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,
 165                struct cpu_dbs_common_info *cdbs, unsigned int sampling_rate)
 166{
 167        int delay = delay_for_sampling_rate(sampling_rate);
 168
 169        INIT_DEFERRABLE_WORK(&cdbs->work, dbs_data->gov_dbs_timer);
 170        schedule_delayed_work_on(cdbs->cpu, &cdbs->work, delay);
 171}
 172
 173static inline void dbs_timer_exit(struct cpu_dbs_common_info *cdbs)
 174{
 175        cancel_delayed_work_sync(&cdbs->work);
 176}
 177
 178int cpufreq_governor_dbs(struct dbs_data *dbs_data,
 179                struct cpufreq_policy *policy, unsigned int event)
 180{
 181        struct od_cpu_dbs_info_s *od_dbs_info = NULL;
 182        struct cs_cpu_dbs_info_s *cs_dbs_info = NULL;
 183        struct od_dbs_tuners *od_tuners = dbs_data->tuners;
 184        struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 185        struct cpu_dbs_common_info *cpu_cdbs;
 186        unsigned int *sampling_rate, latency, ignore_nice, j, cpu = policy->cpu;
 187        int rc;
 188
 189        cpu_cdbs = dbs_data->get_cpu_cdbs(cpu);
 190
 191        if (dbs_data->governor == GOV_CONSERVATIVE) {
 192                cs_dbs_info = dbs_data->get_cpu_dbs_info_s(cpu);
 193                sampling_rate = &cs_tuners->sampling_rate;
 194                ignore_nice = cs_tuners->ignore_nice;
 195        } else {
 196                od_dbs_info = dbs_data->get_cpu_dbs_info_s(cpu);
 197                sampling_rate = &od_tuners->sampling_rate;
 198                ignore_nice = od_tuners->ignore_nice;
 199        }
 200
 201        switch (event) {
 202        case CPUFREQ_GOV_START:
 203                if ((!cpu_online(cpu)) || (!policy->cur))
 204                        return -EINVAL;
 205
 206                mutex_lock(&dbs_data->mutex);
 207
 208                dbs_data->enable++;
 209                cpu_cdbs->cpu = cpu;
 210                for_each_cpu(j, policy->cpus) {
 211                        struct cpu_dbs_common_info *j_cdbs;
 212                        j_cdbs = dbs_data->get_cpu_cdbs(j);
 213
 214                        j_cdbs->cur_policy = policy;
 215                        j_cdbs->prev_cpu_idle = get_cpu_idle_time(j,
 216                                        &j_cdbs->prev_cpu_wall);
 217                        if (ignore_nice)
 218                                j_cdbs->prev_cpu_nice =
 219                                        kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 220                }
 221
 222                /*
 223                 * Start the timerschedule work, when this governor is used for
 224                 * first time
 225                 */
 226                if (dbs_data->enable != 1)
 227                        goto second_time;
 228
 229                rc = sysfs_create_group(cpufreq_global_kobject,
 230                                dbs_data->attr_group);
 231                if (rc) {
 232                        mutex_unlock(&dbs_data->mutex);
 233                        return rc;
 234                }
 235
 236                /* policy latency is in nS. Convert it to uS first */
 237                latency = policy->cpuinfo.transition_latency / 1000;
 238                if (latency == 0)
 239                        latency = 1;
 240
 241                /*
 242                 * conservative does not implement micro like ondemand
 243                 * governor, thus we are bound to jiffes/HZ
 244                 */
 245                if (dbs_data->governor == GOV_CONSERVATIVE) {
 246                        struct cs_ops *ops = dbs_data->gov_ops;
 247
 248                        cpufreq_register_notifier(ops->notifier_block,
 249                                        CPUFREQ_TRANSITION_NOTIFIER);
 250
 251                        dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 252                                jiffies_to_usecs(10);
 253                } else {
 254                        struct od_ops *ops = dbs_data->gov_ops;
 255
 256                        od_tuners->io_is_busy = ops->io_busy();
 257                }
 258
 259                /* Bring kernel and HW constraints together */
 260                dbs_data->min_sampling_rate = max(dbs_data->min_sampling_rate,
 261                                MIN_LATENCY_MULTIPLIER * latency);
 262                *sampling_rate = max(dbs_data->min_sampling_rate, latency *
 263                                LATENCY_MULTIPLIER);
 264
 265second_time:
 266                if (dbs_data->governor == GOV_CONSERVATIVE) {
 267                        cs_dbs_info->down_skip = 0;
 268                        cs_dbs_info->enable = 1;
 269                        cs_dbs_info->requested_freq = policy->cur;
 270                } else {
 271                        struct od_ops *ops = dbs_data->gov_ops;
 272                        od_dbs_info->rate_mult = 1;
 273                        od_dbs_info->sample_type = OD_NORMAL_SAMPLE;
 274                        ops->powersave_bias_init_cpu(cpu);
 275                }
 276                mutex_unlock(&dbs_data->mutex);
 277
 278                mutex_init(&cpu_cdbs->timer_mutex);
 279                dbs_timer_init(dbs_data, cpu_cdbs, *sampling_rate);
 280                break;
 281
 282        case CPUFREQ_GOV_STOP:
 283                if (dbs_data->governor == GOV_CONSERVATIVE)
 284                        cs_dbs_info->enable = 0;
 285
 286                dbs_timer_exit(cpu_cdbs);
 287
 288                mutex_lock(&dbs_data->mutex);
 289                mutex_destroy(&cpu_cdbs->timer_mutex);
 290                dbs_data->enable--;
 291                if (!dbs_data->enable) {
 292                        struct cs_ops *ops = dbs_data->gov_ops;
 293
 294                        sysfs_remove_group(cpufreq_global_kobject,
 295                                        dbs_data->attr_group);
 296                        if (dbs_data->governor == GOV_CONSERVATIVE)
 297                                cpufreq_unregister_notifier(ops->notifier_block,
 298                                                CPUFREQ_TRANSITION_NOTIFIER);
 299                }
 300                mutex_unlock(&dbs_data->mutex);
 301
 302                break;
 303
 304        case CPUFREQ_GOV_LIMITS:
 305                mutex_lock(&cpu_cdbs->timer_mutex);
 306                if (policy->max < cpu_cdbs->cur_policy->cur)
 307                        __cpufreq_driver_target(cpu_cdbs->cur_policy,
 308                                        policy->max, CPUFREQ_RELATION_H);
 309                else if (policy->min > cpu_cdbs->cur_policy->cur)
 310                        __cpufreq_driver_target(cpu_cdbs->cur_policy,
 311                                        policy->min, CPUFREQ_RELATION_L);
 312                dbs_check_cpu(dbs_data, cpu);
 313                mutex_unlock(&cpu_cdbs->timer_mutex);
 314                break;
 315        }
 316        return 0;
 317}
 318EXPORT_SYMBOL_GPL(cpufreq_governor_dbs);
 319
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