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 <asm/cputime.h>
  20#include <linux/cpufreq.h>
  21#include <linux/cpumask.h>
  22#include <linux/export.h>
  23#include <linux/kernel_stat.h>
  24#include <linux/mutex.h>
  25#include <linux/slab.h>
  26#include <linux/types.h>
  27#include <linux/workqueue.h>
  28
  29#include "cpufreq_governor.h"
  30
  31static struct attribute_group *get_sysfs_attr(struct dbs_data *dbs_data)
  32{
  33        if (have_governor_per_policy())
  34                return dbs_data->cdata->attr_group_gov_pol;
  35        else
  36                return dbs_data->cdata->attr_group_gov_sys;
  37}
  38
  39void dbs_check_cpu(struct dbs_data *dbs_data, int cpu)
  40{
  41        struct cpu_dbs_common_info *cdbs = dbs_data->cdata->get_cpu_cdbs(cpu);
  42        struct od_dbs_tuners *od_tuners = dbs_data->tuners;
  43        struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
  44        struct cpufreq_policy *policy;
  45        unsigned int max_load = 0;
  46        unsigned int ignore_nice;
  47        unsigned int j;
  48
  49        if (dbs_data->cdata->governor == GOV_ONDEMAND)
  50                ignore_nice = od_tuners->ignore_nice_load;
  51        else
  52                ignore_nice = cs_tuners->ignore_nice_load;
  53
  54        policy = cdbs->cur_policy;
  55
  56        /* Get Absolute Load (in terms of freq for ondemand gov) */
  57        for_each_cpu(j, policy->cpus) {
  58                struct cpu_dbs_common_info *j_cdbs;
  59                u64 cur_wall_time, cur_idle_time;
  60                unsigned int idle_time, wall_time;
  61                unsigned int load;
  62                int io_busy = 0;
  63
  64                j_cdbs = dbs_data->cdata->get_cpu_cdbs(j);
  65
  66                /*
  67                 * For the purpose of ondemand, waiting for disk IO is
  68                 * an indication that you're performance critical, and
  69                 * not that the system is actually idle. So do not add
  70                 * the iowait time to the cpu idle time.
  71                 */
  72                if (dbs_data->cdata->governor == GOV_ONDEMAND)
  73                        io_busy = od_tuners->io_is_busy;
  74                cur_idle_time = get_cpu_idle_time(j, &cur_wall_time, io_busy);
  75
  76                wall_time = (unsigned int)
  77                        (cur_wall_time - j_cdbs->prev_cpu_wall);
  78                j_cdbs->prev_cpu_wall = cur_wall_time;
  79
  80                idle_time = (unsigned int)
  81                        (cur_idle_time - j_cdbs->prev_cpu_idle);
  82                j_cdbs->prev_cpu_idle = cur_idle_time;
  83
  84                if (ignore_nice) {
  85                        u64 cur_nice;
  86                        unsigned long cur_nice_jiffies;
  87
  88                        cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE] -
  89                                         cdbs->prev_cpu_nice;
  90                        /*
  91                         * Assumption: nice time between sampling periods will
  92                         * be less than 2^32 jiffies for 32 bit sys
  93                         */
  94                        cur_nice_jiffies = (unsigned long)
  95                                        cputime64_to_jiffies64(cur_nice);
  96
  97                        cdbs->prev_cpu_nice =
  98                                kcpustat_cpu(j).cpustat[CPUTIME_NICE];
  99                        idle_time += jiffies_to_usecs(cur_nice_jiffies);
 100                }
 101
 102                if (unlikely(!wall_time || wall_time < idle_time))
 103                        continue;
 104
 105                load = 100 * (wall_time - idle_time) / wall_time;
 106
 107                if (dbs_data->cdata->governor == GOV_ONDEMAND) {
 108                        int freq_avg = __cpufreq_driver_getavg(policy, j);
 109                        if (freq_avg <= 0)
 110                                freq_avg = policy->cur;
 111
 112                        load *= freq_avg;
 113                }
 114
 115                if (load > max_load)
 116                        max_load = load;
 117        }
 118
 119        dbs_data->cdata->gov_check_cpu(cpu, max_load);
 120}
 121EXPORT_SYMBOL_GPL(dbs_check_cpu);
 122
 123static inline void __gov_queue_work(int cpu, struct dbs_data *dbs_data,
 124                unsigned int delay)
 125{
 126        struct cpu_dbs_common_info *cdbs = dbs_data->cdata->get_cpu_cdbs(cpu);
 127
 128        mod_delayed_work_on(cpu, system_wq, &cdbs->work, delay);
 129}
 130
 131void gov_queue_work(struct dbs_data *dbs_data, struct cpufreq_policy *policy,
 132                unsigned int delay, bool all_cpus)
 133{
 134        int i;
 135
 136        if (!all_cpus) {
 137                __gov_queue_work(smp_processor_id(), dbs_data, delay);
 138        } else {
 139                for_each_cpu(i, policy->cpus)
 140                        __gov_queue_work(i, dbs_data, delay);
 141        }
 142}
 143EXPORT_SYMBOL_GPL(gov_queue_work);
 144
 145static inline void gov_cancel_work(struct dbs_data *dbs_data,
 146                struct cpufreq_policy *policy)
 147{
 148        struct cpu_dbs_common_info *cdbs;
 149        int i;
 150
 151        for_each_cpu(i, policy->cpus) {
 152                cdbs = dbs_data->cdata->get_cpu_cdbs(i);
 153                cancel_delayed_work_sync(&cdbs->work);
 154        }
 155}
 156
 157/* Will return if we need to evaluate cpu load again or not */
 158bool need_load_eval(struct cpu_dbs_common_info *cdbs,
 159                unsigned int sampling_rate)
 160{
 161        if (policy_is_shared(cdbs->cur_policy)) {
 162                ktime_t time_now = ktime_get();
 163                s64 delta_us = ktime_us_delta(time_now, cdbs->time_stamp);
 164
 165                /* Do nothing if we recently have sampled */
 166                if (delta_us < (s64)(sampling_rate / 2))
 167                        return false;
 168                else
 169                        cdbs->time_stamp = time_now;
 170        }
 171
 172        return true;
 173}
 174EXPORT_SYMBOL_GPL(need_load_eval);
 175
 176static void set_sampling_rate(struct dbs_data *dbs_data,
 177                unsigned int sampling_rate)
 178{
 179        if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
 180                struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 181                cs_tuners->sampling_rate = sampling_rate;
 182        } else {
 183                struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 184                od_tuners->sampling_rate = sampling_rate;
 185        }
 186}
 187
 188int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 189                struct common_dbs_data *cdata, unsigned int event)
 190{
 191        struct dbs_data *dbs_data;
 192        struct od_cpu_dbs_info_s *od_dbs_info = NULL;
 193        struct cs_cpu_dbs_info_s *cs_dbs_info = NULL;
 194        struct od_ops *od_ops = NULL;
 195        struct od_dbs_tuners *od_tuners = NULL;
 196        struct cs_dbs_tuners *cs_tuners = NULL;
 197        struct cpu_dbs_common_info *cpu_cdbs;
 198        unsigned int sampling_rate, latency, ignore_nice, j, cpu = policy->cpu;
 199        int io_busy = 0;
 200        int rc;
 201
 202        if (have_governor_per_policy())
 203                dbs_data = policy->governor_data;
 204        else
 205                dbs_data = cdata->gdbs_data;
 206
 207        WARN_ON(!dbs_data && (event != CPUFREQ_GOV_POLICY_INIT));
 208
 209        switch (event) {
 210        case CPUFREQ_GOV_POLICY_INIT:
 211                if (have_governor_per_policy()) {
 212                        WARN_ON(dbs_data);
 213                } else if (dbs_data) {
 214                        dbs_data->usage_count++;
 215                        policy->governor_data = dbs_data;
 216                        return 0;
 217                }
 218
 219                dbs_data = kzalloc(sizeof(*dbs_data), GFP_KERNEL);
 220                if (!dbs_data) {
 221                        pr_err("%s: POLICY_INIT: kzalloc failed\n", __func__);
 222                        return -ENOMEM;
 223                }
 224
 225                dbs_data->cdata = cdata;
 226                dbs_data->usage_count = 1;
 227                rc = cdata->init(dbs_data);
 228                if (rc) {
 229                        pr_err("%s: POLICY_INIT: init() failed\n", __func__);
 230                        kfree(dbs_data);
 231                        return rc;
 232                }
 233
 234                if (!have_governor_per_policy())
 235                        WARN_ON(cpufreq_get_global_kobject());
 236
 237                rc = sysfs_create_group(get_governor_parent_kobj(policy),
 238                                get_sysfs_attr(dbs_data));
 239                if (rc) {
 240                        cdata->exit(dbs_data);
 241                        kfree(dbs_data);
 242                        return rc;
 243                }
 244
 245                policy->governor_data = dbs_data;
 246
 247                /* policy latency is in nS. Convert it to uS first */
 248                latency = policy->cpuinfo.transition_latency / 1000;
 249                if (latency == 0)
 250                        latency = 1;
 251
 252                /* Bring kernel and HW constraints together */
 253                dbs_data->min_sampling_rate = max(dbs_data->min_sampling_rate,
 254                                MIN_LATENCY_MULTIPLIER * latency);
 255                set_sampling_rate(dbs_data, max(dbs_data->min_sampling_rate,
 256                                        latency * LATENCY_MULTIPLIER));
 257
 258                if ((cdata->governor == GOV_CONSERVATIVE) &&
 259                                (!policy->governor->initialized)) {
 260                        struct cs_ops *cs_ops = dbs_data->cdata->gov_ops;
 261
 262                        cpufreq_register_notifier(cs_ops->notifier_block,
 263                                        CPUFREQ_TRANSITION_NOTIFIER);
 264                }
 265
 266                if (!have_governor_per_policy())
 267                        cdata->gdbs_data = dbs_data;
 268
 269                return 0;
 270        case CPUFREQ_GOV_POLICY_EXIT:
 271                if (!--dbs_data->usage_count) {
 272                        sysfs_remove_group(get_governor_parent_kobj(policy),
 273                                        get_sysfs_attr(dbs_data));
 274
 275                        if (!have_governor_per_policy())
 276                                cpufreq_put_global_kobject();
 277
 278                        if ((dbs_data->cdata->governor == GOV_CONSERVATIVE) &&
 279                                (policy->governor->initialized == 1)) {
 280                                struct cs_ops *cs_ops = dbs_data->cdata->gov_ops;
 281
 282                                cpufreq_unregister_notifier(cs_ops->notifier_block,
 283                                                CPUFREQ_TRANSITION_NOTIFIER);
 284                        }
 285
 286                        cdata->exit(dbs_data);
 287                        kfree(dbs_data);
 288                        cdata->gdbs_data = NULL;
 289                }
 290
 291                policy->governor_data = NULL;
 292                return 0;
 293        }
 294
 295        cpu_cdbs = dbs_data->cdata->get_cpu_cdbs(cpu);
 296
 297        if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
 298                cs_tuners = dbs_data->tuners;
 299                cs_dbs_info = dbs_data->cdata->get_cpu_dbs_info_s(cpu);
 300                sampling_rate = cs_tuners->sampling_rate;
 301                ignore_nice = cs_tuners->ignore_nice_load;
 302        } else {
 303                od_tuners = dbs_data->tuners;
 304                od_dbs_info = dbs_data->cdata->get_cpu_dbs_info_s(cpu);
 305                sampling_rate = od_tuners->sampling_rate;
 306                ignore_nice = od_tuners->ignore_nice_load;
 307                od_ops = dbs_data->cdata->gov_ops;
 308                io_busy = od_tuners->io_is_busy;
 309        }
 310
 311        switch (event) {
 312        case CPUFREQ_GOV_START:
 313                if (!policy->cur)
 314                        return -EINVAL;
 315
 316                mutex_lock(&dbs_data->mutex);
 317
 318                for_each_cpu(j, policy->cpus) {
 319                        struct cpu_dbs_common_info *j_cdbs =
 320                                dbs_data->cdata->get_cpu_cdbs(j);
 321
 322                        j_cdbs->cpu = j;
 323                        j_cdbs->cur_policy = policy;
 324                        j_cdbs->prev_cpu_idle = get_cpu_idle_time(j,
 325                                               &j_cdbs->prev_cpu_wall, io_busy);
 326                        if (ignore_nice)
 327                                j_cdbs->prev_cpu_nice =
 328                                        kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 329
 330                        mutex_init(&j_cdbs->timer_mutex);
 331                        INIT_DEFERRABLE_WORK(&j_cdbs->work,
 332                                             dbs_data->cdata->gov_dbs_timer);
 333                }
 334
 335                /*
 336                 * conservative does not implement micro like ondemand
 337                 * governor, thus we are bound to jiffes/HZ
 338                 */
 339                if (dbs_data->cdata->governor == GOV_CONSERVATIVE) {
 340                        cs_dbs_info->down_skip = 0;
 341                        cs_dbs_info->enable = 1;
 342                        cs_dbs_info->requested_freq = policy->cur;
 343                } else {
 344                        od_dbs_info->rate_mult = 1;
 345                        od_dbs_info->sample_type = OD_NORMAL_SAMPLE;
 346                        od_ops->powersave_bias_init_cpu(cpu);
 347                }
 348
 349                mutex_unlock(&dbs_data->mutex);
 350
 351                /* Initiate timer time stamp */
 352                cpu_cdbs->time_stamp = ktime_get();
 353
 354                gov_queue_work(dbs_data, policy,
 355                                delay_for_sampling_rate(sampling_rate), true);
 356                break;
 357
 358        case CPUFREQ_GOV_STOP:
 359                if (dbs_data->cdata->governor == GOV_CONSERVATIVE)
 360                        cs_dbs_info->enable = 0;
 361
 362                gov_cancel_work(dbs_data, policy);
 363
 364                mutex_lock(&dbs_data->mutex);
 365                mutex_destroy(&cpu_cdbs->timer_mutex);
 366                cpu_cdbs->cur_policy = NULL;
 367
 368                mutex_unlock(&dbs_data->mutex);
 369
 370                break;
 371
 372        case CPUFREQ_GOV_LIMITS:
 373                mutex_lock(&cpu_cdbs->timer_mutex);
 374                if (policy->max < cpu_cdbs->cur_policy->cur)
 375                        __cpufreq_driver_target(cpu_cdbs->cur_policy,
 376                                        policy->max, CPUFREQ_RELATION_H);
 377                else if (policy->min > cpu_cdbs->cur_policy->cur)
 378                        __cpufreq_driver_target(cpu_cdbs->cur_policy,
 379                                        policy->min, CPUFREQ_RELATION_L);
 380                dbs_check_cpu(dbs_data, cpu);
 381                mutex_unlock(&cpu_cdbs->timer_mutex);
 382                break;
 383        }
 384        return 0;
 385}
 386EXPORT_SYMBOL_GPL(cpufreq_governor_dbs);
 387
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