drivers/cpufreq/cpufreq_ondemand.c

   1 /*
   2  *  drivers/cpufreq/cpufreq_ondemand.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  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14
  15 #include <linux/cpu.h>
  16 #include <linux/percpu-defs.h>
  17 #include <linux/slab.h>
  18 #include <linux/tick.h>
  19 #include <linux/sched/cpufreq.h>
  20
  21 #include "cpufreq_ondemand.h"
  22
  23 /* On-demand governor macros */
  24 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
  25 #define DEF_SAMPLING_DOWN_FACTOR                (1)
  26 #define MAX_SAMPLING_DOWN_FACTOR                (100000)
  27 #define MICRO_FREQUENCY_UP_THRESHOLD            (95)
  28 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE         (10000)
  29 #define MIN_FREQUENCY_UP_THRESHOLD              (1)
  30 #define MAX_FREQUENCY_UP_THRESHOLD              (100)
  31
  32 static struct od_ops od_ops;
  33
  34 static unsigned int default_powersave_bias;
  35
  36 /*
  37  * Not all CPUs want IO time to be accounted as busy; this depends on how
  38  * efficient idling at a higher frequency/voltage is.
  39  * Pavel Machek says this is not so for various generations of AMD and old
  40  * Intel systems.
  41  * Mike Chan (android.com) claims this is also not true for ARM.
  42  * Because of this, whitelist specific known (series) of CPUs by default, and
  43  * leave all others up to the user.
  44  */
  45 static int should_io_be_busy(void)
  46 {
  47 #if defined(CONFIG_X86)
  48         /*
  49          * For Intel, Core 2 (model 15) and later have an efficient idle.
  50          */
  51         if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
  52                         boot_cpu_data.x86 == 6 &&
  53                         boot_cpu_data.x86_model >= 15)
  54                 return 1;
  55 #endif
  56         return 0;
  57 }
  58
  59 /*
  60  * Find right freq to be set now with powersave_bias on.
  61  * Returns the freq_hi to be used right now and will set freq_hi_delay_us,
  62  * freq_lo, and freq_lo_delay_us in percpu area for averaging freqs.
  63  */
  64 static unsigned int generic_powersave_bias_target(struct cpufreq_policy *policy,
  65                 unsigned int freq_next, unsigned int relation)
  66 {
  67         unsigned int freq_req, freq_reduc, freq_avg;
  68         unsigned int freq_hi, freq_lo;
  69         unsigned int index;
  70         unsigned int delay_hi_us;
  71         struct policy_dbs_info *policy_dbs = policy->governor_data;
  72         struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
  73         struct dbs_data *dbs_data = policy_dbs->dbs_data;
  74         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
  75         struct cpufreq_frequency_table *freq_table = policy->freq_table;
  76
  77         if (!freq_table) {
  78                 dbs_info->freq_lo = 0;
  79                 dbs_info->freq_lo_delay_us = 0;
  80                 return freq_next;
  81         }
  82
  83         index = cpufreq_frequency_table_target(policy, freq_next, relation);
  84         freq_req = freq_table[index].frequency;
  85         freq_reduc = freq_req * od_tuners->powersave_bias / 1000;
  86         freq_avg = freq_req - freq_reduc;
  87
  88         /* Find freq bounds for freq_avg in freq_table */
  89         index = cpufreq_table_find_index_h(policy, freq_avg);
  90         freq_lo = freq_table[index].frequency;
  91         index = cpufreq_table_find_index_l(policy, freq_avg);
  92         freq_hi = freq_table[index].frequency;
  93
  94         /* Find out how long we have to be in hi and lo freqs */
  95         if (freq_hi == freq_lo) {
  96                 dbs_info->freq_lo = 0;
  97                 dbs_info->freq_lo_delay_us = 0;
  98                 return freq_lo;
  99         }
 100         delay_hi_us = (freq_avg - freq_lo) * dbs_data->sampling_rate;
 101         delay_hi_us += (freq_hi - freq_lo) / 2;
 102         delay_hi_us /= freq_hi - freq_lo;
 103         dbs_info->freq_hi_delay_us = delay_hi_us;
 104         dbs_info->freq_lo = freq_lo;
 105         dbs_info->freq_lo_delay_us = dbs_data->sampling_rate - delay_hi_us;
 106         return freq_hi;
 107 }
 108
 109 static void ondemand_powersave_bias_init(struct cpufreq_policy *policy)
 110 {
 111         struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
 112
 113         dbs_info->freq_lo = 0;
 114 }
 115
 116 static void dbs_freq_increase(struct cpufreq_policy *policy, unsigned int freq)
 117 {
 118         struct policy_dbs_info *policy_dbs = policy->governor_data;
 119         struct dbs_data *dbs_data = policy_dbs->dbs_data;
 120         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 121
 122         if (od_tuners->powersave_bias)
 123                 freq = od_ops.powersave_bias_target(policy, freq,
 124                                 CPUFREQ_RELATION_H);
 125         else if (policy->cur == policy->max)
 126                 return;
 127
 128         __cpufreq_driver_target(policy, freq, od_tuners->powersave_bias ?
 129                         CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
 130 }
 131
 132 /*
 133  * Every sampling_rate, we check, if current idle time is less than 20%
 134  * (default), then we try to increase frequency. Else, we adjust the frequency
 135  * proportional to load.
 136  */
 137 static void od_update(struct cpufreq_policy *policy)
 138 {
 139         struct policy_dbs_info *policy_dbs = policy->governor_data;
 140         struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
 141         struct dbs_data *dbs_data = policy_dbs->dbs_data;
 142         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 143         unsigned int load = dbs_update(policy);
 144
 145         dbs_info->freq_lo = 0;
 146
 147         /* Check for frequency increase */
 148         if (load > dbs_data->up_threshold) {
 149                 /* If switching to max speed, apply sampling_down_factor */
 150                 if (policy->cur < policy->max)
 151                         policy_dbs->rate_mult = dbs_data->sampling_down_factor;
 152                 dbs_freq_increase(policy, policy->max);
 153         } else {
 154                 /* Calculate the next frequency proportional to load */
 155                 unsigned int freq_next, min_f, max_f;
 156
 157                 min_f = policy->cpuinfo.min_freq;
 158                 max_f = policy->cpuinfo.max_freq;
 159                 freq_next = min_f + load * (max_f - min_f) / 100;
 160
 161                 /* No longer fully busy, reset rate_mult */
 162                 policy_dbs->rate_mult = 1;
 163
 164                 if (od_tuners->powersave_bias)
 165                         freq_next = od_ops.powersave_bias_target(policy,
 166                                                                  freq_next,
 167                                                                  CPUFREQ_RELATION_L);
 168
 169                 __cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_C);
 170         }
 171 }
 172
 173 static unsigned int od_dbs_update(struct cpufreq_policy *policy)
 174 {
 175         struct policy_dbs_info *policy_dbs = policy->governor_data;
 176         struct dbs_data *dbs_data = policy_dbs->dbs_data;
 177         struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
 178         int sample_type = dbs_info->sample_type;
 179
 180         /* Common NORMAL_SAMPLE setup */
 181         dbs_info->sample_type = OD_NORMAL_SAMPLE;
 182         /*
 183          * OD_SUB_SAMPLE doesn't make sense if sample_delay_ns is 0, so ignore
 184          * it then.
 185          */
 186         if (sample_type == OD_SUB_SAMPLE && policy_dbs->sample_delay_ns > 0) {
 187                 __cpufreq_driver_target(policy, dbs_info->freq_lo,
 188                                         CPUFREQ_RELATION_H);
 189                 return dbs_info->freq_lo_delay_us;
 190         }
 191
 192         od_update(policy);
 193
 194         if (dbs_info->freq_lo) {
 195                 /* Setup SUB_SAMPLE */
 196                 dbs_info->sample_type = OD_SUB_SAMPLE;
 197                 return dbs_info->freq_hi_delay_us;
 198         }
 199
 200         return dbs_data->sampling_rate * policy_dbs->rate_mult;
 201 }
 202
 203 /************************** sysfs interface ************************/
 204 static struct dbs_governor od_dbs_gov;
 205
 206 static ssize_t store_io_is_busy(struct gov_attr_set *attr_set, const char *buf,
 207                                 size_t count)
 208 {
 209         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 210         unsigned int input;
 211         int ret;
 212
 213         ret = sscanf(buf, "%u", &input);
 214         if (ret != 1)
 215                 return -EINVAL;
 216         dbs_data->io_is_busy = !!input;
 217
 218         /* we need to re-evaluate prev_cpu_idle */
 219         gov_update_cpu_data(dbs_data);
 220
 221         return count;
 222 }
 223
 224 static ssize_t store_up_threshold(struct gov_attr_set *attr_set,
 225                                   const char *buf, size_t count)
 226 {
 227         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 228         unsigned int input;
 229         int ret;
 230         ret = sscanf(buf, "%u", &input);
 231
 232         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 233                         input < MIN_FREQUENCY_UP_THRESHOLD) {
 234                 return -EINVAL;
 235         }
 236
 237         dbs_data->up_threshold = input;
 238         return count;
 239 }
 240
 241 static ssize_t store_sampling_down_factor(struct gov_attr_set *attr_set,
 242                                           const char *buf, size_t count)
 243 {
 244         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 245         struct policy_dbs_info *policy_dbs;
 246         unsigned int input;
 247         int ret;
 248         ret = sscanf(buf, "%u", &input);
 249
 250         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 251                 return -EINVAL;
 252
 253         dbs_data->sampling_down_factor = input;
 254
 255         /* Reset down sampling multiplier in case it was active */
 256         list_for_each_entry(policy_dbs, &attr_set->policy_list, list) {
 257                 /*
 258                  * Doing this without locking might lead to using different
 259                  * rate_mult values in od_update() and od_dbs_update().
 260                  */
 261                 mutex_lock(&policy_dbs->update_mutex);
 262                 policy_dbs->rate_mult = 1;
 263                 mutex_unlock(&policy_dbs->update_mutex);
 264         }
 265
 266         return count;
 267 }
 268
 269 static ssize_t store_ignore_nice_load(struct gov_attr_set *attr_set,
 270                                       const char *buf, size_t count)
 271 {
 272         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 273         unsigned int input;
 274         int ret;
 275
 276         ret = sscanf(buf, "%u", &input);
 277         if (ret != 1)
 278                 return -EINVAL;
 279
 280         if (input > 1)
 281                 input = 1;
 282
 283         if (input == dbs_data->ignore_nice_load) { /* nothing to do */
 284                 return count;
 285         }
 286         dbs_data->ignore_nice_load = input;
 287
 288         /* we need to re-evaluate prev_cpu_idle */
 289         gov_update_cpu_data(dbs_data);
 290
 291         return count;
 292 }
 293
 294 static ssize_t store_powersave_bias(struct gov_attr_set *attr_set,
 295                                     const char *buf, size_t count)
 296 {
 297         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 298         struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 299         struct policy_dbs_info *policy_dbs;
 300         unsigned int input;
 301         int ret;
 302         ret = sscanf(buf, "%u", &input);
 303
 304         if (ret != 1)
 305                 return -EINVAL;
 306
 307         if (input > 1000)
 308                 input = 1000;
 309
 310         od_tuners->powersave_bias = input;
 311
 312         list_for_each_entry(policy_dbs, &attr_set->policy_list, list)
 313                 ondemand_powersave_bias_init(policy_dbs->policy);
 314
 315         return count;
 316 }
 317
 318 gov_show_one_common(sampling_rate);
 319 gov_show_one_common(up_threshold);
 320 gov_show_one_common(sampling_down_factor);
 321 gov_show_one_common(ignore_nice_load);
 322 gov_show_one_common(min_sampling_rate);
 323 gov_show_one_common(io_is_busy);
 324 gov_show_one(od, powersave_bias);
 325
 326 gov_attr_rw(sampling_rate);
 327 gov_attr_rw(io_is_busy);
 328 gov_attr_rw(up_threshold);
 329 gov_attr_rw(sampling_down_factor);
 330 gov_attr_rw(ignore_nice_load);
 331 gov_attr_rw(powersave_bias);
 332 gov_attr_ro(min_sampling_rate);
 333
 334 static struct attribute *od_attributes[] = {
 335         &min_sampling_rate.attr,
 336         &sampling_rate.attr,
 337         &up_threshold.attr,
 338         &sampling_down_factor.attr,
 339         &ignore_nice_load.attr,
 340         &powersave_bias.attr,
 341         &io_is_busy.attr,
 342         NULL
 343 };
 344
 345 /************************** sysfs end ************************/
 346
 347 static struct policy_dbs_info *od_alloc(void)
 348 {
 349         struct od_policy_dbs_info *dbs_info;
 350
 351         dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL);
 352         return dbs_info ? &dbs_info->policy_dbs : NULL;
 353 }
 354
 355 static void od_free(struct policy_dbs_info *policy_dbs)
 356 {
 357         kfree(to_dbs_info(policy_dbs));
 358 }
 359
 360 static int od_init(struct dbs_data *dbs_data)
 361 {
 362         struct od_dbs_tuners *tuners;
 363         u64 idle_time;
 364         int cpu;
 365
 366         tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 367         if (!tuners)
 368                 return -ENOMEM;
 369
 370         cpu = get_cpu();
 371         idle_time = get_cpu_idle_time_us(cpu, NULL);
 372         put_cpu();
 373         if (idle_time != -1ULL) {
 374                 /* Idle micro accounting is supported. Use finer thresholds */
 375                 dbs_data->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
 376                 /*
 377                  * In nohz/micro accounting case we set the minimum frequency
 378                  * not depending on HZ, but fixed (very low).
 379                 */
 380                 dbs_data->min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
 381         } else {
 382                 dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 383
 384                 /* For correct statistics, we need 10 ticks for each measure */
 385                 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 386                         jiffies_to_usecs(10);
 387         }
 388
 389         dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 390         dbs_data->ignore_nice_load = 0;
 391         tuners->powersave_bias = default_powersave_bias;
 392         dbs_data->io_is_busy = should_io_be_busy();
 393
 394         dbs_data->tuners = tuners;
 395         return 0;
 396 }
 397
 398 static void od_exit(struct dbs_data *dbs_data)
 399 {
 400         kfree(dbs_data->tuners);
 401 }
 402
 403 static void od_start(struct cpufreq_policy *policy)
 404 {
 405         struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
 406
 407         dbs_info->sample_type = OD_NORMAL_SAMPLE;
 408         ondemand_powersave_bias_init(policy);
 409 }
 410
 411 static struct od_ops od_ops = {
 412         .powersave_bias_target = generic_powersave_bias_target,
 413 };
 414
 415 static struct dbs_governor od_dbs_gov = {
 416         .gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("ondemand"),
 417         .kobj_type = { .default_attrs = od_attributes },
 418         .gov_dbs_update = od_dbs_update,
 419         .alloc = od_alloc,
 420         .free = od_free,
 421         .init = od_init,
 422         .exit = od_exit,
 423         .start = od_start,
 424 };
 425
 426 #define CPU_FREQ_GOV_ONDEMAND   (&od_dbs_gov.gov)
 427
 428 static void od_set_powersave_bias(unsigned int powersave_bias)
 429 {
 430         unsigned int cpu;
 431         cpumask_t done;
 432
 433         default_powersave_bias = powersave_bias;
 434         cpumask_clear(&done);
 435
 436         get_online_cpus();
 437         for_each_online_cpu(cpu) {
 438                 struct cpufreq_policy *policy;
 439                 struct policy_dbs_info *policy_dbs;
 440                 struct dbs_data *dbs_data;
 441                 struct od_dbs_tuners *od_tuners;
 442
 443                 if (cpumask_test_cpu(cpu, &done))
 444                         continue;
 445
 446                 policy = cpufreq_cpu_get_raw(cpu);
 447                 if (!policy || policy->governor != CPU_FREQ_GOV_ONDEMAND)
 448                         continue;
 449
 450                 policy_dbs = policy->governor_data;
 451                 if (!policy_dbs)
 452                         continue;
 453
 454                 cpumask_or(&done, &done, policy->cpus);
 455
 456                 dbs_data = policy_dbs->dbs_data;
 457                 od_tuners = dbs_data->tuners;
 458                 od_tuners->powersave_bias = default_powersave_bias;
 459         }
 460         put_online_cpus();
 461 }
 462
 463 void od_register_powersave_bias_handler(unsigned int (*f)
 464                 (struct cpufreq_policy *, unsigned int, unsigned int),
 465                 unsigned int powersave_bias)
 466 {
 467         od_ops.powersave_bias_target = f;
 468         od_set_powersave_bias(powersave_bias);
 469 }
 470 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);
 471
 472 void od_unregister_powersave_bias_handler(void)
 473 {
 474         od_ops.powersave_bias_target = generic_powersave_bias_target;
 475         od_set_powersave_bias(0);
 476 }
 477 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);
 478
 479 static int __init cpufreq_gov_dbs_init(void)
 480 {
 481         return cpufreq_register_governor(CPU_FREQ_GOV_ONDEMAND);
 482 }
 483
 484 static void __exit cpufreq_gov_dbs_exit(void)
 485 {
 486         cpufreq_unregister_governor(CPU_FREQ_GOV_ONDEMAND);
 487 }
 488
 489 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
 490 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
 491 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
 492         "Low Latency Frequency Transition capable processors");
 493 MODULE_LICENSE("GPL");
 494
 495 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 496 struct cpufreq_governor *cpufreq_default_governor(void)
 497 {
 498         return CPU_FREQ_GOV_ONDEMAND;
 499 }
 500
 501 fs_initcall(cpufreq_gov_dbs_init);
 502 #else
 503 module_init(cpufreq_gov_dbs_init);
 504 #endif
 505 module_exit(cpufreq_gov_dbs_exit);