[CPUFREQ] ondemand/conservative: deprecate sampling_rate{min,max}
[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)  2004 Alexander Clouter <alex-kernel@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/smp.h>
17 #include <linux/init.h>
18 #include <linux/interrupt.h>
19 #include <linux/ctype.h>
20 #include <linux/cpufreq.h>
21 #include <linux/sysctl.h>
22 #include <linux/types.h>
23 #include <linux/fs.h>
24 #include <linux/sysfs.h>
25 #include <linux/cpu.h>
26 #include <linux/kmod.h>
27 #include <linux/workqueue.h>
28 #include <linux/jiffies.h>
29 #include <linux/kernel_stat.h>
30 #include <linux/percpu.h>
31 #include <linux/mutex.h>
32 /*
33  * dbs is used in this file as a shortform for demandbased switching
34  * It helps to keep variable names smaller, simpler
35  */
36
37 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
38 #define DEF_FREQUENCY_DOWN_THRESHOLD            (20)
39
40 /*
41  * The polling frequency of this governor depends on the capability of
42  * the processor. Default polling frequency is 1000 times the transition
43  * latency of the processor. The governor will work on any processor with
44  * transition latency <= 10mS, using appropriate sampling
45  * rate.
46  * For CPUs with transition latency > 10mS (mostly drivers
47  * with CPUFREQ_ETERNAL), this governor will not work.
48  * All times here are in uS.
49  */
50 static unsigned int def_sampling_rate;
51 #define MIN_SAMPLING_RATE_RATIO                 (2)
52 /* for correct statistics, we need at least 10 ticks between each measure */
53 #define MIN_STAT_SAMPLING_RATE                  \
54                         (MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10))
55 #define MIN_SAMPLING_RATE                       \
56                         (def_sampling_rate / MIN_SAMPLING_RATE_RATIO)
57 #define MAX_SAMPLING_RATE                       (500 * def_sampling_rate)
58 #define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER    (1000)
59 #define DEF_SAMPLING_DOWN_FACTOR                (1)
60 #define MAX_SAMPLING_DOWN_FACTOR                (10)
61 #define TRANSITION_LATENCY_LIMIT                (10 * 1000 * 1000)
62
63 static void do_dbs_timer(struct work_struct *work);
64
65 struct cpu_dbs_info_s {
66         struct cpufreq_policy *cur_policy;
67         unsigned int prev_cpu_idle_up;
68         unsigned int prev_cpu_idle_down;
69         unsigned int enable;
70         unsigned int down_skip;
71         unsigned int requested_freq;
72 };
73 static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
74
75 static unsigned int dbs_enable; /* number of CPUs using this policy */
76
77 /*
78  * DEADLOCK ALERT! There is a ordering requirement between cpu_hotplug
79  * lock and dbs_mutex. cpu_hotplug lock should always be held before
80  * dbs_mutex. If any function that can potentially take cpu_hotplug lock
81  * (like __cpufreq_driver_target()) is being called with dbs_mutex taken, then
82  * cpu_hotplug lock should be taken before that. Note that cpu_hotplug lock
83  * is recursive for the same process. -Venki
84  */
85 static DEFINE_MUTEX(dbs_mutex);
86 static DECLARE_DELAYED_WORK(dbs_work, do_dbs_timer);
87
88 struct dbs_tuners {
89         unsigned int sampling_rate;
90         unsigned int sampling_down_factor;
91         unsigned int up_threshold;
92         unsigned int down_threshold;
93         unsigned int ignore_nice;
94         unsigned int freq_step;
95 };
96
97 static struct dbs_tuners dbs_tuners_ins = {
98         .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
99         .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD,
100         .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
101         .ignore_nice = 0,
102         .freq_step = 5,
103 };
104
105 static inline unsigned int get_cpu_idle_time(unsigned int cpu)
106 {
107         unsigned int add_nice = 0, ret;
108
109         if (dbs_tuners_ins.ignore_nice)
110                 add_nice = kstat_cpu(cpu).cpustat.nice;
111
112         ret = kstat_cpu(cpu).cpustat.idle +
113                 kstat_cpu(cpu).cpustat.iowait +
114                 add_nice;
115
116         return ret;
117 }
118
119 /* keep track of frequency transitions */
120 static int
121 dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
122                      void *data)
123 {
124         struct cpufreq_freqs *freq = data;
125         struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cpu_dbs_info,
126                                                         freq->cpu);
127
128         if (!this_dbs_info->enable)
129                 return 0;
130
131         this_dbs_info->requested_freq = freq->new;
132
133         return 0;
134 }
135
136 static struct notifier_block dbs_cpufreq_notifier_block = {
137         .notifier_call = dbs_cpufreq_notifier
138 };
139
140 /************************** sysfs interface ************************/
141 static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
142 {
143         static int print_once;
144
145         if (!print_once) {
146                 printk(KERN_INFO "CPUFREQ: conservative sampling_rate_max "
147                        "sysfs file is deprecated - used by: %s\n",
148                        current->comm);
149                 print_once = 1;
150         }
151         return sprintf(buf, "%u\n", MAX_SAMPLING_RATE);
152 }
153
154 static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf)
155 {
156         static int print_once;
157
158         if (!print_once) {
159                 printk(KERN_INFO "CPUFREQ: conservative sampling_rate_max "
160                        "sysfs file is deprecated - used by: %s\n", current->comm);
161                 print_once = 1;
162         }
163         return sprintf(buf, "%u\n", MIN_SAMPLING_RATE);
164 }
165
166 #define define_one_ro(_name)                            \
167 static struct freq_attr _name =                         \
168 __ATTR(_name, 0444, show_##_name, NULL)
169
170 define_one_ro(sampling_rate_max);
171 define_one_ro(sampling_rate_min);
172
173 /* cpufreq_conservative Governor Tunables */
174 #define show_one(file_name, object)                                     \
175 static ssize_t show_##file_name                                         \
176 (struct cpufreq_policy *unused, char *buf)                              \
177 {                                                                       \
178         return sprintf(buf, "%u\n", dbs_tuners_ins.object);             \
179 }
180 show_one(sampling_rate, sampling_rate);
181 show_one(sampling_down_factor, sampling_down_factor);
182 show_one(up_threshold, up_threshold);
183 show_one(down_threshold, down_threshold);
184 show_one(ignore_nice_load, ignore_nice);
185 show_one(freq_step, freq_step);
186
187 static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
188                 const char *buf, size_t count)
189 {
190         unsigned int input;
191         int ret;
192         ret = sscanf(buf, "%u", &input);
193         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
194                 return -EINVAL;
195
196         mutex_lock(&dbs_mutex);
197         dbs_tuners_ins.sampling_down_factor = input;
198         mutex_unlock(&dbs_mutex);
199
200         return count;
201 }
202
203 static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
204                 const char *buf, size_t count)
205 {
206         unsigned int input;
207         int ret;
208         ret = sscanf(buf, "%u", &input);
209
210         mutex_lock(&dbs_mutex);
211         if (ret != 1 || input > MAX_SAMPLING_RATE ||
212             input < MIN_SAMPLING_RATE) {
213                 mutex_unlock(&dbs_mutex);
214                 return -EINVAL;
215         }
216
217         dbs_tuners_ins.sampling_rate = input;
218         mutex_unlock(&dbs_mutex);
219
220         return count;
221 }
222
223 static ssize_t store_up_threshold(struct cpufreq_policy *unused,
224                 const char *buf, size_t count)
225 {
226         unsigned int input;
227         int ret;
228         ret = sscanf(buf, "%u", &input);
229
230         mutex_lock(&dbs_mutex);
231         if (ret != 1 || input > 100 ||
232             input <= dbs_tuners_ins.down_threshold) {
233                 mutex_unlock(&dbs_mutex);
234                 return -EINVAL;
235         }
236
237         dbs_tuners_ins.up_threshold = input;
238         mutex_unlock(&dbs_mutex);
239
240         return count;
241 }
242
243 static ssize_t store_down_threshold(struct cpufreq_policy *unused,
244                 const char *buf, size_t count)
245 {
246         unsigned int input;
247         int ret;
248         ret = sscanf(buf, "%u", &input);
249
250         mutex_lock(&dbs_mutex);
251         if (ret != 1 || input > 100 || input >= dbs_tuners_ins.up_threshold) {
252                 mutex_unlock(&dbs_mutex);
253                 return -EINVAL;
254         }
255
256         dbs_tuners_ins.down_threshold = input;
257         mutex_unlock(&dbs_mutex);
258
259         return count;
260 }
261
262 static ssize_t store_ignore_nice_load(struct cpufreq_policy *policy,
263                 const char *buf, size_t count)
264 {
265         unsigned int input;
266         int ret;
267
268         unsigned int j;
269
270         ret = sscanf(buf, "%u", &input);
271         if (ret != 1)
272                 return -EINVAL;
273
274         if (input > 1)
275                 input = 1;
276
277         mutex_lock(&dbs_mutex);
278         if (input == dbs_tuners_ins.ignore_nice) { /* nothing to do */
279                 mutex_unlock(&dbs_mutex);
280                 return count;
281         }
282         dbs_tuners_ins.ignore_nice = input;
283
284         /* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */
285         for_each_online_cpu(j) {
286                 struct cpu_dbs_info_s *j_dbs_info;
287                 j_dbs_info = &per_cpu(cpu_dbs_info, j);
288                 j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
289                 j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up;
290         }
291         mutex_unlock(&dbs_mutex);
292
293         return count;
294 }
295
296 static ssize_t store_freq_step(struct cpufreq_policy *policy,
297                 const char *buf, size_t count)
298 {
299         unsigned int input;
300         int ret;
301
302         ret = sscanf(buf, "%u", &input);
303
304         if (ret != 1)
305                 return -EINVAL;
306
307         if (input > 100)
308                 input = 100;
309
310         /* no need to test here if freq_step is zero as the user might actually
311          * want this, they would be crazy though :) */
312         mutex_lock(&dbs_mutex);
313         dbs_tuners_ins.freq_step = input;
314         mutex_unlock(&dbs_mutex);
315
316         return count;
317 }
318
319 #define define_one_rw(_name) \
320 static struct freq_attr _name = \
321 __ATTR(_name, 0644, show_##_name, store_##_name)
322
323 define_one_rw(sampling_rate);
324 define_one_rw(sampling_down_factor);
325 define_one_rw(up_threshold);
326 define_one_rw(down_threshold);
327 define_one_rw(ignore_nice_load);
328 define_one_rw(freq_step);
329
330 static struct attribute *dbs_attributes[] = {
331         &sampling_rate_max.attr,
332         &sampling_rate_min.attr,
333         &sampling_rate.attr,
334         &sampling_down_factor.attr,
335         &up_threshold.attr,
336         &down_threshold.attr,
337         &ignore_nice_load.attr,
338         &freq_step.attr,
339         NULL
340 };
341
342 static struct attribute_group dbs_attr_group = {
343         .attrs = dbs_attributes,
344         .name = "conservative",
345 };
346
347 /************************** sysfs end ************************/
348
349 static void dbs_check_cpu(int cpu)
350 {
351         unsigned int idle_ticks, up_idle_ticks, down_idle_ticks;
352         unsigned int tmp_idle_ticks, total_idle_ticks;
353         unsigned int freq_target;
354         unsigned int freq_down_sampling_rate;
355         struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
356         struct cpufreq_policy *policy;
357
358         if (!this_dbs_info->enable)
359                 return;
360
361         policy = this_dbs_info->cur_policy;
362
363         /*
364          * The default safe range is 20% to 80%
365          * Every sampling_rate, we check
366          *      - If current idle time is less than 20%, then we try to
367          *        increase frequency
368          * Every sampling_rate*sampling_down_factor, we check
369          *      - If current idle time is more than 80%, then we try to
370          *        decrease frequency
371          *
372          * Any frequency increase takes it to the maximum frequency.
373          * Frequency reduction happens at minimum steps of
374          * 5% (default) of max_frequency
375          */
376
377         /* Check for frequency increase */
378         idle_ticks = UINT_MAX;
379
380         /* Check for frequency increase */
381         total_idle_ticks = get_cpu_idle_time(cpu);
382         tmp_idle_ticks = total_idle_ticks -
383                 this_dbs_info->prev_cpu_idle_up;
384         this_dbs_info->prev_cpu_idle_up = total_idle_ticks;
385
386         if (tmp_idle_ticks < idle_ticks)
387                 idle_ticks = tmp_idle_ticks;
388
389         /* Scale idle ticks by 100 and compare with up and down ticks */
390         idle_ticks *= 100;
391         up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) *
392                         usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
393
394         if (idle_ticks < up_idle_ticks) {
395                 this_dbs_info->down_skip = 0;
396                 this_dbs_info->prev_cpu_idle_down =
397                         this_dbs_info->prev_cpu_idle_up;
398
399                 /* if we are already at full speed then break out early */
400                 if (this_dbs_info->requested_freq == policy->max)
401                         return;
402
403                 freq_target = (dbs_tuners_ins.freq_step * policy->max) / 100;
404
405                 /* max freq cannot be less than 100. But who knows.... */
406                 if (unlikely(freq_target == 0))
407                         freq_target = 5;
408
409                 this_dbs_info->requested_freq += freq_target;
410                 if (this_dbs_info->requested_freq > policy->max)
411                         this_dbs_info->requested_freq = policy->max;
412
413                 __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
414                         CPUFREQ_RELATION_H);
415                 return;
416         }
417
418         /* Check for frequency decrease */
419         this_dbs_info->down_skip++;
420         if (this_dbs_info->down_skip < dbs_tuners_ins.sampling_down_factor)
421                 return;
422
423         /* Check for frequency decrease */
424         total_idle_ticks = this_dbs_info->prev_cpu_idle_up;
425         tmp_idle_ticks = total_idle_ticks -
426                 this_dbs_info->prev_cpu_idle_down;
427         this_dbs_info->prev_cpu_idle_down = total_idle_ticks;
428
429         if (tmp_idle_ticks < idle_ticks)
430                 idle_ticks = tmp_idle_ticks;
431
432         /* Scale idle ticks by 100 and compare with up and down ticks */
433         idle_ticks *= 100;
434         this_dbs_info->down_skip = 0;
435
436         freq_down_sampling_rate = dbs_tuners_ins.sampling_rate *
437                 dbs_tuners_ins.sampling_down_factor;
438         down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) *
439                 usecs_to_jiffies(freq_down_sampling_rate);
440
441         if (idle_ticks > down_idle_ticks) {
442                 /*
443                  * if we are already at the lowest speed then break out early
444                  * or if we 'cannot' reduce the speed as the user might want
445                  * freq_target to be zero
446                  */
447                 if (this_dbs_info->requested_freq == policy->min
448                                 || dbs_tuners_ins.freq_step == 0)
449                         return;
450
451                 freq_target = (dbs_tuners_ins.freq_step * policy->max) / 100;
452
453                 /* max freq cannot be less than 100. But who knows.... */
454                 if (unlikely(freq_target == 0))
455                         freq_target = 5;
456
457                 this_dbs_info->requested_freq -= freq_target;
458                 if (this_dbs_info->requested_freq < policy->min)
459                         this_dbs_info->requested_freq = policy->min;
460
461                 __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
462                                 CPUFREQ_RELATION_H);
463                 return;
464         }
465 }
466
467 static void do_dbs_timer(struct work_struct *work)
468 {
469         int i;
470         mutex_lock(&dbs_mutex);
471         for_each_online_cpu(i)
472                 dbs_check_cpu(i);
473         schedule_delayed_work(&dbs_work,
474                         usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
475         mutex_unlock(&dbs_mutex);
476 }
477
478 static inline void dbs_timer_init(void)
479 {
480         init_timer_deferrable(&dbs_work.timer);
481         schedule_delayed_work(&dbs_work,
482                         usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
483         return;
484 }
485
486 static inline void dbs_timer_exit(void)
487 {
488         cancel_delayed_work(&dbs_work);
489         return;
490 }
491
492 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
493                                    unsigned int event)
494 {
495         unsigned int cpu = policy->cpu;
496         struct cpu_dbs_info_s *this_dbs_info;
497         unsigned int j;
498         int rc;
499
500         this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
501
502         switch (event) {
503         case CPUFREQ_GOV_START:
504                 if ((!cpu_online(cpu)) || (!policy->cur))
505                         return -EINVAL;
506
507                 if (this_dbs_info->enable) /* Already enabled */
508                         break;
509
510                 mutex_lock(&dbs_mutex);
511
512                 rc = sysfs_create_group(&policy->kobj, &dbs_attr_group);
513                 if (rc) {
514                         mutex_unlock(&dbs_mutex);
515                         return rc;
516                 }
517
518                 for_each_cpu(j, policy->cpus) {
519                         struct cpu_dbs_info_s *j_dbs_info;
520                         j_dbs_info = &per_cpu(cpu_dbs_info, j);
521                         j_dbs_info->cur_policy = policy;
522
523                         j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(cpu);
524                         j_dbs_info->prev_cpu_idle_down
525                                 = j_dbs_info->prev_cpu_idle_up;
526                 }
527                 this_dbs_info->enable = 1;
528                 this_dbs_info->down_skip = 0;
529                 this_dbs_info->requested_freq = policy->cur;
530
531                 dbs_enable++;
532                 /*
533                  * Start the timerschedule work, when this governor
534                  * is used for first time
535                  */
536                 if (dbs_enable == 1) {
537                         unsigned int latency;
538                         /* policy latency is in nS. Convert it to uS first */
539                         latency = policy->cpuinfo.transition_latency / 1000;
540                         if (latency == 0)
541                                 latency = 1;
542
543                         def_sampling_rate = 10 * latency *
544                                         DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
545
546                         if (def_sampling_rate < MIN_STAT_SAMPLING_RATE)
547                                 def_sampling_rate = MIN_STAT_SAMPLING_RATE;
548
549                         dbs_tuners_ins.sampling_rate = def_sampling_rate;
550
551                         dbs_timer_init();
552                         cpufreq_register_notifier(
553                                         &dbs_cpufreq_notifier_block,
554                                         CPUFREQ_TRANSITION_NOTIFIER);
555                 }
556
557                 mutex_unlock(&dbs_mutex);
558                 break;
559
560         case CPUFREQ_GOV_STOP:
561                 mutex_lock(&dbs_mutex);
562                 this_dbs_info->enable = 0;
563                 sysfs_remove_group(&policy->kobj, &dbs_attr_group);
564                 dbs_enable--;
565                 /*
566                  * Stop the timerschedule work, when this governor
567                  * is used for first time
568                  */
569                 if (dbs_enable == 0) {
570                         dbs_timer_exit();
571                         cpufreq_unregister_notifier(
572                                         &dbs_cpufreq_notifier_block,
573                                         CPUFREQ_TRANSITION_NOTIFIER);
574                 }
575
576                 mutex_unlock(&dbs_mutex);
577
578                 break;
579
580         case CPUFREQ_GOV_LIMITS:
581                 mutex_lock(&dbs_mutex);
582                 if (policy->max < this_dbs_info->cur_policy->cur)
583                         __cpufreq_driver_target(
584                                         this_dbs_info->cur_policy,
585                                         policy->max, CPUFREQ_RELATION_H);
586                 else if (policy->min > this_dbs_info->cur_policy->cur)
587                         __cpufreq_driver_target(
588                                         this_dbs_info->cur_policy,
589                                         policy->min, CPUFREQ_RELATION_L);
590                 mutex_unlock(&dbs_mutex);
591                 break;
592         }
593         return 0;
594 }
595
596 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
597 static
598 #endif
599 struct cpufreq_governor cpufreq_gov_conservative = {
600         .name                   = "conservative",
601         .governor               = cpufreq_governor_dbs,
602         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
603         .owner                  = THIS_MODULE,
604 };
605
606 static int __init cpufreq_gov_dbs_init(void)
607 {
608         return cpufreq_register_governor(&cpufreq_gov_conservative);
609 }
610
611 static void __exit cpufreq_gov_dbs_exit(void)
612 {
613         /* Make sure that the scheduled work is indeed not running */
614         flush_scheduled_work();
615
616         cpufreq_unregister_governor(&cpufreq_gov_conservative);
617 }
618
619
620 MODULE_AUTHOR("Alexander Clouter <alex-kernel@digriz.org.uk>");
621 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
622                 "Low Latency Frequency Transition capable processors "
623                 "optimised for use in a battery environment");
624 MODULE_LICENSE("GPL");
625
626 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
627 fs_initcall(cpufreq_gov_dbs_init);
628 #else
629 module_init(cpufreq_gov_dbs_init);
630 #endif
631 module_exit(cpufreq_gov_dbs_exit);