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 macors */
  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_timer_update(struct cs_cpu_dbs_info_s *dbs_info, bool sample,
 115                             struct delayed_work *dw)
 116 {
 117         unsigned int cpu = dbs_info->cdbs.cpu;
 118         int delay = delay_for_sampling_rate(cs_tuners.sampling_rate);
 119
 120         if (sample)
 121                 dbs_check_cpu(&cs_dbs_data, cpu);
 122
 123         schedule_delayed_work_on(smp_processor_id(), dw, delay);
 124 }
 125
 126 static void cs_timer_coordinated(struct cs_cpu_dbs_info_s *dbs_info_local,
 127                                  struct delayed_work *dw)
 128 {
 129         struct cs_cpu_dbs_info_s *dbs_info;
 130         ktime_t time_now;
 131         s64 delta_us;
 132         bool sample = true;
 133
 134         /* use leader CPU's dbs_info */
 135         dbs_info = &per_cpu(cs_cpu_dbs_info, dbs_info_local->cdbs.cpu);
 136         mutex_lock(&dbs_info->cdbs.timer_mutex);
 137
 138         time_now = ktime_get();
 139         delta_us = ktime_us_delta(time_now, dbs_info->cdbs.time_stamp);
 140
 141         /* Do nothing if we recently have sampled */
 142         if (delta_us < (s64)(cs_tuners.sampling_rate / 2))
 143                 sample = false;
 144         else
 145                 dbs_info->cdbs.time_stamp = time_now;
 146
 147         cs_timer_update(dbs_info, sample, dw);
 148         mutex_unlock(&dbs_info->cdbs.timer_mutex);
 149 }
 150
 151 static void cs_dbs_timer(struct work_struct *work)
 152 {
 153         struct delayed_work *dw = to_delayed_work(work);
 154         struct cs_cpu_dbs_info_s *dbs_info = container_of(work,
 155                         struct cs_cpu_dbs_info_s, cdbs.work.work);
 156
 157         if (policy_is_shared(dbs_info->cdbs.cur_policy)) {
 158                 cs_timer_coordinated(dbs_info, dw);
 159         } else {
 160                 mutex_lock(&dbs_info->cdbs.timer_mutex);
 161                 cs_timer_update(dbs_info, true, dw);
 162                 mutex_unlock(&dbs_info->cdbs.timer_mutex);
 163         }
 164 }
 165 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 166                 void *data)
 167 {
 168         struct cpufreq_freqs *freq = data;
 169         struct cs_cpu_dbs_info_s *dbs_info =
 170                                         &per_cpu(cs_cpu_dbs_info, freq->cpu);
 171         struct cpufreq_policy *policy;
 172
 173         if (!dbs_info->enable)
 174                 return 0;
 175
 176         policy = dbs_info->cdbs.cur_policy;
 177
 178         /*
 179          * we only care if our internally tracked freq moves outside the 'valid'
 180          * ranges of freqency available to us otherwise we do not change it
 181         */
 182         if (dbs_info->requested_freq > policy->max
 183                         || dbs_info->requested_freq < policy->min)
 184                 dbs_info->requested_freq = freq->new;
 185
 186         return 0;
 187 }
 188
 189 /************************** sysfs interface ************************/
 190 static ssize_t show_sampling_rate_min(struct kobject *kobj,
 191                                       struct attribute *attr, char *buf)
 192 {
 193         return sprintf(buf, "%u\n", cs_dbs_data.min_sampling_rate);
 194 }
 195
 196 static ssize_t store_sampling_down_factor(struct kobject *a,
 197                                           struct attribute *b,
 198                                           const char *buf, size_t count)
 199 {
 200         unsigned int input;
 201         int ret;
 202         ret = sscanf(buf, "%u", &input);
 203
 204         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 205                 return -EINVAL;
 206
 207         cs_tuners.sampling_down_factor = input;
 208         return count;
 209 }
 210
 211 static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
 212                                    const char *buf, size_t count)
 213 {
 214         unsigned int input;
 215         int ret;
 216         ret = sscanf(buf, "%u", &input);
 217
 218         if (ret != 1)
 219                 return -EINVAL;
 220
 221         cs_tuners.sampling_rate = max(input, cs_dbs_data.min_sampling_rate);
 222         return count;
 223 }
 224
 225 static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
 226                                   const char *buf, size_t count)
 227 {
 228         unsigned int input;
 229         int ret;
 230         ret = sscanf(buf, "%u", &input);
 231
 232         if (ret != 1 || input > 100 || input <= cs_tuners.down_threshold)
 233                 return -EINVAL;
 234
 235         cs_tuners.up_threshold = input;
 236         return count;
 237 }
 238
 239 static ssize_t store_down_threshold(struct kobject *a, struct attribute *b,
 240                                     const char *buf, size_t count)
 241 {
 242         unsigned int input;
 243         int ret;
 244         ret = sscanf(buf, "%u", &input);
 245
 246         /* cannot be lower than 11 otherwise freq will not fall */
 247         if (ret != 1 || input < 11 || input > 100 ||
 248                         input >= cs_tuners.up_threshold)
 249                 return -EINVAL;
 250
 251         cs_tuners.down_threshold = input;
 252         return count;
 253 }
 254
 255 static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
 256                                       const char *buf, size_t count)
 257 {
 258         unsigned int input, j;
 259         int ret;
 260
 261         ret = sscanf(buf, "%u", &input);
 262         if (ret != 1)
 263                 return -EINVAL;
 264
 265         if (input > 1)
 266                 input = 1;
 267
 268         if (input == cs_tuners.ignore_nice) /* nothing to do */
 269                 return count;
 270
 271         cs_tuners.ignore_nice = input;
 272
 273         /* we need to re-evaluate prev_cpu_idle */
 274         for_each_online_cpu(j) {
 275                 struct cs_cpu_dbs_info_s *dbs_info;
 276                 dbs_info = &per_cpu(cs_cpu_dbs_info, j);
 277                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 278                                                 &dbs_info->cdbs.prev_cpu_wall);
 279                 if (cs_tuners.ignore_nice)
 280                         dbs_info->cdbs.prev_cpu_nice =
 281                                 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 282         }
 283         return count;
 284 }
 285
 286 static ssize_t store_freq_step(struct kobject *a, struct attribute *b,
 287                                const char *buf, size_t count)
 288 {
 289         unsigned int input;
 290         int ret;
 291         ret = sscanf(buf, "%u", &input);
 292
 293         if (ret != 1)
 294                 return -EINVAL;
 295
 296         if (input > 100)
 297                 input = 100;
 298
 299         /*
 300          * no need to test here if freq_step is zero as the user might actually
 301          * want this, they would be crazy though :)
 302          */
 303         cs_tuners.freq_step = input;
 304         return count;
 305 }
 306
 307 show_one(cs, sampling_rate, sampling_rate);
 308 show_one(cs, sampling_down_factor, sampling_down_factor);
 309 show_one(cs, up_threshold, up_threshold);
 310 show_one(cs, down_threshold, down_threshold);
 311 show_one(cs, ignore_nice_load, ignore_nice);
 312 show_one(cs, freq_step, freq_step);
 313
 314 define_one_global_rw(sampling_rate);
 315 define_one_global_rw(sampling_down_factor);
 316 define_one_global_rw(up_threshold);
 317 define_one_global_rw(down_threshold);
 318 define_one_global_rw(ignore_nice_load);
 319 define_one_global_rw(freq_step);
 320 define_one_global_ro(sampling_rate_min);
 321
 322 static struct attribute *dbs_attributes[] = {
 323         &sampling_rate_min.attr,
 324         &sampling_rate.attr,
 325         &sampling_down_factor.attr,
 326         &up_threshold.attr,
 327         &down_threshold.attr,
 328         &ignore_nice_load.attr,
 329         &freq_step.attr,
 330         NULL
 331 };
 332
 333 static struct attribute_group cs_attr_group = {
 334         .attrs = dbs_attributes,
 335         .name = "conservative",
 336 };
 337
 338 /************************** sysfs end ************************/
 339
 340 define_get_cpu_dbs_routines(cs_cpu_dbs_info);
 341
 342 static struct notifier_block cs_cpufreq_notifier_block = {
 343         .notifier_call = dbs_cpufreq_notifier,
 344 };
 345
 346 static struct cs_ops cs_ops = {
 347         .notifier_block = &cs_cpufreq_notifier_block,
 348 };
 349
 350 static struct dbs_data cs_dbs_data = {
 351         .governor = GOV_CONSERVATIVE,
 352         .attr_group = &cs_attr_group,
 353         .tuners = &cs_tuners,
 354         .get_cpu_cdbs = get_cpu_cdbs,
 355         .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 356         .gov_dbs_timer = cs_dbs_timer,
 357         .gov_check_cpu = cs_check_cpu,
 358         .gov_ops = &cs_ops,
 359 };
 360
 361 static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy,
 362                                    unsigned int event)
 363 {
 364         return cpufreq_governor_dbs(&cs_dbs_data, policy, event);
 365 }
 366
 367 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 368 static
 369 #endif
 370 struct cpufreq_governor cpufreq_gov_conservative = {
 371         .name                   = "conservative",
 372         .governor               = cs_cpufreq_governor_dbs,
 373         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 374         .owner                  = THIS_MODULE,
 375 };
 376
 377 static int __init cpufreq_gov_dbs_init(void)
 378 {
 379         mutex_init(&cs_dbs_data.mutex);
 380         return cpufreq_register_governor(&cpufreq_gov_conservative);
 381 }
 382
 383 static void __exit cpufreq_gov_dbs_exit(void)
 384 {
 385         cpufreq_unregister_governor(&cpufreq_gov_conservative);
 386 }
 387
 388 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
 389 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
 390                 "Low Latency Frequency Transition capable processors "
 391                 "optimised for use in a battery environment");
 392 MODULE_LICENSE("GPL");
 393
 394 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 395 fs_initcall(cpufreq_gov_dbs_init);
 396 #else
 397 module_init(cpufreq_gov_dbs_init);
 398 #endif
 399 module_exit(cpufreq_gov_dbs_exit);