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/tick.h>
  26#include <linux/types.h>
  27#include <linux/workqueue.h>
  28
  29#include "cpufreq_governor.h"
  30
  31static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall)
  32{
  33        u64 idle_time;
  34        u64 cur_wall_time;
  35        u64 busy_time;
  36
  37        cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
  38
  39        busy_time = kcpustat_cpu(cpu).cpustat[CPUTIME_USER];
  40        busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SYSTEM];
  41        busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_IRQ];
  42        busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SOFTIRQ];
  43        busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_STEAL];
  44        busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_NICE];
  45
  46        idle_time = cur_wall_time - busy_time;
  47        if (wall)
  48                *wall = cputime_to_usecs(cur_wall_time);
  49
  50        return cputime_to_usecs(idle_time);
  51}
  52
  53u64 get_cpu_idle_time(unsigned int cpu, u64 *wall)
  54{
  55        u64 idle_time = get_cpu_idle_time_us(cpu, NULL);
  56
  57        if (idle_time == -1ULL)
  58                return get_cpu_idle_time_jiffy(cpu, wall);
  59        else
  60                idle_time += get_cpu_iowait_time_us(cpu, wall);
  61
  62        return idle_time;
  63}
  64EXPORT_SYMBOL_GPL(get_cpu_idle_time);
  65
  66void dbs_check_cpu(struct dbs_data *dbs_data, int cpu)
  67{
  68        struct cpu_dbs_common_info *cdbs = dbs_data->get_cpu_cdbs(cpu);
  69        struct od_dbs_tuners *od_tuners = dbs_data->tuners;
  70        struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
  71        struct cpufreq_policy *policy;
  72        unsigned int max_load = 0;
  73        unsigned int ignore_nice;
  74        unsigned int j;
  75
  76        if (dbs_data->governor == GOV_ONDEMAND)
  77                ignore_nice = od_tuners->ignore_nice;
  78        else
  79                ignore_nice = cs_tuners->ignore_nice;
  80
  81        policy = cdbs->cur_policy;
  82
  83        /* Get Absolute Load (in terms of freq for ondemand gov) */
  84        for_each_cpu(j, policy->cpus) {
  85                struct cpu_dbs_common_info *j_cdbs;
  86                u64 cur_wall_time, cur_idle_time, cur_iowait_time;
  87                unsigned int idle_time, wall_time, iowait_time;
  88                unsigned int load;
  89
  90                j_cdbs = dbs_data->get_cpu_cdbs(j);
  91
  92                cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
  93
  94                wall_time = (unsigned int)
  95                        (cur_wall_time - j_cdbs->prev_cpu_wall);
  96                j_cdbs->prev_cpu_wall = cur_wall_time;
  97
  98                idle_time = (unsigned int)
  99                        (cur_idle_time - j_cdbs->prev_cpu_idle);
 100                j_cdbs->prev_cpu_idle = cur_idle_time;
 101
 102                if (ignore_nice) {
 103                        u64 cur_nice;
 104                        unsigned long cur_nice_jiffies;
 105
 106                        cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE] -
 107                                         cdbs->prev_cpu_nice;
 108                        /*
 109                         * Assumption: nice time between sampling periods will
 110                         * be less than 2^32 jiffies for 32 bit sys
 111                         */
 112                        cur_nice_jiffies = (unsigned long)
 113                                        cputime64_to_jiffies64(cur_nice);
 114
 115                        cdbs->prev_cpu_nice =
 116                                kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 117                        idle_time += jiffies_to_usecs(cur_nice_jiffies);
 118                }
 119
 120                if (dbs_data->governor == GOV_ONDEMAND) {
 121                        struct od_cpu_dbs_info_s *od_j_dbs_info =
 122                                dbs_data->get_cpu_dbs_info_s(cpu);
 123
 124                        cur_iowait_time = get_cpu_iowait_time_us(j,
 125                                        &cur_wall_time);
 126                        if (cur_iowait_time == -1ULL)
 127                                cur_iowait_time = 0;
 128
 129                        iowait_time = (unsigned int) (cur_iowait_time -
 130                                        od_j_dbs_info->prev_cpu_iowait);
 131                        od_j_dbs_info->prev_cpu_iowait = cur_iowait_time;
 132
 133                        /*
 134                         * For the purpose of ondemand, waiting for disk IO is
 135                         * an indication that you're performance critical, and
 136                         * not that the system is actually idle. So subtract the
 137                         * iowait time from the cpu idle time.
 138                         */
 139                        if (od_tuners->io_is_busy && idle_time >= iowait_time)
 140                                idle_time -= iowait_time;
 141                }
 142
 143                if (unlikely(!wall_time || wall_time < idle_time))
 144                        continue;
 145
 146                load = 100 * (wall_time - idle_time) / wall_time;
 147
 148                if (dbs_data->governor == GOV_ONDEMAND) {
 149                        int freq_avg = __cpufreq_driver_getavg(policy, j);
 150                        if (freq_avg <= 0)
 151                                freq_avg = policy->cur;
 152
 153                        load *= freq_avg;
 154                }
 155
 156                if (load > max_load)
 157                        max_load = load;
 158        }
 159
 160        dbs_data->gov_check_cpu(cpu, max_load);
 161}
 162EXPORT_SYMBOL_GPL(dbs_check_cpu);
 163
 164static inline void dbs_timer_init(struct dbs_data *dbs_data, int cpu,
 165                                  unsigned int sampling_rate)
 166{
 167        int delay = delay_for_sampling_rate(sampling_rate);
 168        struct cpu_dbs_common_info *cdbs = dbs_data->get_cpu_cdbs(cpu);
 169
 170        schedule_delayed_work_on(cpu, &cdbs->work, delay);
 171}
 172
 173static inline void dbs_timer_exit(struct dbs_data *dbs_data, int cpu)
 174{
 175        struct cpu_dbs_common_info *cdbs = dbs_data->get_cpu_cdbs(cpu);
 176
 177        cancel_delayed_work_sync(&cdbs->work);
 178}
 179
 180/* Will return if we need to evaluate cpu load again or not */
 181bool need_load_eval(struct cpu_dbs_common_info *cdbs,
 182                unsigned int sampling_rate)
 183{
 184        if (policy_is_shared(cdbs->cur_policy)) {
 185                ktime_t time_now = ktime_get();
 186                s64 delta_us = ktime_us_delta(time_now, cdbs->time_stamp);
 187
 188                /* Do nothing if we recently have sampled */
 189                if (delta_us < (s64)(sampling_rate / 2))
 190                        return false;
 191                else
 192                        cdbs->time_stamp = time_now;
 193        }
 194
 195        return true;
 196}
 197EXPORT_SYMBOL_GPL(need_load_eval);
 198
 199int cpufreq_governor_dbs(struct dbs_data *dbs_data,
 200                struct cpufreq_policy *policy, unsigned int event)
 201{
 202        struct od_cpu_dbs_info_s *od_dbs_info = NULL;
 203        struct cs_cpu_dbs_info_s *cs_dbs_info = NULL;
 204        struct cs_ops *cs_ops = NULL;
 205        struct od_ops *od_ops = NULL;
 206        struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 207        struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 208        struct cpu_dbs_common_info *cpu_cdbs;
 209        unsigned int *sampling_rate, latency, ignore_nice, j, cpu = policy->cpu;
 210        int rc;
 211
 212        cpu_cdbs = dbs_data->get_cpu_cdbs(cpu);
 213
 214        if (dbs_data->governor == GOV_CONSERVATIVE) {
 215                cs_dbs_info = dbs_data->get_cpu_dbs_info_s(cpu);
 216                sampling_rate = &cs_tuners->sampling_rate;
 217                ignore_nice = cs_tuners->ignore_nice;
 218                cs_ops = dbs_data->gov_ops;
 219        } else {
 220                od_dbs_info = dbs_data->get_cpu_dbs_info_s(cpu);
 221                sampling_rate = &od_tuners->sampling_rate;
 222                ignore_nice = od_tuners->ignore_nice;
 223                od_ops = dbs_data->gov_ops;
 224        }
 225
 226        switch (event) {
 227        case CPUFREQ_GOV_START:
 228                if (!policy->cur)
 229                        return -EINVAL;
 230
 231                mutex_lock(&dbs_data->mutex);
 232
 233                for_each_cpu(j, policy->cpus) {
 234                        struct cpu_dbs_common_info *j_cdbs =
 235                                dbs_data->get_cpu_cdbs(j);
 236
 237                        j_cdbs->cpu = j;
 238                        j_cdbs->cur_policy = policy;
 239                        j_cdbs->prev_cpu_idle = get_cpu_idle_time(j,
 240                                        &j_cdbs->prev_cpu_wall);
 241                        if (ignore_nice)
 242                                j_cdbs->prev_cpu_nice =
 243                                        kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 244
 245                        mutex_init(&j_cdbs->timer_mutex);
 246                        INIT_DEFERRABLE_WORK(&j_cdbs->work,
 247                                             dbs_data->gov_dbs_timer);
 248                }
 249
 250                if (!policy->governor->initialized) {
 251                        rc = sysfs_create_group(cpufreq_global_kobject,
 252                                        dbs_data->attr_group);
 253                        if (rc) {
 254                                mutex_unlock(&dbs_data->mutex);
 255                                return rc;
 256                        }
 257                }
 258
 259                /*
 260                 * conservative does not implement micro like ondemand
 261                 * governor, thus we are bound to jiffes/HZ
 262                 */
 263                if (dbs_data->governor == GOV_CONSERVATIVE) {
 264                        cs_dbs_info->down_skip = 0;
 265                        cs_dbs_info->enable = 1;
 266                        cs_dbs_info->requested_freq = policy->cur;
 267
 268                        if (!policy->governor->initialized) {
 269                                cpufreq_register_notifier(cs_ops->notifier_block,
 270                                                CPUFREQ_TRANSITION_NOTIFIER);
 271
 272                                dbs_data->min_sampling_rate =
 273                                        MIN_SAMPLING_RATE_RATIO *
 274                                        jiffies_to_usecs(10);
 275                        }
 276                } else {
 277                        od_dbs_info->rate_mult = 1;
 278                        od_dbs_info->sample_type = OD_NORMAL_SAMPLE;
 279                        od_ops->powersave_bias_init_cpu(cpu);
 280
 281                        if (!policy->governor->initialized)
 282                                od_tuners->io_is_busy = od_ops->io_busy();
 283                }
 284
 285                if (policy->governor->initialized)
 286                        goto unlock;
 287
 288                /* policy latency is in nS. Convert it to uS first */
 289                latency = policy->cpuinfo.transition_latency / 1000;
 290                if (latency == 0)
 291                        latency = 1;
 292
 293                /* Bring kernel and HW constraints together */
 294                dbs_data->min_sampling_rate = max(dbs_data->min_sampling_rate,
 295                                MIN_LATENCY_MULTIPLIER * latency);
 296                *sampling_rate = max(dbs_data->min_sampling_rate, latency *
 297                                LATENCY_MULTIPLIER);
 298unlock:
 299                mutex_unlock(&dbs_data->mutex);
 300
 301                /* Initiate timer time stamp */
 302                cpu_cdbs->time_stamp = ktime_get();
 303
 304                for_each_cpu(j, policy->cpus)
 305                        dbs_timer_init(dbs_data, j, *sampling_rate);
 306                break;
 307
 308        case CPUFREQ_GOV_STOP:
 309                if (dbs_data->governor == GOV_CONSERVATIVE)
 310                        cs_dbs_info->enable = 0;
 311
 312                for_each_cpu(j, policy->cpus)
 313                        dbs_timer_exit(dbs_data, j);
 314
 315                mutex_lock(&dbs_data->mutex);
 316                mutex_destroy(&cpu_cdbs->timer_mutex);
 317
 318                if (policy->governor->initialized == 1) {
 319                        sysfs_remove_group(cpufreq_global_kobject,
 320                                        dbs_data->attr_group);
 321                        if (dbs_data->governor == GOV_CONSERVATIVE)
 322                                cpufreq_unregister_notifier(cs_ops->notifier_block,
 323                                                CPUFREQ_TRANSITION_NOTIFIER);
 324                }
 325                mutex_unlock(&dbs_data->mutex);
 326
 327                break;
 328
 329        case CPUFREQ_GOV_LIMITS:
 330                mutex_lock(&cpu_cdbs->timer_mutex);
 331                if (policy->max < cpu_cdbs->cur_policy->cur)
 332                        __cpufreq_driver_target(cpu_cdbs->cur_policy,
 333                                        policy->max, CPUFREQ_RELATION_H);
 334                else if (policy->min > cpu_cdbs->cur_policy->cur)
 335                        __cpufreq_driver_target(cpu_cdbs->cur_policy,
 336                                        policy->min, CPUFREQ_RELATION_L);
 337                dbs_check_cpu(dbs_data, cpu);
 338                mutex_unlock(&cpu_cdbs->timer_mutex);
 339                break;
 340        }
 341        return 0;
 342}
 343EXPORT_SYMBOL_GPL(cpufreq_governor_dbs);
 344
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