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