_info =
602	container_of(work, struct cpu_dbs_info_s, work.work);
603	unsigned int cpu = dbs_info->cpu;
604	int sample_type = dbs_info->sample_type;
605
606	int delay;
607
608	mutex_lock(&dbs_info->timer_mutex);
609
610	/* Common NORMAL_SAMPLE setup */
611	dbs_info->sample_type = DBS_NORMAL_SAMPLE;
612	if (!dbs_tuners_ins.powersave_bias \|\|
613	sample_type == DBS_NORMAL_SAMPLE) {
614	dbs_check_cpu(dbs_info);
615	if (dbs_info->freq_lo) {
616	/* Setup timer for SUB_SAMPLE */
617	dbs_info->sample_type = DBS_SUB_SAMPLE;
618	delay = dbs_info->freq_hi_jiffies;
619	} else {
620	/* We want all CPUs to do sampling nearly on
621	* same jiffy
622	*/
623	delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate
624	* dbs_info->rate_mult);
625
626	if (num_online_cpus() > 1)
627	delay -= jiffies % delay;
628	}
629	} else {
630	__cpufreq_driver_target(dbs_info->cur_policy,
631	dbs_info->freq_lo, CPUFREQ_RELATION_H);
632	delay = dbs_info->freq_lo_jiffies;
633	}
634	schedule_delayed_work_on(cpu, &dbs_info->work, delay);
635	mutex_unlock(&dbs_info->timer_mutex);
636	}
637
638	static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
639	{
640	/* We want all CPUs to do sampling nearly on same jiffy */
641	int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
642
643	if (num_online_cpus() > 1)
644	delay -= jiffies % delay;
645
646	dbs_info->sample_type = DBS_NORMAL_SAMPLE;
647	INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer);
648	schedule_delayed_work_on(dbs_info->cpu, &dbs_info->work, delay);
649	}
650
651	static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
652	{
653	cancel_delayed_work_sync(&dbs_info->work);
654	}
655
656	/*
657	* Not all CPUs want IO time to be accounted as busy; this dependson how
658	* efficient idling at a higher frequency/voltage is.
659	* Pavel Machek says this is not so for various generations of AMD and old
660	* Intel systems.
661	* Mike Chan (androidlcom) calis this is also not true for ARM.
662	* Because of this, whitelist specific known (series) of CPUs by default, and
663	* leave all others up to the user.
664	*/
665	static int should_io_be_busy(void)
666	{
667	#if defined(CONFIG_X86)
668	/*
669	* For Intel, Core 2 (model 15) andl later have an efficient idle.
670	*/
671	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
672	boot_cpu_data.x86 == 6 &&
673	boot_cpu_data.x86_model >= 15)
674	return 1;
675	#endif
676	return 0;
677	}
678
679	static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
680	unsigned int event)
681	{
682	unsigned int cpu = policy->cpu;
683	struct cpu_dbs_info_s *this_dbs_info;
684	unsigned int j;
685	int rc;
686
687	this_dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
688
689	switch (event) {
690	case CPUFREQ_GOV_START:
691	if ((!cpu_online(cpu)) \|\| (!policy->cur))
692	return -EINVAL;
693
694	mutex_lock(&dbs_mutex);
695
696	dbs_enable++;
697	for_each_cpu(j, policy->cpus) {
698	struct cpu_dbs_info_s *j_dbs_info;
699	j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
700	j_dbs_info->cur_policy = policy;
701
702	j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
703	&j_dbs_info->prev_cpu_wall);
704	if (dbs_tuners_ins.ignore_nice)
705	j_dbs_info->prev_cpu_nice =
706	kcpustat_cpu(j).cpustat[CPUTIME_NICE];
707	}
708	this_dbs_info->cpu = cpu;
709	this_dbs_info->rate_mult = 1;
710	ondemand_powersave_bias_init_cpu(cpu);
711	/*
712	* Start the timerschedule work, when this governor
713	* is used for first time
714	*/
715	if (dbs_enable == 1) {
716	unsigned int latency;
717
718	rc = sysfs_create_group(cpufreq_global_kobject,
719	&dbs_attr_group);
720	if (rc) {
721	mutex_unlock(&dbs_mutex);
722	return rc;
723	}
724
725	/* policy latency is in nS. Convert it to uS first */
726	latency = policy->cpuinfo.transition_latency / 1000;
727	if (latency == 0)
728	latency = 1;
729	/* Bring kernel and HW constraints together */
730	min_sampling_rate = max(min_sampling_rate,
731	MIN_LATENCY_MULTIPLIER * latency);
732	dbs_tuners_ins.sampling_rate =
733	max(min_sampling_rate,
734	latency * LATENCY_MULTIPLIER);
735	dbs_tuners_ins.io_is_busy = should_io_be_busy();
736	}
737	mutex_unlock(&dbs_mutex);
738
739	mutex_init(&this_dbs_info->timer_mutex);
740	dbs_timer_init(this_dbs_info);
741	break;
742
743	case CPUFREQ_GOV_STOP:
744	dbs_timer_exit(this_dbs_info);
745
746	mutex_lock(&dbs_mutex);
747	mutex_destroy(&this_dbs_info->timer_mutex);
748	dbs_enable--;
749	mutex_unlock(&dbs_mutex);
750	if (!dbs_enable)
751	sysfs_remove_group(cpufreq_global_kobject,
752	&dbs_attr_group);
753
754	break;
755
756	case CPUFREQ_GOV_LIMITS:
757	mutex_lock(&this_dbs_info->timer_mutex);
758	if (policy->max < this_dbs_info->cur_policy->cur)
759	__cpufreq_driver_target(this_dbs_info->cur_policy,
760	policy->max, CPUFREQ_RELATION_H);
761	else if (policy->min > this_dbs_info->cur_policy->cur)
762	__cpufreq_driver_target(this_dbs_info->cur_policy,
763	policy->min, CPUFREQ_RELATION_L);
764	mutex_unlock(&this_dbs_info->timer_mutex);
765	break;
766	}
767	return 0;
768	}
769
770	static int __init cpufreq_gov_dbs_init(void)
771	{
772	u64 idle_time;
773	int cpu = get_cpu();
774
775	idle_time = get_cpu_idle_time_us(cpu, NULL);
776	put_cpu();
777	if (idle_time != -1ULL) {
778	/* Idle micro accounting is supported. Use finer thresholds */
779	dbs_tuners_ins.up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
780	dbs_tuners_ins.down_differential =
781	MICRO_FREQUENCY_DOWN_DIFFERENTIAL;
782	/*
783	* In nohz/micro accounting case we set the minimum frequency
784	* not depending on HZ, but fixed (very low). The deferred
785	* timer might skip some samples if idle/sleeping as needed.
786	*/
787	min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
788	} else {
789	/* For correct statistics, we need 10 ticks for each measure */
790	min_sampling_rate =
791	MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10);
792	}
793
794	return cpufreq_register_governor(&cpufreq_gov_ondemand);
795	}
796
797	static void __exit cpufreq_gov_dbs_exit(void)
798	{
799	cpufreq_unregister_governor(&cpufreq_gov_ondemand);
800	}
801
802
803	MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
804	MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
805	MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
806	"Low Latency Frequency Transition capable processors");
807	MODULE_LICENSE("GPL");
808
809	#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
810	fs_initcall(cpufreq_gov_dbs_init);
811	#else
812	module_init(cpufreq_gov_dbs_init);
813	#endif
814	module_exit(cpufreq_gov_dbs_exit);
815

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