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)  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/cpufreq.h>
  15 #include <linux/init.h>
  16 #include <linux/kernel.h>
  17 #include <linux/kernel_stat.h>
  18 #include <linux/kobject.h>
  19 #include <linux/module.h>
  20 #include <linux/mutex.h>
  21 #include <linux/notifier.h>
  22 #include <linux/percpu-defs.h>
  23 #include <linux/slab.h>
  24 #include <linux/sysfs.h>
  25 #include <linux/types.h>
  26
  27 #include "cpufreq_governor.h"
  28
  29 /* Conservative governor macros */
  30 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
  31 #define DEF_FREQUENCY_DOWN_THRESHOLD            (20)
  32 #define DEF_FREQUENCY_STEP                      (5)
  33 #define DEF_SAMPLING_DOWN_FACTOR                (1)
  34 #define MAX_SAMPLING_DOWN_FACTOR                (10)
  35
  36 static DEFINE_PER_CPU(struct cs_cpu_dbs_info_s, cs_cpu_dbs_info);
  37
  38 static inline unsigned int get_freq_target(struct cs_dbs_tuners *cs_tuners,
  39                                            struct cpufreq_policy *policy)
  40 {
  41         unsigned int freq_target = (cs_tuners->freq_step * policy->max) / 100;
  42
  43         /* max freq cannot be less than 100. But who knows... */
  44         if (unlikely(freq_target == 0))
  45                 freq_target = DEF_FREQUENCY_STEP;
  46
  47         return freq_target;
  48 }
  49
  50 /*
  51  * Every sampling_rate, we check, if current idle time is less than 20%
  52  * (default), then we try to increase frequency. Every sampling_rate *
  53  * sampling_down_factor, we check, if current idle time is more than 80%
  54  * (default), then we try to decrease frequency
  55  *
  56  * Any frequency increase takes it to the maximum frequency. Frequency reduction
  57  * happens at minimum steps of 5% (default) of maximum frequency
  58  */
  59 static void cs_check_cpu(int cpu, unsigned int load)
  60 {
  61         struct cs_cpu_dbs_info_s *dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
  62         struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy;
  63         struct dbs_data *dbs_data = policy->governor_data;
  64         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
  65
  66         /*
  67          * break out if we 'cannot' reduce the speed as the user might
  68          * want freq_step to be zero
  69          */
  70         if (cs_tuners->freq_step == 0)
  71                 return;
  72
  73         /* Check for frequency increase */
  74         if (load > cs_tuners->up_threshold) {
  75                 dbs_info->down_skip = 0;
  76
  77                 /* if we are already at full speed then break out early */
  78                 if (dbs_info->requested_freq == policy->max)
  79                         return;
  80
  81                 dbs_info->requested_freq += get_freq_target(cs_tuners, policy);
  82                 if (dbs_info->requested_freq > policy->max)
  83                         dbs_info->requested_freq = policy->max;
  84
  85                 __cpufreq_driver_target(policy, dbs_info->requested_freq,
  86                         CPUFREQ_RELATION_H);
  87                 return;
  88         }
  89
  90         /* if sampling_down_factor is active break out early */
  91         if (++dbs_info->down_skip < cs_tuners->sampling_down_factor)
  92                 return;
  93         dbs_info->down_skip = 0;
  94
  95         /* Check for frequency decrease */
  96         if (load < cs_tuners->down_threshold) {
  97                 /*
  98                  * if we cannot reduce the frequency anymore, break out early
  99                  */
 100                 if (policy->cur == policy->min)
 101                         return;
 102
 103                 dbs_info->requested_freq -= get_freq_target(cs_tuners, policy);
 104                 if (dbs_info->requested_freq < policy->min)
 105                         dbs_info->requested_freq = policy->min;
 106
 107                 __cpufreq_driver_target(policy, dbs_info->requested_freq,
 108                                 CPUFREQ_RELATION_L);
 109                 return;
 110         }
 111 }
 112
 113 static void cs_dbs_timer(struct work_struct *work)
 114 {
 115         struct cs_cpu_dbs_info_s *dbs_info = container_of(work,
 116                         struct cs_cpu_dbs_info_s, cdbs.work.work);
 117         unsigned int cpu = dbs_info->cdbs.cur_policy->cpu;
 118         struct cs_cpu_dbs_info_s *core_dbs_info = &per_cpu(cs_cpu_dbs_info,
 119                         cpu);
 120         struct dbs_data *dbs_data = dbs_info->cdbs.cur_policy->governor_data;
 121         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 122         int delay = delay_for_sampling_rate(cs_tuners->sampling_rate);
 123         bool modify_all = true;
 124
 125         mutex_lock(&core_dbs_info->cdbs.timer_mutex);
 126         if (!need_load_eval(&core_dbs_info->cdbs, cs_tuners->sampling_rate))
 127                 modify_all = false;
 128         else
 129                 dbs_check_cpu(dbs_data, cpu);
 130
 131         gov_queue_work(dbs_data, dbs_info->cdbs.cur_policy, delay, modify_all);
 132         mutex_unlock(&core_dbs_info->cdbs.timer_mutex);
 133 }
 134
 135 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 136                 void *data)
 137 {
 138         struct cpufreq_freqs *freq = data;
 139         struct cs_cpu_dbs_info_s *dbs_info =
 140                                         &per_cpu(cs_cpu_dbs_info, freq->cpu);
 141         struct cpufreq_policy *policy;
 142
 143         if (!dbs_info->enable)
 144                 return 0;
 145
 146         policy = dbs_info->cdbs.cur_policy;
 147
 148         /*
 149          * we only care if our internally tracked freq moves outside the 'valid'
 150          * ranges of frequency available to us otherwise we do not change it
 151         */
 152         if (dbs_info->requested_freq > policy->max
 153                         || dbs_info->requested_freq < policy->min)
 154                 dbs_info->requested_freq = freq->new;
 155
 156         return 0;
 157 }
 158
 159 /************************** sysfs interface ************************/
 160 static struct common_dbs_data cs_dbs_cdata;
 161
 162 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 163                 const char *buf, size_t count)
 164 {
 165         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 166         unsigned int input;
 167         int ret;
 168         ret = sscanf(buf, "%u", &input);
 169
 170         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 171                 return -EINVAL;
 172
 173         cs_tuners->sampling_down_factor = input;
 174         return count;
 175 }
 176
 177 static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
 178                 size_t count)
 179 {
 180         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 181         unsigned int input;
 182         int ret;
 183         ret = sscanf(buf, "%u", &input);
 184
 185         if (ret != 1)
 186                 return -EINVAL;
 187
 188         cs_tuners->sampling_rate = max(input, dbs_data->min_sampling_rate);
 189         return count;
 190 }
 191
 192 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
 193                 size_t count)
 194 {
 195         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 196         unsigned int input;
 197         int ret;
 198         ret = sscanf(buf, "%u", &input);
 199
 200         if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold)
 201                 return -EINVAL;
 202
 203         cs_tuners->up_threshold = input;
 204         return count;
 205 }
 206
 207 static ssize_t store_down_threshold(struct dbs_data *dbs_data, const char *buf,
 208                 size_t count)
 209 {
 210         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 211         unsigned int input;
 212         int ret;
 213         ret = sscanf(buf, "%u", &input);
 214
 215         /* cannot be lower than 11 otherwise freq will not fall */
 216         if (ret != 1 || input < 11 || input > 100 ||
 217                         input >= cs_tuners->up_threshold)
 218                 return -EINVAL;
 219
 220         cs_tuners->down_threshold = input;
 221         return count;
 222 }
 223
 224 static ssize_t store_ignore_nice(struct dbs_data *dbs_data, const char *buf,
 225                 size_t count)
 226 {
 227         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 228         unsigned int input, j;
 229         int ret;
 230
 231         ret = sscanf(buf, "%u", &input);
 232         if (ret != 1)
 233                 return -EINVAL;
 234
 235         if (input > 1)
 236                 input = 1;
 237
 238         if (input == cs_tuners->ignore_nice) /* nothing to do */
 239                 return count;
 240
 241         cs_tuners->ignore_nice = input;
 242
 243         /* we need to re-evaluate prev_cpu_idle */
 244         for_each_online_cpu(j) {
 245                 struct cs_cpu_dbs_info_s *dbs_info;
 246                 dbs_info = &per_cpu(cs_cpu_dbs_info, j);
 247                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 248                                         &dbs_info->cdbs.prev_cpu_wall, 0);
 249                 if (cs_tuners->ignore_nice)
 250                         dbs_info->cdbs.prev_cpu_nice =
 251                                 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 252         }
 253         return count;
 254 }
 255
 256 static ssize_t store_freq_step(struct dbs_data *dbs_data, const char *buf,
 257                 size_t count)
 258 {
 259         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 260         unsigned int input;
 261         int ret;
 262         ret = sscanf(buf, "%u", &input);
 263
 264         if (ret != 1)
 265                 return -EINVAL;
 266
 267         if (input > 100)
 268                 input = 100;
 269
 270         /*
 271          * no need to test here if freq_step is zero as the user might actually
 272          * want this, they would be crazy though :)
 273          */
 274         cs_tuners->freq_step = input;
 275         return count;
 276 }
 277
 278 show_store_one(cs, sampling_rate);
 279 show_store_one(cs, sampling_down_factor);
 280 show_store_one(cs, up_threshold);
 281 show_store_one(cs, down_threshold);
 282 show_store_one(cs, ignore_nice);
 283 show_store_one(cs, freq_step);
 284 declare_show_sampling_rate_min(cs);
 285
 286 gov_sys_pol_attr_rw(sampling_rate);
 287 gov_sys_pol_attr_rw(sampling_down_factor);
 288 gov_sys_pol_attr_rw(up_threshold);
 289 gov_sys_pol_attr_rw(down_threshold);
 290 gov_sys_pol_attr_rw(ignore_nice);
 291 gov_sys_pol_attr_rw(freq_step);
 292 gov_sys_pol_attr_ro(sampling_rate_min);
 293
 294 static struct attribute *dbs_attributes_gov_sys[] = {
 295         &sampling_rate_min_gov_sys.attr,
 296         &sampling_rate_gov_sys.attr,
 297         &sampling_down_factor_gov_sys.attr,
 298         &up_threshold_gov_sys.attr,
 299         &down_threshold_gov_sys.attr,
 300         &ignore_nice_gov_sys.attr,
 301         &freq_step_gov_sys.attr,
 302         NULL
 303 };
 304
 305 static struct attribute_group cs_attr_group_gov_sys = {
 306         .attrs = dbs_attributes_gov_sys,
 307         .name = "conservative",
 308 };
 309
 310 static struct attribute *dbs_attributes_gov_pol[] = {
 311         &sampling_rate_min_gov_pol.attr,
 312         &sampling_rate_gov_pol.attr,
 313         &sampling_down_factor_gov_pol.attr,
 314         &up_threshold_gov_pol.attr,
 315         &down_threshold_gov_pol.attr,
 316         &ignore_nice_gov_pol.attr,
 317         &freq_step_gov_pol.attr,
 318         NULL
 319 };
 320
 321 static struct attribute_group cs_attr_group_gov_pol = {
 322         .attrs = dbs_attributes_gov_pol,
 323         .name = "conservative",
 324 };
 325
 326 /************************** sysfs end ************************/
 327
 328 static int cs_init(struct dbs_data *dbs_data)
 329 {
 330         struct cs_dbs_tuners *tuners;
 331
 332         tuners = kzalloc(sizeof(struct cs_dbs_tuners), GFP_KERNEL);
 333         if (!tuners) {
 334                 pr_err("%s: kzalloc failed\n", __func__);
 335                 return -ENOMEM;
 336         }
 337
 338         tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 339         tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
 340         tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 341         tuners->ignore_nice = 0;
 342         tuners->freq_step = DEF_FREQUENCY_STEP;
 343
 344         dbs_data->tuners = tuners;
 345         dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 346                 jiffies_to_usecs(10);
 347         mutex_init(&dbs_data->mutex);
 348         return 0;
 349 }
 350
 351 static void cs_exit(struct dbs_data *dbs_data)
 352 {
 353         kfree(dbs_data->tuners);
 354 }
 355
 356 define_get_cpu_dbs_routines(cs_cpu_dbs_info);
 357
 358 static struct notifier_block cs_cpufreq_notifier_block = {
 359         .notifier_call = dbs_cpufreq_notifier,
 360 };
 361
 362 static struct cs_ops cs_ops = {
 363         .notifier_block = &cs_cpufreq_notifier_block,
 364 };
 365
 366 static struct common_dbs_data cs_dbs_cdata = {
 367         .governor = GOV_CONSERVATIVE,
 368         .attr_group_gov_sys = &cs_attr_group_gov_sys,
 369         .attr_group_gov_pol = &cs_attr_group_gov_pol,
 370         .get_cpu_cdbs = get_cpu_cdbs,
 371         .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 372         .gov_dbs_timer = cs_dbs_timer,
 373         .gov_check_cpu = cs_check_cpu,
 374         .gov_ops = &cs_ops,
 375         .init = cs_init,
 376         .exit = cs_exit,
 377 };
 378
 379 static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy,
 380                                    unsigned int event)
 381 {
 382         return cpufreq_governor_dbs(policy, &cs_dbs_cdata, event);
 383 }
 384
 385 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 386 static
 387 #endif
 388 struct cpufreq_governor cpufreq_gov_conservative = {
 389         .name                   = "conservative",
 390         .governor               = cs_cpufreq_governor_dbs,
 391         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 392         .owner                  = THIS_MODULE,
 393 };
 394
 395 static int __init cpufreq_gov_dbs_init(void)
 396 {
 397         return cpufreq_register_governor(&cpufreq_gov_conservative);
 398 }
 399
 400 static void __exit cpufreq_gov_dbs_exit(void)
 401 {
 402         cpufreq_unregister_governor(&cpufreq_gov_conservative);
 403 }
 404
 405 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
 406 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
 407                 "Low Latency Frequency Transition capable processors "
 408                 "optimised for use in a battery environment");
 409 MODULE_LICENSE("GPL");
 410
 411 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 412 fs_initcall(cpufreq_gov_dbs_init);
 413 #else
 414 module_init(cpufreq_gov_dbs_init);
 415 #endif
 416 module_exit(cpufreq_gov_dbs_exit);