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