cpufreq: ondemand: Fix typos in comments
[deliverable/linux.git] / drivers / cpufreq / cpufreq_conservative.c
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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>
11a80a9c 7 * (C) 2009 Alexander Clouter <alex@digriz.org.uk>
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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
b9170836 14#include <linux/cpufreq.h>
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15#include <linux/init.h>
16#include <linux/kernel.h>
b9170836 17#include <linux/kernel_stat.h>
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18#include <linux/kobject.h>
19#include <linux/module.h>
3fc54d37 20#include <linux/mutex.h>
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21#include <linux/notifier.h>
22#include <linux/percpu-defs.h>
23#include <linux/sysfs.h>
24#include <linux/types.h>
8e677ce8 25
4471a34f 26#include "cpufreq_governor.h"
b9170836 27
4471a34f 28/* Conservative governor macors */
b9170836 29#define DEF_FREQUENCY_UP_THRESHOLD (80)
b9170836 30#define DEF_FREQUENCY_DOWN_THRESHOLD (20)
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31#define DEF_SAMPLING_DOWN_FACTOR (1)
32#define MAX_SAMPLING_DOWN_FACTOR (10)
b9170836 33
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34static struct dbs_data cs_dbs_data;
35static DEFINE_PER_CPU(struct cs_cpu_dbs_info_s, cs_cpu_dbs_info);
b9170836 36
4471a34f 37static struct cs_dbs_tuners cs_tuners = {
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38 .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
39 .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD,
40 .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
41 .ignore_nice = 0,
42 .freq_step = 5,
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43};
44
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45/*
46 * Every sampling_rate, we check, if current idle time is less than 20%
47 * (default), then we try to increase frequency Every sampling_rate *
48 * sampling_down_factor, we check, if current idle time is more than 80%, then
49 * we try to decrease frequency
50 *
51 * Any frequency increase takes it to the maximum frequency. Frequency reduction
52 * happens at minimum steps of 5% (default) of maximum frequency
53 */
54static void cs_check_cpu(int cpu, unsigned int load)
a8d7c3bc 55{
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56 struct cs_cpu_dbs_info_s *dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
57 struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy;
58 unsigned int freq_target;
59
60 /*
61 * break out if we 'cannot' reduce the speed as the user might
62 * want freq_step to be zero
63 */
64 if (cs_tuners.freq_step == 0)
65 return;
66
67 /* Check for frequency increase */
68 if (load > cs_tuners.up_threshold) {
69 dbs_info->down_skip = 0;
70
71 /* if we are already at full speed then break out early */
72 if (dbs_info->requested_freq == policy->max)
73 return;
74
75 freq_target = (cs_tuners.freq_step * policy->max) / 100;
76
77 /* max freq cannot be less than 100. But who knows.... */
78 if (unlikely(freq_target == 0))
79 freq_target = 5;
80
81 dbs_info->requested_freq += freq_target;
82 if (dbs_info->requested_freq > policy->max)
83 dbs_info->requested_freq = policy->max;
a8d7c3bc 84
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85 __cpufreq_driver_target(policy, dbs_info->requested_freq,
86 CPUFREQ_RELATION_H);
87 return;
88 }
89
90 /*
91 * The optimal frequency is the frequency that is the lowest that can
92 * support the current CPU usage without triggering the up policy. To be
93 * safe, we focus 10 points under the threshold.
94 */
95 if (load < (cs_tuners.down_threshold - 10)) {
96 freq_target = (cs_tuners.freq_step * policy->max) / 100;
97
98 dbs_info->requested_freq -= freq_target;
99 if (dbs_info->requested_freq < policy->min)
100 dbs_info->requested_freq = policy->min;
101
102 /*
103 * if we cannot reduce the frequency anymore, break out early
104 */
105 if (policy->cur == policy->min)
106 return;
107
108 __cpufreq_driver_target(policy, dbs_info->requested_freq,
109 CPUFREQ_RELATION_H);
110 return;
111 }
112}
113
4447266b 114static void cs_dbs_timer(struct work_struct *work)
4471a34f 115{
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116 struct delayed_work *dw = to_delayed_work(work);
117 struct cs_cpu_dbs_info_s *dbs_info = container_of(work,
118 struct cs_cpu_dbs_info_s, cdbs.work.work);
09dca5ae 119 unsigned int cpu = dbs_info->cdbs.cur_policy->cpu;
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120 struct cs_cpu_dbs_info_s *core_dbs_info = &per_cpu(cs_cpu_dbs_info,
121 cpu);
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122 int delay = delay_for_sampling_rate(cs_tuners.sampling_rate);
123
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124 mutex_lock(&core_dbs_info->cdbs.timer_mutex);
125 if (need_load_eval(&core_dbs_info->cdbs, cs_tuners.sampling_rate))
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126 dbs_check_cpu(&cs_dbs_data, cpu);
127
128 schedule_delayed_work_on(smp_processor_id(), dw, delay);
4447266b 129 mutex_unlock(&core_dbs_info->cdbs.timer_mutex);
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130}
131
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132static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
133 void *data)
134{
135 struct cpufreq_freqs *freq = data;
136 struct cs_cpu_dbs_info_s *dbs_info =
137 &per_cpu(cs_cpu_dbs_info, freq->cpu);
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138 struct cpufreq_policy *policy;
139
4471a34f 140 if (!dbs_info->enable)
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141 return 0;
142
4471a34f 143 policy = dbs_info->cdbs.cur_policy;
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144
145 /*
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146 * we only care if our internally tracked freq moves outside the 'valid'
147 * ranges of freqency available to us otherwise we do not change it
f407a08b 148 */
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149 if (dbs_info->requested_freq > policy->max
150 || dbs_info->requested_freq < policy->min)
151 dbs_info->requested_freq = freq->new;
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152
153 return 0;
154}
155
b9170836 156/************************** sysfs interface ************************/
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157static ssize_t show_sampling_rate_min(struct kobject *kobj,
158 struct attribute *attr, char *buf)
b9170836 159{
4471a34f 160 return sprintf(buf, "%u\n", cs_dbs_data.min_sampling_rate);
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161}
162
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163static ssize_t store_sampling_down_factor(struct kobject *a,
164 struct attribute *b,
165 const char *buf, size_t count)
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166{
167 unsigned int input;
168 int ret;
9acef487 169 ret = sscanf(buf, "%u", &input);
8e677ce8 170
2c906b31 171 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
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172 return -EINVAL;
173
4471a34f 174 cs_tuners.sampling_down_factor = input;
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175 return count;
176}
177
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178static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
179 const char *buf, size_t count)
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180{
181 unsigned int input;
182 int ret;
9acef487 183 ret = sscanf(buf, "%u", &input);
b9170836 184
8e677ce8 185 if (ret != 1)
b9170836 186 return -EINVAL;
8e677ce8 187
4471a34f 188 cs_tuners.sampling_rate = max(input, cs_dbs_data.min_sampling_rate);
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189 return count;
190}
191
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192static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
193 const char *buf, size_t count)
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194{
195 unsigned int input;
196 int ret;
9acef487 197 ret = sscanf(buf, "%u", &input);
b9170836 198
4471a34f 199 if (ret != 1 || input > 100 || input <= cs_tuners.down_threshold)
b9170836 200 return -EINVAL;
b9170836 201
4471a34f 202 cs_tuners.up_threshold = input;
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203 return count;
204}
205
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206static ssize_t store_down_threshold(struct kobject *a, struct attribute *b,
207 const char *buf, size_t count)
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208{
209 unsigned int input;
210 int ret;
9acef487 211 ret = sscanf(buf, "%u", &input);
b9170836 212
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213 /* cannot be lower than 11 otherwise freq will not fall */
214 if (ret != 1 || input < 11 || input > 100 ||
4471a34f 215 input >= cs_tuners.up_threshold)
b9170836 216 return -EINVAL;
b9170836 217
4471a34f 218 cs_tuners.down_threshold = input;
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219 return count;
220}
221
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222static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
223 const char *buf, size_t count)
b9170836 224{
4471a34f 225 unsigned int input, j;
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226 int ret;
227
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228 ret = sscanf(buf, "%u", &input);
229 if (ret != 1)
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230 return -EINVAL;
231
18a7247d 232 if (input > 1)
b9170836 233 input = 1;
18a7247d 234
4471a34f 235 if (input == cs_tuners.ignore_nice) /* nothing to do */
b9170836 236 return count;
326c86de 237
4471a34f 238 cs_tuners.ignore_nice = input;
b9170836 239
8e677ce8 240 /* we need to re-evaluate prev_cpu_idle */
dac1c1a5 241 for_each_online_cpu(j) {
4471a34f 242 struct cs_cpu_dbs_info_s *dbs_info;
245b2e70 243 dbs_info = &per_cpu(cs_cpu_dbs_info, j);
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244 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
245 &dbs_info->cdbs.prev_cpu_wall);
246 if (cs_tuners.ignore_nice)
247 dbs_info->cdbs.prev_cpu_nice =
248 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
b9170836 249 }
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250 return count;
251}
252
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253static ssize_t store_freq_step(struct kobject *a, struct attribute *b,
254 const char *buf, size_t count)
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255{
256 unsigned int input;
257 int ret;
18a7247d 258 ret = sscanf(buf, "%u", &input);
b9170836 259
18a7247d 260 if (ret != 1)
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261 return -EINVAL;
262
18a7247d 263 if (input > 100)
b9170836 264 input = 100;
18a7247d 265
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266 /*
267 * no need to test here if freq_step is zero as the user might actually
268 * want this, they would be crazy though :)
269 */
270 cs_tuners.freq_step = input;
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271 return count;
272}
273
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274show_one(cs, sampling_rate, sampling_rate);
275show_one(cs, sampling_down_factor, sampling_down_factor);
276show_one(cs, up_threshold, up_threshold);
277show_one(cs, down_threshold, down_threshold);
278show_one(cs, ignore_nice_load, ignore_nice);
279show_one(cs, freq_step, freq_step);
280
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281define_one_global_rw(sampling_rate);
282define_one_global_rw(sampling_down_factor);
283define_one_global_rw(up_threshold);
284define_one_global_rw(down_threshold);
285define_one_global_rw(ignore_nice_load);
286define_one_global_rw(freq_step);
4471a34f 287define_one_global_ro(sampling_rate_min);
b9170836 288
9acef487 289static struct attribute *dbs_attributes[] = {
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290 &sampling_rate_min.attr,
291 &sampling_rate.attr,
292 &sampling_down_factor.attr,
293 &up_threshold.attr,
294 &down_threshold.attr,
001893cd 295 &ignore_nice_load.attr,
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296 &freq_step.attr,
297 NULL
298};
299
4471a34f 300static struct attribute_group cs_attr_group = {
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301 .attrs = dbs_attributes,
302 .name = "conservative",
303};
304
305/************************** sysfs end ************************/
306
4471a34f 307define_get_cpu_dbs_routines(cs_cpu_dbs_info);
8e677ce8 308
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309static struct notifier_block cs_cpufreq_notifier_block = {
310 .notifier_call = dbs_cpufreq_notifier,
311};
8e677ce8 312
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313static struct cs_ops cs_ops = {
314 .notifier_block = &cs_cpufreq_notifier_block,
315};
b9170836 316
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317static struct dbs_data cs_dbs_data = {
318 .governor = GOV_CONSERVATIVE,
319 .attr_group = &cs_attr_group,
320 .tuners = &cs_tuners,
321 .get_cpu_cdbs = get_cpu_cdbs,
322 .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
323 .gov_dbs_timer = cs_dbs_timer,
324 .gov_check_cpu = cs_check_cpu,
325 .gov_ops = &cs_ops,
326};
b9170836 327
4471a34f 328static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy,
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329 unsigned int event)
330{
4471a34f 331 return cpufreq_governor_dbs(&cs_dbs_data, policy, event);
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332}
333
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334#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
335static
336#endif
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337struct cpufreq_governor cpufreq_gov_conservative = {
338 .name = "conservative",
4471a34f 339 .governor = cs_cpufreq_governor_dbs,
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340 .max_transition_latency = TRANSITION_LATENCY_LIMIT,
341 .owner = THIS_MODULE,
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342};
343
344static int __init cpufreq_gov_dbs_init(void)
345{
4471a34f 346 mutex_init(&cs_dbs_data.mutex);
57df5573 347 return cpufreq_register_governor(&cpufreq_gov_conservative);
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348}
349
350static void __exit cpufreq_gov_dbs_exit(void)
351{
1c256245 352 cpufreq_unregister_governor(&cpufreq_gov_conservative);
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353}
354
11a80a9c 355MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
9acef487 356MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
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357 "Low Latency Frequency Transition capable processors "
358 "optimised for use in a battery environment");
9acef487 359MODULE_LICENSE("GPL");
b9170836 360
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361#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
362fs_initcall(cpufreq_gov_dbs_init);
363#else
b9170836 364module_init(cpufreq_gov_dbs_init);
6915719b 365#endif
b9170836 366module_exit(cpufreq_gov_dbs_exit);
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