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                 /*
  84                  * if we cannot reduce the frequency anymore, break out early
  85                  */
  86                 if (policy->cur == policy->min)
  87                         return;
  88
  89                 dbs_info->requested_freq -= get_freq_target(cs_tuners, policy);
  90
  91                 __cpufreq_driver_target(policy, dbs_info->requested_freq,
  92                                 CPUFREQ_RELATION_L);
  93                 return;
  94         }
  95 }
  96
  97 static void cs_dbs_timer(struct work_struct *work)
  98 {
  99         struct cs_cpu_dbs_info_s *dbs_info = container_of(work,
 100                         struct cs_cpu_dbs_info_s, cdbs.work.work);
 101         unsigned int cpu = dbs_info->cdbs.cur_policy->cpu;
 102         struct cs_cpu_dbs_info_s *core_dbs_info = &per_cpu(cs_cpu_dbs_info,
 103                         cpu);
 104         struct dbs_data *dbs_data = dbs_info->cdbs.cur_policy->governor_data;
 105         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 106         int delay = delay_for_sampling_rate(cs_tuners->sampling_rate);
 107         bool modify_all = true;
 108
 109         mutex_lock(&core_dbs_info->cdbs.timer_mutex);
 110         if (!need_load_eval(&core_dbs_info->cdbs, cs_tuners->sampling_rate))
 111                 modify_all = false;
 112         else
 113                 dbs_check_cpu(dbs_data, cpu);
 114
 115         gov_queue_work(dbs_data, dbs_info->cdbs.cur_policy, delay, modify_all);
 116         mutex_unlock(&core_dbs_info->cdbs.timer_mutex);
 117 }
 118
 119 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 120                 void *data)
 121 {
 122         struct cpufreq_freqs *freq = data;
 123         struct cs_cpu_dbs_info_s *dbs_info =
 124                                         &per_cpu(cs_cpu_dbs_info, freq->cpu);
 125         struct cpufreq_policy *policy;
 126
 127         if (!dbs_info->enable)
 128                 return 0;
 129
 130         policy = dbs_info->cdbs.cur_policy;
 131
 132         /*
 133          * we only care if our internally tracked freq moves outside the 'valid'
 134          * ranges of frequency available to us otherwise we do not change it
 135         */
 136         if (dbs_info->requested_freq > policy->max
 137                         || dbs_info->requested_freq < policy->min)
 138                 dbs_info->requested_freq = freq->new;
 139
 140         return 0;
 141 }
 142
 143 /************************** sysfs interface ************************/
 144 static struct common_dbs_data cs_dbs_cdata;
 145
 146 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 147                 const char *buf, size_t count)
 148 {
 149         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 150         unsigned int input;
 151         int ret;
 152         ret = sscanf(buf, "%u", &input);
 153
 154         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 155                 return -EINVAL;
 156
 157         cs_tuners->sampling_down_factor = input;
 158         return count;
 159 }
 160
 161 static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
 162                 size_t count)
 163 {
 164         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 165         unsigned int input;
 166         int ret;
 167         ret = sscanf(buf, "%u", &input);
 168
 169         if (ret != 1)
 170                 return -EINVAL;
 171
 172         cs_tuners->sampling_rate = max(input, dbs_data->min_sampling_rate);
 173         return count;
 174 }
 175
 176 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
 177                 size_t count)
 178 {
 179         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 180         unsigned int input;
 181         int ret;
 182         ret = sscanf(buf, "%u", &input);
 183
 184         if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold)
 185                 return -EINVAL;
 186
 187         cs_tuners->up_threshold = input;
 188         return count;
 189 }
 190
 191 static ssize_t store_down_threshold(struct dbs_data *dbs_data, const char *buf,
 192                 size_t count)
 193 {
 194         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 195         unsigned int input;
 196         int ret;
 197         ret = sscanf(buf, "%u", &input);
 198
 199         /* cannot be lower than 11 otherwise freq will not fall */
 200         if (ret != 1 || input < 11 || input > 100 ||
 201                         input >= cs_tuners->up_threshold)
 202                 return -EINVAL;
 203
 204         cs_tuners->down_threshold = input;
 205         return count;
 206 }
 207
 208 static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data,
 209                 const char *buf, size_t count)
 210 {
 211         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 212         unsigned int input, j;
 213         int ret;
 214
 215         ret = sscanf(buf, "%u", &input);
 216         if (ret != 1)
 217                 return -EINVAL;
 218
 219         if (input > 1)
 220                 input = 1;
 221
 222         if (input == cs_tuners->ignore_nice_load) /* nothing to do */
 223                 return count;
 224
 225         cs_tuners->ignore_nice_load = input;
 226
 227         /* we need to re-evaluate prev_cpu_idle */
 228         for_each_online_cpu(j) {
 229                 struct cs_cpu_dbs_info_s *dbs_info;
 230                 dbs_info = &per_cpu(cs_cpu_dbs_info, j);
 231                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 232                                         &dbs_info->cdbs.prev_cpu_wall, 0);
 233                 if (cs_tuners->ignore_nice_load)
 234                         dbs_info->cdbs.prev_cpu_nice =
 235                                 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 236         }
 237         return count;
 238 }
 239
 240 static ssize_t store_freq_step(struct dbs_data *dbs_data, const char *buf,
 241                 size_t count)
 242 {
 243         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 244         unsigned int input;
 245         int ret;
 246         ret = sscanf(buf, "%u", &input);
 247
 248         if (ret != 1)
 249                 return -EINVAL;
 250
 251         if (input > 100)
 252                 input = 100;
 253
 254         /*
 255          * no need to test here if freq_step is zero as the user might actually
 256          * want this, they would be crazy though :)
 257          */
 258         cs_tuners->freq_step = input;
 259         return count;
 260 }
 261
 262 show_store_one(cs, sampling_rate);
 263 show_store_one(cs, sampling_down_factor);
 264 show_store_one(cs, up_threshold);
 265 show_store_one(cs, down_threshold);
 266 show_store_one(cs, ignore_nice_load);
 267 show_store_one(cs, freq_step);
 268 declare_show_sampling_rate_min(cs);
 269
 270 gov_sys_pol_attr_rw(sampling_rate);
 271 gov_sys_pol_attr_rw(sampling_down_factor);
 272 gov_sys_pol_attr_rw(up_threshold);
 273 gov_sys_pol_attr_rw(down_threshold);
 274 gov_sys_pol_attr_rw(ignore_nice_load);
 275 gov_sys_pol_attr_rw(freq_step);
 276 gov_sys_pol_attr_ro(sampling_rate_min);
 277
 278 static struct attribute *dbs_attributes_gov_sys[] = {
 279         &sampling_rate_min_gov_sys.attr,
 280         &sampling_rate_gov_sys.attr,
 281         &sampling_down_factor_gov_sys.attr,
 282         &up_threshold_gov_sys.attr,
 283         &down_threshold_gov_sys.attr,
 284         &ignore_nice_load_gov_sys.attr,
 285         &freq_step_gov_sys.attr,
 286         NULL
 287 };
 288
 289 static struct attribute_group cs_attr_group_gov_sys = {
 290         .attrs = dbs_attributes_gov_sys,
 291         .name = "conservative",
 292 };
 293
 294 static struct attribute *dbs_attributes_gov_pol[] = {
 295         &sampling_rate_min_gov_pol.attr,
 296         &sampling_rate_gov_pol.attr,
 297         &sampling_down_factor_gov_pol.attr,
 298         &up_threshold_gov_pol.attr,
 299         &down_threshold_gov_pol.attr,
 300         &ignore_nice_load_gov_pol.attr,
 301         &freq_step_gov_pol.attr,
 302         NULL
 303 };
 304
 305 static struct attribute_group cs_attr_group_gov_pol = {
 306         .attrs = dbs_attributes_gov_pol,
 307         .name = "conservative",
 308 };
 309
 310 /************************** sysfs end ************************/
 311
 312 static int cs_init(struct dbs_data *dbs_data)
 313 {
 314         struct cs_dbs_tuners *tuners;
 315
 316         tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 317         if (!tuners) {
 318                 pr_err("%s: kzalloc failed\n", __func__);
 319                 return -ENOMEM;
 320         }
 321
 322         tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 323         tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
 324         tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 325         tuners->ignore_nice_load = 0;
 326         tuners->freq_step = DEF_FREQUENCY_STEP;
 327
 328         dbs_data->tuners = tuners;
 329         dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 330                 jiffies_to_usecs(10);
 331         mutex_init(&dbs_data->mutex);
 332         return 0;
 333 }
 334
 335 static void cs_exit(struct dbs_data *dbs_data)
 336 {
 337         kfree(dbs_data->tuners);
 338 }
 339
 340 define_get_cpu_dbs_routines(cs_cpu_dbs_info);
 341
 342 static struct notifier_block cs_cpufreq_notifier_block = {
 343         .notifier_call = dbs_cpufreq_notifier,
 344 };
 345
 346 static struct cs_ops cs_ops = {
 347         .notifier_block = &cs_cpufreq_notifier_block,
 348 };
 349
 350 static struct common_dbs_data cs_dbs_cdata = {
 351         .governor = GOV_CONSERVATIVE,
 352         .attr_group_gov_sys = &cs_attr_group_gov_sys,
 353         .attr_group_gov_pol = &cs_attr_group_gov_pol,
 354         .get_cpu_cdbs = get_cpu_cdbs,
 355         .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 356         .gov_dbs_timer = cs_dbs_timer,
 357         .gov_check_cpu = cs_check_cpu,
 358         .gov_ops = &cs_ops,
 359         .init = cs_init,
 360         .exit = cs_exit,
 361 };
 362
 363 static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy,
 364                                    unsigned int event)
 365 {
 366         return cpufreq_governor_dbs(policy, &cs_dbs_cdata, event);
 367 }
 368
 369 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 370 static
 371 #endif
 372 struct cpufreq_governor cpufreq_gov_conservative = {
 373         .name                   = "conservative",
 374         .governor               = cs_cpufreq_governor_dbs,
 375         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 376         .owner                  = THIS_MODULE,
 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 fs_initcall(cpufreq_gov_dbs_init);
 397 #else
 398 module_init(cpufreq_gov_dbs_init);
 399 #endif
 400 module_exit(cpufreq_gov_dbs_exit);