drivers/cpufreq/cpufreq_ondemand.c

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