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