Pileus Git - ~andy/linux/blob - drivers/cpufreq/cpufreq_conservative.c

   1 /*
   2  *  drivers/cpufreq/cpufreq_conservative.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  *            (C)  2004 Alexander Clouter <alex-kernel@digriz.org.uk>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/smp.h>
  17 #include <linux/init.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/ctype.h>
  20 #include <linux/cpufreq.h>
  21 #include <linux/sysctl.h>
  22 #include <linux/types.h>
  23 #include <linux/fs.h>
  24 #include <linux/sysfs.h>
  25 #include <linux/sched.h>
  26 #include <linux/kmod.h>
  27 #include <linux/workqueue.h>
  28 #include <linux/jiffies.h>
  29 #include <linux/kernel_stat.h>
  30 #include <linux/percpu.h>
  31
  32 /*
  33  * dbs is used in this file as a shortform for demandbased switching
  34  * It helps to keep variable names smaller, simpler
  35  */
  36
  37 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
  38 #define MIN_FREQUENCY_UP_THRESHOLD              (0)
  39 #define MAX_FREQUENCY_UP_THRESHOLD              (100)
  40
  41 #define DEF_FREQUENCY_DOWN_THRESHOLD            (20)
  42 #define MIN_FREQUENCY_DOWN_THRESHOLD            (0)
  43 #define MAX_FREQUENCY_DOWN_THRESHOLD            (100)
  44
  45 /*
  46  * The polling frequency of this governor depends on the capability of
  47  * the processor. Default polling frequency is 1000 times the transition
  48  * latency of the processor. The governor will work on any processor with
  49  * transition latency <= 10mS, using appropriate sampling
  50  * rate.
  51  * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
  52  * this governor will not work.
  53  * All times here are in uS.
  54  */
  55 static unsigned int                             def_sampling_rate;
  56 #define MIN_SAMPLING_RATE                       (def_sampling_rate / 2)
  57 #define MAX_SAMPLING_RATE                       (500 * def_sampling_rate)
  58 #define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER    (100000)
  59 #define DEF_SAMPLING_DOWN_FACTOR                (5)
  60 #define TRANSITION_LATENCY_LIMIT                (10 * 1000)
  61
  62 static void do_dbs_timer(void *data);
  63
  64 struct cpu_dbs_info_s {
  65         struct cpufreq_policy   *cur_policy;
  66         unsigned int            prev_cpu_idle_up;
  67         unsigned int            prev_cpu_idle_down;
  68         unsigned int            enable;
  69 };
  70 static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
  71
  72 static unsigned int dbs_enable; /* number of CPUs using this policy */
  73
  74 static DECLARE_MUTEX    (dbs_sem);
  75 static DECLARE_WORK     (dbs_work, do_dbs_timer, NULL);
  76
  77 struct dbs_tuners {
  78         unsigned int            sampling_rate;
  79         unsigned int            sampling_down_factor;
  80         unsigned int            up_threshold;
  81         unsigned int            down_threshold;
  82         unsigned int            ignore_nice;
  83         unsigned int            freq_step;
  84 };
  85
  86 static struct dbs_tuners dbs_tuners_ins = {
  87         .up_threshold           = DEF_FREQUENCY_UP_THRESHOLD,
  88         .down_threshold         = DEF_FREQUENCY_DOWN_THRESHOLD,
  89         .sampling_down_factor   = DEF_SAMPLING_DOWN_FACTOR,
  90 };
  91
  92 /************************** sysfs interface ************************/
  93 static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
  94 {
  95         return sprintf (buf, "%u\n", MAX_SAMPLING_RATE);
  96 }
  97
  98 static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf)
  99 {
 100         return sprintf (buf, "%u\n", MIN_SAMPLING_RATE);
 101 }
 102
 103 #define define_one_ro(_name)                                    \
 104 static struct freq_attr _name =                                 \
 105 __ATTR(_name, 0444, show_##_name, NULL)
 106
 107 define_one_ro(sampling_rate_max);
 108 define_one_ro(sampling_rate_min);
 109
 110 /* cpufreq_conservative Governor Tunables */
 111 #define show_one(file_name, object)                                     \
 112 static ssize_t show_##file_name                                         \
 113 (struct cpufreq_policy *unused, char *buf)                              \
 114 {                                                                       \
 115         return sprintf(buf, "%u\n", dbs_tuners_ins.object);             \
 116 }
 117 show_one(sampling_rate, sampling_rate);
 118 show_one(sampling_down_factor, sampling_down_factor);
 119 show_one(up_threshold, up_threshold);
 120 show_one(down_threshold, down_threshold);
 121 show_one(ignore_nice, ignore_nice);
 122 show_one(freq_step, freq_step);
 123
 124 static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
 125                 const char *buf, size_t count)
 126 {
 127         unsigned int input;
 128         int ret;
 129         ret = sscanf (buf, "%u", &input);
 130         if (ret != 1 )
 131                 return -EINVAL;
 132
 133         down(&dbs_sem);
 134         dbs_tuners_ins.sampling_down_factor = input;
 135         up(&dbs_sem);
 136
 137         return count;
 138 }
 139
 140 static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
 141                 const char *buf, size_t count)
 142 {
 143         unsigned int input;
 144         int ret;
 145         ret = sscanf (buf, "%u", &input);
 146
 147         down(&dbs_sem);
 148         if (ret != 1 || input > MAX_SAMPLING_RATE || input < MIN_SAMPLING_RATE) {
 149                 up(&dbs_sem);
 150                 return -EINVAL;
 151         }
 152
 153         dbs_tuners_ins.sampling_rate = input;
 154         up(&dbs_sem);
 155
 156         return count;
 157 }
 158
 159 static ssize_t store_up_threshold(struct cpufreq_policy *unused,
 160                 const char *buf, size_t count)
 161 {
 162         unsigned int input;
 163         int ret;
 164         ret = sscanf (buf, "%u", &input);
 165
 166         down(&dbs_sem);
 167         if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 168                         input < MIN_FREQUENCY_UP_THRESHOLD ||
 169                         input <= dbs_tuners_ins.down_threshold) {
 170                 up(&dbs_sem);
 171                 return -EINVAL;
 172         }
 173
 174         dbs_tuners_ins.up_threshold = input;
 175         up(&dbs_sem);
 176
 177         return count;
 178 }
 179
 180 static ssize_t store_down_threshold(struct cpufreq_policy *unused,
 181                 const char *buf, size_t count)
 182 {
 183         unsigned int input;
 184         int ret;
 185         ret = sscanf (buf, "%u", &input);
 186
 187         down(&dbs_sem);
 188         if (ret != 1 || input > MAX_FREQUENCY_DOWN_THRESHOLD ||
 189                         input < MIN_FREQUENCY_DOWN_THRESHOLD ||
 190                         input >= dbs_tuners_ins.up_threshold) {
 191                 up(&dbs_sem);
 192                 return -EINVAL;
 193         }
 194
 195         dbs_tuners_ins.down_threshold = input;
 196         up(&dbs_sem);
 197
 198         return count;
 199 }
 200
 201 static ssize_t store_ignore_nice(struct cpufreq_policy *policy,
 202                 const char *buf, size_t count)
 203 {
 204         unsigned int input;
 205         int ret;
 206
 207         unsigned int j;
 208
 209         ret = sscanf (buf, "%u", &input);
 210         if ( ret != 1 )
 211                 return -EINVAL;
 212
 213         if ( input > 1 )
 214                 input = 1;
 215
 216         down(&dbs_sem);
 217         if ( input == dbs_tuners_ins.ignore_nice ) { /* nothing to do */
 218                 up(&dbs_sem);
 219                 return count;
 220         }
 221         dbs_tuners_ins.ignore_nice = input;
 222
 223         /* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */
 224         for_each_cpu_mask(j, policy->cpus) {
 225                 struct cpu_dbs_info_s *j_dbs_info;
 226                 j_dbs_info = &per_cpu(cpu_dbs_info, j);
 227                 j_dbs_info->cur_policy = policy;
 228
 229                 j_dbs_info->prev_cpu_idle_up =
 230                         kstat_cpu(j).cpustat.idle +
 231                         kstat_cpu(j).cpustat.iowait +
 232                         ( !dbs_tuners_ins.ignore_nice
 233                           ? kstat_cpu(j).cpustat.nice : 0 );
 234                 j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up;
 235         }
 236         up(&dbs_sem);
 237
 238         return count;
 239 }
 240
 241 static ssize_t store_freq_step(struct cpufreq_policy *policy,
 242                 const char *buf, size_t count)
 243 {
 244         unsigned int input;
 245         int ret;
 246
 247         ret = sscanf (buf, "%u", &input);
 248
 249         if ( ret != 1 )
 250                 return -EINVAL;
 251
 252         if ( input > 100 )
 253                 input = 100;
 254
 255         /* no need to test here if freq_step is zero as the user might actually
 256          * want this, they would be crazy though :) */
 257         down(&dbs_sem);
 258         dbs_tuners_ins.freq_step = input;
 259         up(&dbs_sem);
 260
 261         return count;
 262 }
 263
 264 #define define_one_rw(_name) \
 265 static struct freq_attr _name = \
 266 __ATTR(_name, 0644, show_##_name, store_##_name)
 267
 268 define_one_rw(sampling_rate);
 269 define_one_rw(sampling_down_factor);
 270 define_one_rw(up_threshold);
 271 define_one_rw(down_threshold);
 272 define_one_rw(ignore_nice);
 273 define_one_rw(freq_step);
 274
 275 static struct attribute * dbs_attributes[] = {
 276         &sampling_rate_max.attr,
 277         &sampling_rate_min.attr,
 278         &sampling_rate.attr,
 279         &sampling_down_factor.attr,
 280         &up_threshold.attr,
 281         &down_threshold.attr,
 282         &ignore_nice.attr,
 283         &freq_step.attr,
 284         NULL
 285 };
 286
 287 static struct attribute_group dbs_attr_group = {
 288         .attrs = dbs_attributes,
 289         .name = "conservative",
 290 };
 291
 292 /************************** sysfs end ************************/
 293
 294 static void dbs_check_cpu(int cpu)
 295 {
 296         unsigned int idle_ticks, up_idle_ticks, down_idle_ticks;
 297         unsigned int total_idle_ticks;
 298         unsigned int freq_step;
 299         unsigned int freq_down_sampling_rate;
 300         static int down_skip[NR_CPUS];
 301         static int requested_freq[NR_CPUS];
 302         static unsigned short init_flag = 0;
 303         struct cpu_dbs_info_s *this_dbs_info;
 304         struct cpu_dbs_info_s *dbs_info;
 305
 306         struct cpufreq_policy *policy;
 307         unsigned int j;
 308
 309         this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
 310         if (!this_dbs_info->enable)
 311                 return;
 312
 313         policy = this_dbs_info->cur_policy;
 314
 315         if ( init_flag == 0 ) {
 316                 for ( /* NULL */; init_flag < NR_CPUS; init_flag++ ) {
 317                         dbs_info = &per_cpu(cpu_dbs_info, init_flag);
 318                         requested_freq[cpu] = dbs_info->cur_policy->cur;
 319                 }
 320                 init_flag = 1;
 321         }
 322
 323         /*
 324          * The default safe range is 20% to 80%
 325          * Every sampling_rate, we check
 326          *      - If current idle time is less than 20%, then we try to
 327          *        increase frequency
 328          * Every sampling_rate*sampling_down_factor, we check
 329          *      - If current idle time is more than 80%, then we try to
 330          *        decrease frequency
 331          *
 332          * Any frequency increase takes it to the maximum frequency.
 333          * Frequency reduction happens at minimum steps of
 334          * 5% (default) of max_frequency
 335          */
 336
 337         /* Check for frequency increase */
 338         total_idle_ticks = kstat_cpu(cpu).cpustat.idle +
 339                 kstat_cpu(cpu).cpustat.iowait;
 340           /* consider 'nice' tasks as 'idle' time too if required */
 341           if (dbs_tuners_ins.ignore_nice == 0)
 342                 total_idle_ticks += kstat_cpu(cpu).cpustat.nice;
 343         idle_ticks = total_idle_ticks -
 344                 this_dbs_info->prev_cpu_idle_up;
 345         this_dbs_info->prev_cpu_idle_up = total_idle_ticks;
 346
 347
 348         for_each_cpu_mask(j, policy->cpus) {
 349                 unsigned int tmp_idle_ticks;
 350                 struct cpu_dbs_info_s *j_dbs_info;
 351
 352                 if (j == cpu)
 353                         continue;
 354
 355                 j_dbs_info = &per_cpu(cpu_dbs_info, j);
 356                 /* Check for frequency increase */
 357                 total_idle_ticks = kstat_cpu(j).cpustat.idle +
 358                         kstat_cpu(j).cpustat.iowait;
 359                   /* consider 'nice' too? */
 360                   if (dbs_tuners_ins.ignore_nice == 0)
 361                            total_idle_ticks += kstat_cpu(j).cpustat.nice;
 362                 tmp_idle_ticks = total_idle_ticks -
 363                         j_dbs_info->prev_cpu_idle_up;
 364                 j_dbs_info->prev_cpu_idle_up = total_idle_ticks;
 365
 366                 if (tmp_idle_ticks < idle_ticks)
 367                         idle_ticks = tmp_idle_ticks;
 368         }
 369
 370         /* Scale idle ticks by 100 and compare with up and down ticks */
 371         idle_ticks *= 100;
 372         up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) *
 373                 usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
 374
 375         if (idle_ticks < up_idle_ticks) {
 376                 /* if we are already at full speed then break out early */
 377                 if (requested_freq[cpu] == policy->max)
 378                         return;
 379
 380                 freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100;
 381
 382                 /* max freq cannot be less than 100. But who knows.... */
 383                 if (unlikely(freq_step == 0))
 384                         freq_step = 5;
 385
 386                 requested_freq[cpu] += freq_step;
 387                 if (requested_freq[cpu] > policy->max)
 388                         requested_freq[cpu] = policy->max;
 389
 390                 __cpufreq_driver_target(policy, requested_freq[cpu],
 391                         CPUFREQ_RELATION_H);
 392                 down_skip[cpu] = 0;
 393                 this_dbs_info->prev_cpu_idle_down = total_idle_ticks;
 394                 return;
 395         }
 396
 397         /* Check for frequency decrease */
 398         down_skip[cpu]++;
 399         if (down_skip[cpu] < dbs_tuners_ins.sampling_down_factor)
 400                 return;
 401
 402         total_idle_ticks = kstat_cpu(cpu).cpustat.idle +
 403                 kstat_cpu(cpu).cpustat.iowait;
 404           /* consider 'nice' too? */
 405           if (dbs_tuners_ins.ignore_nice == 0)
 406                   total_idle_ticks += kstat_cpu(cpu).cpustat.nice;
 407         idle_ticks = total_idle_ticks -
 408                 this_dbs_info->prev_cpu_idle_down;
 409         this_dbs_info->prev_cpu_idle_down = total_idle_ticks;
 410
 411         for_each_cpu_mask(j, policy->cpus) {
 412                 unsigned int tmp_idle_ticks;
 413                 struct cpu_dbs_info_s *j_dbs_info;
 414
 415                 if (j == cpu)
 416                         continue;
 417
 418                 j_dbs_info = &per_cpu(cpu_dbs_info, j);
 419                 /* Check for frequency increase */
 420                 total_idle_ticks = kstat_cpu(j).cpustat.idle +
 421                         kstat_cpu(j).cpustat.iowait;
 422                   /* consider 'nice' too? */
 423                   if (dbs_tuners_ins.ignore_nice == 0)
 424                         total_idle_ticks += kstat_cpu(j).cpustat.nice;
 425                 tmp_idle_ticks = total_idle_ticks -
 426                         j_dbs_info->prev_cpu_idle_down;
 427                 j_dbs_info->prev_cpu_idle_down = total_idle_ticks;
 428
 429                 if (tmp_idle_ticks < idle_ticks)
 430                         idle_ticks = tmp_idle_ticks;
 431         }
 432
 433         /* Scale idle ticks by 100 and compare with up and down ticks */
 434         idle_ticks *= 100;
 435         down_skip[cpu] = 0;
 436
 437         freq_down_sampling_rate = dbs_tuners_ins.sampling_rate *
 438                 dbs_tuners_ins.sampling_down_factor;
 439         down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) *
 440                         usecs_to_jiffies(freq_down_sampling_rate);
 441
 442         if (idle_ticks > down_idle_ticks ) {
 443                 /* if we are already at the lowest speed then break out early
 444                  * or if we 'cannot' reduce the speed as the user might want
 445                  * freq_step to be zero */
 446                 if (requested_freq[cpu] == policy->min
 447                                 || dbs_tuners_ins.freq_step == 0)
 448                         return;
 449
 450                 freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100;
 451
 452                 /* max freq cannot be less than 100. But who knows.... */
 453                 if (unlikely(freq_step == 0))
 454                         freq_step = 5;
 455
 456                 requested_freq[cpu] -= freq_step;
 457                 if (requested_freq[cpu] < policy->min)
 458                         requested_freq[cpu] = policy->min;
 459
 460                 __cpufreq_driver_target(policy,
 461                         requested_freq[cpu],
 462                         CPUFREQ_RELATION_H);
 463                 return;
 464         }
 465 }
 466
 467 static void do_dbs_timer(void *data)
 468 {
 469         int i;
 470         down(&dbs_sem);
 471         for_each_online_cpu(i)
 472                 dbs_check_cpu(i);
 473         schedule_delayed_work(&dbs_work,
 474                         usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
 475         up(&dbs_sem);
 476 }
 477
 478 static inline void dbs_timer_init(void)
 479 {
 480         INIT_WORK(&dbs_work, do_dbs_timer, NULL);
 481         schedule_delayed_work(&dbs_work,
 482                         usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
 483         return;
 484 }
 485
 486 static inline void dbs_timer_exit(void)
 487 {
 488         cancel_delayed_work(&dbs_work);
 489         return;
 490 }
 491
 492 static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 493                                    unsigned int event)
 494 {
 495         unsigned int cpu = policy->cpu;
 496         struct cpu_dbs_info_s *this_dbs_info;
 497         unsigned int j;
 498
 499         this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
 500
 501         switch (event) {
 502         case CPUFREQ_GOV_START:
 503                 if ((!cpu_online(cpu)) ||
 504                     (!policy->cur))
 505                         return -EINVAL;
 506
 507                 if (policy->cpuinfo.transition_latency >
 508                                 (TRANSITION_LATENCY_LIMIT * 1000))
 509                         return -EINVAL;
 510                 if (this_dbs_info->enable) /* Already enabled */
 511                         break;
 512
 513                 down(&dbs_sem);
 514                 for_each_cpu_mask(j, policy->cpus) {
 515                         struct cpu_dbs_info_s *j_dbs_info;
 516                         j_dbs_info = &per_cpu(cpu_dbs_info, j);
 517                         j_dbs_info->cur_policy = policy;
 518
 519                         j_dbs_info->prev_cpu_idle_up =
 520                                 kstat_cpu(j).cpustat.idle +
 521                                 kstat_cpu(j).cpustat.iowait +
 522                                 ( !dbs_tuners_ins.ignore_nice
 523                                   ? kstat_cpu(j).cpustat.nice : 0 );
 524                         j_dbs_info->prev_cpu_idle_down
 525                                 = j_dbs_info->prev_cpu_idle_up;
 526                 }
 527                 this_dbs_info->enable = 1;
 528                 sysfs_create_group(&policy->kobj, &dbs_attr_group);
 529                 dbs_enable++;
 530                 /*
 531                  * Start the timerschedule work, when this governor
 532                  * is used for first time
 533                  */
 534                 if (dbs_enable == 1) {
 535                         unsigned int latency;
 536                         /* policy latency is in nS. Convert it to uS first */
 537
 538                         latency = policy->cpuinfo.transition_latency;
 539                         if (latency < 1000)
 540                                 latency = 1000;
 541
 542                         def_sampling_rate = (latency / 1000) *
 543                                         DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
 544                         dbs_tuners_ins.sampling_rate = def_sampling_rate;
 545                         dbs_tuners_ins.ignore_nice = 0;
 546                         dbs_tuners_ins.freq_step = 5;
 547
 548                         dbs_timer_init();
 549                 }
 550
 551                 up(&dbs_sem);
 552                 break;
 553
 554         case CPUFREQ_GOV_STOP:
 555                 down(&dbs_sem);
 556                 this_dbs_info->enable = 0;
 557                 sysfs_remove_group(&policy->kobj, &dbs_attr_group);
 558                 dbs_enable--;
 559                 /*
 560                  * Stop the timerschedule work, when this governor
 561                  * is used for first time
 562                  */
 563                 if (dbs_enable == 0)
 564                         dbs_timer_exit();
 565
 566                 up(&dbs_sem);
 567
 568                 break;
 569
 570         case CPUFREQ_GOV_LIMITS:
 571                 down(&dbs_sem);
 572                 if (policy->max < this_dbs_info->cur_policy->cur)
 573                         __cpufreq_driver_target(
 574                                         this_dbs_info->cur_policy,
 575                                         policy->max, CPUFREQ_RELATION_H);
 576                 else if (policy->min > this_dbs_info->cur_policy->cur)
 577                         __cpufreq_driver_target(
 578                                         this_dbs_info->cur_policy,
 579                                         policy->min, CPUFREQ_RELATION_L);
 580                 up(&dbs_sem);
 581                 break;
 582         }
 583         return 0;
 584 }
 585
 586 static struct cpufreq_governor cpufreq_gov_dbs = {
 587         .name           = "conservative",
 588         .governor       = cpufreq_governor_dbs,
 589         .owner          = THIS_MODULE,
 590 };
 591
 592 static int __init cpufreq_gov_dbs_init(void)
 593 {
 594         return cpufreq_register_governor(&cpufreq_gov_dbs);
 595 }
 596
 597 static void __exit cpufreq_gov_dbs_exit(void)
 598 {
 599         /* Make sure that the scheduled work is indeed not running */
 600         flush_scheduled_work();
 601
 602         cpufreq_unregister_governor(&cpufreq_gov_dbs);
 603 }
 604
 605
 606 MODULE_AUTHOR ("Alexander Clouter <alex-kernel@digriz.org.uk>");
 607 MODULE_DESCRIPTION ("'cpufreq_conservative' - A dynamic cpufreq governor for "
 608                 "Low Latency Frequency Transition capable processors "
 609                 "optimised for use in a battery environment");
 610 MODULE_LICENSE ("GPL");
 611
 612 module_init(cpufreq_gov_dbs_init);
 613 module_exit(cpufreq_gov_dbs_exit);