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 inline unsigned int get_freq_target(struct cs_dbs_tuners *cs_tuners,
  27                                            struct cpufreq_policy *policy)
  28 {
  29         unsigned int freq_target = (cs_tuners->freq_step * policy->max) / 100;
  30
  31         /* max freq cannot be less than 100. But who knows... */
  32         if (unlikely(freq_target == 0))
  33                 freq_target = DEF_FREQUENCY_STEP;
  34
  35         return freq_target;
  36 }
  37
  38 /*
  39  * Every sampling_rate, we check, if current idle time is less than 20%
  40  * (default), then we try to increase frequency. Every sampling_rate *
  41  * sampling_down_factor, we check, if current idle time is more than 80%
  42  * (default), then we try to decrease frequency
  43  *
  44  * Any frequency increase takes it to the maximum frequency. Frequency reduction
  45  * happens at minimum steps of 5% (default) of maximum frequency
  46  */
  47 static void cs_check_cpu(int cpu, unsigned int load)
  48 {
  49         struct cs_cpu_dbs_info_s *dbs_info = &per_cpu(cs_cpu_dbs_info, cpu);
  50         struct cpufreq_policy *policy = dbs_info->cdbs.policy_dbs->policy;
  51         struct policy_dbs_info *policy_dbs = policy->governor_data;
  52         struct dbs_data *dbs_data = policy_dbs->dbs_data;
  53         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
  54
  55         /*
  56          * break out if we 'cannot' reduce the speed as the user might
  57          * want freq_step to be zero
  58          */
  59         if (cs_tuners->freq_step == 0)
  60                 return;
  61
  62         /* Check for frequency increase */
  63         if (load > cs_tuners->up_threshold) {
  64                 dbs_info->down_skip = 0;
  65
  66                 /* if we are already at full speed then break out early */
  67                 if (dbs_info->requested_freq == policy->max)
  68                         return;
  69
  70                 dbs_info->requested_freq += get_freq_target(cs_tuners, policy);
  71
  72                 if (dbs_info->requested_freq > policy->max)
  73                         dbs_info->requested_freq = policy->max;
  74
  75                 __cpufreq_driver_target(policy, dbs_info->requested_freq,
  76                         CPUFREQ_RELATION_H);
  77                 return;
  78         }
  79
  80         /* if sampling_down_factor is active break out early */
  81         if (++dbs_info->down_skip < cs_tuners->sampling_down_factor)
  82                 return;
  83         dbs_info->down_skip = 0;
  84
  85         /* Check for frequency decrease */
  86         if (load < cs_tuners->down_threshold) {
  87                 unsigned int freq_target;
  88                 /*
  89                  * if we cannot reduce the frequency anymore, break out early
  90                  */
  91                 if (policy->cur == policy->min)
  92                         return;
  93
  94                 freq_target = get_freq_target(cs_tuners, policy);
  95                 if (dbs_info->requested_freq > freq_target)
  96                         dbs_info->requested_freq -= freq_target;
  97                 else
  98                         dbs_info->requested_freq = policy->min;
  99
 100                 __cpufreq_driver_target(policy, dbs_info->requested_freq,
 101                                 CPUFREQ_RELATION_L);
 102                 return;
 103         }
 104 }
 105
 106 static unsigned int cs_dbs_timer(struct cpufreq_policy *policy)
 107 {
 108         struct policy_dbs_info *policy_dbs = policy->governor_data;
 109         struct dbs_data *dbs_data = policy_dbs->dbs_data;
 110         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 111
 112         dbs_check_cpu(policy);
 113         return delay_for_sampling_rate(cs_tuners->sampling_rate);
 114 }
 115
 116 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 117                                 void *data);
 118
 119 static struct notifier_block cs_cpufreq_notifier_block = {
 120         .notifier_call = dbs_cpufreq_notifier,
 121 };
 122
 123 /************************** sysfs interface ************************/
 124 static struct dbs_governor cs_dbs_gov;
 125
 126 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 127                 const char *buf, size_t count)
 128 {
 129         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 130         unsigned int input;
 131         int ret;
 132         ret = sscanf(buf, "%u", &input);
 133
 134         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 135                 return -EINVAL;
 136
 137         cs_tuners->sampling_down_factor = input;
 138         return count;
 139 }
 140
 141 static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
 142                 size_t count)
 143 {
 144         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 145         unsigned int input;
 146         int ret;
 147         ret = sscanf(buf, "%u", &input);
 148
 149         if (ret != 1)
 150                 return -EINVAL;
 151
 152         cs_tuners->sampling_rate = max(input, dbs_data->min_sampling_rate);
 153         return count;
 154 }
 155
 156 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
 157                 size_t count)
 158 {
 159         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 160         unsigned int input;
 161         int ret;
 162         ret = sscanf(buf, "%u", &input);
 163
 164         if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold)
 165                 return -EINVAL;
 166
 167         cs_tuners->up_threshold = input;
 168         return count;
 169 }
 170
 171 static ssize_t store_down_threshold(struct dbs_data *dbs_data, const char *buf,
 172                 size_t count)
 173 {
 174         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 175         unsigned int input;
 176         int ret;
 177         ret = sscanf(buf, "%u", &input);
 178
 179         /* cannot be lower than 11 otherwise freq will not fall */
 180         if (ret != 1 || input < 11 || input > 100 ||
 181                         input >= cs_tuners->up_threshold)
 182                 return -EINVAL;
 183
 184         cs_tuners->down_threshold = input;
 185         return count;
 186 }
 187
 188 static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data,
 189                 const char *buf, size_t count)
 190 {
 191         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 192         unsigned int input, j;
 193         int ret;
 194
 195         ret = sscanf(buf, "%u", &input);
 196         if (ret != 1)
 197                 return -EINVAL;
 198
 199         if (input > 1)
 200                 input = 1;
 201
 202         if (input == cs_tuners->ignore_nice_load) /* nothing to do */
 203                 return count;
 204
 205         cs_tuners->ignore_nice_load = input;
 206
 207         /* we need to re-evaluate prev_cpu_idle */
 208         for_each_online_cpu(j) {
 209                 struct cs_cpu_dbs_info_s *dbs_info;
 210                 dbs_info = &per_cpu(cs_cpu_dbs_info, j);
 211                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 212                                         &dbs_info->cdbs.prev_cpu_wall, 0);
 213                 if (cs_tuners->ignore_nice_load)
 214                         dbs_info->cdbs.prev_cpu_nice =
 215                                 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 216         }
 217         return count;
 218 }
 219
 220 static ssize_t store_freq_step(struct dbs_data *dbs_data, const char *buf,
 221                 size_t count)
 222 {
 223         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 224         unsigned int input;
 225         int ret;
 226         ret = sscanf(buf, "%u", &input);
 227
 228         if (ret != 1)
 229                 return -EINVAL;
 230
 231         if (input > 100)
 232                 input = 100;
 233
 234         /*
 235          * no need to test here if freq_step is zero as the user might actually
 236          * want this, they would be crazy though :)
 237          */
 238         cs_tuners->freq_step = input;
 239         return count;
 240 }
 241
 242 show_store_one(cs, sampling_rate);
 243 show_store_one(cs, sampling_down_factor);
 244 show_store_one(cs, up_threshold);
 245 show_store_one(cs, down_threshold);
 246 show_store_one(cs, ignore_nice_load);
 247 show_store_one(cs, freq_step);
 248 show_one_common(cs, min_sampling_rate);
 249
 250 gov_sys_pol_attr_rw(sampling_rate);
 251 gov_sys_pol_attr_rw(sampling_down_factor);
 252 gov_sys_pol_attr_rw(up_threshold);
 253 gov_sys_pol_attr_rw(down_threshold);
 254 gov_sys_pol_attr_rw(ignore_nice_load);
 255 gov_sys_pol_attr_rw(freq_step);
 256 gov_sys_pol_attr_ro(min_sampling_rate);
 257
 258 static struct attribute *dbs_attributes_gov_sys[] = {
 259         &min_sampling_rate_gov_sys.attr,
 260         &sampling_rate_gov_sys.attr,
 261         &sampling_down_factor_gov_sys.attr,
 262         &up_threshold_gov_sys.attr,
 263         &down_threshold_gov_sys.attr,
 264         &ignore_nice_load_gov_sys.attr,
 265         &freq_step_gov_sys.attr,
 266         NULL
 267 };
 268
 269 static struct attribute_group cs_attr_group_gov_sys = {
 270         .attrs = dbs_attributes_gov_sys,
 271         .name = "conservative",
 272 };
 273
 274 static struct attribute *dbs_attributes_gov_pol[] = {
 275         &min_sampling_rate_gov_pol.attr,
 276         &sampling_rate_gov_pol.attr,
 277         &sampling_down_factor_gov_pol.attr,
 278         &up_threshold_gov_pol.attr,
 279         &down_threshold_gov_pol.attr,
 280         &ignore_nice_load_gov_pol.attr,
 281         &freq_step_gov_pol.attr,
 282         NULL
 283 };
 284
 285 static struct attribute_group cs_attr_group_gov_pol = {
 286         .attrs = dbs_attributes_gov_pol,
 287         .name = "conservative",
 288 };
 289
 290 /************************** sysfs end ************************/
 291
 292 static int cs_init(struct dbs_data *dbs_data, bool notify)
 293 {
 294         struct cs_dbs_tuners *tuners;
 295
 296         tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 297         if (!tuners) {
 298                 pr_err("%s: kzalloc failed\n", __func__);
 299                 return -ENOMEM;
 300         }
 301
 302         tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 303         tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
 304         tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 305         tuners->ignore_nice_load = 0;
 306         tuners->freq_step = DEF_FREQUENCY_STEP;
 307
 308         dbs_data->tuners = tuners;
 309         dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 310                 jiffies_to_usecs(10);
 311
 312         if (notify)
 313                 cpufreq_register_notifier(&cs_cpufreq_notifier_block,
 314                                           CPUFREQ_TRANSITION_NOTIFIER);
 315
 316         return 0;
 317 }
 318
 319 static void cs_exit(struct dbs_data *dbs_data, bool notify)
 320 {
 321         if (notify)
 322                 cpufreq_unregister_notifier(&cs_cpufreq_notifier_block,
 323                                             CPUFREQ_TRANSITION_NOTIFIER);
 324
 325         kfree(dbs_data->tuners);
 326 }
 327
 328 define_get_cpu_dbs_routines(cs_cpu_dbs_info);
 329
 330 static struct dbs_governor cs_dbs_gov = {
 331         .gov = {
 332                 .name = "conservative",
 333                 .governor = cpufreq_governor_dbs,
 334                 .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 335                 .owner = THIS_MODULE,
 336         },
 337         .governor = GOV_CONSERVATIVE,
 338         .attr_group_gov_sys = &cs_attr_group_gov_sys,
 339         .attr_group_gov_pol = &cs_attr_group_gov_pol,
 340         .get_cpu_cdbs = get_cpu_cdbs,
 341         .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 342         .gov_dbs_timer = cs_dbs_timer,
 343         .gov_check_cpu = cs_check_cpu,
 344         .init = cs_init,
 345         .exit = cs_exit,
 346 };
 347
 348 #define CPU_FREQ_GOV_CONSERVATIVE       (&cs_dbs_gov.gov)
 349
 350 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 351                                 void *data)
 352 {
 353         struct cpufreq_freqs *freq = data;
 354         struct cs_cpu_dbs_info_s *dbs_info =
 355                                         &per_cpu(cs_cpu_dbs_info, freq->cpu);
 356         struct cpufreq_policy *policy = cpufreq_cpu_get_raw(freq->cpu);
 357
 358         if (!policy)
 359                 return 0;
 360
 361         /* policy isn't governed by conservative governor */
 362         if (policy->governor != CPU_FREQ_GOV_CONSERVATIVE)
 363                 return 0;
 364
 365         /*
 366          * we only care if our internally tracked freq moves outside the 'valid'
 367          * ranges of frequency available to us otherwise we do not change it
 368         */
 369         if (dbs_info->requested_freq > policy->max
 370                         || dbs_info->requested_freq < policy->min)
 371                 dbs_info->requested_freq = freq->new;
 372
 373         return 0;
 374 }
 375
 376 static int __init cpufreq_gov_dbs_init(void)
 377 {
 378         return cpufreq_register_governor(CPU_FREQ_GOV_CONSERVATIVE);
 379 }
 380
 381 static void __exit cpufreq_gov_dbs_exit(void)
 382 {
 383         cpufreq_unregister_governor(CPU_FREQ_GOV_CONSERVATIVE);
 384 }
 385
 386 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
 387 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
 388                 "Low Latency Frequency Transition capable processors "
 389                 "optimised for use in a battery environment");
 390 MODULE_LICENSE("GPL");
 391
 392 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 393 struct cpufreq_governor *cpufreq_default_governor(void)
 394 {
 395         return CPU_FREQ_GOV_CONSERVATIVE;
 396 }
 397
 398 fs_initcall(cpufreq_gov_dbs_init);
 399 #else
 400 module_init(cpufreq_gov_dbs_init);
 401 #endif
 402 module_exit(cpufreq_gov_dbs_exit);