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/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 macors */
  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         .down_differential = DEF_FREQUENCY_DOWN_DIFFERENTIAL,
  51         .ignore_nice = 0,
  52         .powersave_bias = 0,
  53 };
  54
  55 static void ondemand_powersave_bias_init_cpu(int cpu)
  56 {
  57         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
  58
  59         dbs_info->freq_table = cpufreq_frequency_get_table(cpu);
  60         dbs_info->freq_lo = 0;
  61 }
  62
  63 /*
  64  * Not all CPUs want IO time to be accounted as busy; this depends on how
  65  * efficient idling at a higher frequency/voltage is.
  66  * Pavel Machek says this is not so for various generations of AMD and old
  67  * Intel systems.
  68  * Mike Chan (androidlcom) calis this is also not true for ARM.
  69  * Because of this, whitelist specific known (series) of CPUs by default, and
  70  * leave all others up to the user.
  71  */
  72 static int should_io_be_busy(void)
  73 {
  74 #if defined(CONFIG_X86)
  75         /*
  76          * For Intel, Core 2 (model 15) andl later have an efficient idle.
  77          */
  78         if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
  79                         boot_cpu_data.x86 == 6 &&
  80                         boot_cpu_data.x86_model >= 15)
  81                 return 1;
  82 #endif
  83         return 0;
  84 }
  85
  86 /*
  87  * Find right freq to be set now with powersave_bias on.
  88  * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
  89  * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
  90  */
  91 static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
  92                 unsigned int freq_next, unsigned int relation)
  93 {
  94         unsigned int freq_req, freq_reduc, freq_avg;
  95         unsigned int freq_hi, freq_lo;
  96         unsigned int index = 0;
  97         unsigned int jiffies_total, jiffies_hi, jiffies_lo;
  98         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
  99                                                    policy->cpu);
 100
 101         if (!dbs_info->freq_table) {
 102                 dbs_info->freq_lo = 0;
 103                 dbs_info->freq_lo_jiffies = 0;
 104                 return freq_next;
 105         }
 106
 107         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
 108                         relation, &index);
 109         freq_req = dbs_info->freq_table[index].frequency;
 110         freq_reduc = freq_req * od_tuners.powersave_bias / 1000;
 111         freq_avg = freq_req - freq_reduc;
 112
 113         /* Find freq bounds for freq_avg in freq_table */
 114         index = 0;
 115         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
 116                         CPUFREQ_RELATION_H, &index);
 117         freq_lo = dbs_info->freq_table[index].frequency;
 118         index = 0;
 119         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
 120                         CPUFREQ_RELATION_L, &index);
 121         freq_hi = dbs_info->freq_table[index].frequency;
 122
 123         /* Find out how long we have to be in hi and lo freqs */
 124         if (freq_hi == freq_lo) {
 125                 dbs_info->freq_lo = 0;
 126                 dbs_info->freq_lo_jiffies = 0;
 127                 return freq_lo;
 128         }
 129         jiffies_total = usecs_to_jiffies(od_tuners.sampling_rate);
 130         jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
 131         jiffies_hi += ((freq_hi - freq_lo) / 2);
 132         jiffies_hi /= (freq_hi - freq_lo);
 133         jiffies_lo = jiffies_total - jiffies_hi;
 134         dbs_info->freq_lo = freq_lo;
 135         dbs_info->freq_lo_jiffies = jiffies_lo;
 136         dbs_info->freq_hi_jiffies = jiffies_hi;
 137         return freq_hi;
 138 }
 139
 140 static void ondemand_powersave_bias_init(void)
 141 {
 142         int i;
 143         for_each_online_cpu(i) {
 144                 ondemand_powersave_bias_init_cpu(i);
 145         }
 146 }
 147
 148 static void dbs_freq_increase(struct cpufreq_policy *p, unsigned int freq)
 149 {
 150         if (od_tuners.powersave_bias)
 151                 freq = powersave_bias_target(p, freq, CPUFREQ_RELATION_H);
 152         else if (p->cur == p->max)
 153                 return;
 154
 155         __cpufreq_driver_target(p, freq, od_tuners.powersave_bias ?
 156                         CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
 157 }
 158
 159 /*
 160  * Every sampling_rate, we check, if current idle time is less than 20%
 161  * (default), then we try to increase frequency Every sampling_rate, we look for
 162  * a the lowest frequency which can sustain the load while keeping idle time
 163  * over 30%. If such a frequency exist, we try to decrease to this frequency.
 164  *
 165  * Any frequency increase takes it to the maximum frequency. Frequency reduction
 166  * happens at minimum steps of 5% (default) of current frequency
 167  */
 168 static void od_check_cpu(int cpu, unsigned int load_freq)
 169 {
 170         struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 171         struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy;
 172
 173         dbs_info->freq_lo = 0;
 174
 175         /* Check for frequency increase */
 176         if (load_freq > od_tuners.up_threshold * policy->cur) {
 177                 /* If switching to max speed, apply sampling_down_factor */
 178                 if (policy->cur < policy->max)
 179                         dbs_info->rate_mult =
 180                                 od_tuners.sampling_down_factor;
 181                 dbs_freq_increase(policy, policy->max);
 182                 return;
 183         }
 184
 185         /* Check for frequency decrease */
 186         /* if we cannot reduce the frequency anymore, break out early */
 187         if (policy->cur == policy->min)
 188                 return;
 189
 190         /*
 191          * The optimal frequency is the frequency that is the lowest that can
 192          * support the current CPU usage without triggering the up policy. To be
 193          * safe, we focus 10 points under the threshold.
 194          */
 195         if (load_freq < (od_tuners.up_threshold - od_tuners.down_differential) *
 196                         policy->cur) {
 197                 unsigned int freq_next;
 198                 freq_next = load_freq / (od_tuners.up_threshold -
 199                                 od_tuners.down_differential);
 200
 201                 /* No longer fully busy, reset rate_mult */
 202                 dbs_info->rate_mult = 1;
 203
 204                 if (freq_next < policy->min)
 205                         freq_next = policy->min;
 206
 207                 if (!od_tuners.powersave_bias) {
 208                         __cpufreq_driver_target(policy, freq_next,
 209                                         CPUFREQ_RELATION_L);
 210                 } else {
 211                         int freq = powersave_bias_target(policy, freq_next,
 212                                         CPUFREQ_RELATION_L);
 213                         __cpufreq_driver_target(policy, freq,
 214                                         CPUFREQ_RELATION_L);
 215                 }
 216         }
 217 }
 218
 219 static void od_timer_update(struct od_cpu_dbs_info_s *dbs_info, bool sample,
 220                             struct delayed_work *dw)
 221 {
 222         unsigned int cpu = dbs_info->cdbs.cpu;
 223         int delay, sample_type = dbs_info->sample_type;
 224
 225         /* Common NORMAL_SAMPLE setup */
 226         dbs_info->sample_type = OD_NORMAL_SAMPLE;
 227         if (sample_type == OD_SUB_SAMPLE) {
 228                 delay = dbs_info->freq_lo_jiffies;
 229                 if (sample)
 230                         __cpufreq_driver_target(dbs_info->cdbs.cur_policy,
 231                                                 dbs_info->freq_lo,
 232                                                 CPUFREQ_RELATION_H);
 233         } else {
 234                 if (sample)
 235                         dbs_check_cpu(&od_dbs_data, cpu);
 236                 if (dbs_info->freq_lo) {
 237                         /* Setup timer for SUB_SAMPLE */
 238                         dbs_info->sample_type = OD_SUB_SAMPLE;
 239                         delay = dbs_info->freq_hi_jiffies;
 240                 } else {
 241                         delay = delay_for_sampling_rate(od_tuners.sampling_rate
 242                                                 * dbs_info->rate_mult);
 243                 }
 244         }
 245
 246         schedule_delayed_work_on(smp_processor_id(), dw, delay);
 247 }
 248
 249 static void od_timer_coordinated(struct od_cpu_dbs_info_s *dbs_info_local,
 250                                  struct delayed_work *dw)
 251 {
 252         struct od_cpu_dbs_info_s *dbs_info;
 253         ktime_t time_now;
 254         s64 delta_us;
 255         bool sample = true;
 256
 257         /* use leader CPU's dbs_info */
 258         dbs_info = &per_cpu(od_cpu_dbs_info, dbs_info_local->cdbs.cpu);
 259         mutex_lock(&dbs_info->cdbs.timer_mutex);
 260
 261         time_now = ktime_get();
 262         delta_us = ktime_us_delta(time_now, dbs_info->cdbs.time_stamp);
 263
 264         /* Do nothing if we recently have sampled */
 265         if (delta_us < (s64)(od_tuners.sampling_rate / 2))
 266                 sample = false;
 267         else
 268                 dbs_info->cdbs.time_stamp = time_now;
 269
 270         od_timer_update(dbs_info, sample, dw);
 271         mutex_unlock(&dbs_info->cdbs.timer_mutex);
 272 }
 273
 274 static void od_dbs_timer(struct work_struct *work)
 275 {
 276         struct delayed_work *dw = to_delayed_work(work);
 277         struct od_cpu_dbs_info_s *dbs_info =
 278                 container_of(work, struct od_cpu_dbs_info_s, cdbs.work.work);
 279
 280         if (policy_is_shared(dbs_info->cdbs.cur_policy)) {
 281                 od_timer_coordinated(dbs_info, dw);
 282         } else {
 283                 mutex_lock(&dbs_info->cdbs.timer_mutex);
 284                 od_timer_update(dbs_info, true, dw);
 285                 mutex_unlock(&dbs_info->cdbs.timer_mutex);
 286         }
 287 }
 288
 289 /************************** sysfs interface ************************/
 290
 291 static ssize_t show_sampling_rate_min(struct kobject *kobj,
 292                                       struct attribute *attr, char *buf)
 293 {
 294         return sprintf(buf, "%u\n", od_dbs_data.min_sampling_rate);
 295 }
 296
 297 /**
 298  * update_sampling_rate - update sampling rate effective immediately if needed.
 299  * @new_rate: new sampling rate
 300  *
 301  * If new rate is smaller than the old, simply updaing
 302  * dbs_tuners_int.sampling_rate might not be appropriate. For example, if the
 303  * original sampling_rate was 1 second and the requested new sampling rate is 10
 304  * ms because the user needs immediate reaction from ondemand governor, but not
 305  * sure if higher frequency will be required or not, then, the governor may
 306  * change the sampling rate too late; up to 1 second later. Thus, if we are
 307  * reducing the sampling rate, we need to make the new value effective
 308  * immediately.
 309  */
 310 static void update_sampling_rate(unsigned int new_rate)
 311 {
 312         int cpu;
 313
 314         od_tuners.sampling_rate = new_rate = max(new_rate,
 315                         od_dbs_data.min_sampling_rate);
 316
 317         for_each_online_cpu(cpu) {
 318                 struct cpufreq_policy *policy;
 319                 struct od_cpu_dbs_info_s *dbs_info;
 320                 unsigned long next_sampling, appointed_at;
 321
 322                 policy = cpufreq_cpu_get(cpu);
 323                 if (!policy)
 324                         continue;
 325                 if (policy->governor != &cpufreq_gov_ondemand) {
 326                         cpufreq_cpu_put(policy);
 327                         continue;
 328                 }
 329                 dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 330                 cpufreq_cpu_put(policy);
 331
 332                 mutex_lock(&dbs_info->cdbs.timer_mutex);
 333
 334                 if (!delayed_work_pending(&dbs_info->cdbs.work)) {
 335                         mutex_unlock(&dbs_info->cdbs.timer_mutex);
 336                         continue;
 337                 }
 338
 339                 next_sampling = jiffies + usecs_to_jiffies(new_rate);
 340                 appointed_at = dbs_info->cdbs.work.timer.expires;
 341
 342                 if (time_before(next_sampling, appointed_at)) {
 343
 344                         mutex_unlock(&dbs_info->cdbs.timer_mutex);
 345                         cancel_delayed_work_sync(&dbs_info->cdbs.work);
 346                         mutex_lock(&dbs_info->cdbs.timer_mutex);
 347
 348                         schedule_delayed_work_on(cpu, &dbs_info->cdbs.work,
 349                                         usecs_to_jiffies(new_rate));
 350
 351                 }
 352                 mutex_unlock(&dbs_info->cdbs.timer_mutex);
 353         }
 354 }
 355
 356 static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
 357                                    const char *buf, size_t count)
 358 {
 359         unsigned int input;
 360         int ret;
 361         ret = sscanf(buf, "%u", &input);
 362         if (ret != 1)
 363                 return -EINVAL;
 364         update_sampling_rate(input);
 365         return count;
 366 }
 367
 368 static ssize_t store_io_is_busy(struct kobject *a, struct attribute *b,
 369                                    const char *buf, size_t count)
 370 {
 371         unsigned int input;
 372         int ret;
 373
 374         ret = sscanf(buf, "%u", &input);
 375         if (ret != 1)
 376                 return -EINVAL;
 377         od_tuners.io_is_busy = !!input;
 378         return count;
 379 }
 380
 381 static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
 382                                   const char *buf, size_t count)
 383 {
 384         unsigned int input;
 385         int ret;
 386         ret = sscanf(buf, "%u", &input);
 387
 388         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 389                         input < MIN_FREQUENCY_UP_THRESHOLD) {
 390                 return -EINVAL;
 391         }
 392         od_tuners.up_threshold = input;
 393         return count;
 394 }
 395
 396 static ssize_t store_sampling_down_factor(struct kobject *a,
 397                         struct attribute *b, const char *buf, size_t count)
 398 {
 399         unsigned int input, j;
 400         int ret;
 401         ret = sscanf(buf, "%u", &input);
 402
 403         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 404                 return -EINVAL;
 405         od_tuners.sampling_down_factor = input;
 406
 407         /* Reset down sampling multiplier in case it was active */
 408         for_each_online_cpu(j) {
 409                 struct od_cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 410                                 j);
 411                 dbs_info->rate_mult = 1;
 412         }
 413         return count;
 414 }
 415
 416 static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
 417                                       const char *buf, size_t count)
 418 {
 419         unsigned int input;
 420         int ret;
 421
 422         unsigned int j;
 423
 424         ret = sscanf(buf, "%u", &input);
 425         if (ret != 1)
 426                 return -EINVAL;
 427
 428         if (input > 1)
 429                 input = 1;
 430
 431         if (input == od_tuners.ignore_nice) { /* nothing to do */
 432                 return count;
 433         }
 434         od_tuners.ignore_nice = input;
 435
 436         /* we need to re-evaluate prev_cpu_idle */
 437         for_each_online_cpu(j) {
 438                 struct od_cpu_dbs_info_s *dbs_info;
 439                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
 440                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 441                                                 &dbs_info->cdbs.prev_cpu_wall);
 442                 if (od_tuners.ignore_nice)
 443                         dbs_info->cdbs.prev_cpu_nice =
 444                                 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 445
 446         }
 447         return count;
 448 }
 449
 450 static ssize_t store_powersave_bias(struct kobject *a, struct attribute *b,
 451                                     const char *buf, size_t count)
 452 {
 453         unsigned int input;
 454         int ret;
 455         ret = sscanf(buf, "%u", &input);
 456
 457         if (ret != 1)
 458                 return -EINVAL;
 459
 460         if (input > 1000)
 461                 input = 1000;
 462
 463         od_tuners.powersave_bias = input;
 464         ondemand_powersave_bias_init();
 465         return count;
 466 }
 467
 468 show_one(od, sampling_rate, sampling_rate);
 469 show_one(od, io_is_busy, io_is_busy);
 470 show_one(od, up_threshold, up_threshold);
 471 show_one(od, sampling_down_factor, sampling_down_factor);
 472 show_one(od, ignore_nice_load, ignore_nice);
 473 show_one(od, powersave_bias, powersave_bias);
 474
 475 define_one_global_rw(sampling_rate);
 476 define_one_global_rw(io_is_busy);
 477 define_one_global_rw(up_threshold);
 478 define_one_global_rw(sampling_down_factor);
 479 define_one_global_rw(ignore_nice_load);
 480 define_one_global_rw(powersave_bias);
 481 define_one_global_ro(sampling_rate_min);
 482
 483 static struct attribute *dbs_attributes[] = {
 484         &sampling_rate_min.attr,
 485         &sampling_rate.attr,
 486         &up_threshold.attr,
 487         &sampling_down_factor.attr,
 488         &ignore_nice_load.attr,
 489         &powersave_bias.attr,
 490         &io_is_busy.attr,
 491         NULL
 492 };
 493
 494 static struct attribute_group od_attr_group = {
 495         .attrs = dbs_attributes,
 496         .name = "ondemand",
 497 };
 498
 499 /************************** sysfs end ************************/
 500
 501 define_get_cpu_dbs_routines(od_cpu_dbs_info);
 502
 503 static struct od_ops od_ops = {
 504         .io_busy = should_io_be_busy,
 505         .powersave_bias_init_cpu = ondemand_powersave_bias_init_cpu,
 506         .powersave_bias_target = powersave_bias_target,
 507         .freq_increase = dbs_freq_increase,
 508 };
 509
 510 static struct dbs_data od_dbs_data = {
 511         .governor = GOV_ONDEMAND,
 512         .attr_group = &od_attr_group,
 513         .tuners = &od_tuners,
 514         .get_cpu_cdbs = get_cpu_cdbs,
 515         .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 516         .gov_dbs_timer = od_dbs_timer,
 517         .gov_check_cpu = od_check_cpu,
 518         .gov_ops = &od_ops,
 519 };
 520
 521 static int od_cpufreq_governor_dbs(struct cpufreq_policy *policy,
 522                 unsigned int event)
 523 {
 524         return cpufreq_governor_dbs(&od_dbs_data, policy, event);
 525 }
 526
 527 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 528 static
 529 #endif
 530 struct cpufreq_governor cpufreq_gov_ondemand = {
 531         .name                   = "ondemand",
 532         .governor               = od_cpufreq_governor_dbs,
 533         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 534         .owner                  = THIS_MODULE,
 535 };
 536
 537 static int __init cpufreq_gov_dbs_init(void)
 538 {
 539         u64 idle_time;
 540         int cpu = get_cpu();
 541
 542         mutex_init(&od_dbs_data.mutex);
 543         idle_time = get_cpu_idle_time_us(cpu, NULL);
 544         put_cpu();
 545         if (idle_time != -1ULL) {
 546                 /* Idle micro accounting is supported. Use finer thresholds */
 547                 od_tuners.up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
 548                 od_tuners.down_differential = MICRO_FREQUENCY_DOWN_DIFFERENTIAL;
 549                 /*
 550                  * In nohz/micro accounting case we set the minimum frequency
 551                  * not depending on HZ, but fixed (very low). The deferred
 552                  * timer might skip some samples if idle/sleeping as needed.
 553                 */
 554                 od_dbs_data.min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
 555         } else {
 556                 /* For correct statistics, we need 10 ticks for each measure */
 557                 od_dbs_data.min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 558                         jiffies_to_usecs(10);
 559         }
 560
 561         return cpufreq_register_governor(&cpufreq_gov_ondemand);
 562 }
 563
 564 static void __exit cpufreq_gov_dbs_exit(void)
 565 {
 566         cpufreq_unregister_governor(&cpufreq_gov_ondemand);
 567 }
 568
 569 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
 570 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
 571 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
 572         "Low Latency Frequency Transition capable processors");
 573 MODULE_LICENSE("GPL");
 574
 575 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 576 fs_initcall(cpufreq_gov_dbs_init);
 577 #else
 578 module_init(cpufreq_gov_dbs_init);
 579 #endif
 580 module_exit(cpufreq_gov_dbs_exit);