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.shared->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 unsigned int cs_dbs_timer(struct cpu_dbs_info *cdbs,
 106                                  struct dbs_data *dbs_data, bool modify_all)
 107 {
 108         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 109
 110         if (modify_all)
 111                 dbs_check_cpu(dbs_data, cdbs->shared->policy->cpu);
 112
 113         return delay_for_sampling_rate(cs_tuners->sampling_rate);
 114 }
 115
 116 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 117                 void *data)
 118 {
 119         struct cpufreq_freqs *freq = data;
 120         struct cs_cpu_dbs_info_s *dbs_info =
 121                                         &per_cpu(cs_cpu_dbs_info, freq->cpu);
 122         struct cpufreq_policy *policy;
 123
 124         if (!dbs_info->enable)
 125                 return 0;
 126
 127         policy = dbs_info->cdbs.shared->policy;
 128
 129         /*
 130          * we only care if our internally tracked freq moves outside the 'valid'
 131          * ranges of frequency available to us otherwise we do not change it
 132         */
 133         if (dbs_info->requested_freq > policy->max
 134                         || dbs_info->requested_freq < policy->min)
 135                 dbs_info->requested_freq = freq->new;
 136
 137         return 0;
 138 }
 139
 140 static struct notifier_block cs_cpufreq_notifier_block = {
 141         .notifier_call = dbs_cpufreq_notifier,
 142 };
 143
 144 /************************** sysfs interface ************************/
 145 static struct common_dbs_data cs_dbs_cdata;
 146
 147 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 148                 const char *buf, size_t count)
 149 {
 150         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 151         unsigned int input;
 152         int ret;
 153         ret = sscanf(buf, "%u", &input);
 154
 155         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 156                 return -EINVAL;
 157
 158         cs_tuners->sampling_down_factor = input;
 159         return count;
 160 }
 161
 162 static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
 163                 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)
 171                 return -EINVAL;
 172
 173         cs_tuners->sampling_rate = max(input, dbs_data->min_sampling_rate);
 174         return count;
 175 }
 176
 177 static ssize_t store_up_threshold(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 || input > 100 || input <= cs_tuners->down_threshold)
 186                 return -EINVAL;
 187
 188         cs_tuners->up_threshold = input;
 189         return count;
 190 }
 191
 192 static ssize_t store_down_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         /* cannot be lower than 11 otherwise freq will not fall */
 201         if (ret != 1 || input < 11 || input > 100 ||
 202                         input >= cs_tuners->up_threshold)
 203                 return -EINVAL;
 204
 205         cs_tuners->down_threshold = input;
 206         return count;
 207 }
 208
 209 static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data,
 210                 const char *buf, size_t count)
 211 {
 212         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 213         unsigned int input, j;
 214         int ret;
 215
 216         ret = sscanf(buf, "%u", &input);
 217         if (ret != 1)
 218                 return -EINVAL;
 219
 220         if (input > 1)
 221                 input = 1;
 222
 223         if (input == cs_tuners->ignore_nice_load) /* nothing to do */
 224                 return count;
 225
 226         cs_tuners->ignore_nice_load = input;
 227
 228         /* we need to re-evaluate prev_cpu_idle */
 229         for_each_online_cpu(j) {
 230                 struct cs_cpu_dbs_info_s *dbs_info;
 231                 dbs_info = &per_cpu(cs_cpu_dbs_info, j);
 232                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 233                                         &dbs_info->cdbs.prev_cpu_wall, 0);
 234                 if (cs_tuners->ignore_nice_load)
 235                         dbs_info->cdbs.prev_cpu_nice =
 236                                 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 237         }
 238         return count;
 239 }
 240
 241 static ssize_t store_freq_step(struct dbs_data *dbs_data, const char *buf,
 242                 size_t count)
 243 {
 244         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 245         unsigned int input;
 246         int ret;
 247         ret = sscanf(buf, "%u", &input);
 248
 249         if (ret != 1)
 250                 return -EINVAL;
 251
 252         if (input > 100)
 253                 input = 100;
 254
 255         /*
 256          * no need to test here if freq_step is zero as the user might actually
 257          * want this, they would be crazy though :)
 258          */
 259         cs_tuners->freq_step = input;
 260         return count;
 261 }
 262
 263 show_store_one(cs, sampling_rate);
 264 show_store_one(cs, sampling_down_factor);
 265 show_store_one(cs, up_threshold);
 266 show_store_one(cs, down_threshold);
 267 show_store_one(cs, ignore_nice_load);
 268 show_store_one(cs, freq_step);
 269 declare_show_sampling_rate_min(cs);
 270
 271 gov_sys_pol_attr_rw(sampling_rate);
 272 gov_sys_pol_attr_rw(sampling_down_factor);
 273 gov_sys_pol_attr_rw(up_threshold);
 274 gov_sys_pol_attr_rw(down_threshold);
 275 gov_sys_pol_attr_rw(ignore_nice_load);
 276 gov_sys_pol_attr_rw(freq_step);
 277 gov_sys_pol_attr_ro(sampling_rate_min);
 278
 279 static struct attribute *dbs_attributes_gov_sys[] = {
 280         &sampling_rate_min_gov_sys.attr,
 281         &sampling_rate_gov_sys.attr,
 282         &sampling_down_factor_gov_sys.attr,
 283         &up_threshold_gov_sys.attr,
 284         &down_threshold_gov_sys.attr,
 285         &ignore_nice_load_gov_sys.attr,
 286         &freq_step_gov_sys.attr,
 287         NULL
 288 };
 289
 290 static struct attribute_group cs_attr_group_gov_sys = {
 291         .attrs = dbs_attributes_gov_sys,
 292         .name = "conservative",
 293 };
 294
 295 static struct attribute *dbs_attributes_gov_pol[] = {
 296         &sampling_rate_min_gov_pol.attr,
 297         &sampling_rate_gov_pol.attr,
 298         &sampling_down_factor_gov_pol.attr,
 299         &up_threshold_gov_pol.attr,
 300         &down_threshold_gov_pol.attr,
 301         &ignore_nice_load_gov_pol.attr,
 302         &freq_step_gov_pol.attr,
 303         NULL
 304 };
 305
 306 static struct attribute_group cs_attr_group_gov_pol = {
 307         .attrs = dbs_attributes_gov_pol,
 308         .name = "conservative",
 309 };
 310
 311 /************************** sysfs end ************************/
 312
 313 static int cs_init(struct dbs_data *dbs_data, bool notify)
 314 {
 315         struct cs_dbs_tuners *tuners;
 316
 317         tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 318         if (!tuners) {
 319                 pr_err("%s: kzalloc failed\n", __func__);
 320                 return -ENOMEM;
 321         }
 322
 323         tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 324         tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
 325         tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 326         tuners->ignore_nice_load = 0;
 327         tuners->freq_step = DEF_FREQUENCY_STEP;
 328
 329         dbs_data->tuners = tuners;
 330         dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 331                 jiffies_to_usecs(10);
 332
 333         if (notify)
 334                 cpufreq_register_notifier(&cs_cpufreq_notifier_block,
 335                                           CPUFREQ_TRANSITION_NOTIFIER);
 336
 337         return 0;
 338 }
 339
 340 static void cs_exit(struct dbs_data *dbs_data, bool notify)
 341 {
 342         if (notify)
 343                 cpufreq_unregister_notifier(&cs_cpufreq_notifier_block,
 344                                             CPUFREQ_TRANSITION_NOTIFIER);
 345
 346         kfree(dbs_data->tuners);
 347 }
 348
 349 define_get_cpu_dbs_routines(cs_cpu_dbs_info);
 350
 351 static struct common_dbs_data cs_dbs_cdata = {
 352         .governor = GOV_CONSERVATIVE,
 353         .attr_group_gov_sys = &cs_attr_group_gov_sys,
 354         .attr_group_gov_pol = &cs_attr_group_gov_pol,
 355         .get_cpu_cdbs = get_cpu_cdbs,
 356         .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 357         .gov_dbs_timer = cs_dbs_timer,
 358         .gov_check_cpu = cs_check_cpu,
 359         .init = cs_init,
 360         .exit = cs_exit,
 361         .mutex = __MUTEX_INITIALIZER(cs_dbs_cdata.mutex),
 362 };
 363
 364 static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy,
 365                                    unsigned int event)
 366 {
 367         return cpufreq_governor_dbs(policy, &cs_dbs_cdata, event);
 368 }
 369
 370 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 371 static
 372 #endif
 373 struct cpufreq_governor cpufreq_gov_conservative = {
 374         .name                   = "conservative",
 375         .governor               = cs_cpufreq_governor_dbs,
 376         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 377         .owner                  = THIS_MODULE,
 378 };
 379
 380 static int __init cpufreq_gov_dbs_init(void)
 381 {
 382         return cpufreq_register_governor(&cpufreq_gov_conservative);
 383 }
 384
 385 static void __exit cpufreq_gov_dbs_exit(void)
 386 {
 387         cpufreq_unregister_governor(&cpufreq_gov_conservative);
 388 }
 389
 390 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
 391 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
 392                 "Low Latency Frequency Transition capable processors "
 393                 "optimised for use in a battery environment");
 394 MODULE_LICENSE("GPL");
 395
 396 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 397 fs_initcall(cpufreq_gov_dbs_init);
 398 #else
 399 module_init(cpufreq_gov_dbs_init);
 400 #endif
 401 module_exit(cpufreq_gov_dbs_exit);