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) 2009 Alexander Clouter <alex@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/slab.h>
15 #include "cpufreq_governor.h"
17 /* Conservative governor macros */
18 #define DEF_FREQUENCY_UP_THRESHOLD (80)
19 #define DEF_FREQUENCY_DOWN_THRESHOLD (20)
20 #define DEF_FREQUENCY_STEP (5)
21 #define DEF_SAMPLING_DOWN_FACTOR (1)
22 #define MAX_SAMPLING_DOWN_FACTOR (10)
24 static DEFINE_PER_CPU(struct cs_cpu_dbs_info_s, cs_cpu_dbs_info);
26 static inline unsigned int get_freq_target(struct cs_dbs_tuners *cs_tuners,
27 struct cpufreq_policy *policy)
29 unsigned int freq_target = (cs_tuners->freq_step * policy->max) / 100;
31 /* max freq cannot be less than 100. But who knows... */
32 if (unlikely(freq_target == 0))
33 freq_target = DEF_FREQUENCY_STEP;
39 * Every sampling_rate, we check, if current idle time is less than 20%
40 * (default), then we try to increase frequency. Every sampling_rate *
41 * sampling_down_factor, we check, if current idle time is more than 80%
42 * (default), then we try to decrease frequency
44 * Any frequency increase takes it to the maximum frequency. Frequency reduction
45 * happens at minimum steps of 5% (default) of maximum frequency
47 static void cs_check_cpu(int cpu, unsigned int load)
49 struct cs_cpu_dbs_info_s *dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
50 struct cpufreq_policy *policy = dbs_info->cdbs.shared->policy;
51 struct dbs_data *dbs_data = policy->governor_data;
52 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
55 * break out if we 'cannot' reduce the speed as the user might
56 * want freq_step to be zero
58 if (cs_tuners->freq_step == 0)
61 /* Check for frequency increase */
62 if (load > cs_tuners->up_threshold) {
63 dbs_info->down_skip = 0;
65 /* if we are already at full speed then break out early */
66 if (dbs_info->requested_freq == policy->max)
69 dbs_info->requested_freq += get_freq_target(cs_tuners, policy);
71 if (dbs_info->requested_freq > policy->max)
72 dbs_info->requested_freq = policy->max;
74 __cpufreq_driver_target(policy, dbs_info->requested_freq,
79 /* if sampling_down_factor is active break out early */
80 if (++dbs_info->down_skip < cs_tuners->sampling_down_factor)
82 dbs_info->down_skip = 0;
84 /* Check for frequency decrease */
85 if (load < cs_tuners->down_threshold) {
86 unsigned int freq_target;
88 * if we cannot reduce the frequency anymore, break out early
90 if (policy->cur == policy->min)
93 freq_target = get_freq_target(cs_tuners, policy);
94 if (dbs_info->requested_freq > freq_target)
95 dbs_info->requested_freq -= freq_target;
97 dbs_info->requested_freq = policy->min;
99 __cpufreq_driver_target(policy, dbs_info->requested_freq,
105 static unsigned int cs_dbs_timer(struct cpufreq_policy *policy)
107 struct dbs_data *dbs_data = policy->governor_data;
108 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
110 dbs_check_cpu(dbs_data, policy->cpu);
111 return delay_for_sampling_rate(cs_tuners->sampling_rate);
114 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
117 static struct notifier_block cs_cpufreq_notifier_block = {
118 .notifier_call = dbs_cpufreq_notifier,
121 /************************** sysfs interface ************************/
122 static struct common_dbs_data cs_dbs_cdata;
124 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
125 const char *buf, size_t count)
127 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
130 ret = sscanf(buf, "%u", &input);
132 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
135 cs_tuners->sampling_down_factor = input;
139 static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
142 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
145 ret = sscanf(buf, "%u", &input);
150 cs_tuners->sampling_rate = max(input, dbs_data->min_sampling_rate);
154 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
157 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
160 ret = sscanf(buf, "%u", &input);
162 if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold)
165 cs_tuners->up_threshold = input;
169 static ssize_t store_down_threshold(struct dbs_data *dbs_data, const char *buf,
172 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
175 ret = sscanf(buf, "%u", &input);
177 /* cannot be lower than 11 otherwise freq will not fall */
178 if (ret != 1 || input < 11 || input > 100 ||
179 input >= cs_tuners->up_threshold)
182 cs_tuners->down_threshold = input;
186 static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data,
187 const char *buf, size_t count)
189 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
190 unsigned int input, j;
193 ret = sscanf(buf, "%u", &input);
200 if (input == cs_tuners->ignore_nice_load) /* nothing to do */
203 cs_tuners->ignore_nice_load = input;
205 /* we need to re-evaluate prev_cpu_idle */
206 for_each_online_cpu(j) {
207 struct cs_cpu_dbs_info_s *dbs_info;
208 dbs_info = &per_cpu(cs_cpu_dbs_info, j);
209 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
210 &dbs_info->cdbs.prev_cpu_wall, 0);
211 if (cs_tuners->ignore_nice_load)
212 dbs_info->cdbs.prev_cpu_nice =
213 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
218 static ssize_t store_freq_step(struct dbs_data *dbs_data, const char *buf,
221 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
224 ret = sscanf(buf, "%u", &input);
233 * no need to test here if freq_step is zero as the user might actually
234 * want this, they would be crazy though :)
236 cs_tuners->freq_step = input;
240 show_store_one(cs, sampling_rate);
241 show_store_one(cs, sampling_down_factor);
242 show_store_one(cs, up_threshold);
243 show_store_one(cs, down_threshold);
244 show_store_one(cs, ignore_nice_load);
245 show_store_one(cs, freq_step);
246 declare_show_sampling_rate_min(cs);
248 gov_sys_pol_attr_rw(sampling_rate);
249 gov_sys_pol_attr_rw(sampling_down_factor);
250 gov_sys_pol_attr_rw(up_threshold);
251 gov_sys_pol_attr_rw(down_threshold);
252 gov_sys_pol_attr_rw(ignore_nice_load);
253 gov_sys_pol_attr_rw(freq_step);
254 gov_sys_pol_attr_ro(sampling_rate_min);
256 static struct attribute *dbs_attributes_gov_sys[] = {
257 &sampling_rate_min_gov_sys.attr,
258 &sampling_rate_gov_sys.attr,
259 &sampling_down_factor_gov_sys.attr,
260 &up_threshold_gov_sys.attr,
261 &down_threshold_gov_sys.attr,
262 &ignore_nice_load_gov_sys.attr,
263 &freq_step_gov_sys.attr,
267 static struct attribute_group cs_attr_group_gov_sys = {
268 .attrs = dbs_attributes_gov_sys,
269 .name = "conservative",
272 static struct attribute *dbs_attributes_gov_pol[] = {
273 &sampling_rate_min_gov_pol.attr,
274 &sampling_rate_gov_pol.attr,
275 &sampling_down_factor_gov_pol.attr,
276 &up_threshold_gov_pol.attr,
277 &down_threshold_gov_pol.attr,
278 &ignore_nice_load_gov_pol.attr,
279 &freq_step_gov_pol.attr,
283 static struct attribute_group cs_attr_group_gov_pol = {
284 .attrs = dbs_attributes_gov_pol,
285 .name = "conservative",
288 /************************** sysfs end ************************/
290 static int cs_init(struct dbs_data *dbs_data, bool notify)
292 struct cs_dbs_tuners *tuners;
294 tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
296 pr_err("%s: kzalloc failed\n", __func__);
300 tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
301 tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
302 tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
303 tuners->ignore_nice_load = 0;
304 tuners->freq_step = DEF_FREQUENCY_STEP;
306 dbs_data->tuners = tuners;
307 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
308 jiffies_to_usecs(10);
311 cpufreq_register_notifier(&cs_cpufreq_notifier_block,
312 CPUFREQ_TRANSITION_NOTIFIER);
317 static void cs_exit(struct dbs_data *dbs_data, bool notify)
320 cpufreq_unregister_notifier(&cs_cpufreq_notifier_block,
321 CPUFREQ_TRANSITION_NOTIFIER);
323 kfree(dbs_data->tuners);
326 define_get_cpu_dbs_routines(cs_cpu_dbs_info);
328 static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy,
331 static struct common_dbs_data cs_dbs_cdata = {
333 .name = "conservative",
334 .governor = cs_cpufreq_governor_dbs,
335 .max_transition_latency = TRANSITION_LATENCY_LIMIT,
336 .owner = THIS_MODULE,
338 .governor = GOV_CONSERVATIVE,
339 .attr_group_gov_sys = &cs_attr_group_gov_sys,
340 .attr_group_gov_pol = &cs_attr_group_gov_pol,
341 .get_cpu_cdbs = get_cpu_cdbs,
342 .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
343 .gov_dbs_timer = cs_dbs_timer,
344 .gov_check_cpu = cs_check_cpu,
349 #define CPU_FREQ_GOV_CONSERVATIVE (&cs_dbs_cdata.gov)
351 static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy,
354 return cpufreq_governor_dbs(policy, &cs_dbs_cdata, event);
357 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
360 struct cpufreq_freqs *freq = data;
361 struct cs_cpu_dbs_info_s *dbs_info =
362 &per_cpu(cs_cpu_dbs_info, freq->cpu);
363 struct cpufreq_policy *policy = cpufreq_cpu_get_raw(freq->cpu);
368 /* policy isn't governed by conservative governor */
369 if (policy->governor != CPU_FREQ_GOV_CONSERVATIVE)
373 * we only care if our internally tracked freq moves outside the 'valid'
374 * ranges of frequency available to us otherwise we do not change it
376 if (dbs_info->requested_freq > policy->max
377 || dbs_info->requested_freq < policy->min)
378 dbs_info->requested_freq = freq->new;
383 static int __init cpufreq_gov_dbs_init(void)
385 return cpufreq_register_governor(CPU_FREQ_GOV_CONSERVATIVE);
388 static void __exit cpufreq_gov_dbs_exit(void)
390 cpufreq_unregister_governor(CPU_FREQ_GOV_CONSERVATIVE);
393 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
394 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
395 "Low Latency Frequency Transition capable processors "
396 "optimised for use in a battery environment");
397 MODULE_LICENSE("GPL");
399 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
400 struct cpufreq_governor *cpufreq_default_governor(void)
402 return CPU_FREQ_GOV_CONSERVATIVE;
405 fs_initcall(cpufreq_gov_dbs_init);
407 module_init(cpufreq_gov_dbs_init);
409 module_exit(cpufreq_gov_dbs_exit);