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