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