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