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 int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy,
  27                                    unsigned int event);
  28
  29 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
  30 static
  31 #endif
  32 struct cpufreq_governor cpufreq_gov_conservative = {
  33         .name                   = "conservative",
  34         .governor               = cs_cpufreq_governor_dbs,
  35         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
  36         .owner                  = THIS_MODULE,
  37 };
  38
  39 static inline unsigned int get_freq_target(struct cs_dbs_tuners *cs_tuners,
  40                                            struct cpufreq_policy *policy)
  41 {
  42         unsigned int freq_target = (cs_tuners->freq_step * policy->max) / 100;
  43
  44         /* max freq cannot be less than 100. But who knows... */
  45         if (unlikely(freq_target == 0))
  46                 freq_target = DEF_FREQUENCY_STEP;
  47
  48         return freq_target;
  49 }
  50
  51 /*
  52  * Every sampling_rate, we check, if current idle time is less than 20%
  53  * (default), then we try to increase frequency. Every sampling_rate *
  54  * sampling_down_factor, we check, if current idle time is more than 80%
  55  * (default), then we try to decrease frequency
  56  *
  57  * Any frequency increase takes it to the maximum frequency. Frequency reduction
  58  * happens at minimum steps of 5% (default) of maximum frequency
  59  */
  60 static void cs_check_cpu(int cpu, unsigned int load)
  61 {
  62         struct cs_cpu_dbs_info_s *dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
  63         struct cpufreq_policy *policy = dbs_info->cdbs.shared->policy;
  64         struct dbs_data *dbs_data = policy->governor_data;
  65         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
  66
  67         /*
  68          * break out if we 'cannot' reduce the speed as the user might
  69          * want freq_step to be zero
  70          */
  71         if (cs_tuners->freq_step == 0)
  72                 return;
  73
  74         /* Check for frequency increase */
  75         if (load > cs_tuners->up_threshold) {
  76                 dbs_info->down_skip = 0;
  77
  78                 /* if we are already at full speed then break out early */
  79                 if (dbs_info->requested_freq == policy->max)
  80                         return;
  81
  82                 dbs_info->requested_freq += get_freq_target(cs_tuners, policy);
  83
  84                 if (dbs_info->requested_freq > policy->max)
  85                         dbs_info->requested_freq = policy->max;
  86
  87                 __cpufreq_driver_target(policy, dbs_info->requested_freq,
  88                         CPUFREQ_RELATION_H);
  89                 return;
  90         }
  91
  92         /* if sampling_down_factor is active break out early */
  93         if (++dbs_info->down_skip < cs_tuners->sampling_down_factor)
  94                 return;
  95         dbs_info->down_skip = 0;
  96
  97         /* Check for frequency decrease */
  98         if (load < cs_tuners->down_threshold) {
  99                 unsigned int freq_target;
 100                 /*
 101                  * if we cannot reduce the frequency anymore, break out early
 102                  */
 103                 if (policy->cur == policy->min)
 104                         return;
 105
 106                 freq_target = get_freq_target(cs_tuners, policy);
 107                 if (dbs_info->requested_freq > freq_target)
 108                         dbs_info->requested_freq -= freq_target;
 109                 else
 110                         dbs_info->requested_freq = policy->min;
 111
 112                 __cpufreq_driver_target(policy, dbs_info->requested_freq,
 113                                 CPUFREQ_RELATION_L);
 114                 return;
 115         }
 116 }
 117
 118 static unsigned int cs_dbs_timer(struct cpufreq_policy *policy, bool modify_all)
 119 {
 120         struct dbs_data *dbs_data = policy->governor_data;
 121         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 122
 123         if (modify_all)
 124                 dbs_check_cpu(dbs_data, policy->cpu);
 125
 126         return delay_for_sampling_rate(cs_tuners->sampling_rate);
 127 }
 128
 129 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 130                 void *data)
 131 {
 132         struct cpufreq_freqs *freq = data;
 133         struct cs_cpu_dbs_info_s *dbs_info =
 134                                         &per_cpu(cs_cpu_dbs_info, freq->cpu);
 135         struct cpufreq_policy *policy = cpufreq_cpu_get_raw(freq->cpu);
 136
 137         if (!policy)
 138                 return 0;
 139
 140         /* policy isn't governed by conservative governor */
 141         if (policy->governor != &cpufreq_gov_conservative)
 142                 return 0;
 143
 144         /*
 145          * we only care if our internally tracked freq moves outside the 'valid'
 146          * ranges of frequency available to us otherwise we do not change it
 147         */
 148         if (dbs_info->requested_freq > policy->max
 149                         || dbs_info->requested_freq < policy->min)
 150                 dbs_info->requested_freq = freq->new;
 151
 152         return 0;
 153 }
 154
 155 static struct notifier_block cs_cpufreq_notifier_block = {
 156         .notifier_call = dbs_cpufreq_notifier,
 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_load(struct dbs_data *dbs_data,
 225                 const char *buf, 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_load) /* nothing to do */
 239                 return count;
 240
 241         cs_tuners->ignore_nice_load = 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_load)
 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_load);
 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_load);
 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_load_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_load_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, bool notify)
 329 {
 330         struct cs_dbs_tuners *tuners;
 331
 332         tuners = kzalloc(sizeof(*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_load = 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
 348         if (notify)
 349                 cpufreq_register_notifier(&cs_cpufreq_notifier_block,
 350                                           CPUFREQ_TRANSITION_NOTIFIER);
 351
 352         return 0;
 353 }
 354
 355 static void cs_exit(struct dbs_data *dbs_data, bool notify)
 356 {
 357         if (notify)
 358                 cpufreq_unregister_notifier(&cs_cpufreq_notifier_block,
 359                                             CPUFREQ_TRANSITION_NOTIFIER);
 360
 361         kfree(dbs_data->tuners);
 362 }
 363
 364 define_get_cpu_dbs_routines(cs_cpu_dbs_info);
 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         .init = cs_init,
 375         .exit = cs_exit,
 376         .mutex = __MUTEX_INITIALIZER(cs_dbs_cdata.mutex),
 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 static int __init cpufreq_gov_dbs_init(void)
 386 {
 387         return cpufreq_register_governor(&cpufreq_gov_conservative);
 388 }
 389
 390 static void __exit cpufreq_gov_dbs_exit(void)
 391 {
 392         cpufreq_unregister_governor(&cpufreq_gov_conservative);
 393 }
 394
 395 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
 396 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
 397                 "Low Latency Frequency Transition capable processors "
 398                 "optimised for use in a battery environment");
 399 MODULE_LICENSE("GPL");
 400
 401 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 402 fs_initcall(cpufreq_gov_dbs_init);
 403 #else
 404 module_init(cpufreq_gov_dbs_init);
 405 #endif
 406 module_exit(cpufreq_gov_dbs_exit);