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/slab.h>
  15 #include "cpufreq_governor.h"
  16
  17 /* Conservative governor macros */
  18 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
  19 #define DEF_FREQUENCY_DOWN_THRESHOLD            (20)
  20 #define DEF_FREQUENCY_STEP                      (5)
  21 #define DEF_SAMPLING_DOWN_FACTOR                (1)
  22 #define MAX_SAMPLING_DOWN_FACTOR                (10)
  23
  24 static DEFINE_PER_CPU(struct cs_cpu_dbs_info_s, cs_cpu_dbs_info);
  25
  26 static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy,
  27                                    unsigned int event);
  28
  29 static struct cpufreq_governor cpufreq_gov_conservative = {
  30         .name                   = "conservative",
  31         .governor               = cs_cpufreq_governor_dbs,
  32         .max_transition_latency = TRANSITION_LATENCY_LIMIT,
  33         .owner                  = THIS_MODULE,
  34 };
  35
  36 static inline unsigned int get_freq_target(struct cs_dbs_tuners *cs_tuners,
  37                                            struct cpufreq_policy *policy)
  38 {
  39         unsigned int freq_target = (cs_tuners->freq_step * policy->max) / 100;
  40
  41         /* max freq cannot be less than 100. But who knows... */
  42         if (unlikely(freq_target == 0))
  43                 freq_target = DEF_FREQUENCY_STEP;
  44
  45         return freq_target;
  46 }
  47
  48 /*
  49  * Every sampling_rate, we check, if current idle time is less than 20%
  50  * (default), then we try to increase frequency. Every sampling_rate *
  51  * sampling_down_factor, we check, if current idle time is more than 80%
  52  * (default), then we try to decrease frequency
  53  *
  54  * Any frequency increase takes it to the maximum frequency. Frequency reduction
  55  * happens at minimum steps of 5% (default) of maximum frequency
  56  */
  57 static void cs_check_cpu(int cpu, unsigned int load)
  58 {
  59         struct cs_cpu_dbs_info_s *dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
  60         struct cpufreq_policy *policy = dbs_info->cdbs.shared->policy;
  61         struct dbs_data *dbs_data = policy->governor_data;
  62         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
  63
  64         /*
  65          * break out if we 'cannot' reduce the speed as the user might
  66          * want freq_step to be zero
  67          */
  68         if (cs_tuners->freq_step == 0)
  69                 return;
  70
  71         /* Check for frequency increase */
  72         if (load > cs_tuners->up_threshold) {
  73                 dbs_info->down_skip = 0;
  74
  75                 /* if we are already at full speed then break out early */
  76                 if (dbs_info->requested_freq == policy->max)
  77                         return;
  78
  79                 dbs_info->requested_freq += get_freq_target(cs_tuners, policy);
  80
  81                 if (dbs_info->requested_freq > policy->max)
  82                         dbs_info->requested_freq = policy->max;
  83
  84                 __cpufreq_driver_target(policy, dbs_info->requested_freq,
  85                         CPUFREQ_RELATION_H);
  86                 return;
  87         }
  88
  89         /* if sampling_down_factor is active break out early */
  90         if (++dbs_info->down_skip < cs_tuners->sampling_down_factor)
  91                 return;
  92         dbs_info->down_skip = 0;
  93
  94         /* Check for frequency decrease */
  95         if (load < cs_tuners->down_threshold) {
  96                 unsigned int freq_target;
  97                 /*
  98                  * if we cannot reduce the frequency anymore, break out early
  99                  */
 100                 if (policy->cur == policy->min)
 101                         return;
 102
 103                 freq_target = get_freq_target(cs_tuners, policy);
 104                 if (dbs_info->requested_freq > freq_target)
 105                         dbs_info->requested_freq -= freq_target;
 106                 else
 107                         dbs_info->requested_freq = policy->min;
 108
 109                 __cpufreq_driver_target(policy, dbs_info->requested_freq,
 110                                 CPUFREQ_RELATION_L);
 111                 return;
 112         }
 113 }
 114
 115 static unsigned int cs_dbs_timer(struct cpufreq_policy *policy, bool modify_all)
 116 {
 117         struct dbs_data *dbs_data = policy->governor_data;
 118         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 119
 120         if (modify_all)
 121                 dbs_check_cpu(dbs_data, policy->cpu);
 122
 123         return delay_for_sampling_rate(cs_tuners->sampling_rate);
 124 }
 125
 126 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 127                 void *data)
 128 {
 129         struct cpufreq_freqs *freq = data;
 130         struct cs_cpu_dbs_info_s *dbs_info =
 131                                         &per_cpu(cs_cpu_dbs_info, freq->cpu);
 132         struct cpufreq_policy *policy = cpufreq_cpu_get_raw(freq->cpu);
 133
 134         if (!policy)
 135                 return 0;
 136
 137         /* policy isn't governed by conservative governor */
 138         if (policy->governor != &cpufreq_gov_conservative)
 139                 return 0;
 140
 141         /*
 142          * we only care if our internally tracked freq moves outside the 'valid'
 143          * ranges of frequency available to us otherwise we do not change it
 144         */
 145         if (dbs_info->requested_freq > policy->max
 146                         || dbs_info->requested_freq < policy->min)
 147                 dbs_info->requested_freq = freq->new;
 148
 149         return 0;
 150 }
 151
 152 static struct notifier_block cs_cpufreq_notifier_block = {
 153         .notifier_call = dbs_cpufreq_notifier,
 154 };
 155
 156 /************************** sysfs interface ************************/
 157 static struct common_dbs_data cs_dbs_cdata;
 158
 159 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 160                 const char *buf, size_t count)
 161 {
 162         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 163         unsigned int input;
 164         int ret;
 165         ret = sscanf(buf, "%u", &input);
 166
 167         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 168                 return -EINVAL;
 169
 170         cs_tuners->sampling_down_factor = input;
 171         return count;
 172 }
 173
 174 static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
 175                 size_t count)
 176 {
 177         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 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, dbs_data->min_sampling_rate);
 186         return count;
 187 }
 188
 189 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
 190                 size_t count)
 191 {
 192         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 193         unsigned int input;
 194         int ret;
 195         ret = sscanf(buf, "%u", &input);
 196
 197         if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold)
 198                 return -EINVAL;
 199
 200         cs_tuners->up_threshold = input;
 201         return count;
 202 }
 203
 204 static ssize_t store_down_threshold(struct dbs_data *dbs_data, const char *buf,
 205                 size_t count)
 206 {
 207         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 208         unsigned int input;
 209         int ret;
 210         ret = sscanf(buf, "%u", &input);
 211
 212         /* cannot be lower than 11 otherwise freq will not fall */
 213         if (ret != 1 || input < 11 || input > 100 ||
 214                         input >= cs_tuners->up_threshold)
 215                 return -EINVAL;
 216
 217         cs_tuners->down_threshold = input;
 218         return count;
 219 }
 220
 221 static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data,
 222                 const char *buf, size_t count)
 223 {
 224         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 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_load) /* nothing to do */
 236                 return count;
 237
 238         cs_tuners->ignore_nice_load = 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, 0);
 246                 if (cs_tuners->ignore_nice_load)
 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 dbs_data *dbs_data, const char *buf,
 254                 size_t count)
 255 {
 256         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 257         unsigned int input;
 258         int ret;
 259         ret = sscanf(buf, "%u", &input);
 260
 261         if (ret != 1)
 262                 return -EINVAL;
 263
 264         if (input > 100)
 265                 input = 100;
 266
 267         /*
 268          * no need to test here if freq_step is zero as the user might actually
 269          * want this, they would be crazy though :)
 270          */
 271         cs_tuners->freq_step = input;
 272         return count;
 273 }
 274
 275 show_store_one(cs, sampling_rate);
 276 show_store_one(cs, sampling_down_factor);
 277 show_store_one(cs, up_threshold);
 278 show_store_one(cs, down_threshold);
 279 show_store_one(cs, ignore_nice_load);
 280 show_store_one(cs, freq_step);
 281 declare_show_sampling_rate_min(cs);
 282
 283 gov_sys_pol_attr_rw(sampling_rate);
 284 gov_sys_pol_attr_rw(sampling_down_factor);
 285 gov_sys_pol_attr_rw(up_threshold);
 286 gov_sys_pol_attr_rw(down_threshold);
 287 gov_sys_pol_attr_rw(ignore_nice_load);
 288 gov_sys_pol_attr_rw(freq_step);
 289 gov_sys_pol_attr_ro(sampling_rate_min);
 290
 291 static struct attribute *dbs_attributes_gov_sys[] = {
 292         &sampling_rate_min_gov_sys.attr,
 293         &sampling_rate_gov_sys.attr,
 294         &sampling_down_factor_gov_sys.attr,
 295         &up_threshold_gov_sys.attr,
 296         &down_threshold_gov_sys.attr,
 297         &ignore_nice_load_gov_sys.attr,
 298         &freq_step_gov_sys.attr,
 299         NULL
 300 };
 301
 302 static struct attribute_group cs_attr_group_gov_sys = {
 303         .attrs = dbs_attributes_gov_sys,
 304         .name = "conservative",
 305 };
 306
 307 static struct attribute *dbs_attributes_gov_pol[] = {
 308         &sampling_rate_min_gov_pol.attr,
 309         &sampling_rate_gov_pol.attr,
 310         &sampling_down_factor_gov_pol.attr,
 311         &up_threshold_gov_pol.attr,
 312         &down_threshold_gov_pol.attr,
 313         &ignore_nice_load_gov_pol.attr,
 314         &freq_step_gov_pol.attr,
 315         NULL
 316 };
 317
 318 static struct attribute_group cs_attr_group_gov_pol = {
 319         .attrs = dbs_attributes_gov_pol,
 320         .name = "conservative",
 321 };
 322
 323 /************************** sysfs end ************************/
 324
 325 static int cs_init(struct dbs_data *dbs_data, bool notify)
 326 {
 327         struct cs_dbs_tuners *tuners;
 328
 329         tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 330         if (!tuners) {
 331                 pr_err("%s: kzalloc failed\n", __func__);
 332                 return -ENOMEM;
 333         }
 334
 335         tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 336         tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
 337         tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 338         tuners->ignore_nice_load = 0;
 339         tuners->freq_step = DEF_FREQUENCY_STEP;
 340
 341         dbs_data->tuners = tuners;
 342         dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 343                 jiffies_to_usecs(10);
 344
 345         if (notify)
 346                 cpufreq_register_notifier(&cs_cpufreq_notifier_block,
 347                                           CPUFREQ_TRANSITION_NOTIFIER);
 348
 349         return 0;
 350 }
 351
 352 static void cs_exit(struct dbs_data *dbs_data, bool notify)
 353 {
 354         if (notify)
 355                 cpufreq_unregister_notifier(&cs_cpufreq_notifier_block,
 356                                             CPUFREQ_TRANSITION_NOTIFIER);
 357
 358         kfree(dbs_data->tuners);
 359 }
 360
 361 define_get_cpu_dbs_routines(cs_cpu_dbs_info);
 362
 363 static struct common_dbs_data cs_dbs_cdata = {
 364         .governor = GOV_CONSERVATIVE,
 365         .attr_group_gov_sys = &cs_attr_group_gov_sys,
 366         .attr_group_gov_pol = &cs_attr_group_gov_pol,
 367         .get_cpu_cdbs = get_cpu_cdbs,
 368         .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 369         .gov_dbs_timer = cs_dbs_timer,
 370         .gov_check_cpu = cs_check_cpu,
 371         .init = cs_init,
 372         .exit = cs_exit,
 373         .mutex = __MUTEX_INITIALIZER(cs_dbs_cdata.mutex),
 374 };
 375
 376 static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy,
 377                                    unsigned int event)
 378 {
 379         return cpufreq_governor_dbs(policy, &cs_dbs_cdata, event);
 380 }
 381
 382 static int __init cpufreq_gov_dbs_init(void)
 383 {
 384         return cpufreq_register_governor(&cpufreq_gov_conservative);
 385 }
 386
 387 static void __exit cpufreq_gov_dbs_exit(void)
 388 {
 389         cpufreq_unregister_governor(&cpufreq_gov_conservative);
 390 }
 391
 392 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
 393 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
 394                 "Low Latency Frequency Transition capable processors "
 395                 "optimised for use in a battery environment");
 396 MODULE_LICENSE("GPL");
 397
 398 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 399 struct cpufreq_governor *cpufreq_default_governor(void)
 400 {
 401         return &cpufreq_gov_conservative;
 402 }
 403
 404 fs_initcall(cpufreq_gov_dbs_init);
 405 #else
 406 module_init(cpufreq_gov_dbs_init);
 407 #endif
 408 module_exit(cpufreq_gov_dbs_exit);