[ALSA] Optimize for config without PROC_FS
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / cpufreq / cpufreq_conservative.c
blob2ed5c4363b536220843d942af2e84276b9a1dbd0
1 /*
2 * drivers/cpufreq/cpufreq_conservative.c
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>
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.
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/sched.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>
33 * dbs is used in this file as a shortform for demandbased switching
34 * It helps to keep variable names smaller, simpler
37 #define DEF_FREQUENCY_UP_THRESHOLD (80)
38 #define MIN_FREQUENCY_UP_THRESHOLD (0)
39 #define MAX_FREQUENCY_UP_THRESHOLD (100)
41 #define DEF_FREQUENCY_DOWN_THRESHOLD (20)
42 #define MIN_FREQUENCY_DOWN_THRESHOLD (0)
43 #define MAX_FREQUENCY_DOWN_THRESHOLD (100)
45 /*
46 * The polling frequency of this governor depends on the capability of
47 * the processor. Default polling frequency is 1000 times the transition
48 * latency of the processor. The governor will work on any processor with
49 * transition latency <= 10mS, using appropriate sampling
50 * rate.
51 * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
52 * this governor will not work.
53 * All times here are in uS.
55 static unsigned int def_sampling_rate;
56 #define MIN_SAMPLING_RATE (def_sampling_rate / 2)
57 #define MAX_SAMPLING_RATE (500 * def_sampling_rate)
58 #define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER (100000)
59 #define DEF_SAMPLING_DOWN_FACTOR (5)
60 #define TRANSITION_LATENCY_LIMIT (10 * 1000)
62 static void do_dbs_timer(void *data);
64 struct cpu_dbs_info_s {
65 struct cpufreq_policy *cur_policy;
66 unsigned int prev_cpu_idle_up;
67 unsigned int prev_cpu_idle_down;
68 unsigned int enable;
70 static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
72 static unsigned int dbs_enable; /* number of CPUs using this policy */
74 static DECLARE_MUTEX (dbs_sem);
75 static DECLARE_WORK (dbs_work, do_dbs_timer, NULL);
77 struct dbs_tuners {
78 unsigned int sampling_rate;
79 unsigned int sampling_down_factor;
80 unsigned int up_threshold;
81 unsigned int down_threshold;
82 unsigned int ignore_nice;
83 unsigned int freq_step;
86 static struct dbs_tuners dbs_tuners_ins = {
87 .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
88 .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD,
89 .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
92 static inline unsigned int get_cpu_idle_time(unsigned int cpu)
94 return kstat_cpu(cpu).cpustat.idle +
95 kstat_cpu(cpu).cpustat.iowait +
96 ( !dbs_tuners_ins.ignore_nice ?
97 kstat_cpu(cpu).cpustat.nice :
98 0);
101 /************************** sysfs interface ************************/
102 static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
104 return sprintf (buf, "%u\n", MAX_SAMPLING_RATE);
107 static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf)
109 return sprintf (buf, "%u\n", MIN_SAMPLING_RATE);
112 #define define_one_ro(_name) \
113 static struct freq_attr _name = \
114 __ATTR(_name, 0444, show_##_name, NULL)
116 define_one_ro(sampling_rate_max);
117 define_one_ro(sampling_rate_min);
119 /* cpufreq_conservative Governor Tunables */
120 #define show_one(file_name, object) \
121 static ssize_t show_##file_name \
122 (struct cpufreq_policy *unused, char *buf) \
124 return sprintf(buf, "%u\n", dbs_tuners_ins.object); \
126 show_one(sampling_rate, sampling_rate);
127 show_one(sampling_down_factor, sampling_down_factor);
128 show_one(up_threshold, up_threshold);
129 show_one(down_threshold, down_threshold);
130 show_one(ignore_nice, ignore_nice);
131 show_one(freq_step, freq_step);
133 static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
134 const char *buf, size_t count)
136 unsigned int input;
137 int ret;
138 ret = sscanf (buf, "%u", &input);
139 if (ret != 1 )
140 return -EINVAL;
142 down(&dbs_sem);
143 dbs_tuners_ins.sampling_down_factor = input;
144 up(&dbs_sem);
146 return count;
149 static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
150 const char *buf, size_t count)
152 unsigned int input;
153 int ret;
154 ret = sscanf (buf, "%u", &input);
156 down(&dbs_sem);
157 if (ret != 1 || input > MAX_SAMPLING_RATE || input < MIN_SAMPLING_RATE) {
158 up(&dbs_sem);
159 return -EINVAL;
162 dbs_tuners_ins.sampling_rate = input;
163 up(&dbs_sem);
165 return count;
168 static ssize_t store_up_threshold(struct cpufreq_policy *unused,
169 const char *buf, size_t count)
171 unsigned int input;
172 int ret;
173 ret = sscanf (buf, "%u", &input);
175 down(&dbs_sem);
176 if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
177 input < MIN_FREQUENCY_UP_THRESHOLD ||
178 input <= dbs_tuners_ins.down_threshold) {
179 up(&dbs_sem);
180 return -EINVAL;
183 dbs_tuners_ins.up_threshold = input;
184 up(&dbs_sem);
186 return count;
189 static ssize_t store_down_threshold(struct cpufreq_policy *unused,
190 const char *buf, size_t count)
192 unsigned int input;
193 int ret;
194 ret = sscanf (buf, "%u", &input);
196 down(&dbs_sem);
197 if (ret != 1 || input > MAX_FREQUENCY_DOWN_THRESHOLD ||
198 input < MIN_FREQUENCY_DOWN_THRESHOLD ||
199 input >= dbs_tuners_ins.up_threshold) {
200 up(&dbs_sem);
201 return -EINVAL;
204 dbs_tuners_ins.down_threshold = input;
205 up(&dbs_sem);
207 return count;
210 static ssize_t store_ignore_nice(struct cpufreq_policy *policy,
211 const char *buf, size_t count)
213 unsigned int input;
214 int ret;
216 unsigned int j;
218 ret = sscanf (buf, "%u", &input);
219 if ( ret != 1 )
220 return -EINVAL;
222 if ( input > 1 )
223 input = 1;
225 down(&dbs_sem);
226 if ( input == dbs_tuners_ins.ignore_nice ) { /* nothing to do */
227 up(&dbs_sem);
228 return count;
230 dbs_tuners_ins.ignore_nice = input;
232 /* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */
233 for_each_online_cpu(j) {
234 struct cpu_dbs_info_s *j_dbs_info;
235 j_dbs_info = &per_cpu(cpu_dbs_info, j);
236 j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
237 j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up;
239 up(&dbs_sem);
241 return count;
244 static ssize_t store_freq_step(struct cpufreq_policy *policy,
245 const char *buf, size_t count)
247 unsigned int input;
248 int ret;
250 ret = sscanf (buf, "%u", &input);
252 if ( ret != 1 )
253 return -EINVAL;
255 if ( input > 100 )
256 input = 100;
258 /* no need to test here if freq_step is zero as the user might actually
259 * want this, they would be crazy though :) */
260 down(&dbs_sem);
261 dbs_tuners_ins.freq_step = input;
262 up(&dbs_sem);
264 return count;
267 #define define_one_rw(_name) \
268 static struct freq_attr _name = \
269 __ATTR(_name, 0644, show_##_name, store_##_name)
271 define_one_rw(sampling_rate);
272 define_one_rw(sampling_down_factor);
273 define_one_rw(up_threshold);
274 define_one_rw(down_threshold);
275 define_one_rw(ignore_nice);
276 define_one_rw(freq_step);
278 static struct attribute * dbs_attributes[] = {
279 &sampling_rate_max.attr,
280 &sampling_rate_min.attr,
281 &sampling_rate.attr,
282 &sampling_down_factor.attr,
283 &up_threshold.attr,
284 &down_threshold.attr,
285 &ignore_nice.attr,
286 &freq_step.attr,
287 NULL
290 static struct attribute_group dbs_attr_group = {
291 .attrs = dbs_attributes,
292 .name = "conservative",
295 /************************** sysfs end ************************/
297 static void dbs_check_cpu(int cpu)
299 unsigned int idle_ticks, up_idle_ticks, down_idle_ticks;
300 unsigned int freq_step;
301 unsigned int freq_down_sampling_rate;
302 static int down_skip[NR_CPUS];
303 static int requested_freq[NR_CPUS];
304 static unsigned short init_flag = 0;
305 struct cpu_dbs_info_s *this_dbs_info;
306 struct cpu_dbs_info_s *dbs_info;
308 struct cpufreq_policy *policy;
309 unsigned int j;
311 this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
312 if (!this_dbs_info->enable)
313 return;
315 policy = this_dbs_info->cur_policy;
317 if ( init_flag == 0 ) {
318 for_each_online_cpu(j) {
319 dbs_info = &per_cpu(cpu_dbs_info, j);
320 requested_freq[j] = dbs_info->cur_policy->cur;
322 init_flag = 1;
326 * The default safe range is 20% to 80%
327 * Every sampling_rate, we check
328 * - If current idle time is less than 20%, then we try to
329 * increase frequency
330 * Every sampling_rate*sampling_down_factor, we check
331 * - If current idle time is more than 80%, then we try to
332 * decrease frequency
334 * Any frequency increase takes it to the maximum frequency.
335 * Frequency reduction happens at minimum steps of
336 * 5% (default) of max_frequency
339 /* Check for frequency increase */
341 idle_ticks = UINT_MAX;
342 for_each_cpu_mask(j, policy->cpus) {
343 unsigned int tmp_idle_ticks, total_idle_ticks;
344 struct cpu_dbs_info_s *j_dbs_info;
346 j_dbs_info = &per_cpu(cpu_dbs_info, j);
347 /* Check for frequency increase */
348 total_idle_ticks = get_cpu_idle_time(j);
349 tmp_idle_ticks = total_idle_ticks -
350 j_dbs_info->prev_cpu_idle_up;
351 j_dbs_info->prev_cpu_idle_up = total_idle_ticks;
353 if (tmp_idle_ticks < idle_ticks)
354 idle_ticks = tmp_idle_ticks;
357 /* Scale idle ticks by 100 and compare with up and down ticks */
358 idle_ticks *= 100;
359 up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) *
360 usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
362 if (idle_ticks < up_idle_ticks) {
363 down_skip[cpu] = 0;
364 for_each_cpu_mask(j, policy->cpus) {
365 struct cpu_dbs_info_s *j_dbs_info;
367 j_dbs_info = &per_cpu(cpu_dbs_info, j);
368 j_dbs_info->prev_cpu_idle_down =
369 j_dbs_info->prev_cpu_idle_up;
371 /* if we are already at full speed then break out early */
372 if (requested_freq[cpu] == policy->max)
373 return;
375 freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100;
377 /* max freq cannot be less than 100. But who knows.... */
378 if (unlikely(freq_step == 0))
379 freq_step = 5;
381 requested_freq[cpu] += freq_step;
382 if (requested_freq[cpu] > policy->max)
383 requested_freq[cpu] = policy->max;
385 __cpufreq_driver_target(policy, requested_freq[cpu],
386 CPUFREQ_RELATION_H);
387 return;
390 /* Check for frequency decrease */
391 down_skip[cpu]++;
392 if (down_skip[cpu] < dbs_tuners_ins.sampling_down_factor)
393 return;
395 idle_ticks = UINT_MAX;
396 for_each_cpu_mask(j, policy->cpus) {
397 unsigned int tmp_idle_ticks, total_idle_ticks;
398 struct cpu_dbs_info_s *j_dbs_info;
400 j_dbs_info = &per_cpu(cpu_dbs_info, j);
401 total_idle_ticks = j_dbs_info->prev_cpu_idle_up;
402 tmp_idle_ticks = total_idle_ticks -
403 j_dbs_info->prev_cpu_idle_down;
404 j_dbs_info->prev_cpu_idle_down = total_idle_ticks;
406 if (tmp_idle_ticks < idle_ticks)
407 idle_ticks = tmp_idle_ticks;
410 /* Scale idle ticks by 100 and compare with up and down ticks */
411 idle_ticks *= 100;
412 down_skip[cpu] = 0;
414 freq_down_sampling_rate = dbs_tuners_ins.sampling_rate *
415 dbs_tuners_ins.sampling_down_factor;
416 down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) *
417 usecs_to_jiffies(freq_down_sampling_rate);
419 if (idle_ticks > down_idle_ticks) {
420 /* if we are already at the lowest speed then break out early
421 * or if we 'cannot' reduce the speed as the user might want
422 * freq_step to be zero */
423 if (requested_freq[cpu] == policy->min
424 || dbs_tuners_ins.freq_step == 0)
425 return;
427 freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100;
429 /* max freq cannot be less than 100. But who knows.... */
430 if (unlikely(freq_step == 0))
431 freq_step = 5;
433 requested_freq[cpu] -= freq_step;
434 if (requested_freq[cpu] < policy->min)
435 requested_freq[cpu] = policy->min;
437 __cpufreq_driver_target(policy,
438 requested_freq[cpu],
439 CPUFREQ_RELATION_H);
440 return;
444 static void do_dbs_timer(void *data)
446 int i;
447 down(&dbs_sem);
448 for_each_online_cpu(i)
449 dbs_check_cpu(i);
450 schedule_delayed_work(&dbs_work,
451 usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
452 up(&dbs_sem);
455 static inline void dbs_timer_init(void)
457 INIT_WORK(&dbs_work, do_dbs_timer, NULL);
458 schedule_delayed_work(&dbs_work,
459 usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
460 return;
463 static inline void dbs_timer_exit(void)
465 cancel_delayed_work(&dbs_work);
466 return;
469 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
470 unsigned int event)
472 unsigned int cpu = policy->cpu;
473 struct cpu_dbs_info_s *this_dbs_info;
474 unsigned int j;
476 this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
478 switch (event) {
479 case CPUFREQ_GOV_START:
480 if ((!cpu_online(cpu)) ||
481 (!policy->cur))
482 return -EINVAL;
484 if (policy->cpuinfo.transition_latency >
485 (TRANSITION_LATENCY_LIMIT * 1000))
486 return -EINVAL;
487 if (this_dbs_info->enable) /* Already enabled */
488 break;
490 down(&dbs_sem);
491 for_each_cpu_mask(j, policy->cpus) {
492 struct cpu_dbs_info_s *j_dbs_info;
493 j_dbs_info = &per_cpu(cpu_dbs_info, j);
494 j_dbs_info->cur_policy = policy;
496 j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
497 j_dbs_info->prev_cpu_idle_down
498 = j_dbs_info->prev_cpu_idle_up;
500 this_dbs_info->enable = 1;
501 sysfs_create_group(&policy->kobj, &dbs_attr_group);
502 dbs_enable++;
504 * Start the timerschedule work, when this governor
505 * is used for first time
507 if (dbs_enable == 1) {
508 unsigned int latency;
509 /* policy latency is in nS. Convert it to uS first */
511 latency = policy->cpuinfo.transition_latency;
512 if (latency < 1000)
513 latency = 1000;
515 def_sampling_rate = (latency / 1000) *
516 DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
517 dbs_tuners_ins.sampling_rate = def_sampling_rate;
518 dbs_tuners_ins.ignore_nice = 0;
519 dbs_tuners_ins.freq_step = 5;
521 dbs_timer_init();
524 up(&dbs_sem);
525 break;
527 case CPUFREQ_GOV_STOP:
528 down(&dbs_sem);
529 this_dbs_info->enable = 0;
530 sysfs_remove_group(&policy->kobj, &dbs_attr_group);
531 dbs_enable--;
533 * Stop the timerschedule work, when this governor
534 * is used for first time
536 if (dbs_enable == 0)
537 dbs_timer_exit();
539 up(&dbs_sem);
541 break;
543 case CPUFREQ_GOV_LIMITS:
544 down(&dbs_sem);
545 if (policy->max < this_dbs_info->cur_policy->cur)
546 __cpufreq_driver_target(
547 this_dbs_info->cur_policy,
548 policy->max, CPUFREQ_RELATION_H);
549 else if (policy->min > this_dbs_info->cur_policy->cur)
550 __cpufreq_driver_target(
551 this_dbs_info->cur_policy,
552 policy->min, CPUFREQ_RELATION_L);
553 up(&dbs_sem);
554 break;
556 return 0;
559 static struct cpufreq_governor cpufreq_gov_dbs = {
560 .name = "conservative",
561 .governor = cpufreq_governor_dbs,
562 .owner = THIS_MODULE,
565 static int __init cpufreq_gov_dbs_init(void)
567 return cpufreq_register_governor(&cpufreq_gov_dbs);
570 static void __exit cpufreq_gov_dbs_exit(void)
572 /* Make sure that the scheduled work is indeed not running */
573 flush_scheduled_work();
575 cpufreq_unregister_governor(&cpufreq_gov_dbs);
579 MODULE_AUTHOR ("Alexander Clouter <alex-kernel@digriz.org.uk>");
580 MODULE_DESCRIPTION ("'cpufreq_conservative' - A dynamic cpufreq governor for "
581 "Low Latency Frequency Transition capable processors "
582 "optimised for use in a battery environment");
583 MODULE_LICENSE ("GPL");
585 module_init(cpufreq_gov_dbs_init);
586 module_exit(cpufreq_gov_dbs_exit);