drivers/cpufreq/cpufreq_governor.c

   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
  31 static 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
  53 u64 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 }
  64 EXPORT_SYMBOL_GPL(get_cpu_idle_time);
  65
  66 void 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 }
 162 EXPORT_SYMBOL_GPL(dbs_check_cpu);
 163
 164 static 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
 173 static 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 */
 181 bool 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 }
 197 EXPORT_SYMBOL_GPL(need_load_eval);
 198
 199 int 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);
 298 unlock:
 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 }
 343 EXPORT_SYMBOL_GPL(cpufreq_governor_dbs);