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