1 /* 2 * drivers/cpufreq/cpufreq_ondemand.c 3 * 4 * Copyright (C) 2001 Russell King 5 * (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>. 6 * Jun Nakajima <jun.nakajima@intel.com> 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 */ 12 13 #include <linux/kernel.h> 14 #include <linux/module.h> 15 #include <linux/init.h> 16 #include <linux/cpufreq.h> 17 #include <linux/cpu.h> 18 #include <linux/jiffies.h> 19 #include <linux/kernel_stat.h> 20 #include <linux/mutex.h> 21 #include <linux/hrtimer.h> 22 #include <linux/tick.h> 23 #include <linux/ktime.h> 24 #include <linux/sched.h> 25 26 /* 27 * dbs is used in this file as a shortform for demandbased switching 28 * It helps to keep variable names smaller, simpler 29 */ 30 31 #define DEF_FREQUENCY_DOWN_DIFFERENTIAL (10) 32 #define DEF_FREQUENCY_UP_THRESHOLD (80) 33 #define DEF_SAMPLING_DOWN_FACTOR (1) 34 #define MAX_SAMPLING_DOWN_FACTOR (100000) 35 #define MICRO_FREQUENCY_DOWN_DIFFERENTIAL (3) 36 #define MICRO_FREQUENCY_UP_THRESHOLD (95) 37 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE (10000) 38 #define MIN_FREQUENCY_UP_THRESHOLD (11) 39 #define MAX_FREQUENCY_UP_THRESHOLD (100) 40 41 /* 42 * The polling frequency of this governor depends on the capability of 43 * the processor. Default polling frequency is 1000 times the transition 44 * latency of the processor. The governor will work on any processor with 45 * transition latency <= 10mS, using appropriate sampling 46 * rate. 47 * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL) 48 * this governor will not work. 49 * All times here are in uS. 50 */ 51 #define MIN_SAMPLING_RATE_RATIO (2) 52 53 static unsigned int min_sampling_rate; 54 55 #define LATENCY_MULTIPLIER (1000) 56 #define MIN_LATENCY_MULTIPLIER (100) 57 #define TRANSITION_LATENCY_LIMIT (10 * 1000 * 1000) 58 59 static void do_dbs_timer(struct work_struct *work); 60 static int cpufreq_governor_dbs(struct cpufreq_policy *policy, 61 unsigned int event); 62 63 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND 64 static 65 #endif 66 struct cpufreq_governor cpufreq_gov_ondemand = { 67 .name = "ondemand", 68 .governor = cpufreq_governor_dbs, 69 .max_transition_latency = TRANSITION_LATENCY_LIMIT, 70 .owner = THIS_MODULE, 71 }; 72 73 /* Sampling types */ 74 enum {DBS_NORMAL_SAMPLE, DBS_SUB_SAMPLE}; 75 76 struct cpu_dbs_info_s { 77 cputime64_t prev_cpu_idle; 78 cputime64_t prev_cpu_iowait; 79 cputime64_t prev_cpu_wall; 80 cputime64_t prev_cpu_nice; 81 struct cpufreq_policy *cur_policy; 82 struct delayed_work work; 83 struct cpufreq_frequency_table *freq_table; 84 unsigned int freq_lo; 85 unsigned int freq_lo_jiffies; 86 unsigned int freq_hi_jiffies; 87 unsigned int rate_mult; 88 int cpu; 89 unsigned int sample_type:1; 90 /* 91 * percpu mutex that serializes governor limit change with 92 * do_dbs_timer invocation. We do not want do_dbs_timer to run 93 * when user is changing the governor or limits. 94 */ 95 struct mutex timer_mutex; 96 }; 97 static DEFINE_PER_CPU(struct cpu_dbs_info_s, od_cpu_dbs_info); 98 99 static unsigned int dbs_enable; /* number of CPUs using this policy */ 100 101 /* 102 * dbs_mutex protects dbs_enable in governor start/stop. 103 */ 104 static DEFINE_MUTEX(dbs_mutex); 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 sampling_down_factor; 112 unsigned int powersave_bias; 113 unsigned int io_is_busy; 114 } dbs_tuners_ins = { 115 .up_threshold = DEF_FREQUENCY_UP_THRESHOLD, 116 .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR, 117 .down_differential = DEF_FREQUENCY_DOWN_DIFFERENTIAL, 118 .ignore_nice = 0, 119 .powersave_bias = 0, 120 }; 121 122 static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall) 123 { 124 u64 idle_time; 125 u64 cur_wall_time; 126 u64 busy_time; 127 128 cur_wall_time = jiffies64_to_cputime64(get_jiffies_64()); 129 130 busy_time = kcpustat_cpu(cpu).cpustat[CPUTIME_USER]; 131 busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SYSTEM]; 132 busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_IRQ]; 133 busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SOFTIRQ]; 134 busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_STEAL]; 135 busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_NICE]; 136 137 idle_time = cur_wall_time - busy_time; 138 if (wall) 139 *wall = jiffies_to_usecs(cur_wall_time); 140 141 return jiffies_to_usecs(idle_time); 142 } 143 144 static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall) 145 { 146 u64 idle_time = get_cpu_idle_time_us(cpu, NULL); 147 148 if (idle_time == -1ULL) 149 return get_cpu_idle_time_jiffy(cpu, wall); 150 else 151 idle_time += get_cpu_iowait_time_us(cpu, wall); 152 153 return idle_time; 154 } 155 156 static inline cputime64_t get_cpu_iowait_time(unsigned int cpu, cputime64_t *wall) 157 { 158 u64 iowait_time = get_cpu_iowait_time_us(cpu, wall); 159 160 if (iowait_time == -1ULL) 161 return 0; 162 163 return iowait_time; 164 } 165 166 /* 167 * Find right freq to be set now with powersave_bias on. 168 * Returns the freq_hi to be used right now and will set freq_hi_jiffies, 169 * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs. 170 */ 171 static unsigned int powersave_bias_target(struct cpufreq_policy *policy, 172 unsigned int freq_next, 173 unsigned int relation) 174 { 175 unsigned int freq_req, freq_reduc, freq_avg; 176 unsigned int freq_hi, freq_lo; 177 unsigned int index = 0; 178 unsigned int jiffies_total, jiffies_hi, jiffies_lo; 179 struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, 180 policy->cpu); 181 182 if (!dbs_info->freq_table) { 183 dbs_info->freq_lo = 0; 184 dbs_info->freq_lo_jiffies = 0; 185 return freq_next; 186 } 187 188 cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next, 189 relation, &index); 190 freq_req = dbs_info->freq_table[index].frequency; 191 freq_reduc = freq_req * dbs_tuners_ins.powersave_bias / 1000; 192 freq_avg = freq_req - freq_reduc; 193 194 /* Find freq bounds for freq_avg in freq_table */ 195 index = 0; 196 cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg, 197 CPUFREQ_RELATION_H, &index); 198 freq_lo = dbs_info->freq_table[index].frequency; 199 index = 0; 200 cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg, 201 CPUFREQ_RELATION_L, &index); 202 freq_hi = dbs_info->freq_table[index].frequency; 203 204 /* Find out how long we have to be in hi and lo freqs */ 205 if (freq_hi == freq_lo) { 206 dbs_info->freq_lo = 0; 207 dbs_info->freq_lo_jiffies = 0; 208 return freq_lo; 209 } 210 jiffies_total = usecs_to_jiffies(dbs_tuners_ins.sampling_rate); 211 jiffies_hi = (freq_avg - freq_lo) * jiffies_total; 212 jiffies_hi += ((freq_hi - freq_lo) / 2); 213 jiffies_hi /= (freq_hi - freq_lo); 214 jiffies_lo = jiffies_total - jiffies_hi; 215 dbs_info->freq_lo = freq_lo; 216 dbs_info->freq_lo_jiffies = jiffies_lo; 217 dbs_info->freq_hi_jiffies = jiffies_hi; 218 return freq_hi; 219 } 220 221 static void ondemand_powersave_bias_init_cpu(int cpu) 222 { 223 struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu); 224 dbs_info->freq_table = cpufreq_frequency_get_table(cpu); 225 dbs_info->freq_lo = 0; 226 } 227 228 static void ondemand_powersave_bias_init(void) 229 { 230 int i; 231 for_each_online_cpu(i) { 232 ondemand_powersave_bias_init_cpu(i); 233 } 234 } 235 236 /************************** sysfs interface ************************/ 237 238 static ssize_t show_sampling_rate_min(struct kobject *kobj, 239 struct attribute *attr, char *buf) 240 { 241 return sprintf(buf, "%u\n", min_sampling_rate); 242 } 243 244 define_one_global_ro(sampling_rate_min); 245 246 /* cpufreq_ondemand Governor Tunables */ 247 #define show_one(file_name, object) \ 248 static ssize_t show_##file_name \ 249 (struct kobject *kobj, struct attribute *attr, char *buf) \ 250 { \ 251 return sprintf(buf, "%u\n", dbs_tuners_ins.object); \ 252 } 253 show_one(sampling_rate, sampling_rate); 254 show_one(io_is_busy, io_is_busy); 255 show_one(up_threshold, up_threshold); 256 show_one(sampling_down_factor, sampling_down_factor); 257 show_one(ignore_nice_load, ignore_nice); 258 show_one(powersave_bias, powersave_bias); 259 260 static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b, 261 const char *buf, size_t count) 262 { 263 unsigned int input; 264 int ret; 265 ret = sscanf(buf, "%u", &input); 266 if (ret != 1) 267 return -EINVAL; 268 dbs_tuners_ins.sampling_rate = max(input, min_sampling_rate); 269 return count; 270 } 271 272 static ssize_t store_io_is_busy(struct kobject *a, struct attribute *b, 273 const char *buf, size_t count) 274 { 275 unsigned int input; 276 int ret; 277 278 ret = sscanf(buf, "%u", &input); 279 if (ret != 1) 280 return -EINVAL; 281 dbs_tuners_ins.io_is_busy = !!input; 282 return count; 283 } 284 285 static ssize_t store_up_threshold(struct kobject *a, struct attribute *b, 286 const char *buf, size_t count) 287 { 288 unsigned int input; 289 int ret; 290 ret = sscanf(buf, "%u", &input); 291 292 if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD || 293 input < MIN_FREQUENCY_UP_THRESHOLD) { 294 return -EINVAL; 295 } 296 dbs_tuners_ins.up_threshold = input; 297 return count; 298 } 299 300 static ssize_t store_sampling_down_factor(struct kobject *a, 301 struct attribute *b, const char *buf, size_t count) 302 { 303 unsigned int input, j; 304 int ret; 305 ret = sscanf(buf, "%u", &input); 306 307 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1) 308 return -EINVAL; 309 dbs_tuners_ins.sampling_down_factor = input; 310 311 /* Reset down sampling multiplier in case it was active */ 312 for_each_online_cpu(j) { 313 struct cpu_dbs_info_s *dbs_info; 314 dbs_info = &per_cpu(od_cpu_dbs_info, j); 315 dbs_info->rate_mult = 1; 316 } 317 return count; 318 } 319 320 static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b, 321 const char *buf, size_t count) 322 { 323 unsigned int input; 324 int ret; 325 326 unsigned int j; 327 328 ret = sscanf(buf, "%u", &input); 329 if (ret != 1) 330 return -EINVAL; 331 332 if (input > 1) 333 input = 1; 334 335 if (input == dbs_tuners_ins.ignore_nice) { /* nothing to do */ 336 return count; 337 } 338 dbs_tuners_ins.ignore_nice = input; 339 340 /* we need to re-evaluate prev_cpu_idle */ 341 for_each_online_cpu(j) { 342 struct cpu_dbs_info_s *dbs_info; 343 dbs_info = &per_cpu(od_cpu_dbs_info, j); 344 dbs_info->prev_cpu_idle = get_cpu_idle_time(j, 345 &dbs_info->prev_cpu_wall); 346 if (dbs_tuners_ins.ignore_nice) 347 dbs_info->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE]; 348 349 } 350 return count; 351 } 352 353 static ssize_t store_powersave_bias(struct kobject *a, struct attribute *b, 354 const char *buf, size_t count) 355 { 356 unsigned int input; 357 int ret; 358 ret = sscanf(buf, "%u", &input); 359 360 if (ret != 1) 361 return -EINVAL; 362 363 if (input > 1000) 364 input = 1000; 365 366 dbs_tuners_ins.powersave_bias = input; 367 ondemand_powersave_bias_init(); 368 return count; 369 } 370 371 define_one_global_rw(sampling_rate); 372 define_one_global_rw(io_is_busy); 373 define_one_global_rw(up_threshold); 374 define_one_global_rw(sampling_down_factor); 375 define_one_global_rw(ignore_nice_load); 376 define_one_global_rw(powersave_bias); 377 378 static struct attribute *dbs_attributes[] = { 379 &sampling_rate_min.attr, 380 &sampling_rate.attr, 381 &up_threshold.attr, 382 &sampling_down_factor.attr, 383 &ignore_nice_load.attr, 384 &powersave_bias.attr, 385 &io_is_busy.attr, 386 NULL 387 }; 388 389 static struct attribute_group dbs_attr_group = { 390 .attrs = dbs_attributes, 391 .name = "ondemand", 392 }; 393 394 /************************** sysfs end ************************/ 395 396 static void dbs_freq_increase(struct cpufreq_policy *p, unsigned int freq) 397 { 398 if (dbs_tuners_ins.powersave_bias) 399 freq = powersave_bias_target(p, freq, CPUFREQ_RELATION_H); 400 else if (p->cur == p->max) 401 return; 402 403 __cpufreq_driver_target(p, freq, dbs_tuners_ins.powersave_bias ? 404 CPUFREQ_RELATION_L : CPUFREQ_RELATION_H); 405 } 406 407 static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info) 408 { 409 unsigned int max_load_freq; 410 411 struct cpufreq_policy *policy; 412 unsigned int j; 413 414 this_dbs_info->freq_lo = 0; 415 policy = this_dbs_info->cur_policy; 416 417 /* 418 * Every sampling_rate, we check, if current idle time is less 419 * than 20% (default), then we try to increase frequency 420 * Every sampling_rate, we look for a the lowest 421 * frequency which can sustain the load while keeping idle time over 422 * 30%. If such a frequency exist, we try to decrease to this frequency. 423 * 424 * Any frequency increase takes it to the maximum frequency. 425 * Frequency reduction happens at minimum steps of 426 * 5% (default) of current frequency 427 */ 428 429 /* Get Absolute Load - in terms of freq */ 430 max_load_freq = 0; 431 432 for_each_cpu(j, policy->cpus) { 433 struct cpu_dbs_info_s *j_dbs_info; 434 cputime64_t cur_wall_time, cur_idle_time, cur_iowait_time; 435 unsigned int idle_time, wall_time, iowait_time; 436 unsigned int load, load_freq; 437 int freq_avg; 438 439 j_dbs_info = &per_cpu(od_cpu_dbs_info, j); 440 441 cur_idle_time = get_cpu_idle_time(j, &cur_wall_time); 442 cur_iowait_time = get_cpu_iowait_time(j, &cur_wall_time); 443 444 wall_time = (unsigned int) 445 (cur_wall_time - j_dbs_info->prev_cpu_wall); 446 j_dbs_info->prev_cpu_wall = cur_wall_time; 447 448 idle_time = (unsigned int) 449 (cur_idle_time - j_dbs_info->prev_cpu_idle); 450 j_dbs_info->prev_cpu_idle = cur_idle_time; 451 452 iowait_time = (unsigned int) 453 (cur_iowait_time - j_dbs_info->prev_cpu_iowait); 454 j_dbs_info->prev_cpu_iowait = cur_iowait_time; 455 456 if (dbs_tuners_ins.ignore_nice) { 457 u64 cur_nice; 458 unsigned long cur_nice_jiffies; 459 460 cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE] - 461 j_dbs_info->prev_cpu_nice; 462 /* 463 * Assumption: nice time between sampling periods will 464 * be less than 2^32 jiffies for 32 bit sys 465 */ 466 cur_nice_jiffies = (unsigned long) 467 cputime64_to_jiffies64(cur_nice); 468 469 j_dbs_info->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE]; 470 idle_time += jiffies_to_usecs(cur_nice_jiffies); 471 } 472 473 /* 474 * For the purpose of ondemand, waiting for disk IO is an 475 * indication that you're performance critical, and not that 476 * the system is actually idle. So subtract the iowait time 477 * from the cpu idle time. 478 */ 479 480 if (dbs_tuners_ins.io_is_busy && idle_time >= iowait_time) 481 idle_time -= iowait_time; 482 483 if (unlikely(!wall_time || wall_time < idle_time)) 484 continue; 485 486 load = 100 * (wall_time - idle_time) / wall_time; 487 488 freq_avg = __cpufreq_driver_getavg(policy, j); 489 if (freq_avg <= 0) 490 freq_avg = policy->cur; 491 492 load_freq = load * freq_avg; 493 if (load_freq > max_load_freq) 494 max_load_freq = load_freq; 495 } 496 497 /* Check for frequency increase */ 498 if (max_load_freq > dbs_tuners_ins.up_threshold * policy->cur) { 499 /* If switching to max speed, apply sampling_down_factor */ 500 if (policy->cur < policy->max) 501 this_dbs_info->rate_mult = 502 dbs_tuners_ins.sampling_down_factor; 503 dbs_freq_increase(policy, policy->max); 504 return; 505 } 506 507 /* Check for frequency decrease */ 508 /* if we cannot reduce the frequency anymore, break out early */ 509 if (policy->cur == policy->min) 510 return; 511 512 /* 513 * The optimal frequency is the frequency that is the lowest that 514 * can support the current CPU usage without triggering the up 515 * policy. To be safe, we focus 10 points under the threshold. 516 */ 517 if (max_load_freq < 518 (dbs_tuners_ins.up_threshold - dbs_tuners_ins.down_differential) * 519 policy->cur) { 520 unsigned int freq_next; 521 freq_next = max_load_freq / 522 (dbs_tuners_ins.up_threshold - 523 dbs_tuners_ins.down_differential); 524 525 /* No longer fully busy, reset rate_mult */ 526 this_dbs_info->rate_mult = 1; 527 528 if (freq_next < policy->min) 529 freq_next = policy->min; 530 531 if (!dbs_tuners_ins.powersave_bias) { 532 __cpufreq_driver_target(policy, freq_next, 533 CPUFREQ_RELATION_L); 534 } else { 535 int freq = powersave_bias_target(policy, freq_next, 536 CPUFREQ_RELATION_L); 537 __cpufreq_driver_target(policy, freq, 538 CPUFREQ_RELATION_L); 539 } 540 } 541 } 542 543 static void do_dbs_timer(struct work_struct *work) 544 { 545 struct cpu_dbs_info_s *dbs_info = 546 container_of(work, struct cpu_dbs_info_s, work.work); 547 unsigned int cpu = dbs_info->cpu; 548 int sample_type = dbs_info->sample_type; 549 550 int delay; 551 552 mutex_lock(&dbs_info->timer_mutex); 553 554 /* Common NORMAL_SAMPLE setup */ 555 dbs_info->sample_type = DBS_NORMAL_SAMPLE; 556 if (!dbs_tuners_ins.powersave_bias || 557 sample_type == DBS_NORMAL_SAMPLE) { 558 dbs_check_cpu(dbs_info); 559 if (dbs_info->freq_lo) { 560 /* Setup timer for SUB_SAMPLE */ 561 dbs_info->sample_type = DBS_SUB_SAMPLE; 562 delay = dbs_info->freq_hi_jiffies; 563 } else { 564 /* We want all CPUs to do sampling nearly on 565 * same jiffy 566 */ 567 delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate 568 * dbs_info->rate_mult); 569 570 if (num_online_cpus() > 1) 571 delay -= jiffies % delay; 572 } 573 } else { 574 __cpufreq_driver_target(dbs_info->cur_policy, 575 dbs_info->freq_lo, CPUFREQ_RELATION_H); 576 delay = dbs_info->freq_lo_jiffies; 577 } 578 schedule_delayed_work_on(cpu, &dbs_info->work, delay); 579 mutex_unlock(&dbs_info->timer_mutex); 580 } 581 582 static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info) 583 { 584 /* We want all CPUs to do sampling nearly on same jiffy */ 585 int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate); 586 587 if (num_online_cpus() > 1) 588 delay -= jiffies % delay; 589 590 dbs_info->sample_type = DBS_NORMAL_SAMPLE; 591 INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer); 592 schedule_delayed_work_on(dbs_info->cpu, &dbs_info->work, delay); 593 } 594 595 static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info) 596 { 597 cancel_delayed_work_sync(&dbs_info->work); 598 } 599 600 /* 601 * Not all CPUs want IO time to be accounted as busy; this dependson how 602 * efficient idling at a higher frequency/voltage is. 603 * Pavel Machek says this is not so for various generations of AMD and old 604 * Intel systems. 605 * Mike Chan (androidlcom) calis this is also not true for ARM. 606 * Because of this, whitelist specific known (series) of CPUs by default, and 607 * leave all others up to the user. 608 */ 609 static int should_io_be_busy(void) 610 { 611 #if defined(CONFIG_X86) 612 /* 613 * For Intel, Core 2 (model 15) andl later have an efficient idle. 614 */ 615 if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL && 616 boot_cpu_data.x86 == 6 && 617 boot_cpu_data.x86_model >= 15) 618 return 1; 619 #endif 620 return 0; 621 } 622 623 static int cpufreq_governor_dbs(struct cpufreq_policy *policy, 624 unsigned int event) 625 { 626 unsigned int cpu = policy->cpu; 627 struct cpu_dbs_info_s *this_dbs_info; 628 unsigned int j; 629 int rc; 630 631 this_dbs_info = &per_cpu(od_cpu_dbs_info, cpu); 632 633 switch (event) { 634 case CPUFREQ_GOV_START: 635 if ((!cpu_online(cpu)) || (!policy->cur)) 636 return -EINVAL; 637 638 mutex_lock(&dbs_mutex); 639 640 dbs_enable++; 641 for_each_cpu(j, policy->cpus) { 642 struct cpu_dbs_info_s *j_dbs_info; 643 j_dbs_info = &per_cpu(od_cpu_dbs_info, j); 644 j_dbs_info->cur_policy = policy; 645 646 j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j, 647 &j_dbs_info->prev_cpu_wall); 648 if (dbs_tuners_ins.ignore_nice) 649 j_dbs_info->prev_cpu_nice = 650 kcpustat_cpu(j).cpustat[CPUTIME_NICE]; 651 } 652 this_dbs_info->cpu = cpu; 653 this_dbs_info->rate_mult = 1; 654 ondemand_powersave_bias_init_cpu(cpu); 655 /* 656 * Start the timerschedule work, when this governor 657 * is used for first time 658 */ 659 if (dbs_enable == 1) { 660 unsigned int latency; 661 662 rc = sysfs_create_group(cpufreq_global_kobject, 663 &dbs_attr_group); 664 if (rc) { 665 mutex_unlock(&dbs_mutex); 666 return rc; 667 } 668 669 /* policy latency is in nS. Convert it to uS first */ 670 latency = policy->cpuinfo.transition_latency / 1000; 671 if (latency == 0) 672 latency = 1; 673 /* Bring kernel and HW constraints together */ 674 min_sampling_rate = max(min_sampling_rate, 675 MIN_LATENCY_MULTIPLIER * latency); 676 dbs_tuners_ins.sampling_rate = 677 max(min_sampling_rate, 678 latency * LATENCY_MULTIPLIER); 679 dbs_tuners_ins.io_is_busy = should_io_be_busy(); 680 } 681 mutex_unlock(&dbs_mutex); 682 683 mutex_init(&this_dbs_info->timer_mutex); 684 dbs_timer_init(this_dbs_info); 685 break; 686 687 case CPUFREQ_GOV_STOP: 688 dbs_timer_exit(this_dbs_info); 689 690 mutex_lock(&dbs_mutex); 691 mutex_destroy(&this_dbs_info->timer_mutex); 692 dbs_enable--; 693 mutex_unlock(&dbs_mutex); 694 if (!dbs_enable) 695 sysfs_remove_group(cpufreq_global_kobject, 696 &dbs_attr_group); 697 698 break; 699 700 case CPUFREQ_GOV_LIMITS: 701 mutex_lock(&this_dbs_info->timer_mutex); 702 if (policy->max < this_dbs_info->cur_policy->cur) 703 __cpufreq_driver_target(this_dbs_info->cur_policy, 704 policy->max, CPUFREQ_RELATION_H); 705 else if (policy->min > this_dbs_info->cur_policy->cur) 706 __cpufreq_driver_target(this_dbs_info->cur_policy, 707 policy->min, CPUFREQ_RELATION_L); 708 mutex_unlock(&this_dbs_info->timer_mutex); 709 break; 710 } 711 return 0; 712 } 713 714 static int __init cpufreq_gov_dbs_init(void) 715 { 716 u64 idle_time; 717 int cpu = get_cpu(); 718 719 idle_time = get_cpu_idle_time_us(cpu, NULL); 720 put_cpu(); 721 if (idle_time != -1ULL) { 722 /* Idle micro accounting is supported. Use finer thresholds */ 723 dbs_tuners_ins.up_threshold = MICRO_FREQUENCY_UP_THRESHOLD; 724 dbs_tuners_ins.down_differential = 725 MICRO_FREQUENCY_DOWN_DIFFERENTIAL; 726 /* 727 * In nohz/micro accounting case we set the minimum frequency 728 * not depending on HZ, but fixed (very low). The deferred 729 * timer might skip some samples if idle/sleeping as needed. 730 */ 731 min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE; 732 } else { 733 /* For correct statistics, we need 10 ticks for each measure */ 734 min_sampling_rate = 735 MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10); 736 } 737 738 return cpufreq_register_governor(&cpufreq_gov_ondemand); 739 } 740 741 static void __exit cpufreq_gov_dbs_exit(void) 742 { 743 cpufreq_unregister_governor(&cpufreq_gov_ondemand); 744 } 745 746 747 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>"); 748 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>"); 749 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for " 750 "Low Latency Frequency Transition capable processors"); 751 MODULE_LICENSE("GPL"); 752 753 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND 754 fs_initcall(cpufreq_gov_dbs_init); 755 #else 756 module_init(cpufreq_gov_dbs_init); 757 #endif 758 module_exit(cpufreq_gov_dbs_exit); 759