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