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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * drivers/cpufreq/cpufreq_conservative.c
4 *
5 * Copyright (C) 2001 Russell King
6 * (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
7 * Jun Nakajima <jun.nakajima@intel.com>
8 * (C) 2009 Alexander Clouter <alex@digriz.org.uk>
9 */
10
11#include <linux/slab.h>
12#include "cpufreq_governor.h"
13
14struct cs_policy_dbs_info {
15 struct policy_dbs_info policy_dbs;
16 unsigned int down_skip;
17 unsigned int requested_freq;
18};
19
20static inline struct cs_policy_dbs_info *to_dbs_info(struct policy_dbs_info *policy_dbs)
21{
22 return container_of(policy_dbs, struct cs_policy_dbs_info, policy_dbs);
23}
24
25struct cs_dbs_tuners {
26 unsigned int down_threshold;
27 unsigned int freq_step;
28};
29
30/* Conservative governor macros */
31#define DEF_FREQUENCY_UP_THRESHOLD (80)
32#define DEF_FREQUENCY_DOWN_THRESHOLD (20)
33#define DEF_FREQUENCY_STEP (5)
34#define DEF_SAMPLING_DOWN_FACTOR (1)
35#define MAX_SAMPLING_DOWN_FACTOR (10)
36
37static inline unsigned int get_freq_step(struct cs_dbs_tuners *cs_tuners,
38 struct cpufreq_policy *policy)
39{
40 unsigned int freq_step = (cs_tuners->freq_step * policy->max) / 100;
41
42 /* max freq cannot be less than 100. But who knows... */
43 if (unlikely(freq_step == 0))
44 freq_step = DEF_FREQUENCY_STEP;
45
46 return freq_step;
47}
48
49/*
50 * Every sampling_rate, we check, if current idle time is less than 20%
51 * (default), then we try to increase frequency. Every sampling_rate *
52 * sampling_down_factor, we check, if current idle time is more than 80%
53 * (default), then we try to decrease frequency
54 *
55 * Frequency updates happen at minimum steps of 5% (default) of maximum
56 * frequency
57 */
58static unsigned int cs_dbs_update(struct cpufreq_policy *policy)
59{
60 struct policy_dbs_info *policy_dbs = policy->governor_data;
61 struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
62 unsigned int requested_freq = dbs_info->requested_freq;
63 struct dbs_data *dbs_data = policy_dbs->dbs_data;
64 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
65 unsigned int load = dbs_update(policy);
66 unsigned int freq_step;
67
68 /*
69 * break out if we 'cannot' reduce the speed as the user might
70 * want freq_step to be zero
71 */
72 if (cs_tuners->freq_step == 0)
73 goto out;
74
75 /*
76 * If requested_freq is out of range, it is likely that the limits
77 * changed in the meantime, so fall back to current frequency in that
78 * case.
79 */
80 if (requested_freq > policy->max || requested_freq < policy->min) {
81 requested_freq = policy->cur;
82 dbs_info->requested_freq = requested_freq;
83 }
84
85 freq_step = get_freq_step(cs_tuners, policy);
86
87 /*
88 * Decrease requested_freq one freq_step for each idle period that
89 * we didn't update the frequency.
90 */
91 if (policy_dbs->idle_periods < UINT_MAX) {
92 unsigned int freq_steps = policy_dbs->idle_periods * freq_step;
93
94 if (requested_freq > policy->min + freq_steps)
95 requested_freq -= freq_steps;
96 else
97 requested_freq = policy->min;
98
99 policy_dbs->idle_periods = UINT_MAX;
100 }
101
102 /* Check for frequency increase */
103 if (load > dbs_data->up_threshold) {
104 dbs_info->down_skip = 0;
105
106 /* if we are already at full speed then break out early */
107 if (requested_freq == policy->max)
108 goto out;
109
110 requested_freq += freq_step;
111 if (requested_freq > policy->max)
112 requested_freq = policy->max;
113
114 __cpufreq_driver_target(policy, requested_freq,
115 CPUFREQ_RELATION_HE);
116 dbs_info->requested_freq = requested_freq;
117 goto out;
118 }
119
120 /* if sampling_down_factor is active break out early */
121 if (++dbs_info->down_skip < dbs_data->sampling_down_factor)
122 goto out;
123 dbs_info->down_skip = 0;
124
125 /* Check for frequency decrease */
126 if (load < cs_tuners->down_threshold) {
127 /*
128 * if we cannot reduce the frequency anymore, break out early
129 */
130 if (requested_freq == policy->min)
131 goto out;
132
133 if (requested_freq > freq_step)
134 requested_freq -= freq_step;
135 else
136 requested_freq = policy->min;
137
138 __cpufreq_driver_target(policy, requested_freq,
139 CPUFREQ_RELATION_LE);
140 dbs_info->requested_freq = requested_freq;
141 }
142
143 out:
144 return dbs_data->sampling_rate;
145}
146
147/************************** sysfs interface ************************/
148
149static ssize_t sampling_down_factor_store(struct gov_attr_set *attr_set,
150 const char *buf, size_t count)
151{
152 struct dbs_data *dbs_data = to_dbs_data(attr_set);
153 unsigned int input;
154 int ret;
155 ret = sscanf(buf, "%u", &input);
156
157 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
158 return -EINVAL;
159
160 dbs_data->sampling_down_factor = input;
161 return count;
162}
163
164static ssize_t up_threshold_store(struct gov_attr_set *attr_set,
165 const char *buf, size_t count)
166{
167 struct dbs_data *dbs_data = to_dbs_data(attr_set);
168 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
169 unsigned int input;
170 int ret;
171 ret = sscanf(buf, "%u", &input);
172
173 if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold)
174 return -EINVAL;
175
176 dbs_data->up_threshold = input;
177 return count;
178}
179
180static ssize_t down_threshold_store(struct gov_attr_set *attr_set,
181 const char *buf, size_t count)
182{
183 struct dbs_data *dbs_data = to_dbs_data(attr_set);
184 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
185 unsigned int input;
186 int ret;
187 ret = sscanf(buf, "%u", &input);
188
189 /* cannot be lower than 1 otherwise freq will not fall */
190 if (ret != 1 || input < 1 || input >= dbs_data->up_threshold)
191 return -EINVAL;
192
193 cs_tuners->down_threshold = input;
194 return count;
195}
196
197static ssize_t ignore_nice_load_store(struct gov_attr_set *attr_set,
198 const char *buf, size_t count)
199{
200 struct dbs_data *dbs_data = to_dbs_data(attr_set);
201 unsigned int input;
202 int ret;
203
204 ret = sscanf(buf, "%u", &input);
205 if (ret != 1)
206 return -EINVAL;
207
208 if (input > 1)
209 input = 1;
210
211 if (input == dbs_data->ignore_nice_load) /* nothing to do */
212 return count;
213
214 dbs_data->ignore_nice_load = input;
215
216 /* we need to re-evaluate prev_cpu_idle */
217 gov_update_cpu_data(dbs_data);
218
219 return count;
220}
221
222static ssize_t freq_step_store(struct gov_attr_set *attr_set, const char *buf,
223 size_t count)
224{
225 struct dbs_data *dbs_data = to_dbs_data(attr_set);
226 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
227 unsigned int input;
228 int ret;
229 ret = sscanf(buf, "%u", &input);
230
231 if (ret != 1)
232 return -EINVAL;
233
234 if (input > 100)
235 input = 100;
236
237 /*
238 * no need to test here if freq_step is zero as the user might actually
239 * want this, they would be crazy though :)
240 */
241 cs_tuners->freq_step = input;
242 return count;
243}
244
245gov_show_one_common(sampling_rate);
246gov_show_one_common(sampling_down_factor);
247gov_show_one_common(up_threshold);
248gov_show_one_common(ignore_nice_load);
249gov_show_one(cs, down_threshold);
250gov_show_one(cs, freq_step);
251
252gov_attr_rw(sampling_rate);
253gov_attr_rw(sampling_down_factor);
254gov_attr_rw(up_threshold);
255gov_attr_rw(ignore_nice_load);
256gov_attr_rw(down_threshold);
257gov_attr_rw(freq_step);
258
259static struct attribute *cs_attrs[] = {
260 &sampling_rate.attr,
261 &sampling_down_factor.attr,
262 &up_threshold.attr,
263 &down_threshold.attr,
264 &ignore_nice_load.attr,
265 &freq_step.attr,
266 NULL
267};
268ATTRIBUTE_GROUPS(cs);
269
270/************************** sysfs end ************************/
271
272static struct policy_dbs_info *cs_alloc(void)
273{
274 struct cs_policy_dbs_info *dbs_info;
275
276 dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL);
277 return dbs_info ? &dbs_info->policy_dbs : NULL;
278}
279
280static void cs_free(struct policy_dbs_info *policy_dbs)
281{
282 kfree(to_dbs_info(policy_dbs));
283}
284
285static int cs_init(struct dbs_data *dbs_data)
286{
287 struct cs_dbs_tuners *tuners;
288
289 tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
290 if (!tuners)
291 return -ENOMEM;
292
293 tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
294 tuners->freq_step = DEF_FREQUENCY_STEP;
295 dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
296 dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
297 dbs_data->ignore_nice_load = 0;
298 dbs_data->tuners = tuners;
299
300 return 0;
301}
302
303static void cs_exit(struct dbs_data *dbs_data)
304{
305 kfree(dbs_data->tuners);
306}
307
308static void cs_start(struct cpufreq_policy *policy)
309{
310 struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
311
312 dbs_info->down_skip = 0;
313 dbs_info->requested_freq = policy->cur;
314}
315
316static struct dbs_governor cs_governor = {
317 .gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("conservative"),
318 .kobj_type = { .default_groups = cs_groups },
319 .gov_dbs_update = cs_dbs_update,
320 .alloc = cs_alloc,
321 .free = cs_free,
322 .init = cs_init,
323 .exit = cs_exit,
324 .start = cs_start,
325};
326
327#define CPU_FREQ_GOV_CONSERVATIVE (cs_governor.gov)
328
329MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
330MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
331 "Low Latency Frequency Transition capable processors "
332 "optimised for use in a battery environment");
333MODULE_LICENSE("GPL");
334
335#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
336struct cpufreq_governor *cpufreq_default_governor(void)
337{
338 return &CPU_FREQ_GOV_CONSERVATIVE;
339}
340#endif
341
342cpufreq_governor_init(CPU_FREQ_GOV_CONSERVATIVE);
343cpufreq_governor_exit(CPU_FREQ_GOV_CONSERVATIVE);
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) 2009 Alexander Clouter <alex@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/init.h>
17#include <linux/cpufreq.h>
18#include <linux/cpu.h>
19#include <linux/jiffies.h>
20#include <linux/kernel_stat.h>
21#include <linux/mutex.h>
22#include <linux/hrtimer.h>
23#include <linux/tick.h>
24#include <linux/ktime.h>
25#include <linux/sched.h>
26
27/*
28 * dbs is used in this file as a shortform for demandbased switching
29 * It helps to keep variable names smaller, simpler
30 */
31
32#define DEF_FREQUENCY_UP_THRESHOLD (80)
33#define DEF_FREQUENCY_DOWN_THRESHOLD (20)
34
35/*
36 * The polling frequency of this governor depends on the capability of
37 * the processor. Default polling frequency is 1000 times the transition
38 * latency of the processor. The governor will work on any processor with
39 * transition latency <= 10mS, using appropriate sampling
40 * rate.
41 * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
42 * this governor will not work.
43 * All times here are in uS.
44 */
45#define MIN_SAMPLING_RATE_RATIO (2)
46
47static unsigned int min_sampling_rate;
48
49#define LATENCY_MULTIPLIER (1000)
50#define MIN_LATENCY_MULTIPLIER (100)
51#define DEF_SAMPLING_DOWN_FACTOR (1)
52#define MAX_SAMPLING_DOWN_FACTOR (10)
53#define TRANSITION_LATENCY_LIMIT (10 * 1000 * 1000)
54
55static void do_dbs_timer(struct work_struct *work);
56
57struct cpu_dbs_info_s {
58 cputime64_t prev_cpu_idle;
59 cputime64_t prev_cpu_wall;
60 cputime64_t prev_cpu_nice;
61 struct cpufreq_policy *cur_policy;
62 struct delayed_work work;
63 unsigned int down_skip;
64 unsigned int requested_freq;
65 int cpu;
66 unsigned int enable:1;
67 /*
68 * percpu mutex that serializes governor limit change with
69 * do_dbs_timer invocation. We do not want do_dbs_timer to run
70 * when user is changing the governor or limits.
71 */
72 struct mutex timer_mutex;
73};
74static DEFINE_PER_CPU(struct cpu_dbs_info_s, cs_cpu_dbs_info);
75
76static unsigned int dbs_enable; /* number of CPUs using this policy */
77
78/*
79 * dbs_mutex protects dbs_enable in governor start/stop.
80 */
81static DEFINE_MUTEX(dbs_mutex);
82
83static struct dbs_tuners {
84 unsigned int sampling_rate;
85 unsigned int sampling_down_factor;
86 unsigned int up_threshold;
87 unsigned int down_threshold;
88 unsigned int ignore_nice;
89 unsigned int freq_step;
90} dbs_tuners_ins = {
91 .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
92 .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD,
93 .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
94 .ignore_nice = 0,
95 .freq_step = 5,
96};
97
98static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall)
99{
100 u64 idle_time;
101 u64 cur_wall_time;
102 u64 busy_time;
103
104 cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
105
106 busy_time = kcpustat_cpu(cpu).cpustat[CPUTIME_USER];
107 busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SYSTEM];
108 busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_IRQ];
109 busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SOFTIRQ];
110 busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_STEAL];
111 busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_NICE];
112
113 idle_time = cur_wall_time - busy_time;
114 if (wall)
115 *wall = jiffies_to_usecs(cur_wall_time);
116
117 return jiffies_to_usecs(idle_time);
118}
119
120static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
121{
122 u64 idle_time = get_cpu_idle_time_us(cpu, NULL);
123
124 if (idle_time == -1ULL)
125 return get_cpu_idle_time_jiffy(cpu, wall);
126 else
127 idle_time += get_cpu_iowait_time_us(cpu, wall);
128
129 return idle_time;
130}
131
132/* keep track of frequency transitions */
133static int
134dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
135 void *data)
136{
137 struct cpufreq_freqs *freq = data;
138 struct cpu_dbs_info_s *this_dbs_info = &per_cpu(cs_cpu_dbs_info,
139 freq->cpu);
140
141 struct cpufreq_policy *policy;
142
143 if (!this_dbs_info->enable)
144 return 0;
145
146 policy = this_dbs_info->cur_policy;
147
148 /*
149 * we only care if our internally tracked freq moves outside
150 * the 'valid' ranges of freqency available to us otherwise
151 * we do not change it
152 */
153 if (this_dbs_info->requested_freq > policy->max
154 || this_dbs_info->requested_freq < policy->min)
155 this_dbs_info->requested_freq = freq->new;
156
157 return 0;
158}
159
160static struct notifier_block dbs_cpufreq_notifier_block = {
161 .notifier_call = dbs_cpufreq_notifier
162};
163
164/************************** sysfs interface ************************/
165static ssize_t show_sampling_rate_min(struct kobject *kobj,
166 struct attribute *attr, char *buf)
167{
168 return sprintf(buf, "%u\n", min_sampling_rate);
169}
170
171define_one_global_ro(sampling_rate_min);
172
173/* cpufreq_conservative Governor Tunables */
174#define show_one(file_name, object) \
175static ssize_t show_##file_name \
176(struct kobject *kobj, struct attribute *attr, char *buf) \
177{ \
178 return sprintf(buf, "%u\n", dbs_tuners_ins.object); \
179}
180show_one(sampling_rate, sampling_rate);
181show_one(sampling_down_factor, sampling_down_factor);
182show_one(up_threshold, up_threshold);
183show_one(down_threshold, down_threshold);
184show_one(ignore_nice_load, ignore_nice);
185show_one(freq_step, freq_step);
186
187static ssize_t store_sampling_down_factor(struct kobject *a,
188 struct attribute *b,
189 const char *buf, size_t count)
190{
191 unsigned int input;
192 int ret;
193 ret = sscanf(buf, "%u", &input);
194
195 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
196 return -EINVAL;
197
198 dbs_tuners_ins.sampling_down_factor = input;
199 return count;
200}
201
202static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
203 const char *buf, size_t count)
204{
205 unsigned int input;
206 int ret;
207 ret = sscanf(buf, "%u", &input);
208
209 if (ret != 1)
210 return -EINVAL;
211
212 dbs_tuners_ins.sampling_rate = max(input, min_sampling_rate);
213 return count;
214}
215
216static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
217 const char *buf, size_t count)
218{
219 unsigned int input;
220 int ret;
221 ret = sscanf(buf, "%u", &input);
222
223 if (ret != 1 || input > 100 ||
224 input <= dbs_tuners_ins.down_threshold)
225 return -EINVAL;
226
227 dbs_tuners_ins.up_threshold = input;
228 return count;
229}
230
231static ssize_t store_down_threshold(struct kobject *a, struct attribute *b,
232 const char *buf, size_t count)
233{
234 unsigned int input;
235 int ret;
236 ret = sscanf(buf, "%u", &input);
237
238 /* cannot be lower than 11 otherwise freq will not fall */
239 if (ret != 1 || input < 11 || input > 100 ||
240 input >= dbs_tuners_ins.up_threshold)
241 return -EINVAL;
242
243 dbs_tuners_ins.down_threshold = input;
244 return count;
245}
246
247static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
248 const char *buf, size_t count)
249{
250 unsigned int input;
251 int ret;
252
253 unsigned int j;
254
255 ret = sscanf(buf, "%u", &input);
256 if (ret != 1)
257 return -EINVAL;
258
259 if (input > 1)
260 input = 1;
261
262 if (input == dbs_tuners_ins.ignore_nice) /* nothing to do */
263 return count;
264
265 dbs_tuners_ins.ignore_nice = input;
266
267 /* we need to re-evaluate prev_cpu_idle */
268 for_each_online_cpu(j) {
269 struct cpu_dbs_info_s *dbs_info;
270 dbs_info = &per_cpu(cs_cpu_dbs_info, j);
271 dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
272 &dbs_info->prev_cpu_wall);
273 if (dbs_tuners_ins.ignore_nice)
274 dbs_info->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE];
275 }
276 return count;
277}
278
279static ssize_t store_freq_step(struct kobject *a, struct attribute *b,
280 const char *buf, size_t count)
281{
282 unsigned int input;
283 int ret;
284 ret = sscanf(buf, "%u", &input);
285
286 if (ret != 1)
287 return -EINVAL;
288
289 if (input > 100)
290 input = 100;
291
292 /* no need to test here if freq_step is zero as the user might actually
293 * want this, they would be crazy though :) */
294 dbs_tuners_ins.freq_step = input;
295 return count;
296}
297
298define_one_global_rw(sampling_rate);
299define_one_global_rw(sampling_down_factor);
300define_one_global_rw(up_threshold);
301define_one_global_rw(down_threshold);
302define_one_global_rw(ignore_nice_load);
303define_one_global_rw(freq_step);
304
305static struct attribute *dbs_attributes[] = {
306 &sampling_rate_min.attr,
307 &sampling_rate.attr,
308 &sampling_down_factor.attr,
309 &up_threshold.attr,
310 &down_threshold.attr,
311 &ignore_nice_load.attr,
312 &freq_step.attr,
313 NULL
314};
315
316static struct attribute_group dbs_attr_group = {
317 .attrs = dbs_attributes,
318 .name = "conservative",
319};
320
321/************************** sysfs end ************************/
322
323static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
324{
325 unsigned int load = 0;
326 unsigned int max_load = 0;
327 unsigned int freq_target;
328
329 struct cpufreq_policy *policy;
330 unsigned int j;
331
332 policy = this_dbs_info->cur_policy;
333
334 /*
335 * Every sampling_rate, we check, if current idle time is less
336 * than 20% (default), then we try to increase frequency
337 * Every sampling_rate*sampling_down_factor, we check, if current
338 * idle time is more than 80%, then we try to decrease frequency
339 *
340 * Any frequency increase takes it to the maximum frequency.
341 * Frequency reduction happens at minimum steps of
342 * 5% (default) of maximum frequency
343 */
344
345 /* Get Absolute Load */
346 for_each_cpu(j, policy->cpus) {
347 struct cpu_dbs_info_s *j_dbs_info;
348 cputime64_t cur_wall_time, cur_idle_time;
349 unsigned int idle_time, wall_time;
350
351 j_dbs_info = &per_cpu(cs_cpu_dbs_info, j);
352
353 cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
354
355 wall_time = (unsigned int)
356 (cur_wall_time - j_dbs_info->prev_cpu_wall);
357 j_dbs_info->prev_cpu_wall = cur_wall_time;
358
359 idle_time = (unsigned int)
360 (cur_idle_time - j_dbs_info->prev_cpu_idle);
361 j_dbs_info->prev_cpu_idle = cur_idle_time;
362
363 if (dbs_tuners_ins.ignore_nice) {
364 u64 cur_nice;
365 unsigned long cur_nice_jiffies;
366
367 cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE] -
368 j_dbs_info->prev_cpu_nice;
369 /*
370 * Assumption: nice time between sampling periods will
371 * be less than 2^32 jiffies for 32 bit sys
372 */
373 cur_nice_jiffies = (unsigned long)
374 cputime64_to_jiffies64(cur_nice);
375
376 j_dbs_info->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE];
377 idle_time += jiffies_to_usecs(cur_nice_jiffies);
378 }
379
380 if (unlikely(!wall_time || wall_time < idle_time))
381 continue;
382
383 load = 100 * (wall_time - idle_time) / wall_time;
384
385 if (load > max_load)
386 max_load = load;
387 }
388
389 /*
390 * break out if we 'cannot' reduce the speed as the user might
391 * want freq_step to be zero
392 */
393 if (dbs_tuners_ins.freq_step == 0)
394 return;
395
396 /* Check for frequency increase */
397 if (max_load > dbs_tuners_ins.up_threshold) {
398 this_dbs_info->down_skip = 0;
399
400 /* if we are already at full speed then break out early */
401 if (this_dbs_info->requested_freq == policy->max)
402 return;
403
404 freq_target = (dbs_tuners_ins.freq_step * policy->max) / 100;
405
406 /* max freq cannot be less than 100. But who knows.... */
407 if (unlikely(freq_target == 0))
408 freq_target = 5;
409
410 this_dbs_info->requested_freq += freq_target;
411 if (this_dbs_info->requested_freq > policy->max)
412 this_dbs_info->requested_freq = policy->max;
413
414 __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
415 CPUFREQ_RELATION_H);
416 return;
417 }
418
419 /*
420 * The optimal frequency is the frequency that is the lowest that
421 * can support the current CPU usage without triggering the up
422 * policy. To be safe, we focus 10 points under the threshold.
423 */
424 if (max_load < (dbs_tuners_ins.down_threshold - 10)) {
425 freq_target = (dbs_tuners_ins.freq_step * policy->max) / 100;
426
427 this_dbs_info->requested_freq -= freq_target;
428 if (this_dbs_info->requested_freq < policy->min)
429 this_dbs_info->requested_freq = policy->min;
430
431 /*
432 * if we cannot reduce the frequency anymore, break out early
433 */
434 if (policy->cur == policy->min)
435 return;
436
437 __cpufreq_driver_target(policy, this_dbs_info->requested_freq,
438 CPUFREQ_RELATION_H);
439 return;
440 }
441}
442
443static void do_dbs_timer(struct work_struct *work)
444{
445 struct cpu_dbs_info_s *dbs_info =
446 container_of(work, struct cpu_dbs_info_s, work.work);
447 unsigned int cpu = dbs_info->cpu;
448
449 /* We want all CPUs to do sampling nearly on same jiffy */
450 int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
451
452 delay -= jiffies % delay;
453
454 mutex_lock(&dbs_info->timer_mutex);
455
456 dbs_check_cpu(dbs_info);
457
458 schedule_delayed_work_on(cpu, &dbs_info->work, delay);
459 mutex_unlock(&dbs_info->timer_mutex);
460}
461
462static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
463{
464 /* We want all CPUs to do sampling nearly on same jiffy */
465 int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
466 delay -= jiffies % delay;
467
468 dbs_info->enable = 1;
469 INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer);
470 schedule_delayed_work_on(dbs_info->cpu, &dbs_info->work, delay);
471}
472
473static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
474{
475 dbs_info->enable = 0;
476 cancel_delayed_work_sync(&dbs_info->work);
477}
478
479static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
480 unsigned int event)
481{
482 unsigned int cpu = policy->cpu;
483 struct cpu_dbs_info_s *this_dbs_info;
484 unsigned int j;
485 int rc;
486
487 this_dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
488
489 switch (event) {
490 case CPUFREQ_GOV_START:
491 if ((!cpu_online(cpu)) || (!policy->cur))
492 return -EINVAL;
493
494 mutex_lock(&dbs_mutex);
495
496 for_each_cpu(j, policy->cpus) {
497 struct cpu_dbs_info_s *j_dbs_info;
498 j_dbs_info = &per_cpu(cs_cpu_dbs_info, j);
499 j_dbs_info->cur_policy = policy;
500
501 j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
502 &j_dbs_info->prev_cpu_wall);
503 if (dbs_tuners_ins.ignore_nice)
504 j_dbs_info->prev_cpu_nice =
505 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
506 }
507 this_dbs_info->down_skip = 0;
508 this_dbs_info->requested_freq = policy->cur;
509
510 mutex_init(&this_dbs_info->timer_mutex);
511 dbs_enable++;
512 /*
513 * Start the timerschedule work, when this governor
514 * is used for first time
515 */
516 if (dbs_enable == 1) {
517 unsigned int latency;
518 /* policy latency is in nS. Convert it to uS first */
519 latency = policy->cpuinfo.transition_latency / 1000;
520 if (latency == 0)
521 latency = 1;
522
523 rc = sysfs_create_group(cpufreq_global_kobject,
524 &dbs_attr_group);
525 if (rc) {
526 mutex_unlock(&dbs_mutex);
527 return rc;
528 }
529
530 /*
531 * conservative does not implement micro like ondemand
532 * governor, thus we are bound to jiffes/HZ
533 */
534 min_sampling_rate =
535 MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10);
536 /* Bring kernel and HW constraints together */
537 min_sampling_rate = max(min_sampling_rate,
538 MIN_LATENCY_MULTIPLIER * latency);
539 dbs_tuners_ins.sampling_rate =
540 max(min_sampling_rate,
541 latency * LATENCY_MULTIPLIER);
542
543 cpufreq_register_notifier(
544 &dbs_cpufreq_notifier_block,
545 CPUFREQ_TRANSITION_NOTIFIER);
546 }
547 mutex_unlock(&dbs_mutex);
548
549 dbs_timer_init(this_dbs_info);
550
551 break;
552
553 case CPUFREQ_GOV_STOP:
554 dbs_timer_exit(this_dbs_info);
555
556 mutex_lock(&dbs_mutex);
557 dbs_enable--;
558 mutex_destroy(&this_dbs_info->timer_mutex);
559
560 /*
561 * Stop the timerschedule work, when this governor
562 * is used for first time
563 */
564 if (dbs_enable == 0)
565 cpufreq_unregister_notifier(
566 &dbs_cpufreq_notifier_block,
567 CPUFREQ_TRANSITION_NOTIFIER);
568
569 mutex_unlock(&dbs_mutex);
570 if (!dbs_enable)
571 sysfs_remove_group(cpufreq_global_kobject,
572 &dbs_attr_group);
573
574 break;
575
576 case CPUFREQ_GOV_LIMITS:
577 mutex_lock(&this_dbs_info->timer_mutex);
578 if (policy->max < this_dbs_info->cur_policy->cur)
579 __cpufreq_driver_target(
580 this_dbs_info->cur_policy,
581 policy->max, CPUFREQ_RELATION_H);
582 else if (policy->min > this_dbs_info->cur_policy->cur)
583 __cpufreq_driver_target(
584 this_dbs_info->cur_policy,
585 policy->min, CPUFREQ_RELATION_L);
586 mutex_unlock(&this_dbs_info->timer_mutex);
587
588 break;
589 }
590 return 0;
591}
592
593#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
594static
595#endif
596struct cpufreq_governor cpufreq_gov_conservative = {
597 .name = "conservative",
598 .governor = cpufreq_governor_dbs,
599 .max_transition_latency = TRANSITION_LATENCY_LIMIT,
600 .owner = THIS_MODULE,
601};
602
603static int __init cpufreq_gov_dbs_init(void)
604{
605 return cpufreq_register_governor(&cpufreq_gov_conservative);
606}
607
608static void __exit cpufreq_gov_dbs_exit(void)
609{
610 cpufreq_unregister_governor(&cpufreq_gov_conservative);
611}
612
613
614MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
615MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
616 "Low Latency Frequency Transition capable processors "
617 "optimised for use in a battery environment");
618MODULE_LICENSE("GPL");
619
620#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
621fs_initcall(cpufreq_gov_dbs_init);
622#else
623module_init(cpufreq_gov_dbs_init);
624#endif
625module_exit(cpufreq_gov_dbs_exit);