drivers/cpufreq/cpufreq_conservative.c

   1 /*
   2  *  drivers/cpufreq/cpufreq_conservative.c
   3  *
   4  *  Copyright (C)  2001 Russell King
   5  *            (C)  2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
   6  *                      Jun Nakajima <jun.nakajima@intel.com>
   7  *            (C)  2009 Alexander Clouter <alex@digriz.org.uk>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 #include <linux/cpufreq.h>
  15 #include <linux/init.h>
  16 #include <linux/kernel.h>
  17 #include <linux/kernel_stat.h>
  18 #include <linux/kobject.h>
  19 #include <linux/module.h>
  20 #include <linux/mutex.h>
  21 #include <linux/notifier.h>
  22 #include <linux/percpu-defs.h>
  23 #include <linux/sysfs.h>
  24 #include <linux/types.h>
  25
  26 #include "cpufreq_governor.h"
  27
  28 /* Conservative governor macros */
  29 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
  30 #define DEF_FREQUENCY_DOWN_THRESHOLD            (20)
  31 #define DEF_SAMPLING_DOWN_FACTOR                (1)
  32 #define MAX_SAMPLING_DOWN_FACTOR                (10)
  33
  34 static struct dbs_data cs_dbs_data;
  35 static DEFINE_PER_CPU(struct cs_cpu_dbs_info_s, cs_cpu_dbs_info);
  36
  37 static struct cs_dbs_tuners cs_tuners = {
  38         .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
  39         .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD,
  40         .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
  41         .ignore_nice = 0,
  42         .freq_step = 5,
  43 };
  44
  45 /*
  46  * Every sampling_rate, we check, if current idle time is less than 20%
  47  * (default), then we try to increase frequency Every sampling_rate *
  48  * sampling_down_factor, we check, if current idle time is more than 80%, then
  49  * we try to decrease frequency
  50  *
  51  * Any frequency increase takes it to the maximum frequency. Frequency reduction
  52  * happens at minimum steps of 5% (default) of maximum frequency
  53  */
  54 static void cs_check_cpu(int cpu, unsigned int load)
  55 {
  56         struct cs_cpu_dbs_info_s *dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
  57         struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy;
  58         unsigned int freq_target;
  59
  60         /*
  61          * break out if we 'cannot' reduce the speed as the user might
  62          * want freq_step to be zero
  63          */
  64         if (cs_tuners.freq_step == 0)
  65                 return;
  66
  67         /* Check for frequency increase */
  68         if (load > cs_tuners.up_threshold) {
  69                 dbs_info->down_skip = 0;
  70
  71                 /* if we are already at full speed then break out early */
  72                 if (dbs_info->requested_freq == policy->max)
  73                         return;
  74
  75                 freq_target = (cs_tuners.freq_step * policy->max) / 100;
  76
  77                 /* max freq cannot be less than 100. But who knows.... */
  78                 if (unlikely(freq_target == 0))
  79                         freq_target = 5;
  80
  81                 dbs_info->requested_freq += freq_target;
  82                 if (dbs_info->requested_freq > policy->max)
  83                         dbs_info->requested_freq = policy->max;
  84
  85                 __cpufreq_driver_target(policy, dbs_info->requested_freq,
  86                         CPUFREQ_RELATION_H);
  87                 return;
  88         }
  89
  90         /*
  91          * The optimal frequency is the frequency that is the lowest that can
  92          * support the current CPU usage without triggering the up policy. To be
  93          * safe, we focus 10 points under the threshold.
  94          */
  95         if (load < (cs_tuners.down_threshold - 10)) {
  96                 freq_target = (cs_tuners.freq_step * policy->max) / 100;
  97
  98                 dbs_info->requested_freq -= freq_target;
  99                 if (dbs_info->requested_freq < policy->min)
 100                         dbs_info->requested_freq = policy->min;
 101
 102                 /*
 103                  * if we cannot reduce the frequency anymore, break out early
 104                  */
 105                 if (policy->cur == policy->min)
 106                         return;
 107
 108                 __cpufreq_driver_target(policy, dbs_info->requested_freq,
 109                                 CPUFREQ_RELATION_H);
 110                 return;
 111         }
 112 }
 113
 114 static void cs_dbs_timer(struct work_struct *work)
 115 {
 116         struct delayed_work *dw = to_delayed_work(work);
 117         struct cs_cpu_dbs_info_s *dbs_info = container_of(work,
 118                         struct cs_cpu_dbs_info_s, cdbs.work.work);
 119         unsigned int cpu = dbs_info->cdbs.cur_policy->cpu;
 120         struct cs_cpu_dbs_info_s *core_dbs_info = &per_cpu(cs_cpu_dbs_info,
 121                         cpu);
 122         int delay = delay_for_sampling_rate(cs_tuners.sampling_rate);
 123
 124         mutex_lock(&core_dbs_info->cdbs.timer_mutex);
 125         if (need_load_eval(&core_dbs_info->cdbs, cs_tuners.sampling_rate))
 126                 dbs_check_cpu(&cs_dbs_data, cpu);
 127
 128         schedule_delayed_work_on(smp_processor_id(), dw, delay);
 129         mutex_unlock(&core_dbs_info->cdbs.timer_mutex);
 130 }
 131
 132 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 133                 void *data)
 134 {
 135         struct cpufreq_freqs *freq = data;
 136         struct cs_cpu_dbs_info_s *dbs_info =
 137                                         &per_cpu(cs_cpu_dbs_info, freq->cpu);
 138         struct cpufreq_policy *policy;
 139
 140         if (!dbs_info->enable)
 141                 return 0;
 142
 143         policy = dbs_info->cdbs.cur_policy;
 144
 145         /*
 146          * we only care if our internally tracked freq moves outside the 'valid'
 147          * ranges of frequency available to us otherwise we do not change it
 148         */
 149         if (dbs_info->requested_freq > policy->max
 150                         || dbs_info->requested_freq < policy->min)
 151                 dbs_info->requested_freq = freq->new;
 152
 153         return 0;
 154 }
 155
 156 /************************** sysfs interface ************************/
 157 static ssize_t show_sampling_rate_min(struct kobject *kobj,
 158                                       struct attribute *attr, char *buf)
 159 {
 160         return sprintf(buf, "%u\n", cs_dbs_data.min_sampling_rate);
 161 }
 162
 163 static ssize_t store_sampling_down_factor(struct kobject *a,
 164                                           struct attribute *b,
 165                                           const char *buf, size_t count)
 166 {
 167         unsigned int input;
 168         int ret;
 169         ret = sscanf(buf, "%u", &input);
 170
 171         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 172                 return -EINVAL;
 173
 174         cs_tuners.sampling_down_factor = input;
 175         return count;
 176 }
 177
 178 static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
 179                                    const char *buf, size_t count)
 180 {
 181         unsigned int input;
 182         int ret;
 183         ret = sscanf(buf, "%u", &input);
 184
 185         if (ret != 1)
 186                 return -EINVAL;
 187
 188         cs_tuners.sampling_rate = max(input, cs_dbs_data.min_sampling_rate);
 189         return count;
 190 }
 191
 192 static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
 193                                   const char *buf, size_t count)
 194 {
 195         unsigned int input;
 196         int ret;
 197         ret = sscanf(buf, "%u", &input);
 198
 199         if (ret != 1 || input > 100 || input <= cs_tuners.down_threshold)
 200                 return -EINVAL;
 201
 202         cs_tuners.up_threshold = input;
 203         return count;
 204 }
 205
 206 static ssize_t store_down_threshold(struct kobject *a, struct attribute *b,
 207                                     const char *buf, size_t count)
 208 {
 209         unsigned int input;
 210         int ret;
 211         ret = sscanf(buf, "%u", &input);
 212
 213         /* cannot be lower than 11 otherwise freq will not fall */
 214         if (ret != 1 || input < 11 || input > 100 ||
 215                         input >= cs_tuners.up_threshold)
 216                 return -EINVAL;
 217
 218         cs_tuners.down_threshold = input;
 219         return count;
 220 }
 221
 222 static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
 223                                       const char *buf, size_t count)
 224 {
 225         unsigned int input, j;
 226         int ret;
 227
 228         ret = sscanf(buf, "%u", &input);
 229         if (ret != 1)
 230                 return -EINVAL;
 231
 232         if (input > 1)
 233                 input = 1;
 234
 235         if (input == cs_tuners.ignore_nice) /* nothing to do */
 236                 return count;
 237
 238         cs_tuners.ignore_nice = input;
 239
 240         /* we need to re-evaluate prev_cpu_idle */
 241         for_each_online_cpu(j) {
 242                 struct cs_cpu_dbs_info_s *dbs_info;
 243                 dbs_info = &per_cpu(cs_cpu_dbs_info, j);
 244                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 245                                                 &dbs_info->cdbs.prev_cpu_wall);
 246                 if (cs_tuners.ignore_nice)
 247                         dbs_info->cdbs.prev_cpu_nice =
 248                                 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 249         }
 250         return count;
 251 }
 252
 253 static ssize_t store_freq_step(struct kobject *a, struct attribute *b,
 254                                const char *buf, size_t count)
 255 {
 256         unsigned int input;
 257         int ret;
 258         ret = sscanf(buf, "%u", &input);
 259
 260         if (ret != 1)
 261                 return -EINVAL;
 262
 263         if (input > 100)
 264                 input = 100;
 265
 266         /*
 267          * no need to test here if freq_step is zero as the user might actually
 268          * want this, they would be crazy though :)
 269          */
 270         cs_tuners.freq_step = input;
 271         return count;
 272 }
 273
 274 show_one(cs, sampling_rate, sampling_rate);
 275 show_one(cs, sampling_down_factor, sampling_down_factor);
 276 show_one(cs, up_threshold, up_threshold);
 277 show_one(cs, down_threshold, down_threshold);
 278 show_one(cs, ignore_nice_load, ignore_nice);
 279 show_one(cs, freq_step, freq_step);
 280
 281 define_one_global_rw(sampling_rate);
 282 define_one_global_rw(sampling_down_factor);
 283 define_one_global_rw(up_threshold);
 284 define_one_global_rw(down_threshold);
 285 define_one_global_rw(ignore_nice_load);
 286 define_one_global_rw(freq_step);
 287 define_one_global_ro(sampling_rate_min);
 288
 289 static struct attribute *dbs_attributes[] = {
 290         &sampling_rate_min.attr,
 291         &sampling_rate.attr,
 292         &sampling_down_factor.attr,
 293         &up_threshold.attr,
 294         &down_threshold.attr,
 295         &ignore_nice_load.attr,
 296         &freq_step.attr,
 297         NULL
 298 };
 299
 300 static struct attribute_group cs_attr_group = {
 301         .attrs = dbs_attributes,
 302         .name = "conservative",
 303 };
 304
 305 /************************** sysfs end ************************/
 306
 307 define_get_cpu_dbs_routines(cs_cpu_dbs_info);
 308
 309 static struct notifier_block cs_cpufreq_notifier_block = {
 310         .notifier_call = dbs_cpufreq_notifier,
 311 };
 312
 313 static struct cs_ops cs_ops = {
 314         .notifier_block = &cs_cpufreq_notifier_block,
 315 };
 316
 317 static struct dbs_data cs_dbs_data = {
 318         .governor = GOV_CONSERVATIVE,
 319         .attr_group = &cs_attr_group,
 320         .tuners = &cs_tuners,
 321         .get_cpu_cdbs = get_cpu_cdbs,
 322         .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 323         .gov_dbs_timer = cs_dbs_timer,
 324         .gov_check_cpu = cs_check_cpu,
 325         .gov_ops = &cs_ops,
 326 };
 327
 328 static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy,
 329                                    unsigned int event)
 330 {
 331         return cpufreq_governor_dbs(&cs_dbs_data, policy, event);
 332 }
 333
 334 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 335 static
 336 #endif
 337 struct cpufreq_governor cpufreq_gov_conservative = {
 338         .name                   = "conservative",
 339         .governor               = cs_cpufreq_governor_dbs,
 340         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 341         .owner                  = THIS_MODULE,
 342 };
 343
 344 static int __init cpufreq_gov_dbs_init(void)
 345 {
 346         mutex_init(&cs_dbs_data.mutex);
 347         return cpufreq_register_governor(&cpufreq_gov_conservative);
 348 }
 349
 350 static void __exit cpufreq_gov_dbs_exit(void)
 351 {
 352         cpufreq_unregister_governor(&cpufreq_gov_conservative);
 353 }
 354
 355 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
 356 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
 357                 "Low Latency Frequency Transition capable processors "
 358                 "optimised for use in a battery environment");
 359 MODULE_LICENSE("GPL");
 360
 361 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 362 fs_initcall(cpufreq_gov_dbs_init);
 363 #else
 364 module_init(cpufreq_gov_dbs_init);
 365 #endif
 366 module_exit(cpufreq_gov_dbs_exit);