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