linux/drivers/cpufreq/cpufreq_ondemand.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  drivers/cpufreq/cpufreq_ondemand.c
   4 *
   5 *  Copyright (C)  2001 Russell King
   6 *            (C)  2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
   7 *                      Jun Nakajima <jun.nakajima@intel.com>
   8 */
   9
  10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12#include <linux/cpu.h>
  13#include <linux/percpu-defs.h>
  14#include <linux/slab.h>
  15#include <linux/tick.h>
  16#include <linux/sched/cpufreq.h>
  17
  18#include "cpufreq_ondemand.h"
  19
  20/* On-demand governor macros */
  21#define DEF_FREQUENCY_UP_THRESHOLD              (80)
  22#define DEF_SAMPLING_DOWN_FACTOR                (1)
  23#define MAX_SAMPLING_DOWN_FACTOR                (100000)
  24#define MICRO_FREQUENCY_UP_THRESHOLD            (95)
  25#define MICRO_FREQUENCY_MIN_SAMPLE_RATE         (10000)
  26#define MIN_FREQUENCY_UP_THRESHOLD              (1)
  27#define MAX_FREQUENCY_UP_THRESHOLD              (100)
  28
  29static struct od_ops od_ops;
  30
  31static unsigned int default_powersave_bias;
  32
  33/*
  34 * Not all CPUs want IO time to be accounted as busy; this depends on how
  35 * efficient idling at a higher frequency/voltage is.
  36 * Pavel Machek says this is not so for various generations of AMD and old
  37 * Intel systems.
  38 * Mike Chan (android.com) claims this is also not true for ARM.
  39 * Because of this, whitelist specific known (series) of CPUs by default, and
  40 * leave all others up to the user.
  41 */
  42static int should_io_be_busy(void)
  43{
  44#if defined(CONFIG_X86)
  45        /*
  46         * For Intel, Core 2 (model 15) and later have an efficient idle.
  47         */
  48        if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
  49                        boot_cpu_data.x86 == 6 &&
  50                        boot_cpu_data.x86_model >= 15)
  51                return 1;
  52#endif
  53        return 0;
  54}
  55
  56/*
  57 * Find right freq to be set now with powersave_bias on.
  58 * Returns the freq_hi to be used right now and will set freq_hi_delay_us,
  59 * freq_lo, and freq_lo_delay_us in percpu area for averaging freqs.
  60 */
  61static unsigned int generic_powersave_bias_target(struct cpufreq_policy *policy,
  62                unsigned int freq_next, unsigned int relation)
  63{
  64        unsigned int freq_req, freq_reduc, freq_avg;
  65        unsigned int freq_hi, freq_lo;
  66        unsigned int index;
  67        unsigned int delay_hi_us;
  68        struct policy_dbs_info *policy_dbs = policy->governor_data;
  69        struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
  70        struct dbs_data *dbs_data = policy_dbs->dbs_data;
  71        struct od_dbs_tuners *od_tuners = dbs_data->tuners;
  72        struct cpufreq_frequency_table *freq_table = policy->freq_table;
  73
  74        if (!freq_table) {
  75                dbs_info->freq_lo = 0;
  76                dbs_info->freq_lo_delay_us = 0;
  77                return freq_next;
  78        }
  79
  80        index = cpufreq_frequency_table_target(policy, freq_next, relation);
  81        freq_req = freq_table[index].frequency;
  82        freq_reduc = freq_req * od_tuners->powersave_bias / 1000;
  83        freq_avg = freq_req - freq_reduc;
  84
  85        /* Find freq bounds for freq_avg in freq_table */
  86        index = cpufreq_table_find_index_h(policy, freq_avg);
  87        freq_lo = freq_table[index].frequency;
  88        index = cpufreq_table_find_index_l(policy, freq_avg);
  89        freq_hi = freq_table[index].frequency;
  90
  91        /* Find out how long we have to be in hi and lo freqs */
  92        if (freq_hi == freq_lo) {
  93                dbs_info->freq_lo = 0;
  94                dbs_info->freq_lo_delay_us = 0;
  95                return freq_lo;
  96        }
  97        delay_hi_us = (freq_avg - freq_lo) * dbs_data->sampling_rate;
  98        delay_hi_us += (freq_hi - freq_lo) / 2;
  99        delay_hi_us /= freq_hi - freq_lo;
 100        dbs_info->freq_hi_delay_us = delay_hi_us;
 101        dbs_info->freq_lo = freq_lo;
 102        dbs_info->freq_lo_delay_us = dbs_data->sampling_rate - delay_hi_us;
 103        return freq_hi;
 104}
 105
 106static void ondemand_powersave_bias_init(struct cpufreq_policy *policy)
 107{
 108        struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
 109
 110        dbs_info->freq_lo = 0;
 111}
 112
 113static void dbs_freq_increase(struct cpufreq_policy *policy, unsigned int freq)
 114{
 115        struct policy_dbs_info *policy_dbs = policy->governor_data;
 116        struct dbs_data *dbs_data = policy_dbs->dbs_data;
 117        struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 118
 119        if (od_tuners->powersave_bias)
 120                freq = od_ops.powersave_bias_target(policy, freq,
 121                                CPUFREQ_RELATION_H);
 122        else if (policy->cur == policy->max)
 123                return;
 124
 125        __cpufreq_driver_target(policy, freq, od_tuners->powersave_bias ?
 126                        CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
 127}
 128
 129/*
 130 * Every sampling_rate, we check, if current idle time is less than 20%
 131 * (default), then we try to increase frequency. Else, we adjust the frequency
 132 * proportional to load.
 133 */
 134static void od_update(struct cpufreq_policy *policy)
 135{
 136        struct policy_dbs_info *policy_dbs = policy->governor_data;
 137        struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
 138        struct dbs_data *dbs_data = policy_dbs->dbs_data;
 139        struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 140        unsigned int load = dbs_update(policy);
 141
 142        dbs_info->freq_lo = 0;
 143
 144        /* Check for frequency increase */
 145        if (load > dbs_data->up_threshold) {
 146                /* If switching to max speed, apply sampling_down_factor */
 147                if (policy->cur < policy->max)
 148                        policy_dbs->rate_mult = dbs_data->sampling_down_factor;
 149                dbs_freq_increase(policy, policy->max);
 150        } else {
 151                /* Calculate the next frequency proportional to load */
 152                unsigned int freq_next, min_f, max_f;
 153
 154                min_f = policy->cpuinfo.min_freq;
 155                max_f = policy->cpuinfo.max_freq;
 156                freq_next = min_f + load * (max_f - min_f) / 100;
 157
 158                /* No longer fully busy, reset rate_mult */
 159                policy_dbs->rate_mult = 1;
 160
 161                if (od_tuners->powersave_bias)
 162                        freq_next = od_ops.powersave_bias_target(policy,
 163                                                                 freq_next,
 164                                                                 CPUFREQ_RELATION_L);
 165
 166                __cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_C);
 167        }
 168}
 169
 170static unsigned int od_dbs_update(struct cpufreq_policy *policy)
 171{
 172        struct policy_dbs_info *policy_dbs = policy->governor_data;
 173        struct dbs_data *dbs_data = policy_dbs->dbs_data;
 174        struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
 175        int sample_type = dbs_info->sample_type;
 176
 177        /* Common NORMAL_SAMPLE setup */
 178        dbs_info->sample_type = OD_NORMAL_SAMPLE;
 179        /*
 180         * OD_SUB_SAMPLE doesn't make sense if sample_delay_ns is 0, so ignore
 181         * it then.
 182         */
 183        if (sample_type == OD_SUB_SAMPLE && policy_dbs->sample_delay_ns > 0) {
 184                __cpufreq_driver_target(policy, dbs_info->freq_lo,
 185                                        CPUFREQ_RELATION_H);
 186                return dbs_info->freq_lo_delay_us;
 187        }
 188
 189        od_update(policy);
 190
 191        if (dbs_info->freq_lo) {
 192                /* Setup SUB_SAMPLE */
 193                dbs_info->sample_type = OD_SUB_SAMPLE;
 194                return dbs_info->freq_hi_delay_us;
 195        }
 196
 197        return dbs_data->sampling_rate * policy_dbs->rate_mult;
 198}
 199
 200/************************** sysfs interface ************************/
 201static struct dbs_governor od_dbs_gov;
 202
 203static ssize_t store_io_is_busy(struct gov_attr_set *attr_set, const char *buf,
 204                                size_t count)
 205{
 206        struct dbs_data *dbs_data = to_dbs_data(attr_set);
 207        unsigned int input;
 208        int ret;
 209
 210        ret = sscanf(buf, "%u", &input);
 211        if (ret != 1)
 212                return -EINVAL;
 213        dbs_data->io_is_busy = !!input;
 214
 215        /* we need to re-evaluate prev_cpu_idle */
 216        gov_update_cpu_data(dbs_data);
 217
 218        return count;
 219}
 220
 221static ssize_t store_up_threshold(struct gov_attr_set *attr_set,
 222                                  const char *buf, size_t count)
 223{
 224        struct dbs_data *dbs_data = to_dbs_data(attr_set);
 225        unsigned int input;
 226        int ret;
 227        ret = sscanf(buf, "%u", &input);
 228
 229        if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
 230                        input < MIN_FREQUENCY_UP_THRESHOLD) {
 231                return -EINVAL;
 232        }
 233
 234        dbs_data->up_threshold = input;
 235        return count;
 236}
 237
 238static ssize_t store_sampling_down_factor(struct gov_attr_set *attr_set,
 239                                          const char *buf, size_t count)
 240{
 241        struct dbs_data *dbs_data = to_dbs_data(attr_set);
 242        struct policy_dbs_info *policy_dbs;
 243        unsigned int input;
 244        int ret;
 245        ret = sscanf(buf, "%u", &input);
 246
 247        if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 248                return -EINVAL;
 249
 250        dbs_data->sampling_down_factor = input;
 251
 252        /* Reset down sampling multiplier in case it was active */
 253        list_for_each_entry(policy_dbs, &attr_set->policy_list, list) {
 254                /*
 255                 * Doing this without locking might lead to using different
 256                 * rate_mult values in od_update() and od_dbs_update().
 257                 */
 258                mutex_lock(&policy_dbs->update_mutex);
 259                policy_dbs->rate_mult = 1;
 260                mutex_unlock(&policy_dbs->update_mutex);
 261        }
 262
 263        return count;
 264}
 265
 266static ssize_t store_ignore_nice_load(struct gov_attr_set *attr_set,
 267                                      const char *buf, size_t count)
 268{
 269        struct dbs_data *dbs_data = to_dbs_data(attr_set);
 270        unsigned int input;
 271        int ret;
 272
 273        ret = sscanf(buf, "%u", &input);
 274        if (ret != 1)
 275                return -EINVAL;
 276
 277        if (input > 1)
 278                input = 1;
 279
 280        if (input == dbs_data->ignore_nice_load) { /* nothing to do */
 281                return count;
 282        }
 283        dbs_data->ignore_nice_load = input;
 284
 285        /* we need to re-evaluate prev_cpu_idle */
 286        gov_update_cpu_data(dbs_data);
 287
 288        return count;
 289}
 290
 291static ssize_t store_powersave_bias(struct gov_attr_set *attr_set,
 292                                    const char *buf, size_t count)
 293{
 294        struct dbs_data *dbs_data = to_dbs_data(attr_set);
 295        struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 296        struct policy_dbs_info *policy_dbs;
 297        unsigned int input;
 298        int ret;
 299        ret = sscanf(buf, "%u", &input);
 300
 301        if (ret != 1)
 302                return -EINVAL;
 303
 304        if (input > 1000)
 305                input = 1000;
 306
 307        od_tuners->powersave_bias = input;
 308
 309        list_for_each_entry(policy_dbs, &attr_set->policy_list, list)
 310                ondemand_powersave_bias_init(policy_dbs->policy);
 311
 312        return count;
 313}
 314
 315gov_show_one_common(sampling_rate);
 316gov_show_one_common(up_threshold);
 317gov_show_one_common(sampling_down_factor);
 318gov_show_one_common(ignore_nice_load);
 319gov_show_one_common(io_is_busy);
 320gov_show_one(od, powersave_bias);
 321
 322gov_attr_rw(sampling_rate);
 323gov_attr_rw(io_is_busy);
 324gov_attr_rw(up_threshold);
 325gov_attr_rw(sampling_down_factor);
 326gov_attr_rw(ignore_nice_load);
 327gov_attr_rw(powersave_bias);
 328
 329static struct attribute *od_attributes[] = {
 330        &sampling_rate.attr,
 331        &up_threshold.attr,
 332        &sampling_down_factor.attr,
 333        &ignore_nice_load.attr,
 334        &powersave_bias.attr,
 335        &io_is_busy.attr,
 336        NULL
 337};
 338
 339/************************** sysfs end ************************/
 340
 341static struct policy_dbs_info *od_alloc(void)
 342{
 343        struct od_policy_dbs_info *dbs_info;
 344
 345        dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL);
 346        return dbs_info ? &dbs_info->policy_dbs : NULL;
 347}
 348
 349static void od_free(struct policy_dbs_info *policy_dbs)
 350{
 351        kfree(to_dbs_info(policy_dbs));
 352}
 353
 354static int od_init(struct dbs_data *dbs_data)
 355{
 356        struct od_dbs_tuners *tuners;
 357        u64 idle_time;
 358        int cpu;
 359
 360        tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 361        if (!tuners)
 362                return -ENOMEM;
 363
 364        cpu = get_cpu();
 365        idle_time = get_cpu_idle_time_us(cpu, NULL);
 366        put_cpu();
 367        if (idle_time != -1ULL) {
 368                /* Idle micro accounting is supported. Use finer thresholds */
 369                dbs_data->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
 370        } else {
 371                dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 372        }
 373
 374        dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 375        dbs_data->ignore_nice_load = 0;
 376        tuners->powersave_bias = default_powersave_bias;
 377        dbs_data->io_is_busy = should_io_be_busy();
 378
 379        dbs_data->tuners = tuners;
 380        return 0;
 381}
 382
 383static void od_exit(struct dbs_data *dbs_data)
 384{
 385        kfree(dbs_data->tuners);
 386}
 387
 388static void od_start(struct cpufreq_policy *policy)
 389{
 390        struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
 391
 392        dbs_info->sample_type = OD_NORMAL_SAMPLE;
 393        ondemand_powersave_bias_init(policy);
 394}
 395
 396static struct od_ops od_ops = {
 397        .powersave_bias_target = generic_powersave_bias_target,
 398};
 399
 400static struct dbs_governor od_dbs_gov = {
 401        .gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("ondemand"),
 402        .kobj_type = { .default_attrs = od_attributes },
 403        .gov_dbs_update = od_dbs_update,
 404        .alloc = od_alloc,
 405        .free = od_free,
 406        .init = od_init,
 407        .exit = od_exit,
 408        .start = od_start,
 409};
 410
 411#define CPU_FREQ_GOV_ONDEMAND   (&od_dbs_gov.gov)
 412
 413static void od_set_powersave_bias(unsigned int powersave_bias)
 414{
 415        unsigned int cpu;
 416        cpumask_t done;
 417
 418        default_powersave_bias = powersave_bias;
 419        cpumask_clear(&done);
 420
 421        get_online_cpus();
 422        for_each_online_cpu(cpu) {
 423                struct cpufreq_policy *policy;
 424                struct policy_dbs_info *policy_dbs;
 425                struct dbs_data *dbs_data;
 426                struct od_dbs_tuners *od_tuners;
 427
 428                if (cpumask_test_cpu(cpu, &done))
 429                        continue;
 430
 431                policy = cpufreq_cpu_get_raw(cpu);
 432                if (!policy || policy->governor != CPU_FREQ_GOV_ONDEMAND)
 433                        continue;
 434
 435                policy_dbs = policy->governor_data;
 436                if (!policy_dbs)
 437                        continue;
 438
 439                cpumask_or(&done, &done, policy->cpus);
 440
 441                dbs_data = policy_dbs->dbs_data;
 442                od_tuners = dbs_data->tuners;
 443                od_tuners->powersave_bias = default_powersave_bias;
 444        }
 445        put_online_cpus();
 446}
 447
 448void od_register_powersave_bias_handler(unsigned int (*f)
 449                (struct cpufreq_policy *, unsigned int, unsigned int),
 450                unsigned int powersave_bias)
 451{
 452        od_ops.powersave_bias_target = f;
 453        od_set_powersave_bias(powersave_bias);
 454}
 455EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler);
 456
 457void od_unregister_powersave_bias_handler(void)
 458{
 459        od_ops.powersave_bias_target = generic_powersave_bias_target;
 460        od_set_powersave_bias(0);
 461}
 462EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler);
 463
 464static int __init cpufreq_gov_dbs_init(void)
 465{
 466        return cpufreq_register_governor(CPU_FREQ_GOV_ONDEMAND);
 467}
 468
 469static void __exit cpufreq_gov_dbs_exit(void)
 470{
 471        cpufreq_unregister_governor(CPU_FREQ_GOV_ONDEMAND);
 472}
 473
 474MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
 475MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
 476MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
 477        "Low Latency Frequency Transition capable processors");
 478MODULE_LICENSE("GPL");
 479
 480#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
 481struct cpufreq_governor *cpufreq_default_governor(void)
 482{
 483        return CPU_FREQ_GOV_ONDEMAND;
 484}
 485
 486fs_initcall(cpufreq_gov_dbs_init);
 487#else
 488module_init(cpufreq_gov_dbs_init);
 489#endif
 490module_exit(cpufreq_gov_dbs_exit);
 491