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 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/init.h>
  16 #include <linux/cpufreq.h>
  17 #include <linux/cpu.h>
  18 #include <linux/jiffies.h>
  19 #include <linux/kernel_stat.h>
  20 #include <linux/mutex.h>
  21 #include <linux/hrtimer.h>
  22 #include <linux/tick.h>
  23 #include <linux/ktime.h>
  24 #include <linux/sched.h>
  25
  26 /*
  27  * dbs is used in this file as a shortform for demandbased switching
  28  * It helps to keep variable names smaller, simpler
  29  */
  30
  31 #define DEF_FREQUENCY_DOWN_DIFFERENTIAL         (10)
  32 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
  33 #define DEF_SAMPLING_DOWN_FACTOR                (1)
  34 #define MAX_SAMPLING_DOWN_FACTOR                (100000)
  35 #define MICRO_FREQUENCY_DOWN_DIFFERENTIAL       (3)
  36 #define MICRO_FREQUENCY_UP_THRESHOLD            (95)
  37 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE         (10000)
  38 #define MIN_FREQUENCY_UP_THRESHOLD              (11)
  39 #define MAX_FREQUENCY_UP_THRESHOLD              (100)
  40
  41 /*
  42  * The polling frequency of this governor depends on the capability of
  43  * the processor. Default polling frequency is 1000 times the transition
  44  * latency of the processor. The governor will work on any processor with
  45  * transition latency <= 10mS, using appropriate sampling
  46  * rate.
  47  * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
  48  * this governor will not work.
  49  * All times here are in uS.
  50  */
  51 #define MIN_SAMPLING_RATE_RATIO                 (2)
  52
  53 static unsigned int min_sampling_rate;
  54
  55 #define LATENCY_MULTIPLIER                      (1000)
  56 #define MIN_LATENCY_MULTIPLIER                  (100)
  57 #define TRANSITION_LATENCY_LIMIT                (10 * 1000 * 1000)
  58
  59 static void do_dbs_timer(struct work_struct *work);
  60 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
  61                                 unsigned int event);
  62
  63 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
  64 static
  65 #endif
  66 struct cpufreq_governor cpufreq_gov_ondemand = {
  67        .name                   = "ondemand",
  68        .governor               = cpufreq_governor_dbs,
  69        .max_transition_latency = TRANSITION_LATENCY_LIMIT,
  70        .owner                  = THIS_MODULE,
  71 };
  72
  73 /* Sampling types */
  74 enum {DBS_NORMAL_SAMPLE, DBS_SUB_SAMPLE};
  75
  76 struct cpu_dbs_info_s {
  77         cputime64_t prev_cpu_idle;
  78         cputime64_t prev_cpu_iowait;
  79         cputime64_t prev_cpu_wall;
  80         cputime64_t prev_cpu_nice;
  81         struct cpufreq_policy *cur_policy;
  82         struct delayed_work work;
  83         struct cpufreq_frequency_table *freq_table;
  84         unsigned int freq_lo;
  85         unsigned int freq_lo_jiffies;
  86         unsigned int freq_hi_jiffies;
  87         unsigned int rate_mult;
  88         int cpu;
  89         unsigned int sample_type:1;
  90         /*
  91          * percpu mutex that serializes governor limit change with
  92          * do_dbs_timer invocation. We do not want do_dbs_timer to run
  93          * when user is changing the governor or limits.
  94          */
  95         struct mutex timer_mutex;
  96 };
  97 static DEFINE_PER_CPU(struct cpu_dbs_info_s, od_cpu_dbs_info);
  98
  99 static unsigned int dbs_enable; /* number of CPUs using this policy */
 100
 101 /*
 102  * dbs_mutex protects data in dbs_tuners_ins from concurrent changes on
 103  * different CPUs. It protects dbs_enable in governor start/stop.
 104  */
 105 static DEFINE_MUTEX(dbs_mutex);
 106
 107 static struct workqueue_struct  *kondemand_wq;
 108
 109 static struct dbs_tuners {
 110         unsigned int sampling_rate;
 111         unsigned int up_threshold;
 112         unsigned int down_differential;
 113         unsigned int ignore_nice;
 114         unsigned int sampling_down_factor;
 115         unsigned int powersave_bias;
 116         unsigned int io_is_busy;
 117 } dbs_tuners_ins = {
 118         .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
 119         .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
 120         .down_differential = DEF_FREQUENCY_DOWN_DIFFERENTIAL,
 121         .ignore_nice = 0,
 122         .powersave_bias = 0,
 123 };
 124
 125 static inline cputime64_t get_cpu_idle_time_jiffy(unsigned int cpu,
 126                                                         cputime64_t *wall)
 127 {
 128         cputime64_t idle_time;
 129         cputime64_t cur_wall_time;
 130         cputime64_t busy_time;
 131
 132         cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
 133         busy_time = cputime64_add(kstat_cpu(cpu).cpustat.user,
 134                         kstat_cpu(cpu).cpustat.system);
 135
 136         busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.irq);
 137         busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.softirq);
 138         busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.steal);
 139         busy_time = cputime64_add(busy_time, kstat_cpu(cpu).cpustat.nice);
 140
 141         idle_time = cputime64_sub(cur_wall_time, busy_time);
 142         if (wall)
 143                 *wall = (cputime64_t)jiffies_to_usecs(cur_wall_time);
 144
 145         return (cputime64_t)jiffies_to_usecs(idle_time);
 146 }
 147
 148 static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
 149 {
 150         u64 idle_time = get_cpu_idle_time_us(cpu, wall);
 151
 152         if (idle_time == -1ULL)
 153                 return get_cpu_idle_time_jiffy(cpu, wall);
 154
 155         return idle_time;
 156 }
 157
 158 static inline cputime64_t get_cpu_iowait_time(unsigned int cpu, cputime64_t *wall)
 159 {
 160         u64 iowait_time = get_cpu_iowait_time_us(cpu, wall);
 161
 162         if (iowait_time == -1ULL)
 163                 return 0;
 164
 165         return iowait_time;
 166 }
 167
 168 /*
 169  * Find right freq to be set now with powersave_bias on.
 170  * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
 171  * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
 172  */
 173 static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
 174                                           unsigned int freq_next,
 175                                           unsigned int relation)
 176 {
 177         unsigned int freq_req, freq_reduc, freq_avg;
 178         unsigned int freq_hi, freq_lo;
 179         unsigned int index = 0;
 180         unsigned int jiffies_total, jiffies_hi, jiffies_lo;
 181         struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
 182                                                    policy->cpu);
 183
 184         if (!dbs_info->freq_table) {
 185                 dbs_info->freq_lo = 0;
 186                 dbs_info->freq_lo_jiffies = 0;
 187                 return freq_next;
 188         }
 189
 190         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
 191                         relation, &index);
 192         freq_req = dbs_info->freq_table[index].frequency;
 193         freq_reduc = freq_req * dbs_tuners_ins.powersave_bias / 1000;
 194         freq_avg = freq_req - freq_reduc;
 195
 196         /* Find freq bounds for freq_avg in freq_table */
 197         index = 0;
 198         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
 199                         CPUFREQ_RELATION_H, &index);
 200         freq_lo = dbs_info->freq_table[index].frequency;
 201         index = 0;
 202         cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
 203                         CPUFREQ_RELATION_L, &index);
 204         freq_hi = dbs_info->freq_table[index].frequency;
 205
 206         /* Find out how long we have to be in hi and lo freqs */
 207         if (freq_hi == freq_lo) {
 208                 dbs_info->freq_lo = 0;
 209                 dbs_info->freq_lo_jiffies = 0;
 210                 return freq_lo;
 211         }
 212         jiffies_total = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
 213         jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
 214         jiffies_hi += ((freq_hi - freq_lo) / 2);
 215         jiffies_hi /= (freq_hi - freq_lo);
 216         jiffies_lo = jiffies_total - jiffies_hi;
 217         dbs_info->freq_lo = freq_lo;
 218         dbs_info->freq_lo_jiffies = jiffies_lo;
 219         dbs_info->freq_hi_jiffies = jiffies_hi;
 220         return freq_hi;
 221 }
 222
 223 static void ondemand_powersave_bias_init_cpu(int cpu)
 224 {
 225         struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 226         dbs_info->freq_table = cpufreq_frequency_get_table(cpu);
 227         dbs_info->freq_lo = 0;
 228 }
 229
 230 static void ondemand_powersave_bias_init(void)
 231 {
 232         int i;
 233         for_each_online_cpu(i) {
 234                 ondemand_powersave_bias_init_cpu(i);
 235         }
 236 }
 237
 238 /************************** sysfs interface ************************/
 239
 240 static ssize_t show_sampling_rate_max(struct kobject *kobj,
 241                                       struct attribute *attr, char *buf)
 242 {
 243         printk_once(KERN_INFO "CPUFREQ: ondemand sampling_rate_max "
 244                "sysfs file is deprecated - used by: %s\n", current->comm);
 245         return sprintf(buf, "%u\n", -1U);
 246 }
 247
 248 static ssize_t show_sampling_rate_min(struct kobject *kobj,
 249                                       struct attribute *attr, char *buf)
 250 {
 251         return sprintf(buf, "%u\n", min_sampling_rate);
 252 }
 253
 254 define_one_global_ro(sampling_rate_max);
 255 define_one_global_ro(sampling_rate_min);
 256
 257 /* cpufreq_ondemand Governor Tunables */
 258 #define show_one(file_name, object)                                     \
 259 static ssize_t show_##file_name                                         \
 260 (struct kobject *kobj, struct attribute *attr, char *buf)              \
 261 {                                                                       \
 262         return sprintf(buf, "%u\n", dbs_tuners_ins.object);             \
 263 }
 264 show_one(sampling_rate, sampling_rate);
 265 show_one(io_is_busy, io_is_busy);
 266 show_one(up_threshold, up_threshold);
 267 show_one(sampling_down_factor, sampling_down_factor);
 268 show_one(ignore_nice_load, ignore_nice);
 269 show_one(powersave_bias, powersave_bias);
 270
 271 /*** delete after deprecation time ***/
 272
 273 #define DEPRECATION_MSG(file_name)                                      \
 274         printk_once(KERN_INFO "CPUFREQ: Per core ondemand sysfs "       \
 275                     "interface is deprecated - " #file_name "\n");
 276
 277 #define show_one_old(file_name)                                         \
 278 static ssize_t show_##file_name##_old                                   \
 279 (struct cpufreq_policy *unused, char *buf)                              \
 280 {                                                                       \
 281         printk_once(KERN_INFO "CPUFREQ: Per core ondemand sysfs "       \
 282                     "interface is deprecated - " #file_name "\n");      \
 283         return show_##file_name(NULL, NULL, buf);                       \
 284 }
 285 show_one_old(sampling_rate);
 286 show_one_old(up_threshold);
 287 show_one_old(ignore_nice_load);
 288 show_one_old(powersave_bias);
 289 show_one_old(sampling_rate_min);
 290 show_one_old(sampling_rate_max);
 291
 292 cpufreq_freq_attr_ro_old(sampling_rate_min);
 293 cpufreq_freq_attr_ro_old(sampling_rate_max);
 294
 295 /*** delete after deprecation time ***/
 296
 297 static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
 298                                    const char *buf, size_t count)
 299 {
 300         unsigned int input;
 301         int ret;
 302         ret = sscanf(buf, "%u", &input);
 303         if (ret != 1)
 304                 return -EINVAL;
 305
 306         mutex_lock(&dbs_mutex);
 307         dbs_tuners_ins.sampling_rate = max(input, min_sampling_rate);
 308         mutex_unlock(&dbs_mutex);
 309
 310         return count;
 311 }
 312
 313 static ssize_t store_io_is_busy(struct kobject *a, struct attribute *b,
 314                                    const char *buf, size_t count)
 315 {
 316         unsigned int input;
 317         int ret;
 318
 319         ret = sscanf(buf, "%u", &input);
 320         if (ret != 1)
 321                 return -EINVAL;
 322
 323         mutex_lock(&dbs_mutex);
 324         dbs_tuners_ins.io_is_busy = !!input;
 325         mutex_unlock(&dbs_mutex);
 326
 327         return count;
 328 }
 329
 330 static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
 331                                   const char *buf, size_t count)
 332 {
 333         unsigned int input;
 334         int ret;
 335         ret = sscanf(buf, "%u", &input);
 336
 337         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 338                         input < MIN_FREQUENCY_UP_THRESHOLD) {
 339                 return -EINVAL;
 340         }
 341
 342         mutex_lock(&dbs_mutex);
 343         dbs_tuners_ins.up_threshold = input;
 344         mutex_unlock(&dbs_mutex);
 345
 346         return count;
 347 }
 348
 349 static ssize_t store_sampling_down_factor(struct kobject *a,
 350                         struct attribute *b, const char *buf, size_t count)
 351 {
 352         unsigned int input, j;
 353         int ret;
 354         ret = sscanf(buf, "%u", &input);
 355
 356         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 357                 return -EINVAL;
 358         mutex_lock(&dbs_mutex);
 359         dbs_tuners_ins.sampling_down_factor = input;
 360
 361         /* Reset down sampling multiplier in case it was active */
 362         for_each_online_cpu(j) {
 363                 struct cpu_dbs_info_s *dbs_info;
 364                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
 365                 dbs_info->rate_mult = 1;
 366         }
 367         mutex_unlock(&dbs_mutex);
 368
 369         return count;
 370 }
 371
 372 static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
 373                                       const char *buf, size_t count)
 374 {
 375         unsigned int input;
 376         int ret;
 377
 378         unsigned int j;
 379
 380         ret = sscanf(buf, "%u", &input);
 381         if (ret != 1)
 382                 return -EINVAL;
 383
 384         if (input > 1)
 385                 input = 1;
 386
 387         mutex_lock(&dbs_mutex);
 388         if (input == dbs_tuners_ins.ignore_nice) { /* nothing to do */
 389                 mutex_unlock(&dbs_mutex);
 390                 return count;
 391         }
 392         dbs_tuners_ins.ignore_nice = input;
 393
 394         /* we need to re-evaluate prev_cpu_idle */
 395         for_each_online_cpu(j) {
 396                 struct cpu_dbs_info_s *dbs_info;
 397                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
 398                 dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
 399                                                 &dbs_info->prev_cpu_wall);
 400                 if (dbs_tuners_ins.ignore_nice)
 401                         dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
 402
 403         }
 404         mutex_unlock(&dbs_mutex);
 405
 406         return count;
 407 }
 408
 409 static ssize_t store_powersave_bias(struct kobject *a, struct attribute *b,
 410                                     const char *buf, size_t count)
 411 {
 412         unsigned int input;
 413         int ret;
 414         ret = sscanf(buf, "%u", &input);
 415
 416         if (ret != 1)
 417                 return -EINVAL;
 418
 419         if (input > 1000)
 420                 input = 1000;
 421
 422         mutex_lock(&dbs_mutex);
 423         dbs_tuners_ins.powersave_bias = input;
 424         ondemand_powersave_bias_init();
 425         mutex_unlock(&dbs_mutex);
 426
 427         return count;
 428 }
 429
 430 define_one_global_rw(sampling_rate);
 431 define_one_global_rw(io_is_busy);
 432 define_one_global_rw(up_threshold);
 433 define_one_global_rw(sampling_down_factor);
 434 define_one_global_rw(ignore_nice_load);
 435 define_one_global_rw(powersave_bias);
 436
 437 static struct attribute *dbs_attributes[] = {
 438         &sampling_rate_max.attr,
 439         &sampling_rate_min.attr,
 440         &sampling_rate.attr,
 441         &up_threshold.attr,
 442         &sampling_down_factor.attr,
 443         &ignore_nice_load.attr,
 444         &powersave_bias.attr,
 445         &io_is_busy.attr,
 446         NULL
 447 };
 448
 449 static struct attribute_group dbs_attr_group = {
 450         .attrs = dbs_attributes,
 451         .name = "ondemand",
 452 };
 453
 454 /*** delete after deprecation time ***/
 455
 456 #define write_one_old(file_name)                                        \
 457 static ssize_t store_##file_name##_old                                  \
 458 (struct cpufreq_policy *unused, const char *buf, size_t count)          \
 459 {                                                                       \
 460        printk_once(KERN_INFO "CPUFREQ: Per core ondemand sysfs "        \
 461                    "interface is deprecated - " #file_name "\n");       \
 462        return store_##file_name(NULL, NULL, buf, count);                \
 463 }
 464 write_one_old(sampling_rate);
 465 write_one_old(up_threshold);
 466 write_one_old(ignore_nice_load);
 467 write_one_old(powersave_bias);
 468
 469 cpufreq_freq_attr_rw_old(sampling_rate);
 470 cpufreq_freq_attr_rw_old(up_threshold);
 471 cpufreq_freq_attr_rw_old(ignore_nice_load);
 472 cpufreq_freq_attr_rw_old(powersave_bias);
 473
 474 static struct attribute *dbs_attributes_old[] = {
 475        &sampling_rate_max_old.attr,
 476        &sampling_rate_min_old.attr,
 477        &sampling_rate_old.attr,
 478        &up_threshold_old.attr,
 479        &ignore_nice_load_old.attr,
 480        &powersave_bias_old.attr,
 481        NULL
 482 };
 483
 484 static struct attribute_group dbs_attr_group_old = {
 485        .attrs = dbs_attributes_old,
 486        .name = "ondemand",
 487 };
 488
 489 /*** delete after deprecation time ***/
 490
 491 /************************** sysfs end ************************/
 492
 493 static void dbs_freq_increase(struct cpufreq_policy *p, unsigned int freq)
 494 {
 495         if (dbs_tuners_ins.powersave_bias)
 496                 freq = powersave_bias_target(p, freq, CPUFREQ_RELATION_H);
 497         else if (p->cur == p->max)
 498                 return;
 499
 500         __cpufreq_driver_target(p, freq, dbs_tuners_ins.powersave_bias ?
 501                         CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
 502 }
 503
 504 static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
 505 {
 506         unsigned int max_load_freq;
 507
 508         struct cpufreq_policy *policy;
 509         unsigned int j;
 510
 511         this_dbs_info->freq_lo = 0;
 512         policy = this_dbs_info->cur_policy;
 513
 514         /*
 515          * Every sampling_rate, we check, if current idle time is less
 516          * than 20% (default), then we try to increase frequency
 517          * Every sampling_rate, we look for a the lowest
 518          * frequency which can sustain the load while keeping idle time over
 519          * 30%. If such a frequency exist, we try to decrease to this frequency.
 520          *
 521          * Any frequency increase takes it to the maximum frequency.
 522          * Frequency reduction happens at minimum steps of
 523          * 5% (default) of current frequency
 524          */
 525
 526         /* Get Absolute Load - in terms of freq */
 527         max_load_freq = 0;
 528
 529         for_each_cpu(j, policy->cpus) {
 530                 struct cpu_dbs_info_s *j_dbs_info;
 531                 cputime64_t cur_wall_time, cur_idle_time, cur_iowait_time;
 532                 unsigned int idle_time, wall_time, iowait_time;
 533                 unsigned int load, load_freq;
 534                 int freq_avg;
 535
 536                 j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
 537
 538                 cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
 539                 cur_iowait_time = get_cpu_iowait_time(j, &cur_wall_time);
 540
 541                 wall_time = (unsigned int) cputime64_sub(cur_wall_time,
 542                                 j_dbs_info->prev_cpu_wall);
 543                 j_dbs_info->prev_cpu_wall = cur_wall_time;
 544
 545                 idle_time = (unsigned int) cputime64_sub(cur_idle_time,
 546                                 j_dbs_info->prev_cpu_idle);
 547                 j_dbs_info->prev_cpu_idle = cur_idle_time;
 548
 549                 iowait_time = (unsigned int) cputime64_sub(cur_iowait_time,
 550                                 j_dbs_info->prev_cpu_iowait);
 551                 j_dbs_info->prev_cpu_iowait = cur_iowait_time;
 552
 553                 if (dbs_tuners_ins.ignore_nice) {
 554                         cputime64_t cur_nice;
 555                         unsigned long cur_nice_jiffies;
 556
 557                         cur_nice = cputime64_sub(kstat_cpu(j).cpustat.nice,
 558                                          j_dbs_info->prev_cpu_nice);
 559                         /*
 560                          * Assumption: nice time between sampling periods will
 561                          * be less than 2^32 jiffies for 32 bit sys
 562                          */
 563                         cur_nice_jiffies = (unsigned long)
 564                                         cputime64_to_jiffies64(cur_nice);
 565
 566                         j_dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
 567                         idle_time += jiffies_to_usecs(cur_nice_jiffies);
 568                 }
 569
 570                 /*
 571                  * For the purpose of ondemand, waiting for disk IO is an
 572                  * indication that you're performance critical, and not that
 573                  * the system is actually idle. So subtract the iowait time
 574                  * from the cpu idle time.
 575                  */
 576
 577                 if (dbs_tuners_ins.io_is_busy && idle_time >= iowait_time)
 578                         idle_time -= iowait_time;
 579
 580                 if (unlikely(!wall_time || wall_time < idle_time))
 581                         continue;
 582
 583                 load = 100 * (wall_time - idle_time) / wall_time;
 584
 585                 freq_avg = __cpufreq_driver_getavg(policy, j);
 586                 if (freq_avg <= 0)
 587                         freq_avg = policy->cur;
 588
 589                 load_freq = load * freq_avg;
 590                 if (load_freq > max_load_freq)
 591                         max_load_freq = load_freq;
 592         }
 593
 594         /* Check for frequency increase */
 595         if (max_load_freq > dbs_tuners_ins.up_threshold * policy->cur) {
 596                 /* If switching to max speed, apply sampling_down_factor */
 597                 if (policy->cur < policy->max)
 598                         this_dbs_info->rate_mult =
 599                                 dbs_tuners_ins.sampling_down_factor;
 600                 dbs_freq_increase(policy, policy->max);
 601                 return;
 602         }
 603
 604         /* Check for frequency decrease */
 605         /* if we cannot reduce the frequency anymore, break out early */
 606         if (policy->cur == policy->min)
 607                 return;
 608
 609         /*
 610          * The optimal frequency is the frequency that is the lowest that
 611          * can support the current CPU usage without triggering the up
 612          * policy. To be safe, we focus 10 points under the threshold.
 613          */
 614         if (max_load_freq <
 615             (dbs_tuners_ins.up_threshold - dbs_tuners_ins.down_differential) *
 616              policy->cur) {
 617                 unsigned int freq_next;
 618                 freq_next = max_load_freq /
 619                                 (dbs_tuners_ins.up_threshold -
 620                                  dbs_tuners_ins.down_differential);
 621
 622                 /* No longer fully busy, reset rate_mult */
 623                 this_dbs_info->rate_mult = 1;
 624
 625                 if (freq_next < policy->min)
 626                         freq_next = policy->min;
 627
 628                 if (!dbs_tuners_ins.powersave_bias) {
 629                         __cpufreq_driver_target(policy, freq_next,
 630                                         CPUFREQ_RELATION_L);
 631                 } else {
 632                         int freq = powersave_bias_target(policy, freq_next,
 633                                         CPUFREQ_RELATION_L);
 634                         __cpufreq_driver_target(policy, freq,
 635                                 CPUFREQ_RELATION_L);
 636                 }
 637         }
 638 }
 639
 640 static void do_dbs_timer(struct work_struct *work)
 641 {
 642         struct cpu_dbs_info_s *dbs_info =
 643                 container_of(work, struct cpu_dbs_info_s, work.work);
 644         unsigned int cpu = dbs_info->cpu;
 645         int sample_type = dbs_info->sample_type;
 646
 647         /* We want all CPUs to do sampling nearly on same jiffy */
 648         int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate
 649                 * dbs_info->rate_mult);
 650
 651         if (num_online_cpus() > 1)
 652                 delay -= jiffies % delay;
 653
 654         mutex_lock(&dbs_info->timer_mutex);
 655
 656         /* Common NORMAL_SAMPLE setup */
 657         dbs_info->sample_type = DBS_NORMAL_SAMPLE;
 658         if (!dbs_tuners_ins.powersave_bias ||
 659             sample_type == DBS_NORMAL_SAMPLE) {
 660                 dbs_check_cpu(dbs_info);
 661                 if (dbs_info->freq_lo) {
 662                         /* Setup timer for SUB_SAMPLE */
 663                         dbs_info->sample_type = DBS_SUB_SAMPLE;
 664                         delay = dbs_info->freq_hi_jiffies;
 665                 }
 666         } else {
 667                 __cpufreq_driver_target(dbs_info->cur_policy,
 668                         dbs_info->freq_lo, CPUFREQ_RELATION_H);
 669         }
 670         queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work, delay);
 671         mutex_unlock(&dbs_info->timer_mutex);
 672 }
 673
 674 static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
 675 {
 676         /* We want all CPUs to do sampling nearly on same jiffy */
 677         int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
 678
 679         if (num_online_cpus() > 1)
 680                 delay -= jiffies % delay;
 681
 682         dbs_info->sample_type = DBS_NORMAL_SAMPLE;
 683         INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer);
 684         queue_delayed_work_on(dbs_info->cpu, kondemand_wq, &dbs_info->work,
 685                 delay);
 686 }
 687
 688 static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
 689 {
 690         cancel_delayed_work_sync(&dbs_info->work);
 691 }
 692
 693 /*
 694  * Not all CPUs want IO time to be accounted as busy; this dependson how
 695  * efficient idling at a higher frequency/voltage is.
 696  * Pavel Machek says this is not so for various generations of AMD and old
 697  * Intel systems.
 698  * Mike Chan (androidlcom) calis this is also not true for ARM.
 699  * Because of this, whitelist specific known (series) of CPUs by default, and
 700  * leave all others up to the user.
 701  */
 702 static int should_io_be_busy(void)
 703 {
 704 #if defined(CONFIG_X86)
 705         /*
 706          * For Intel, Core 2 (model 15) andl later have an efficient idle.
 707          */
 708         if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
 709             boot_cpu_data.x86 == 6 &&
 710             boot_cpu_data.x86_model >= 15)
 711                 return 1;
 712 #endif
 713         return 0;
 714 }
 715
 716 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 717                                    unsigned int event)
 718 {
 719         unsigned int cpu = policy->cpu;
 720         struct cpu_dbs_info_s *this_dbs_info;
 721         unsigned int j;
 722         int rc;
 723
 724         this_dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 725
 726         switch (event) {
 727         case CPUFREQ_GOV_START:
 728                 if ((!cpu_online(cpu)) || (!policy->cur))
 729                         return -EINVAL;
 730
 731                 mutex_lock(&dbs_mutex);
 732
 733                 rc = sysfs_create_group(&policy->kobj, &dbs_attr_group_old);
 734                 if (rc) {
 735                         mutex_unlock(&dbs_mutex);
 736                         return rc;
 737                 }
 738
 739                 dbs_enable++;
 740                 for_each_cpu(j, policy->cpus) {
 741                         struct cpu_dbs_info_s *j_dbs_info;
 742                         j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
 743                         j_dbs_info->cur_policy = policy;
 744
 745                         j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
 746                                                 &j_dbs_info->prev_cpu_wall);
 747                         if (dbs_tuners_ins.ignore_nice) {
 748                                 j_dbs_info->prev_cpu_nice =
 749                                                 kstat_cpu(j).cpustat.nice;
 750                         }
 751                 }
 752                 this_dbs_info->cpu = cpu;
 753                 this_dbs_info->rate_mult = 1;
 754                 ondemand_powersave_bias_init_cpu(cpu);
 755                 /*
 756                  * Start the timerschedule work, when this governor
 757                  * is used for first time
 758                  */
 759                 if (dbs_enable == 1) {
 760                         unsigned int latency;
 761
 762                         rc = sysfs_create_group(cpufreq_global_kobject,
 763                                                 &dbs_attr_group);
 764                         if (rc) {
 765                                 mutex_unlock(&dbs_mutex);
 766                                 return rc;
 767                         }
 768
 769                         /* policy latency is in nS. Convert it to uS first */
 770                         latency = policy->cpuinfo.transition_latency / 1000;
 771                         if (latency == 0)
 772                                 latency = 1;
 773                         /* Bring kernel and HW constraints together */
 774                         min_sampling_rate = max(min_sampling_rate,
 775                                         MIN_LATENCY_MULTIPLIER * latency);
 776                         dbs_tuners_ins.sampling_rate =
 777                                 max(min_sampling_rate,
 778                                     latency * LATENCY_MULTIPLIER);
 779                         dbs_tuners_ins.io_is_busy = should_io_be_busy();
 780                 }
 781                 mutex_unlock(&dbs_mutex);
 782
 783                 mutex_init(&this_dbs_info->timer_mutex);
 784                 dbs_timer_init(this_dbs_info);
 785                 break;
 786
 787         case CPUFREQ_GOV_STOP:
 788                 dbs_timer_exit(this_dbs_info);
 789
 790                 mutex_lock(&dbs_mutex);
 791                 sysfs_remove_group(&policy->kobj, &dbs_attr_group_old);
 792                 mutex_destroy(&this_dbs_info->timer_mutex);
 793                 dbs_enable--;
 794                 mutex_unlock(&dbs_mutex);
 795                 if (!dbs_enable)
 796                         sysfs_remove_group(cpufreq_global_kobject,
 797                                            &dbs_attr_group);
 798
 799                 break;
 800
 801         case CPUFREQ_GOV_LIMITS:
 802                 mutex_lock(&this_dbs_info->timer_mutex);
 803                 if (policy->max < this_dbs_info->cur_policy->cur)
 804                         __cpufreq_driver_target(this_dbs_info->cur_policy,
 805                                 policy->max, CPUFREQ_RELATION_H);
 806                 else if (policy->min > this_dbs_info->cur_policy->cur)
 807                         __cpufreq_driver_target(this_dbs_info->cur_policy,
 808                                 policy->min, CPUFREQ_RELATION_L);
 809                 mutex_unlock(&this_dbs_info->timer_mutex);
 810                 break;
 811         }
 812         return 0;
 813 }
 814
 815 static int __init cpufreq_gov_dbs_init(void)
 816 {
 817         int err;
 818         cputime64_t wall;
 819         u64 idle_time;
 820         int cpu = get_cpu();
 821
 822         idle_time = get_cpu_idle_time_us(cpu, &wall);
 823         put_cpu();
 824         if (idle_time != -1ULL) {
 825                 /* Idle micro accounting is supported. Use finer thresholds */
 826                 dbs_tuners_ins.up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
 827                 dbs_tuners_ins.down_differential =
 828                                         MICRO_FREQUENCY_DOWN_DIFFERENTIAL;
 829                 /*
 830                  * In no_hz/micro accounting case we set the minimum frequency
 831                  * not depending on HZ, but fixed (very low). The deferred
 832                  * timer might skip some samples if idle/sleeping as needed.
 833                 */
 834                 min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
 835         } else {
 836                 /* For correct statistics, we need 10 ticks for each measure */
 837                 min_sampling_rate =
 838                         MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10);
 839         }
 840
 841         kondemand_wq = create_workqueue("kondemand");
 842         if (!kondemand_wq) {
 843                 printk(KERN_ERR "Creation of kondemand failed\n");
 844                 return -EFAULT;
 845         }
 846         err = cpufreq_register_governor(&cpufreq_gov_ondemand);
 847         if (err)
 848                 destroy_workqueue(kondemand_wq);
 849
 850         return err;
 851 }
 852
 853 static void __exit cpufreq_gov_dbs_exit(void)
 854 {
 855         cpufreq_unregister_governor(&cpufreq_gov_ondemand);
 856         destroy_workqueue(kondemand_wq);
 857 }
 858
 859
 860 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
 861 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
 862 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
 863         "Low Latency Frequency Transition capable processors");
 864 MODULE_LICENSE("GPL");
 865
 866 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 867 fs_initcall(cpufreq_gov_dbs_init);
 868 #else
 869 module_init(cpufreq_gov_dbs_init);
 870 #endif
 871 module_exit(cpufreq_gov_dbs_exit);