drivers/cpufreq/cpufreq_ondemand.c

   1 /*
   2  *  drivers/cpufreq/cpufreq_ondemand.c
   3  *
   4  *  Copyright (C)  2001 Russell King
   5  *            (C)  2003 Venkatesh Pallipadi <[email protected]>.
   6  *                      Jun Nakajima <[email protected]>
   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/cpufreq.h>
  16 #include <linux/init.h>
  17 #include <linux/kernel.h>
  18 #include <linux/kernel_stat.h>
  19 #include <linux/kobject.h>
  20 #include <linux/module.h>
  21 #include <linux/mutex.h>
  22 #include <linux/percpu-defs.h>
  23 #include <linux/sysfs.h>
  24 #include <linux/tick.h>
  25 #include <linux/types.h>
  26
  27 #include "cpufreq_governor.h"
  28
  29 /* On-demand governor macros */
  30 #define DEF_FREQUENCY_DOWN_DIFFERENTIAL         (10)
  31 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
  32 #define DEF_SAMPLING_DOWN_FACTOR                (1)
  33 #define MAX_SAMPLING_DOWN_FACTOR                (100000)
  34 #define MICRO_FREQUENCY_DOWN_DIFFERENTIAL       (3)
  35 #define MICRO_FREQUENCY_UP_THRESHOLD            (95)
  36 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE         (10000)
  37 #define MIN_FREQUENCY_UP_THRESHOLD              (11)
  38 #define MAX_FREQUENCY_UP_THRESHOLD              (100)
  39
  40 static struct dbs_data od_dbs_data;
  41 static DEFINE_PER_CPU(struct od_cpu_dbs_info_s, od_cpu_dbs_info);
  42
  43 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
  44 static struct cpufreq_governor cpufreq_gov_ondemand;
  45 #endif
  46
  47 static struct od_dbs_tuners od_tuners = {
  48         .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
  49         .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
  50         .adj_up_threshold = DEF_FREQUENCY_UP_THRESHOLD -
  51                             DEF_FREQUENCY_DOWN_DIFFERENTIAL,
  52         .ignore_nice = 0,
  53         .powersave_bias = 0,
  54 };
  55
  56 static void ondemand_powersave_bias_init_cpu(int cpu)
  57 {
  58         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
  59
  60         dbs_info->freq_table = cpufreq_frequency_get_table(cpu);
  61         dbs_info->freq_lo = 0;
  62 }
  63
  64 /*
  65  * Not all CPUs want IO time to be accounted as busy; this depends on how
  66  * efficient idling at a higher frequency/voltage is.
  67  * Pavel Machek says this is not so for various generations of AMD and old
  68  * Intel systems.
  69  * Mike Chan (android.com) claims this is also not true for ARM.
  70  * Because of this, whitelist specific known (series) of CPUs by default, and
  71  * leave all others up to the user.
  72  */
  73 static int should_io_be_busy(void)
  74 {
  75 #if defined(CONFIG_X86)
  76         /*
  77          * For Intel, Core 2 (model 15) and later have an efficient idle.
  78          */
  79         if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
  80                         boot_cpu_data.x86 == 6 &&
  81                         boot_cpu_data.x86_model >= 15)
  82                 return 1;
  83 #endif
  84         return 0;
  85 }
  86
  87 /*
  88  * Find right freq to be set now with powersave_bias on.
  89  * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
  90  * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
  91  */
  92 static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
  93                 unsigned int freq_next, unsigned int relation)
  94 {
  95         unsigned int freq_req, freq_reduc, freq_avg;
  96         unsigned int freq_hi, freq_lo;
  97         unsigned int index = 0;
  98         unsigned int jiffies_total, jiffies_hi, jiffies_lo;
  99         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 100                                                    policy->cpu);
 101
 102         if (!dbs_info->freq_table) {
 103                 dbs_info->freq_lo = 0;
 104                 dbs_info->freq_lo_jiffies = 0;
 105                 return freq_next;
 106         }
 107
 108         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
 109                         relation, &index);
 110         freq_req = dbs_info->freq_table[index].frequency;
 111         freq_reduc = freq_req * od_tuners.powersave_bias / 1000;
 112         freq_avg = freq_req - freq_reduc;
 113
 114         /* Find freq bounds for freq_avg in freq_table */
 115         index = 0;
 116         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
 117                         CPUFREQ_RELATION_H, &index);
 118         freq_lo = dbs_info->freq_table[index].frequency;
 119         index = 0;
 120         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
 121                         CPUFREQ_RELATION_L, &index);
 122         freq_hi = dbs_info->freq_table[index].frequency;
 123
 124         /* Find out how long we have to be in hi and lo freqs */
 125         if (freq_hi == freq_lo) {
 126                 dbs_info->freq_lo = 0;
 127                 dbs_info->freq_lo_jiffies = 0;
 128                 return freq_lo;
 129         }
 130         jiffies_total = usecs_to_jiffies(od_tuners.sampling_rate);
 131         jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
 132         jiffies_hi += ((freq_hi - freq_lo) / 2);
 133         jiffies_hi /= (freq_hi - freq_lo);
 134         jiffies_lo = jiffies_total - jiffies_hi;
 135         dbs_info->freq_lo = freq_lo;
 136         dbs_info->freq_lo_jiffies = jiffies_lo;
 137         dbs_info->freq_hi_jiffies = jiffies_hi;
 138         return freq_hi;
 139 }
 140
 141 static void ondemand_powersave_bias_init(void)
 142 {
 143         int i;
 144         for_each_online_cpu(i) {
 145                 ondemand_powersave_bias_init_cpu(i);
 146         }
 147 }
 148
 149 static void dbs_freq_increase(struct cpufreq_policy *p, unsigned int freq)
 150 {
 151         if (od_tuners.powersave_bias)
 152                 freq = powersave_bias_target(p, freq, CPUFREQ_RELATION_H);
 153         else if (p->cur == p->max)
 154                 return;
 155
 156         __cpufreq_driver_target(p, freq, od_tuners.powersave_bias ?
 157                         CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
 158 }
 159
 160 /*
 161  * Every sampling_rate, we check, if current idle time is less than 20%
 162  * (default), then we try to increase frequency. Every sampling_rate, we look
 163  * for the lowest frequency which can sustain the load while keeping idle time
 164  * over 30%. If such a frequency exist, we try to decrease to this frequency.
 165  *
 166  * Any frequency increase takes it to the maximum frequency. Frequency reduction
 167  * happens at minimum steps of 5% (default) of current frequency
 168  */
 169 static void od_check_cpu(int cpu, unsigned int load_freq)
 170 {
 171         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 172         struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy;
 173
 174         dbs_info->freq_lo = 0;
 175
 176         /* Check for frequency increase */
 177         if (load_freq > od_tuners.up_threshold * policy->cur) {
 178                 /* If switching to max speed, apply sampling_down_factor */
 179                 if (policy->cur < policy->max)
 180                         dbs_info->rate_mult =
 181                                 od_tuners.sampling_down_factor;
 182                 dbs_freq_increase(policy, policy->max);
 183                 return;
 184         }
 185
 186         /* Check for frequency decrease */
 187         /* if we cannot reduce the frequency anymore, break out early */
 188         if (policy->cur == policy->min)
 189                 return;
 190
 191         /*
 192          * The optimal frequency is the frequency that is the lowest that can
 193          * support the current CPU usage without triggering the up policy. To be
 194          * safe, we focus 10 points under the threshold.
 195          */
 196         if (load_freq < od_tuners.adj_up_threshold * policy->cur) {
 197                 unsigned int freq_next;
 198                 freq_next = load_freq / od_tuners.adj_up_threshold;
 199
 200                 /* No longer fully busy, reset rate_mult */
 201                 dbs_info->rate_mult = 1;
 202
 203                 if (freq_next < policy->min)
 204                         freq_next = policy->min;
 205
 206                 if (!od_tuners.powersave_bias) {
 207                         __cpufreq_driver_target(policy, freq_next,
 208                                         CPUFREQ_RELATION_L);
 209                 } else {
 210                         int freq = powersave_bias_target(policy, freq_next,
 211                                         CPUFREQ_RELATION_L);
 212                         __cpufreq_driver_target(policy, freq,
 213                                         CPUFREQ_RELATION_L);
 214                 }
 215         }
 216 }
 217
 218 static void od_dbs_timer(struct work_struct *work)
 219 {
 220         struct delayed_work *dw = to_delayed_work(work);
 221         struct od_cpu_dbs_info_s *dbs_info =
 222                 container_of(work, struct od_cpu_dbs_info_s, cdbs.work.work);
 223         unsigned int cpu = dbs_info->cdbs.cur_policy->cpu;
 224         struct od_cpu_dbs_info_s *core_dbs_info = &per_cpu(od_cpu_dbs_info,
 225                         cpu);
 226         int delay, sample_type = core_dbs_info->sample_type;
 227         bool eval_load;
 228
 229         mutex_lock(&core_dbs_info->cdbs.timer_mutex);
 230         eval_load = need_load_eval(&core_dbs_info->cdbs,
 231                         od_tuners.sampling_rate);
 232
 233         /* Common NORMAL_SAMPLE setup */
 234         core_dbs_info->sample_type = OD_NORMAL_SAMPLE;
 235         if (sample_type == OD_SUB_SAMPLE) {
 236                 delay = core_dbs_info->freq_lo_jiffies;
 237                 if (eval_load)
 238                         __cpufreq_driver_target(core_dbs_info->cdbs.cur_policy,
 239                                                 core_dbs_info->freq_lo,
 240                                                 CPUFREQ_RELATION_H);
 241         } else {
 242                 if (eval_load)
 243                         dbs_check_cpu(&od_dbs_data, cpu);
 244                 if (core_dbs_info->freq_lo) {
 245                         /* Setup timer for SUB_SAMPLE */
 246                         core_dbs_info->sample_type = OD_SUB_SAMPLE;
 247                         delay = core_dbs_info->freq_hi_jiffies;
 248                 } else {
 249                         delay = delay_for_sampling_rate(od_tuners.sampling_rate
 250                                                 * core_dbs_info->rate_mult);
 251                 }
 252         }
 253
 254         schedule_delayed_work_on(smp_processor_id(), dw, delay);
 255         mutex_unlock(&core_dbs_info->cdbs.timer_mutex);
 256 }
 257
 258 /************************** sysfs interface ************************/
 259
 260 static ssize_t show_sampling_rate_min(struct kobject *kobj,
 261                                       struct attribute *attr, char *buf)
 262 {
 263         return sprintf(buf, "%u\n", od_dbs_data.min_sampling_rate);
 264 }
 265
 266 /**
 267  * update_sampling_rate - update sampling rate effective immediately if needed.
 268  * @new_rate: new sampling rate
 269  *
 270  * If new rate is smaller than the old, simply updating
 271  * dbs_tuners_int.sampling_rate might not be appropriate. For example, if the
 272  * original sampling_rate was 1 second and the requested new sampling rate is 10
 273  * ms because the user needs immediate reaction from ondemand governor, but not
 274  * sure if higher frequency will be required or not, then, the governor may
 275  * change the sampling rate too late; up to 1 second later. Thus, if we are
 276  * reducing the sampling rate, we need to make the new value effective
 277  * immediately.
 278  */
 279 static void update_sampling_rate(unsigned int new_rate)
 280 {
 281         int cpu;
 282
 283         od_tuners.sampling_rate = new_rate = max(new_rate,
 284                         od_dbs_data.min_sampling_rate);
 285
 286         for_each_online_cpu(cpu) {
 287                 struct cpufreq_policy *policy;
 288                 struct od_cpu_dbs_info_s *dbs_info;
 289                 unsigned long next_sampling, appointed_at;
 290
 291                 policy = cpufreq_cpu_get(cpu);
 292                 if (!policy)
 293                         continue;
 294                 if (policy->governor != &cpufreq_gov_ondemand) {
 295                         cpufreq_cpu_put(policy);
 296                         continue;
 297                 }
 298                 dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 299                 cpufreq_cpu_put(policy);
 300
 301                 mutex_lock(&dbs_info->cdbs.timer_mutex);
 302
 303                 if (!delayed_work_pending(&dbs_info->cdbs.work)) {
 304                         mutex_unlock(&dbs_info->cdbs.timer_mutex);
 305                         continue;
 306                 }
 307
 308                 next_sampling = jiffies + usecs_to_jiffies(new_rate);
 309                 appointed_at = dbs_info->cdbs.work.timer.expires;
 310
 311                 if (time_before(next_sampling, appointed_at)) {
 312
 313                         mutex_unlock(&dbs_info->cdbs.timer_mutex);
 314                         cancel_delayed_work_sync(&dbs_info->cdbs.work);
 315                         mutex_lock(&dbs_info->cdbs.timer_mutex);
 316
 317                         schedule_delayed_work_on(cpu, &dbs_info->cdbs.work,
 318                                         usecs_to_jiffies(new_rate));
 319
 320                 }
 321                 mutex_unlock(&dbs_info->cdbs.timer_mutex);
 322         }
 323 }
 324
 325 static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
 326                                    const char *buf, size_t count)
 327 {
 328         unsigned int input;
 329         int ret;
 330         ret = sscanf(buf, "%u", &input);
 331         if (ret != 1)
 332                 return -EINVAL;
 333         update_sampling_rate(input);
 334         return count;
 335 }
 336
 337 static ssize_t store_io_is_busy(struct kobject *a, struct attribute *b,
 338                                    const char *buf, size_t count)
 339 {
 340         unsigned int input;
 341         int ret;
 342
 343         ret = sscanf(buf, "%u", &input);
 344         if (ret != 1)
 345                 return -EINVAL;
 346         od_tuners.io_is_busy = !!input;
 347         return count;
 348 }
 349
 350 static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
 351                                   const char *buf, size_t count)
 352 {
 353         unsigned int input;
 354         int ret;
 355         ret = sscanf(buf, "%u", &input);
 356
 357         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 358                         input < MIN_FREQUENCY_UP_THRESHOLD) {
 359                 return -EINVAL;
 360         }
 361         /* Calculate the new adj_up_threshold */
 362         od_tuners.adj_up_threshold += input;
 363         od_tuners.adj_up_threshold -= od_tuners.up_threshold;
 364
 365         od_tuners.up_threshold = input;
 366         return count;
 367 }
 368
 369 static ssize_t store_sampling_down_factor(struct kobject *a,
 370                         struct attribute *b, const char *buf, size_t count)
 371 {
 372         unsigned int input, j;
 373         int ret;
 374         ret = sscanf(buf, "%u", &input);
 375
 376         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 377                 return -EINVAL;
 378         od_tuners.sampling_down_factor = input;
 379
 380         /* Reset down sampling multiplier in case it was active */
 381         for_each_online_cpu(j) {
 382                 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 383                                 j);
 384                 dbs_info->rate_mult = 1;
 385         }
 386         return count;
 387 }
 388
 389 static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
 390                                       const char *buf, size_t count)
 391 {
 392         unsigned int input;
 393         int ret;
 394
 395         unsigned int j;
 396
 397         ret = sscanf(buf, "%u", &input);
 398         if (ret != 1)
 399                 return -EINVAL;
 400
 401         if (input > 1)
 402                 input = 1;
 403
 404         if (input == od_tuners.ignore_nice) { /* nothing to do */
 405                 return count;
 406         }
 407         od_tuners.ignore_nice = input;
 408
 409         /* we need to re-evaluate prev_cpu_idle */
 410         for_each_online_cpu(j) {
 411                 struct od_cpu_dbs_info_s *dbs_info;
 412                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
 413                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 414                                                 &dbs_info->cdbs.prev_cpu_wall);
 415                 if (od_tuners.ignore_nice)
 416                         dbs_info->cdbs.prev_cpu_nice =
 417                                 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 418
 419         }
 420         return count;
 421 }
 422
 423 static ssize_t store_powersave_bias(struct kobject *a, struct attribute *b,
 424                                     const char *buf, size_t count)
 425 {
 426         unsigned int input;
 427         int ret;
 428         ret = sscanf(buf, "%u", &input);
 429
 430         if (ret != 1)
 431                 return -EINVAL;
 432
 433         if (input > 1000)
 434                 input = 1000;
 435
 436         od_tuners.powersave_bias = input;
 437         ondemand_powersave_bias_init();
 438         return count;
 439 }
 440
 441 show_one(od, sampling_rate, sampling_rate);
 442 show_one(od, io_is_busy, io_is_busy);
 443 show_one(od, up_threshold, up_threshold);
 444 show_one(od, sampling_down_factor, sampling_down_factor);
 445 show_one(od, ignore_nice_load, ignore_nice);
 446 show_one(od, powersave_bias, powersave_bias);
 447
 448 define_one_global_rw(sampling_rate);
 449 define_one_global_rw(io_is_busy);
 450 define_one_global_rw(up_threshold);
 451 define_one_global_rw(sampling_down_factor);
 452 define_one_global_rw(ignore_nice_load);
 453 define_one_global_rw(powersave_bias);
 454 define_one_global_ro(sampling_rate_min);
 455
 456 static struct attribute *dbs_attributes[] = {
 457         &sampling_rate_min.attr,
 458         &sampling_rate.attr,
 459         &up_threshold.attr,
 460         &sampling_down_factor.attr,
 461         &ignore_nice_load.attr,
 462         &powersave_bias.attr,
 463         &io_is_busy.attr,
 464         NULL
 465 };
 466
 467 static struct attribute_group od_attr_group = {
 468         .attrs = dbs_attributes,
 469         .name = "ondemand",
 470 };
 471
 472 /************************** sysfs end ************************/
 473
 474 define_get_cpu_dbs_routines(od_cpu_dbs_info);
 475
 476 static struct od_ops od_ops = {
 477         .io_busy = should_io_be_busy,
 478         .powersave_bias_init_cpu = ondemand_powersave_bias_init_cpu,
 479         .powersave_bias_target = powersave_bias_target,
 480         .freq_increase = dbs_freq_increase,
 481 };
 482
 483 static struct dbs_data od_dbs_data = {
 484         .governor = GOV_ONDEMAND,
 485         .attr_group = &od_attr_group,
 486         .tuners = &od_tuners,
 487         .get_cpu_cdbs = get_cpu_cdbs,
 488         .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 489         .gov_dbs_timer = od_dbs_timer,
 490         .gov_check_cpu = od_check_cpu,
 491         .gov_ops = &od_ops,
 492 };
 493
 494 static int od_cpufreq_governor_dbs(struct cpufreq_policy *policy,
 495                 unsigned int event)
 496 {
 497         return cpufreq_governor_dbs(&od_dbs_data, policy, event);
 498 }
 499
 500 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 501 static
 502 #endif
 503 struct cpufreq_governor cpufreq_gov_ondemand = {
 504         .name                   = "ondemand",
 505         .governor               = od_cpufreq_governor_dbs,
 506         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 507         .owner                  = THIS_MODULE,
 508 };
 509
 510 static int __init cpufreq_gov_dbs_init(void)
 511 {
 512         u64 idle_time;
 513         int cpu = get_cpu();
 514
 515         mutex_init(&od_dbs_data.mutex);
 516         idle_time = get_cpu_idle_time_us(cpu, NULL);
 517         put_cpu();
 518         if (idle_time != -1ULL) {
 519                 /* Idle micro accounting is supported. Use finer thresholds */
 520                 od_tuners.up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
 521                 od_tuners.adj_up_threshold = MICRO_FREQUENCY_UP_THRESHOLD -
 522                                              MICRO_FREQUENCY_DOWN_DIFFERENTIAL;
 523                 /*
 524                  * In nohz/micro accounting case we set the minimum frequency
 525                  * not depending on HZ, but fixed (very low). The deferred
 526                  * timer might skip some samples if idle/sleeping as needed.
 527                 */
 528                 od_dbs_data.min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
 529         } else {
 530                 /* For correct statistics, we need 10 ticks for each measure */
 531                 od_dbs_data.min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 532                         jiffies_to_usecs(10);
 533         }
 534
 535         return cpufreq_register_governor(&cpufreq_gov_ondemand);
 536 }
 537
 538 static void __exit cpufreq_gov_dbs_exit(void)
 539 {
 540         cpufreq_unregister_governor(&cpufreq_gov_ondemand);
 541 }
 542
 543 MODULE_AUTHOR("Venkatesh Pallipadi <[email protected]>");
 544 MODULE_AUTHOR("Alexey Starikovskiy <[email protected]>");
 545 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
 546         "Low Latency Frequency Transition capable processors");
 547 MODULE_LICENSE("GPL");
 548
 549 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 550 fs_initcall(cpufreq_gov_dbs_init);
 551 #else
 552 module_init(cpufreq_gov_dbs_init);
 553 #endif
 554 module_exit(cpufreq_gov_dbs_exit);