linux/drivers/cpufreq/cpufreq_governor.c
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   1/*
   2 * drivers/cpufreq/cpufreq_governor.c
   3 *
   4 * CPUFREQ governors common code
   5 *
   6 * Copyright    (C) 2001 Russell King
   7 *              (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
   8 *              (C) 2003 Jun Nakajima <jun.nakajima@intel.com>
   9 *              (C) 2009 Alexander Clouter <alex@digriz.org.uk>
  10 *              (c) 2012 Viresh Kumar <viresh.kumar@linaro.org>
  11 *
  12 * This program is free software; you can redistribute it and/or modify
  13 * it under the terms of the GNU General Public License version 2 as
  14 * published by the Free Software Foundation.
  15 */
  16
  17#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  18
  19#include <linux/export.h>
  20#include <linux/kernel_stat.h>
  21#include <linux/slab.h>
  22
  23#include "cpufreq_governor.h"
  24
  25static struct attribute_group *get_sysfs_attr(struct dbs_data *dbs_data)
  26{
  27        if (have_governor_per_policy())
  28                return dbs_data->cdata->attr_group_gov_pol;
  29        else
  30                return dbs_data->cdata->attr_group_gov_sys;
  31}
  32
  33void dbs_check_cpu(struct dbs_data *dbs_data, int cpu)
  34{
  35        struct cpu_dbs_common_info *cdbs = dbs_data->cdata->get_cpu_cdbs(cpu);
  36        struct od_dbs_tuners *od_tuners = dbs_data->tuners;
  37        struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
  38        struct cpufreq_policy *policy;
  39        unsigned int max_load = 0;
  40        unsigned int ignore_nice;
  41        unsigned int j;
  42
  43        if (dbs_data->cdata->governor == GOV_ONDEMAND)
  44                ignore_nice = od_tuners->ignore_nice_load;
  45        else
  46                ignore_nice = cs_tuners->ignore_nice_load;
  47
  48        policy = cdbs->cur_policy;
  49
  50        /* Get Absolute Load */
  51        for_each_cpu(j, policy->cpus) {
  52                struct cpu_dbs_common_info *j_cdbs;
  53                u64 cur_wall_time, cur_idle_time;
  54                unsigned int idle_time, wall_time;
  55                unsigned int load;
  56                int io_busy = 0;
  57
  58                j_cdbs = dbs_data->cdata->get_cpu_cdbs(j);
  59
  60                /*
  61                 * For the purpose of ondemand, waiting for disk IO is
  62                 * an indication that you're performance critical, and
  63                 * not that the system is actually idle. So do not add
  64                 * the iowait time to the cpu idle time.
  65                 */
  66                if (dbs_data->cdata->governor == GOV_ONDEMAND)
  67                        io_busy = od_tuners->io_is_busy;
  68                cur_idle_time = get_cpu_idle_time(j, &cur_wall_time, io_busy);
  69
  70                wall_time = (unsigned int)
  71                        (cur_wall_time - j_cdbs->prev_cpu_wall);
  72                j_cdbs->prev_cpu_wall = cur_wall_time;
  73
  74                idle_time = (unsigned int)
  75                        (cur_idle_time - j_cdbs->prev_cpu_idle);
  76                j_cdbs->prev_cpu_idle = cur_idle_time;
  77
  78                if (ignore_nice) {
  79                        u64 cur_nice;
  80                        unsigned long cur_nice_jiffies;
  81
  82                        cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE] -
  83                                         cdbs->prev_cpu_nice;
  84                        /*
  85                         * Assumption: nice time between sampling periods will
  86                         * be less than 2^32 jiffies for 32 bit sys
  87                         */
  88                        cur_nice_jiffies = (unsigned long)
  89                                        cputime64_to_jiffies64(cur_nice);
  90
  91                        cdbs->prev_cpu_nice =
  92                                kcpustat_cpu(j).cpustat[CPUTIME_NICE];
  93                        idle_time += jiffies_to_usecs(cur_nice_jiffies);
  94                }
  95
  96                if (unlikely(!wall_time || wall_time < idle_time))
  97                        continue;
  98
  99                load = 100 * (wall_time - idle_time) / wall_time;
 100
 101                if (load > max_load)
 102                        max_load = load;
 103        }
 104
 105        dbs_data->cdata->gov_check_cpu(cpu, max_load);
 106}
 107EXPORT_SYMBOL_GPL(dbs_check_cpu);
 108
 109static inline void __gov_queue_work(int cpu, struct dbs_data *dbs_data,
 110                unsigned int delay)
 111{
 112        struct cpu_dbs_common_info *cdbs = dbs_data->cdata->get_cpu_cdbs(cpu);
 113
 114        mod_delayed_work_on(cpu, system_wq, &cdbs->work, delay);
 115}
 116
 117void gov_queue_work(struct dbs_data *dbs_data, struct cpufreq_policy *policy,
 118                unsigned int delay, bool all_cpus)
 119{
 120        int i;
 121
 122        if (!policy->governor_enabled)
 123                return;
 124
 125        if (!all_cpus) {
 126                /*
 127                 * Use raw_smp_processor_id() to avoid preemptible warnings.
 128                 * We know that this is only called with all_cpus == false from
 129                 * works that have been queued with *_work_on() functions and
 130                 * those works are canceled during CPU_DOWN_PREPARE so they
 131                 * can't possibly run on any other CPU.
 132                 */
 133                __gov_queue_work(raw_smp_processor_id(), dbs_data, delay);
 134        } else {
 135                for_each_cpu(i, policy->cpus)
 136                        __gov_queue_work(i, dbs_data, delay);
 137        }
 138}
 139EXPORT_SYMBOL_GPL(gov_queue_work);
 140
 141static inline void gov_cancel_work(struct dbs_data *dbs_data,
 142                struct cpufreq_policy *policy)
 143{
 144        struct cpu_dbs_common_info *cdbs;
 145        int i;
 146
 147        for_each_cpu(i, policy->cpus) {
 148                cdbs = dbs_data->cdata->get_cpu_cdbs(i);
 149                cancel_delayed_work_sync(&cdbs->work);
 150        }
 151}
 152
 153/* Will return if we need to evaluate cpu load again or not */
 154bool need_load_eval(struct cpu_dbs_common_info *cdbs,
 155                unsigned int sampling_rate)
 156{
 157        if (policy_is_shared(cdbs->cur_policy)) {
 158                ktime_t time_now = ktime_get();
 159                s64 delta_us = ktime_us_delta(time_now, cdbs->time_stamp);
 160
 161                /* Do nothing if we recently have sampled */
 162                if (delta_us < (s64)(sampling_rate / 2))
 163                        return false;
 164                else
 165                        cdbs->time_stamp = time_now;
 166        }
 167
 168        return true;
 169}
 170EXPORT_SYMBOL_GPL(need_load_eval);
 171
 172static void set_sampling_rate(struct dbs_data *dbs_data,
 173                unsigned int sampling_rate)
 174{
 175        if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
 176                struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 177                cs_tuners->sampling_rate = sampling_rate;
 178        } else {
 179                struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 180                od_tuners->sampling_rate = sampling_rate;
 181        }
 182}
 183
 184int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 185                struct common_dbs_data *cdata, unsigned int event)
 186{
 187        struct dbs_data *dbs_data;
 188        struct od_cpu_dbs_info_s *od_dbs_info = NULL;
 189        struct cs_cpu_dbs_info_s *cs_dbs_info = NULL;
 190        struct od_ops *od_ops = NULL;
 191        struct od_dbs_tuners *od_tuners = NULL;
 192        struct cs_dbs_tuners *cs_tuners = NULL;
 193        struct cpu_dbs_common_info *cpu_cdbs;
 194        unsigned int sampling_rate, latency, ignore_nice, j, cpu = policy->cpu;
 195        int io_busy = 0;
 196        int rc;
 197
 198        if (have_governor_per_policy())
 199                dbs_data = policy->governor_data;
 200        else
 201                dbs_data = cdata->gdbs_data;
 202
 203        WARN_ON(!dbs_data && (event != CPUFREQ_GOV_POLICY_INIT));
 204
 205        switch (event) {
 206        case CPUFREQ_GOV_POLICY_INIT:
 207                if (have_governor_per_policy()) {
 208                        WARN_ON(dbs_data);
 209                } else if (dbs_data) {
 210                        dbs_data->usage_count++;
 211                        policy->governor_data = dbs_data;
 212                        return 0;
 213                }
 214
 215                dbs_data = kzalloc(sizeof(*dbs_data), GFP_KERNEL);
 216                if (!dbs_data) {
 217                        pr_err("%s: POLICY_INIT: kzalloc failed\n", __func__);
 218                        return -ENOMEM;
 219                }
 220
 221                dbs_data->cdata = cdata;
 222                dbs_data->usage_count = 1;
 223                rc = cdata->init(dbs_data);
 224                if (rc) {
 225                        pr_err("%s: POLICY_INIT: init() failed\n", __func__);
 226                        kfree(dbs_data);
 227                        return rc;
 228                }
 229
 230                if (!have_governor_per_policy())
 231                        WARN_ON(cpufreq_get_global_kobject());
 232
 233                rc = sysfs_create_group(get_governor_parent_kobj(policy),
 234                                get_sysfs_attr(dbs_data));
 235                if (rc) {
 236                        cdata->exit(dbs_data);
 237                        kfree(dbs_data);
 238                        return rc;
 239                }
 240
 241                policy->governor_data = dbs_data;
 242
 243                /* policy latency is in ns. Convert it to us first */
 244                latency = policy->cpuinfo.transition_latency / 1000;
 245                if (latency == 0)
 246                        latency = 1;
 247
 248                /* Bring kernel and HW constraints together */
 249                dbs_data->min_sampling_rate = max(dbs_data->min_sampling_rate,
 250                                MIN_LATENCY_MULTIPLIER * latency);
 251                set_sampling_rate(dbs_data, max(dbs_data->min_sampling_rate,
 252                                        latency * LATENCY_MULTIPLIER));
 253
 254                if ((cdata->governor == GOV_CONSERVATIVE) &&
 255                                (!policy->governor->initialized)) {
 256                        struct cs_ops *cs_ops = dbs_data->cdata->gov_ops;
 257
 258                        cpufreq_register_notifier(cs_ops->notifier_block,
 259                                        CPUFREQ_TRANSITION_NOTIFIER);
 260                }
 261
 262                if (!have_governor_per_policy())
 263                        cdata->gdbs_data = dbs_data;
 264
 265                return 0;
 266        case CPUFREQ_GOV_POLICY_EXIT:
 267                if (!--dbs_data->usage_count) {
 268                        sysfs_remove_group(get_governor_parent_kobj(policy),
 269                                        get_sysfs_attr(dbs_data));
 270
 271                        if (!have_governor_per_policy())
 272                                cpufreq_put_global_kobject();
 273
 274                        if ((dbs_data->cdata->governor == GOV_CONSERVATIVE) &&
 275                                (policy->governor->initialized == 1)) {
 276                                struct cs_ops *cs_ops = dbs_data->cdata->gov_ops;
 277
 278                                cpufreq_unregister_notifier(cs_ops->notifier_block,
 279                                                CPUFREQ_TRANSITION_NOTIFIER);
 280                        }
 281
 282                        cdata->exit(dbs_data);
 283                        kfree(dbs_data);
 284                        cdata->gdbs_data = NULL;
 285                }
 286
 287                policy->governor_data = NULL;
 288                return 0;
 289        }
 290
 291        cpu_cdbs = dbs_data->cdata->get_cpu_cdbs(cpu);
 292
 293        if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
 294                cs_tuners = dbs_data->tuners;
 295                cs_dbs_info = dbs_data->cdata->get_cpu_dbs_info_s(cpu);
 296                sampling_rate = cs_tuners->sampling_rate;
 297                ignore_nice = cs_tuners->ignore_nice_load;
 298        } else {
 299                od_tuners = dbs_data->tuners;
 300                od_dbs_info = dbs_data->cdata->get_cpu_dbs_info_s(cpu);
 301                sampling_rate = od_tuners->sampling_rate;
 302                ignore_nice = od_tuners->ignore_nice_load;
 303                od_ops = dbs_data->cdata->gov_ops;
 304                io_busy = od_tuners->io_is_busy;
 305        }
 306
 307        switch (event) {
 308        case CPUFREQ_GOV_START:
 309                if (!policy->cur)
 310                        return -EINVAL;
 311
 312                mutex_lock(&dbs_data->mutex);
 313
 314                for_each_cpu(j, policy->cpus) {
 315                        struct cpu_dbs_common_info *j_cdbs =
 316                                dbs_data->cdata->get_cpu_cdbs(j);
 317
 318                        j_cdbs->cpu = j;
 319                        j_cdbs->cur_policy = policy;
 320                        j_cdbs->prev_cpu_idle = get_cpu_idle_time(j,
 321                                               &j_cdbs->prev_cpu_wall, io_busy);
 322                        if (ignore_nice)
 323                                j_cdbs->prev_cpu_nice =
 324                                        kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 325
 326                        mutex_init(&j_cdbs->timer_mutex);
 327                        INIT_DEFERRABLE_WORK(&j_cdbs->work,
 328                                             dbs_data->cdata->gov_dbs_timer);
 329                }
 330
 331                /*
 332                 * conservative does not implement micro like ondemand
 333                 * governor, thus we are bound to jiffes/HZ
 334                 */
 335                if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
 336                        cs_dbs_info->down_skip = 0;
 337                        cs_dbs_info->enable = 1;
 338                        cs_dbs_info->requested_freq = policy->cur;
 339                } else {
 340                        od_dbs_info->rate_mult = 1;
 341                        od_dbs_info->sample_type = OD_NORMAL_SAMPLE;
 342                        od_ops->powersave_bias_init_cpu(cpu);
 343                }
 344
 345                mutex_unlock(&dbs_data->mutex);
 346
 347                /* Initiate timer time stamp */
 348                cpu_cdbs->time_stamp = ktime_get();
 349
 350                gov_queue_work(dbs_data, policy,
 351                                delay_for_sampling_rate(sampling_rate), true);
 352                break;
 353
 354        case CPUFREQ_GOV_STOP:
 355                if (dbs_data->cdata->governor == GOV_CONSERVATIVE)
 356                        cs_dbs_info->enable = 0;
 357
 358                gov_cancel_work(dbs_data, policy);
 359
 360                mutex_lock(&dbs_data->mutex);
 361                mutex_destroy(&cpu_cdbs->timer_mutex);
 362                cpu_cdbs->cur_policy = NULL;
 363
 364                mutex_unlock(&dbs_data->mutex);
 365
 366                break;
 367
 368        case CPUFREQ_GOV_LIMITS:
 369                mutex_lock(&cpu_cdbs->timer_mutex);
 370                if (policy->max < cpu_cdbs->cur_policy->cur)
 371                        __cpufreq_driver_target(cpu_cdbs->cur_policy,
 372                                        policy->max, CPUFREQ_RELATION_H);
 373                else if (policy->min > cpu_cdbs->cur_policy->cur)
 374                        __cpufreq_driver_target(cpu_cdbs->cur_policy,
 375                                        policy->min, CPUFREQ_RELATION_L);
 376                dbs_check_cpu(dbs_data, cpu);
 377                mutex_unlock(&cpu_cdbs->timer_mutex);
 378                break;
 379        }
 380        return 0;
 381}
 382EXPORT_SYMBOL_GPL(cpufreq_governor_dbs);
 383
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