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 = cpufreq_frequency_get_table(policy->cpu);
 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 dbs_data *dbs_data, const char *buf,
 211                 size_t count)
 212 {
 213         unsigned int input;
 214         int ret;
 215
 216         ret = sscanf(buf, "%u", &input);
 217         if (ret != 1)
 218                 return -EINVAL;
 219         dbs_data->io_is_busy = !!input;
 220
 221         /* we need to re-evaluate prev_cpu_idle */
 222         gov_update_cpu_data(dbs_data);
 223
 224         return count;
 225 }
 226
 227 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
 228                 size_t count)
 229 {
 230         unsigned int input;
 231         int ret;
 232         ret = sscanf(buf, "%u", &input);
 233
 234         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 235                         input < MIN_FREQUENCY_UP_THRESHOLD) {
 236                 return -EINVAL;
 237         }
 238
 239         dbs_data->up_threshold = input;
 240         return count;
 241 }
 242
 243 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 244                 const char *buf, size_t count)
 245 {
 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, &dbs_data->policy_dbs_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 dbs_data *dbs_data,
 271                 const char *buf, size_t count)
 272 {
 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 dbs_data *dbs_data, const char *buf,
 295                 size_t count)
 296 {
 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, &dbs_data->policy_dbs_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, bool notify)
 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                 pr_err("%s: kzalloc failed\n", __func__);
 368                 return -ENOMEM;
 369         }
 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, bool notify)
 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 = {
 419                 .name = "ondemand",
 420                 .governor = cpufreq_governor_dbs,
 421                 .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 422                 .owner = THIS_MODULE,
 423         },
 424         .kobj_type = { .default_attrs = od_attributes },
 425         .gov_dbs_timer = od_dbs_timer,
 426         .alloc = od_alloc,
 427         .free = od_free,
 428         .init = od_init,
 429         .exit = od_exit,
 430         .start = od_start,
 431 };
 432
 433 #define CPU_FREQ_GOV_ONDEMAND   (&od_dbs_gov.gov)
 434
 435 static void od_set_powersave_bias(unsigned int powersave_bias)
 436 {
 437         unsigned int cpu;
 438         cpumask_t done;
 439
 440         default_powersave_bias = powersave_bias;
 441         cpumask_clear(&done);
 442
 443         get_online_cpus();
 444         for_each_online_cpu(cpu) {
 445                 struct cpufreq_policy *policy;
 446                 struct policy_dbs_info *policy_dbs;
 447                 struct dbs_data *dbs_data;
 448                 struct od_dbs_tuners *od_tuners;
 449
 450                 if (cpumask_test_cpu(cpu, &done))
 451                         continue;
 452
 453                 policy = cpufreq_cpu_get_raw(cpu);
 454                 if (!policy || policy->governor != CPU_FREQ_GOV_ONDEMAND)
 455                         continue;
 456
 457                 policy_dbs = policy->governor_data;
 458                 if (!policy_dbs)
 459                         continue;
 460
 461                 cpumask_or(&done, &done, policy->cpus);
 462
 463                 dbs_data = policy_dbs->dbs_data;
 464                 od_tuners = dbs_data->tuners;
 465                 od_tuners->powersave_bias = default_powersave_bias;
 466         }
 467         put_online_cpus();
 468 }
 469
 470 void od_register_powersave_bias_handler(unsigned int (*f)
 471                 (struct cpufreq_policy *, unsigned int, unsigned int),
 472                 unsigned int powersave_bias)
 473 {
 474         od_ops.powersave_bias_target = f;
 475         od_set_powersave_bias(powersave_bias);
 476 }
 477 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);
 478
 479 void od_unregister_powersave_bias_handler(void)
 480 {
 481         od_ops.powersave_bias_target = generic_powersave_bias_target;
 482         od_set_powersave_bias(0);
 483 }
 484 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);
 485
 486 static int __init cpufreq_gov_dbs_init(void)
 487 {
 488         return cpufreq_register_governor(CPU_FREQ_GOV_ONDEMAND);
 489 }
 490
 491 static void __exit cpufreq_gov_dbs_exit(void)
 492 {
 493         cpufreq_unregister_governor(CPU_FREQ_GOV_ONDEMAND);
 494 }
 495
 496 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
 497 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
 498 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
 499         "Low Latency Frequency Transition capable processors");
 500 MODULE_LICENSE("GPL");
 501
 502 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 503 struct cpufreq_governor *cpufreq_default_governor(void)
 504 {
 505         return CPU_FREQ_GOV_ONDEMAND;
 506 }
 507
 508 fs_initcall(cpufreq_gov_dbs_init);
 509 #else
 510 module_init(cpufreq_gov_dbs_init);
 511 #endif
 512 module_exit(cpufreq_gov_dbs_exit);