root/drivers/cpufreq/cpufreq_ondemand.c

DEFINITIONS

1. should_io_be_busy
2. generic_powersave_bias_target
3. ondemand_powersave_bias_init
4. dbs_freq_increase
5. od_update
6. od_dbs_update
7. store_io_is_busy
8. store_up_threshold
9. store_sampling_down_factor
10. store_ignore_nice_load
11. store_powersave_bias
12. od_alloc
13. od_free
14. od_init
15. od_exit
16. od_start
17. od_set_powersave_bias
18. od_register_powersave_bias_handler
19. od_unregister_powersave_bias_handler
20. cpufreq_gov_dbs_init
21. cpufreq_gov_dbs_exit
22. cpufreq_default_governor

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  drivers/cpufreq/cpufreq_ondemand.c
   4  *
   5  *  Copyright (C)  2001 Russell King
   6  *            (C)  2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
   7  *                      Jun Nakajima <jun.nakajima@intel.com>
   8  */
   9 
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11 
  12 #include <linux/cpu.h>
  13 #include <linux/percpu-defs.h>
  14 #include <linux/slab.h>
  15 #include <linux/tick.h>
  16 #include <linux/sched/cpufreq.h>
  17 
  18 #include "cpufreq_ondemand.h"
  19 
  20 /* On-demand governor macros */
  21 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
  22 #define DEF_SAMPLING_DOWN_FACTOR                (1)
  23 #define MAX_SAMPLING_DOWN_FACTOR                (100000)
  24 #define MICRO_FREQUENCY_UP_THRESHOLD            (95)
  25 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE         (10000)
  26 #define MIN_FREQUENCY_UP_THRESHOLD              (1)
  27 #define MAX_FREQUENCY_UP_THRESHOLD              (100)
  28 
  29 static struct od_ops od_ops;
  30 
  31 static unsigned int default_powersave_bias;
  32 
  33 /*
  34  * Not all CPUs want IO time to be accounted as busy; this depends on how
  35  * efficient idling at a higher frequency/voltage is.
  36  * Pavel Machek says this is not so for various generations of AMD and old
  37  * Intel systems.
  38  * Mike Chan (android.com) claims this is also not true for ARM.
  39  * Because of this, whitelist specific known (series) of CPUs by default, and
  40  * leave all others up to the user.
  41  */
  42 static int should_io_be_busy(void)
  43 {
  44 #if defined(CONFIG_X86)
  45         /*
  46          * For Intel, Core 2 (model 15) and later have an efficient idle.
  47          */
  48         if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
  49                         boot_cpu_data.x86 == 6 &&
  50                         boot_cpu_data.x86_model >= 15)
  51                 return 1;
  52 #endif
  53         return 0;
  54 }
  55 
  56 /*
  57  * Find right freq to be set now with powersave_bias on.
  58  * Returns the freq_hi to be used right now and will set freq_hi_delay_us,
  59  * freq_lo, and freq_lo_delay_us in percpu area for averaging freqs.
  60  */
  61 static unsigned int generic_powersave_bias_target(struct cpufreq_policy *policy,
  62                 unsigned int freq_next, unsigned int relation)
  63 {
  64         unsigned int freq_req, freq_reduc, freq_avg;
  65         unsigned int freq_hi, freq_lo;
  66         unsigned int index;
  67         unsigned int delay_hi_us;
  68         struct policy_dbs_info *policy_dbs = policy->governor_data;
  69         struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
  70         struct dbs_data *dbs_data = policy_dbs->dbs_data;
  71         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
  72         struct cpufreq_frequency_table *freq_table = policy->freq_table;
  73 
  74         if (!freq_table) {
  75                 dbs_info->freq_lo = 0;
  76                 dbs_info->freq_lo_delay_us = 0;
  77                 return freq_next;
  78         }
  79 
  80         index = cpufreq_frequency_table_target(policy, freq_next, relation);
  81         freq_req = freq_table[index].frequency;
  82         freq_reduc = freq_req * od_tuners->powersave_bias / 1000;
  83         freq_avg = freq_req - freq_reduc;
  84 
  85         /* Find freq bounds for freq_avg in freq_table */
  86         index = cpufreq_table_find_index_h(policy, freq_avg);
  87         freq_lo = freq_table[index].frequency;
  88         index = cpufreq_table_find_index_l(policy, freq_avg);
  89         freq_hi = freq_table[index].frequency;
  90 
  91         /* Find out how long we have to be in hi and lo freqs */
  92         if (freq_hi == freq_lo) {
  93                 dbs_info->freq_lo = 0;
  94                 dbs_info->freq_lo_delay_us = 0;
  95                 return freq_lo;
  96         }
  97         delay_hi_us = (freq_avg - freq_lo) * dbs_data->sampling_rate;
  98         delay_hi_us += (freq_hi - freq_lo) / 2;
  99         delay_hi_us /= freq_hi - freq_lo;
 100         dbs_info->freq_hi_delay_us = delay_hi_us;
 101         dbs_info->freq_lo = freq_lo;
 102         dbs_info->freq_lo_delay_us = dbs_data->sampling_rate - delay_hi_us;
 103         return freq_hi;
 104 }
 105 
 106 static void ondemand_powersave_bias_init(struct cpufreq_policy *policy)
 107 {
 108         struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
 109 
 110         dbs_info->freq_lo = 0;
 111 }
 112 
 113 static void dbs_freq_increase(struct cpufreq_policy *policy, unsigned int freq)
 114 {
 115         struct policy_dbs_info *policy_dbs = policy->governor_data;
 116         struct dbs_data *dbs_data = policy_dbs->dbs_data;
 117         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 118 
 119         if (od_tuners->powersave_bias)
 120                 freq = od_ops.powersave_bias_target(policy, freq,
 121                                 CPUFREQ_RELATION_H);
 122         else if (policy->cur == policy->max)
 123                 return;
 124 
 125         __cpufreq_driver_target(policy, freq, od_tuners->powersave_bias ?
 126                         CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
 127 }
 128 
 129 /*
 130  * Every sampling_rate, we check, if current idle time is less than 20%
 131  * (default), then we try to increase frequency. Else, we adjust the frequency
 132  * proportional to load.
 133  */
 134 static void od_update(struct cpufreq_policy *policy)
 135 {
 136         struct policy_dbs_info *policy_dbs = policy->governor_data;
 137         struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
 138         struct dbs_data *dbs_data = policy_dbs->dbs_data;
 139         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 140         unsigned int load = dbs_update(policy);
 141 
 142         dbs_info->freq_lo = 0;
 143 
 144         /* Check for frequency increase */
 145         if (load > dbs_data->up_threshold) {
 146                 /* If switching to max speed, apply sampling_down_factor */
 147                 if (policy->cur < policy->max)
 148                         policy_dbs->rate_mult = dbs_data->sampling_down_factor;
 149                 dbs_freq_increase(policy, policy->max);
 150         } else {
 151                 /* Calculate the next frequency proportional to load */
 152                 unsigned int freq_next, min_f, max_f;
 153 
 154                 min_f = policy->cpuinfo.min_freq;
 155                 max_f = policy->cpuinfo.max_freq;
 156                 freq_next = min_f + load * (max_f - min_f) / 100;
 157 
 158                 /* No longer fully busy, reset rate_mult */
 159                 policy_dbs->rate_mult = 1;
 160 
 161                 if (od_tuners->powersave_bias)
 162                         freq_next = od_ops.powersave_bias_target(policy,
 163                                                                  freq_next,
 164                                                                  CPUFREQ_RELATION_L);
 165 
 166                 __cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_C);
 167         }
 168 }
 169 
 170 static unsigned int od_dbs_update(struct cpufreq_policy *policy)
 171 {
 172         struct policy_dbs_info *policy_dbs = policy->governor_data;
 173         struct dbs_data *dbs_data = policy_dbs->dbs_data;
 174         struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
 175         int sample_type = dbs_info->sample_type;
 176 
 177         /* Common NORMAL_SAMPLE setup */
 178         dbs_info->sample_type = OD_NORMAL_SAMPLE;
 179         /*
 180          * OD_SUB_SAMPLE doesn't make sense if sample_delay_ns is 0, so ignore
 181          * it then.
 182          */
 183         if (sample_type == OD_SUB_SAMPLE && policy_dbs->sample_delay_ns > 0) {
 184                 __cpufreq_driver_target(policy, dbs_info->freq_lo,
 185                                         CPUFREQ_RELATION_H);
 186                 return dbs_info->freq_lo_delay_us;
 187         }
 188 
 189         od_update(policy);
 190 
 191         if (dbs_info->freq_lo) {
 192                 /* Setup SUB_SAMPLE */
 193                 dbs_info->sample_type = OD_SUB_SAMPLE;
 194                 return dbs_info->freq_hi_delay_us;
 195         }
 196 
 197         return dbs_data->sampling_rate * policy_dbs->rate_mult;
 198 }
 199 
 200 /************************** sysfs interface ************************/
 201 static struct dbs_governor od_dbs_gov;
 202 
 203 static ssize_t store_io_is_busy(struct gov_attr_set *attr_set, const char *buf,
 204                                 size_t count)
 205 {
 206         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 207         unsigned int input;
 208         int ret;
 209 
 210         ret = sscanf(buf, "%u", &input);
 211         if (ret != 1)
 212                 return -EINVAL;
 213         dbs_data->io_is_busy = !!input;
 214 
 215         /* we need to re-evaluate prev_cpu_idle */
 216         gov_update_cpu_data(dbs_data);
 217 
 218         return count;
 219 }
 220 
 221 static ssize_t store_up_threshold(struct gov_attr_set *attr_set,
 222                                   const char *buf, size_t count)
 223 {
 224         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 225         unsigned int input;
 226         int ret;
 227         ret = sscanf(buf, "%u", &input);
 228 
 229         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 230                         input < MIN_FREQUENCY_UP_THRESHOLD) {
 231                 return -EINVAL;
 232         }
 233 
 234         dbs_data->up_threshold = input;
 235         return count;
 236 }
 237 
 238 static ssize_t store_sampling_down_factor(struct gov_attr_set *attr_set,
 239                                           const char *buf, size_t count)
 240 {
 241         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 242         struct policy_dbs_info *policy_dbs;
 243         unsigned int input;
 244         int ret;
 245         ret = sscanf(buf, "%u", &input);
 246 
 247         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 248                 return -EINVAL;
 249 
 250         dbs_data->sampling_down_factor = input;
 251 
 252         /* Reset down sampling multiplier in case it was active */
 253         list_for_each_entry(policy_dbs, &attr_set->policy_list, list) {
 254                 /*
 255                  * Doing this without locking might lead to using different
 256                  * rate_mult values in od_update() and od_dbs_update().
 257                  */
 258                 mutex_lock(&policy_dbs->update_mutex);
 259                 policy_dbs->rate_mult = 1;
 260                 mutex_unlock(&policy_dbs->update_mutex);
 261         }
 262 
 263         return count;
 264 }
 265 
 266 static ssize_t store_ignore_nice_load(struct gov_attr_set *attr_set,
 267                                       const char *buf, size_t count)
 268 {
 269         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 270         unsigned int input;
 271         int ret;
 272 
 273         ret = sscanf(buf, "%u", &input);
 274         if (ret != 1)
 275                 return -EINVAL;
 276 
 277         if (input > 1)
 278                 input = 1;
 279 
 280         if (input == dbs_data->ignore_nice_load) { /* nothing to do */
 281                 return count;
 282         }
 283         dbs_data->ignore_nice_load = input;
 284 
 285         /* we need to re-evaluate prev_cpu_idle */
 286         gov_update_cpu_data(dbs_data);
 287 
 288         return count;
 289 }
 290 
 291 static ssize_t store_powersave_bias(struct gov_attr_set *attr_set,
 292                                     const char *buf, size_t count)
 293 {
 294         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 295         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 296         struct policy_dbs_info *policy_dbs;
 297         unsigned int input;
 298         int ret;
 299         ret = sscanf(buf, "%u", &input);
 300 
 301         if (ret != 1)
 302                 return -EINVAL;
 303 
 304         if (input > 1000)
 305                 input = 1000;
 306 
 307         od_tuners->powersave_bias = input;
 308 
 309         list_for_each_entry(policy_dbs, &attr_set->policy_list, list)
 310                 ondemand_powersave_bias_init(policy_dbs->policy);
 311 
 312         return count;
 313 }
 314 
 315 gov_show_one_common(sampling_rate);
 316 gov_show_one_common(up_threshold);
 317 gov_show_one_common(sampling_down_factor);
 318 gov_show_one_common(ignore_nice_load);
 319 gov_show_one_common(io_is_busy);
 320 gov_show_one(od, powersave_bias);
 321 
 322 gov_attr_rw(sampling_rate);
 323 gov_attr_rw(io_is_busy);
 324 gov_attr_rw(up_threshold);
 325 gov_attr_rw(sampling_down_factor);
 326 gov_attr_rw(ignore_nice_load);
 327 gov_attr_rw(powersave_bias);
 328 
 329 static struct attribute *od_attributes[] = {
 330         &sampling_rate.attr,
 331         &up_threshold.attr,
 332         &sampling_down_factor.attr,
 333         &ignore_nice_load.attr,
 334         &powersave_bias.attr,
 335         &io_is_busy.attr,
 336         NULL
 337 };
 338 
 339 /************************** sysfs end ************************/
 340 
 341 static struct policy_dbs_info *od_alloc(void)
 342 {
 343         struct od_policy_dbs_info *dbs_info;
 344 
 345         dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL);
 346         return dbs_info ? &dbs_info->policy_dbs : NULL;
 347 }
 348 
 349 static void od_free(struct policy_dbs_info *policy_dbs)
 350 {
 351         kfree(to_dbs_info(policy_dbs));
 352 }
 353 
 354 static int od_init(struct dbs_data *dbs_data)
 355 {
 356         struct od_dbs_tuners *tuners;
 357         u64 idle_time;
 358         int cpu;
 359 
 360         tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 361         if (!tuners)
 362                 return -ENOMEM;
 363 
 364         cpu = get_cpu();
 365         idle_time = get_cpu_idle_time_us(cpu, NULL);
 366         put_cpu();
 367         if (idle_time != -1ULL) {
 368                 /* Idle micro accounting is supported. Use finer thresholds */
 369                 dbs_data->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
 370         } else {
 371                 dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 372         }
 373 
 374         dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 375         dbs_data->ignore_nice_load = 0;
 376         tuners->powersave_bias = default_powersave_bias;
 377         dbs_data->io_is_busy = should_io_be_busy();
 378 
 379         dbs_data->tuners = tuners;
 380         return 0;
 381 }
 382 
 383 static void od_exit(struct dbs_data *dbs_data)
 384 {
 385         kfree(dbs_data->tuners);
 386 }
 387 
 388 static void od_start(struct cpufreq_policy *policy)
 389 {
 390         struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
 391 
 392         dbs_info->sample_type = OD_NORMAL_SAMPLE;
 393         ondemand_powersave_bias_init(policy);
 394 }
 395 
 396 static struct od_ops od_ops = {
 397         .powersave_bias_target = generic_powersave_bias_target,
 398 };
 399 
 400 static struct dbs_governor od_dbs_gov = {
 401         .gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("ondemand"),
 402         .kobj_type = { .default_attrs = od_attributes },
 403         .gov_dbs_update = od_dbs_update,
 404         .alloc = od_alloc,
 405         .free = od_free,
 406         .init = od_init,
 407         .exit = od_exit,
 408         .start = od_start,
 409 };
 410 
 411 #define CPU_FREQ_GOV_ONDEMAND   (&od_dbs_gov.gov)
 412 
 413 static void od_set_powersave_bias(unsigned int powersave_bias)
 414 {
 415         unsigned int cpu;
 416         cpumask_t done;
 417 
 418         default_powersave_bias = powersave_bias;
 419         cpumask_clear(&done);
 420 
 421         get_online_cpus();
 422         for_each_online_cpu(cpu) {
 423                 struct cpufreq_policy *policy;
 424                 struct policy_dbs_info *policy_dbs;
 425                 struct dbs_data *dbs_data;
 426                 struct od_dbs_tuners *od_tuners;
 427 
 428                 if (cpumask_test_cpu(cpu, &done))
 429                         continue;
 430 
 431                 policy = cpufreq_cpu_get_raw(cpu);
 432                 if (!policy || policy->governor != CPU_FREQ_GOV_ONDEMAND)
 433                         continue;
 434 
 435                 policy_dbs = policy->governor_data;
 436                 if (!policy_dbs)
 437                         continue;
 438 
 439                 cpumask_or(&done, &done, policy->cpus);
 440 
 441                 dbs_data = policy_dbs->dbs_data;
 442                 od_tuners = dbs_data->tuners;
 443                 od_tuners->powersave_bias = default_powersave_bias;
 444         }
 445         put_online_cpus();
 446 }
 447 
 448 void od_register_powersave_bias_handler(unsigned int (*f)
 449                 (struct cpufreq_policy *, unsigned int, unsigned int),
 450                 unsigned int powersave_bias)
 451 {
 452         od_ops.powersave_bias_target = f;
 453         od_set_powersave_bias(powersave_bias);
 454 }
 455 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);
 456 
 457 void od_unregister_powersave_bias_handler(void)
 458 {
 459         od_ops.powersave_bias_target = generic_powersave_bias_target;
 460         od_set_powersave_bias(0);
 461 }
 462 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);
 463 
 464 static int __init cpufreq_gov_dbs_init(void)
 465 {
 466         return cpufreq_register_governor(CPU_FREQ_GOV_ONDEMAND);
 467 }
 468 
 469 static void __exit cpufreq_gov_dbs_exit(void)
 470 {
 471         cpufreq_unregister_governor(CPU_FREQ_GOV_ONDEMAND);
 472 }
 473 
 474 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
 475 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
 476 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
 477         "Low Latency Frequency Transition capable processors");
 478 MODULE_LICENSE("GPL");
 479 
 480 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 481 struct cpufreq_governor *cpufreq_default_governor(void)
 482 {
 483         return CPU_FREQ_GOV_ONDEMAND;
 484 }
 485 
 486 fs_initcall(cpufreq_gov_dbs_init);
 487 #else
 488 module_init(cpufreq_gov_dbs_init);
 489 #endif
 490 module_exit(cpufreq_gov_dbs_exit);