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 define_one_ro(_name)            \
 250 static struct global_attr _name =       \
 251 __ATTR(_name, 0444, show_##_name, NULL)
 252
 253 define_one_ro(sampling_rate_max);
 254 define_one_ro(sampling_rate_min);
 255
 256 /* cpufreq_ondemand Governor Tunables */
 257 #define show_one(file_name, object)                                     \
 258 static ssize_t show_##file_name                                         \
 259 (struct kobject *kobj, struct attribute *attr, char *buf)              \
 260 {                                                                       \
 261         return sprintf(buf, "%u\n", dbs_tuners_ins.object);             \
 262 }
 263 show_one(sampling_rate, sampling_rate);
 264 show_one(io_is_busy, io_is_busy);
 265 show_one(up_threshold, up_threshold);
 266 show_one(ignore_nice_load, ignore_nice);
 267 show_one(powersave_bias, powersave_bias);
 268
 269 /*** delete after deprecation time ***/
 270
 271 #define DEPRECATION_MSG(file_name)                                      \
 272         printk_once(KERN_INFO "CPUFREQ: Per core ondemand sysfs "       \
 273                     "interface is deprecated - " #file_name "\n");
 274
 275 #define show_one_old(file_name)                                         \
 276 static ssize_t show_##file_name##_old                                   \
 277 (struct cpufreq_policy *unused, char *buf)                              \
 278 {                                                                       \
 279         printk_once(KERN_INFO "CPUFREQ: Per core ondemand sysfs "       \
 280                     "interface is deprecated - " #file_name "\n");      \
 281         return show_##file_name(NULL, NULL, buf);                       \
 282 }
 283 show_one_old(sampling_rate);
 284 show_one_old(up_threshold);
 285 show_one_old(ignore_nice_load);
 286 show_one_old(powersave_bias);
 287 show_one_old(sampling_rate_min);
 288 show_one_old(sampling_rate_max);
 289
 290 #define define_one_ro_old(object, _name)       \
 291 static struct freq_attr object =               \
 292 __ATTR(_name, 0444, show_##_name##_old, NULL)
 293
 294 define_one_ro_old(sampling_rate_min_old, sampling_rate_min);
 295 define_one_ro_old(sampling_rate_max_old, sampling_rate_max);
 296
 297 /*** delete after deprecation time ***/
 298
 299 static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
 300                                    const char *buf, size_t count)
 301 {
 302         unsigned int input;
 303         int ret;
 304         ret = sscanf(buf, "%u", &input);
 305         if (ret != 1)
 306                 return -EINVAL;
 307
 308         mutex_lock(&dbs_mutex);
 309         dbs_tuners_ins.sampling_rate = max(input, min_sampling_rate);
 310         mutex_unlock(&dbs_mutex);
 311
 312         return count;
 313 }
 314
 315 static ssize_t store_io_is_busy(struct kobject *a, struct attribute *b,
 316                                    const char *buf, size_t count)
 317 {
 318         unsigned int input;
 319         int ret;
 320
 321         ret = sscanf(buf, "%u", &input);
 322         if (ret != 1)
 323                 return -EINVAL;
 324
 325         mutex_lock(&dbs_mutex);
 326         dbs_tuners_ins.io_is_busy = !!input;
 327         mutex_unlock(&dbs_mutex);
 328
 329         return count;
 330 }
 331
 332 static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
 333                                   const char *buf, size_t count)
 334 {
 335         unsigned int input;
 336         int ret;
 337         ret = sscanf(buf, "%u", &input);
 338
 339         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 340                         input < MIN_FREQUENCY_UP_THRESHOLD) {
 341                 return -EINVAL;
 342         }
 343
 344         mutex_lock(&dbs_mutex);
 345         dbs_tuners_ins.up_threshold = input;
 346         mutex_unlock(&dbs_mutex);
 347
 348         return count;
 349 }
 350
 351 static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
 352                                       const char *buf, size_t count)
 353 {
 354         unsigned int input;
 355         int ret;
 356
 357         unsigned int j;
 358
 359         ret = sscanf(buf, "%u", &input);
 360         if (ret != 1)
 361                 return -EINVAL;
 362
 363         if (input > 1)
 364                 input = 1;
 365
 366         mutex_lock(&dbs_mutex);
 367         if (input == dbs_tuners_ins.ignore_nice) { /* nothing to do */
 368                 mutex_unlock(&dbs_mutex);
 369                 return count;
 370         }
 371         dbs_tuners_ins.ignore_nice = input;
 372
 373         /* we need to re-evaluate prev_cpu_idle */
 374         for_each_online_cpu(j) {
 375                 struct cpu_dbs_info_s *dbs_info;
 376                 dbs_info = &per_cpu(od_cpu_dbs_info, j);
 377                 dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
 378                                                 &dbs_info->prev_cpu_wall);
 379                 if (dbs_tuners_ins.ignore_nice)
 380                         dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
 381
 382         }
 383         mutex_unlock(&dbs_mutex);
 384
 385         return count;
 386 }
 387
 388 static ssize_t store_powersave_bias(struct kobject *a, struct attribute *b,
 389                                     const char *buf, size_t count)
 390 {
 391         unsigned int input;
 392         int ret;
 393         ret = sscanf(buf, "%u", &input);
 394
 395         if (ret != 1)
 396                 return -EINVAL;
 397
 398         if (input > 1000)
 399                 input = 1000;
 400
 401         mutex_lock(&dbs_mutex);
 402         dbs_tuners_ins.powersave_bias = input;
 403         ondemand_powersave_bias_init();
 404         mutex_unlock(&dbs_mutex);
 405
 406         return count;
 407 }
 408
 409 #define define_one_rw(_name) \
 410 static struct global_attr _name = \
 411 __ATTR(_name, 0644, show_##_name, store_##_name)
 412
 413 define_one_rw(sampling_rate);
 414 define_one_rw(io_is_busy);
 415 define_one_rw(up_threshold);
 416 define_one_rw(ignore_nice_load);
 417 define_one_rw(powersave_bias);
 418
 419 static struct attribute *dbs_attributes[] = {
 420         &sampling_rate_max.attr,
 421         &sampling_rate_min.attr,
 422         &sampling_rate.attr,
 423         &up_threshold.attr,
 424         &ignore_nice_load.attr,
 425         &powersave_bias.attr,
 426         &io_is_busy.attr,
 427         NULL
 428 };
 429
 430 static struct attribute_group dbs_attr_group = {
 431         .attrs = dbs_attributes,
 432         .name = "ondemand",
 433 };
 434
 435 /*** delete after deprecation time ***/
 436
 437 #define write_one_old(file_name)                                        \
 438 static ssize_t store_##file_name##_old                                  \
 439 (struct cpufreq_policy *unused, const char *buf, size_t count)          \
 440 {                                                                       \
 441        printk_once(KERN_INFO "CPUFREQ: Per core ondemand sysfs "        \
 442                    "interface is deprecated - " #file_name "\n");       \
 443        return store_##file_name(NULL, NULL, buf, count);                \
 444 }
 445 write_one_old(sampling_rate);
 446 write_one_old(up_threshold);
 447 write_one_old(ignore_nice_load);
 448 write_one_old(powersave_bias);
 449
 450 #define define_one_rw_old(object, _name)       \
 451 static struct freq_attr object =               \
 452 __ATTR(_name, 0644, show_##_name##_old, store_##_name##_old)
 453
 454 define_one_rw_old(sampling_rate_old, sampling_rate);
 455 define_one_rw_old(up_threshold_old, up_threshold);
 456 define_one_rw_old(ignore_nice_load_old, ignore_nice_load);
 457 define_one_rw_old(powersave_bias_old, powersave_bias);
 458
 459 static struct attribute *dbs_attributes_old[] = {
 460        &sampling_rate_max_old.attr,
 461        &sampling_rate_min_old.attr,
 462        &sampling_rate_old.attr,
 463        &up_threshold_old.attr,
 464        &ignore_nice_load_old.attr,
 465        &powersave_bias_old.attr,
 466        NULL
 467 };
 468
 469 static struct attribute_group dbs_attr_group_old = {
 470        .attrs = dbs_attributes_old,
 471        .name = "ondemand",
 472 };
 473
 474 /*** delete after deprecation time ***/
 475
 476 /************************** sysfs end ************************/
 477
 478 static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
 479 {
 480         unsigned int max_load_freq;
 481
 482         struct cpufreq_policy *policy;
 483         unsigned int j;
 484
 485         this_dbs_info->freq_lo = 0;
 486         policy = this_dbs_info->cur_policy;
 487
 488         /*
 489          * Every sampling_rate, we check, if current idle time is less
 490          * than 20% (default), then we try to increase frequency
 491          * Every sampling_rate, we look for a the lowest
 492          * frequency which can sustain the load while keeping idle time over
 493          * 30%. If such a frequency exist, we try to decrease to this frequency.
 494          *
 495          * Any frequency increase takes it to the maximum frequency.
 496          * Frequency reduction happens at minimum steps of
 497          * 5% (default) of current frequency
 498          */
 499
 500         /* Get Absolute Load - in terms of freq */
 501         max_load_freq = 0;
 502
 503         for_each_cpu(j, policy->cpus) {
 504                 struct cpu_dbs_info_s *j_dbs_info;
 505                 cputime64_t cur_wall_time, cur_idle_time, cur_iowait_time;
 506                 unsigned int idle_time, wall_time, iowait_time;
 507                 unsigned int load, load_freq;
 508                 int freq_avg;
 509
 510                 j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
 511
 512                 cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
 513                 cur_iowait_time = get_cpu_iowait_time(j, &cur_wall_time);
 514
 515                 wall_time = (unsigned int) cputime64_sub(cur_wall_time,
 516                                 j_dbs_info->prev_cpu_wall);
 517                 j_dbs_info->prev_cpu_wall = cur_wall_time;
 518
 519                 idle_time = (unsigned int) cputime64_sub(cur_idle_time,
 520                                 j_dbs_info->prev_cpu_idle);
 521                 j_dbs_info->prev_cpu_idle = cur_idle_time;
 522
 523                 iowait_time = (unsigned int) cputime64_sub(cur_iowait_time,
 524                                 j_dbs_info->prev_cpu_iowait);
 525                 j_dbs_info->prev_cpu_iowait = cur_iowait_time;
 526
 527                 if (dbs_tuners_ins.ignore_nice) {
 528                         cputime64_t cur_nice;
 529                         unsigned long cur_nice_jiffies;
 530
 531                         cur_nice = cputime64_sub(kstat_cpu(j).cpustat.nice,
 532                                          j_dbs_info->prev_cpu_nice);
 533                         /*
 534                          * Assumption: nice time between sampling periods will
 535                          * be less than 2^32 jiffies for 32 bit sys
 536                          */
 537                         cur_nice_jiffies = (unsigned long)
 538                                         cputime64_to_jiffies64(cur_nice);
 539
 540                         j_dbs_info->prev_cpu_nice = kstat_cpu(j).cpustat.nice;
 541                         idle_time += jiffies_to_usecs(cur_nice_jiffies);
 542                 }
 543
 544                 /*
 545                  * For the purpose of ondemand, waiting for disk IO is an
 546                  * indication that you're performance critical, and not that
 547                  * the system is actually idle. So subtract the iowait time
 548                  * from the cpu idle time.
 549                  */
 550
 551                 if (dbs_tuners_ins.io_is_busy && idle_time >= iowait_time)
 552                         idle_time -= iowait_time;
 553
 554                 if (unlikely(!wall_time || wall_time < idle_time))
 555                         continue;
 556
 557                 load = 100 * (wall_time - idle_time) / wall_time;
 558
 559                 freq_avg = __cpufreq_driver_getavg(policy, j);
 560                 if (freq_avg <= 0)
 561                         freq_avg = policy->cur;
 562
 563                 load_freq = load * freq_avg;
 564                 if (load_freq > max_load_freq)
 565                         max_load_freq = load_freq;
 566         }
 567
 568         /* Check for frequency increase */
 569         if (max_load_freq > dbs_tuners_ins.up_threshold * policy->cur) {
 570                 /* if we are already at full speed then break out early */
 571                 if (!dbs_tuners_ins.powersave_bias) {
 572                         if (policy->cur == policy->max)
 573                                 return;
 574
 575                         __cpufreq_driver_target(policy, policy->max,
 576                                 CPUFREQ_RELATION_H);
 577                 } else {
 578                         int freq = powersave_bias_target(policy, policy->max,
 579                                         CPUFREQ_RELATION_H);
 580                         __cpufreq_driver_target(policy, freq,
 581                                 CPUFREQ_RELATION_L);
 582                 }
 583                 return;
 584         }
 585
 586         /* Check for frequency decrease */
 587         /* if we cannot reduce the frequency anymore, break out early */
 588         if (policy->cur == policy->min)
 589                 return;
 590
 591         /*
 592          * The optimal frequency is the frequency that is the lowest that
 593          * can support the current CPU usage without triggering the up
 594          * policy. To be safe, we focus 10 points under the threshold.
 595          */
 596         if (max_load_freq <
 597             (dbs_tuners_ins.up_threshold - dbs_tuners_ins.down_differential) *
 598              policy->cur) {
 599                 unsigned int freq_next;
 600                 freq_next = max_load_freq /
 601                                 (dbs_tuners_ins.up_threshold -
 602                                  dbs_tuners_ins.down_differential);
 603
 604                 if (freq_next < policy->min)
 605                         freq_next = policy->min;
 606
 607                 if (!dbs_tuners_ins.powersave_bias) {
 608                         __cpufreq_driver_target(policy, freq_next,
 609                                         CPUFREQ_RELATION_L);
 610                 } else {
 611                         int freq = powersave_bias_target(policy, freq_next,
 612                                         CPUFREQ_RELATION_L);
 613                         __cpufreq_driver_target(policy, freq,
 614                                 CPUFREQ_RELATION_L);
 615                 }
 616         }
 617 }
 618
 619 static void do_dbs_timer(struct work_struct *work)
 620 {
 621         struct cpu_dbs_info_s *dbs_info =
 622                 container_of(work, struct cpu_dbs_info_s, work.work);
 623         unsigned int cpu = dbs_info->cpu;
 624         int sample_type = dbs_info->sample_type;
 625
 626         /* We want all CPUs to do sampling nearly on same jiffy */
 627         int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
 628
 629         delay -= jiffies % delay;
 630         mutex_lock(&dbs_info->timer_mutex);
 631
 632         /* Common NORMAL_SAMPLE setup */
 633         dbs_info->sample_type = DBS_NORMAL_SAMPLE;
 634         if (!dbs_tuners_ins.powersave_bias ||
 635             sample_type == DBS_NORMAL_SAMPLE) {
 636                 dbs_check_cpu(dbs_info);
 637                 if (dbs_info->freq_lo) {
 638                         /* Setup timer for SUB_SAMPLE */
 639                         dbs_info->sample_type = DBS_SUB_SAMPLE;
 640                         delay = dbs_info->freq_hi_jiffies;
 641                 }
 642         } else {
 643                 __cpufreq_driver_target(dbs_info->cur_policy,
 644                         dbs_info->freq_lo, CPUFREQ_RELATION_H);
 645         }
 646         queue_delayed_work_on(cpu, kondemand_wq, &dbs_info->work, delay);
 647         mutex_unlock(&dbs_info->timer_mutex);
 648 }
 649
 650 static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
 651 {
 652         /* We want all CPUs to do sampling nearly on same jiffy */
 653         int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
 654         delay -= jiffies % delay;
 655
 656         dbs_info->sample_type = DBS_NORMAL_SAMPLE;
 657         INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer);
 658         queue_delayed_work_on(dbs_info->cpu, kondemand_wq, &dbs_info->work,
 659                 delay);
 660 }
 661
 662 static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
 663 {
 664         cancel_delayed_work_sync(&dbs_info->work);
 665 }
 666
 667 /*
 668  * Not all CPUs want IO time to be accounted as busy; this dependson how
 669  * efficient idling at a higher frequency/voltage is.
 670  * Pavel Machek says this is not so for various generations of AMD and old
 671  * Intel systems.
 672  * Mike Chan (androidlcom) calis this is also not true for ARM.
 673  * Because of this, whitelist specific known (series) of CPUs by default, and
 674  * leave all others up to the user.
 675  */
 676 static int should_io_be_busy(void)
 677 {
 678 #if defined(CONFIG_X86)
 679         /*
 680          * For Intel, Core 2 (model 15) andl later have an efficient idle.
 681          */
 682         if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
 683             boot_cpu_data.x86 == 6 &&
 684             boot_cpu_data.x86_model >= 15)
 685                 return 1;
 686 #endif
 687         return 0;
 688 }
 689
 690 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 691                                    unsigned int event)
 692 {
 693         unsigned int cpu = policy->cpu;
 694         struct cpu_dbs_info_s *this_dbs_info;
 695         unsigned int j;
 696         int rc;
 697
 698         this_dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
 699
 700         switch (event) {
 701         case CPUFREQ_GOV_START:
 702                 if ((!cpu_online(cpu)) || (!policy->cur))
 703                         return -EINVAL;
 704
 705                 mutex_lock(&dbs_mutex);
 706
 707                 rc = sysfs_create_group(&policy->kobj, &dbs_attr_group_old);
 708                 if (rc) {
 709                         mutex_unlock(&dbs_mutex);
 710                         return rc;
 711                 }
 712
 713                 dbs_enable++;
 714                 for_each_cpu(j, policy->cpus) {
 715                         struct cpu_dbs_info_s *j_dbs_info;
 716                         j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
 717                         j_dbs_info->cur_policy = policy;
 718
 719                         j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
 720                                                 &j_dbs_info->prev_cpu_wall);
 721                         if (dbs_tuners_ins.ignore_nice) {
 722                                 j_dbs_info->prev_cpu_nice =
 723                                                 kstat_cpu(j).cpustat.nice;
 724                         }
 725                 }
 726                 this_dbs_info->cpu = cpu;
 727                 ondemand_powersave_bias_init_cpu(cpu);
 728                 /*
 729                  * Start the timerschedule work, when this governor
 730                  * is used for first time
 731                  */
 732                 if (dbs_enable == 1) {
 733                         unsigned int latency;
 734
 735                         rc = sysfs_create_group(cpufreq_global_kobject,
 736                                                 &dbs_attr_group);
 737                         if (rc) {
 738                                 mutex_unlock(&dbs_mutex);
 739                                 return rc;
 740                         }
 741
 742                         /* policy latency is in nS. Convert it to uS first */
 743                         latency = policy->cpuinfo.transition_latency / 1000;
 744                         if (latency == 0)
 745                                 latency = 1;
 746                         /* Bring kernel and HW constraints together */
 747                         min_sampling_rate = max(min_sampling_rate,
 748                                         MIN_LATENCY_MULTIPLIER * latency);
 749                         dbs_tuners_ins.sampling_rate =
 750                                 max(min_sampling_rate,
 751                                     latency * LATENCY_MULTIPLIER);
 752                         dbs_tuners_ins.io_is_busy = should_io_be_busy();
 753                 }
 754                 mutex_unlock(&dbs_mutex);
 755
 756                 mutex_init(&this_dbs_info->timer_mutex);
 757                 dbs_timer_init(this_dbs_info);
 758                 break;
 759
 760         case CPUFREQ_GOV_STOP:
 761                 dbs_timer_exit(this_dbs_info);
 762
 763                 mutex_lock(&dbs_mutex);
 764                 sysfs_remove_group(&policy->kobj, &dbs_attr_group_old);
 765                 mutex_destroy(&this_dbs_info->timer_mutex);
 766                 dbs_enable--;
 767                 mutex_unlock(&dbs_mutex);
 768                 if (!dbs_enable)
 769                         sysfs_remove_group(cpufreq_global_kobject,
 770                                            &dbs_attr_group);
 771
 772                 break;
 773
 774         case CPUFREQ_GOV_LIMITS:
 775                 mutex_lock(&this_dbs_info->timer_mutex);
 776                 if (policy->max < this_dbs_info->cur_policy->cur)
 777                         __cpufreq_driver_target(this_dbs_info->cur_policy,
 778                                 policy->max, CPUFREQ_RELATION_H);
 779                 else if (policy->min > this_dbs_info->cur_policy->cur)
 780                         __cpufreq_driver_target(this_dbs_info->cur_policy,
 781                                 policy->min, CPUFREQ_RELATION_L);
 782                 mutex_unlock(&this_dbs_info->timer_mutex);
 783                 break;
 784         }
 785         return 0;
 786 }
 787
 788 static int __init cpufreq_gov_dbs_init(void)
 789 {
 790         int err;
 791         cputime64_t wall;
 792         u64 idle_time;
 793         int cpu = get_cpu();
 794
 795         idle_time = get_cpu_idle_time_us(cpu, &wall);
 796         put_cpu();
 797         if (idle_time != -1ULL) {
 798                 /* Idle micro accounting is supported. Use finer thresholds */
 799                 dbs_tuners_ins.up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
 800                 dbs_tuners_ins.down_differential =
 801                                         MICRO_FREQUENCY_DOWN_DIFFERENTIAL;
 802                 /*
 803                  * In no_hz/micro accounting case we set the minimum frequency
 804                  * not depending on HZ, but fixed (very low). The deferred
 805                  * timer might skip some samples if idle/sleeping as needed.
 806                 */
 807                 min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
 808         } else {
 809                 /* For correct statistics, we need 10 ticks for each measure */
 810                 min_sampling_rate =
 811                         MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10);
 812         }
 813
 814         kondemand_wq = create_workqueue("kondemand");
 815         if (!kondemand_wq) {
 816                 printk(KERN_ERR "Creation of kondemand failed\n");
 817                 return -EFAULT;
 818         }
 819         err = cpufreq_register_governor(&cpufreq_gov_ondemand);
 820         if (err)
 821                 destroy_workqueue(kondemand_wq);
 822
 823         return err;
 824 }
 825
 826 static void __exit cpufreq_gov_dbs_exit(void)
 827 {
 828         cpufreq_unregister_governor(&cpufreq_gov_ondemand);
 829         destroy_workqueue(kondemand_wq);
 830 }
 831
 832
 833 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
 834 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
 835 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
 836         "Low Latency Frequency Transition capable processors");
 837 MODULE_LICENSE("GPL");
 838
 839 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 840 fs_initcall(cpufreq_gov_dbs_init);
 841 #else
 842 module_init(cpufreq_gov_dbs_init);
 843 #endif
 844 module_exit(cpufreq_gov_dbs_exit);