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 static struct cpufreq_governor cpufreq_gov_conservative = {
  30         .name                   = "conservative",
  31         .governor               = cs_cpufreq_governor_dbs,
  32         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
  33         .owner                  = THIS_MODULE,
  34 };
  35
  36 static inline unsigned int get_freq_target(struct cs_dbs_tuners *cs_tuners,
  37                                            struct cpufreq_policy *policy)
  38 {
  39         unsigned int freq_target = (cs_tuners->freq_step * policy->max) / 100;
  40
  41         /* max freq cannot be less than 100. But who knows... */
  42         if (unlikely(freq_target == 0))
  43                 freq_target = DEF_FREQUENCY_STEP;
  44
  45         return freq_target;
  46 }
  47
  48 /*
  49  * Every sampling_rate, we check, if current idle time is less than 20%
  50  * (default), then we try to increase frequency. Every sampling_rate *
  51  * sampling_down_factor, we check, if current idle time is more than 80%
  52  * (default), then we try to decrease frequency
  53  *
  54  * Any frequency increase takes it to the maximum frequency. Frequency reduction
  55  * happens at minimum steps of 5% (default) of maximum frequency
  56  */
  57 static void cs_check_cpu(int cpu, unsigned int load)
  58 {
  59         struct cs_cpu_dbs_info_s *dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
  60         struct cpufreq_policy *policy = dbs_info->cdbs.shared->policy;
  61         struct dbs_data *dbs_data = policy->governor_data;
  62         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
  63
  64         /*
  65          * break out if we 'cannot' reduce the speed as the user might
  66          * want freq_step to be zero
  67          */
  68         if (cs_tuners->freq_step == 0)
  69                 return;
  70
  71         /* Check for frequency increase */
  72         if (load > cs_tuners->up_threshold) {
  73                 dbs_info->down_skip = 0;
  74
  75                 /* if we are already at full speed then break out early */
  76                 if (dbs_info->requested_freq == policy->max)
  77                         return;
  78
  79                 dbs_info->requested_freq += get_freq_target(cs_tuners, policy);
  80
  81                 if (dbs_info->requested_freq > policy->max)
  82                         dbs_info->requested_freq = policy->max;
  83
  84                 __cpufreq_driver_target(policy, dbs_info->requested_freq,
  85                         CPUFREQ_RELATION_H);
  86                 return;
  87         }
  88
  89         /* if sampling_down_factor is active break out early */
  90         if (++dbs_info->down_skip < cs_tuners->sampling_down_factor)
  91                 return;
  92         dbs_info->down_skip = 0;
  93
  94         /* Check for frequency decrease */
  95         if (load < cs_tuners->down_threshold) {
  96                 unsigned int freq_target;
  97                 /*
  98                  * if we cannot reduce the frequency anymore, break out early
  99                  */
 100                 if (policy->cur == policy->min)
 101                         return;
 102
 103                 freq_target = get_freq_target(cs_tuners, policy);
 104                 if (dbs_info->requested_freq > freq_target)
 105                         dbs_info->requested_freq -= freq_target;
 106                 else
 107                         dbs_info->requested_freq = policy->min;
 108
 109                 __cpufreq_driver_target(policy, dbs_info->requested_freq,
 110                                 CPUFREQ_RELATION_L);
 111                 return;
 112         }
 113 }
 114
 115 static unsigned int cs_dbs_timer(struct cpufreq_policy *policy)
 116 {
 117         struct dbs_data *dbs_data = policy->governor_data;
 118         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 119
 120         dbs_check_cpu(dbs_data, policy->cpu);
 121         return delay_for_sampling_rate(cs_tuners->sampling_rate);
 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 = cpufreq_cpu_get_raw(freq->cpu);
 131
 132         if (!policy)
 133                 return 0;
 134
 135         /* policy isn't governed by conservative governor */
 136         if (policy->governor != &cpufreq_gov_conservative)
 137                 return 0;
 138
 139         /*
 140          * we only care if our internally tracked freq moves outside the 'valid'
 141          * ranges of frequency available to us otherwise we do not change it
 142         */
 143         if (dbs_info->requested_freq > policy->max
 144                         || dbs_info->requested_freq < policy->min)
 145                 dbs_info->requested_freq = freq->new;
 146
 147         return 0;
 148 }
 149
 150 static struct notifier_block cs_cpufreq_notifier_block = {
 151         .notifier_call = dbs_cpufreq_notifier,
 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_load(struct dbs_data *dbs_data,
 220                 const char *buf, 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_load) /* nothing to do */
 234                 return count;
 235
 236         cs_tuners->ignore_nice_load = 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, 0);
 244                 if (cs_tuners->ignore_nice_load)
 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_load);
 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_load);
 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_load_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_load_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, bool notify)
 324 {
 325         struct cs_dbs_tuners *tuners;
 326
 327         tuners = kzalloc(sizeof(*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_load = 0;
 337         tuners->freq_step = DEF_FREQUENCY_STEP;
 338
 339         dbs_data->tuners = tuners;
 340         dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 341                 jiffies_to_usecs(10);
 342
 343         if (notify)
 344                 cpufreq_register_notifier(&cs_cpufreq_notifier_block,
 345                                           CPUFREQ_TRANSITION_NOTIFIER);
 346
 347         return 0;
 348 }
 349
 350 static void cs_exit(struct dbs_data *dbs_data, bool notify)
 351 {
 352         if (notify)
 353                 cpufreq_unregister_notifier(&cs_cpufreq_notifier_block,
 354                                             CPUFREQ_TRANSITION_NOTIFIER);
 355
 356         kfree(dbs_data->tuners);
 357 }
 358
 359 define_get_cpu_dbs_routines(cs_cpu_dbs_info);
 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         .init = cs_init,
 370         .exit = cs_exit,
 371 };
 372
 373 static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy,
 374                                    unsigned int event)
 375 {
 376         return cpufreq_governor_dbs(policy, &cs_dbs_cdata, event);
 377 }
 378
 379 static int __init cpufreq_gov_dbs_init(void)
 380 {
 381         return cpufreq_register_governor(&cpufreq_gov_conservative);
 382 }
 383
 384 static void __exit cpufreq_gov_dbs_exit(void)
 385 {
 386         cpufreq_unregister_governor(&cpufreq_gov_conservative);
 387 }
 388
 389 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
 390 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
 391                 "Low Latency Frequency Transition capable processors "
 392                 "optimised for use in a battery environment");
 393 MODULE_LICENSE("GPL");
 394
 395 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 396 struct cpufreq_governor *cpufreq_default_governor(void)
 397 {
 398         return &cpufreq_gov_conservative;
 399 }
 400
 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);