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 struct cs_policy_dbs_info {
  18         struct policy_dbs_info policy_dbs;
  19         unsigned int down_skip;
  20         unsigned int requested_freq;
  21 };
  22
  23 static inline struct cs_policy_dbs_info *to_dbs_info(struct policy_dbs_info *policy_dbs)
  24 {
  25         return container_of(policy_dbs, struct cs_policy_dbs_info, policy_dbs);
  26 }
  27
  28 /* Conservative governor macros */
  29 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
  30 #define DEF_FREQUENCY_DOWN_THRESHOLD            (20)
  31 #define DEF_FREQUENCY_STEP                      (5)
  32 #define DEF_SAMPLING_DOWN_FACTOR                (1)
  33 #define MAX_SAMPLING_DOWN_FACTOR                (10)
  34
  35 static DEFINE_PER_CPU(struct cs_cpu_dbs_info_s, cs_cpu_dbs_info);
  36
  37 static struct dbs_governor cs_dbs_gov;
  38
  39 static inline unsigned int get_freq_target(struct cs_dbs_tuners *cs_tuners,
  40                                            struct cpufreq_policy *policy)
  41 {
  42         unsigned int freq_target = (cs_tuners->freq_step * policy->max) / 100;
  43
  44         /* max freq cannot be less than 100. But who knows... */
  45         if (unlikely(freq_target == 0))
  46                 freq_target = DEF_FREQUENCY_STEP;
  47
  48         return freq_target;
  49 }
  50
  51 /*
  52  * Every sampling_rate, we check, if current idle time is less than 20%
  53  * (default), then we try to increase frequency. Every sampling_rate *
  54  * sampling_down_factor, we check, if current idle time is more than 80%
  55  * (default), then we try to decrease frequency
  56  *
  57  * Any frequency increase takes it to the maximum frequency. Frequency reduction
  58  * happens at minimum steps of 5% (default) of maximum frequency
  59  */
  60 static unsigned int cs_dbs_timer(struct cpufreq_policy *policy)
  61 {
  62         struct policy_dbs_info *policy_dbs = policy->governor_data;
  63         struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
  64         struct dbs_data *dbs_data = policy_dbs->dbs_data;
  65         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
  66         unsigned int load = dbs_update(policy);
  67
  68         /*
  69          * break out if we 'cannot' reduce the speed as the user might
  70          * want freq_step to be zero
  71          */
  72         if (cs_tuners->freq_step == 0)
  73                 goto out;
  74
  75         /* Check for frequency increase */
  76         if (load > dbs_data->up_threshold) {
  77                 dbs_info->down_skip = 0;
  78
  79                 /* if we are already at full speed then break out early */
  80                 if (dbs_info->requested_freq == policy->max)
  81                         goto out;
  82
  83                 dbs_info->requested_freq += get_freq_target(cs_tuners, policy);
  84
  85                 if (dbs_info->requested_freq > policy->max)
  86                         dbs_info->requested_freq = policy->max;
  87
  88                 __cpufreq_driver_target(policy, dbs_info->requested_freq,
  89                         CPUFREQ_RELATION_H);
  90                 goto out;
  91         }
  92
  93         /* if sampling_down_factor is active break out early */
  94         if (++dbs_info->down_skip < dbs_data->sampling_down_factor)
  95                 goto out;
  96         dbs_info->down_skip = 0;
  97
  98         /* Check for frequency decrease */
  99         if (load < cs_tuners->down_threshold) {
 100                 unsigned int freq_target;
 101                 /*
 102                  * if we cannot reduce the frequency anymore, break out early
 103                  */
 104                 if (policy->cur == policy->min)
 105                         goto out;
 106
 107                 freq_target = get_freq_target(cs_tuners, policy);
 108                 if (dbs_info->requested_freq > freq_target)
 109                         dbs_info->requested_freq -= freq_target;
 110                 else
 111                         dbs_info->requested_freq = policy->min;
 112
 113                 __cpufreq_driver_target(policy, dbs_info->requested_freq,
 114                                 CPUFREQ_RELATION_L);
 115         }
 116
 117  out:
 118         return dbs_data->sampling_rate;
 119 }
 120
 121 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 122                                 void *data);
 123
 124 static struct notifier_block cs_cpufreq_notifier_block = {
 125         .notifier_call = dbs_cpufreq_notifier,
 126 };
 127
 128 /************************** sysfs interface ************************/
 129 static struct dbs_governor cs_dbs_gov;
 130
 131 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 132                 const char *buf, size_t count)
 133 {
 134         unsigned int input;
 135         int ret;
 136         ret = sscanf(buf, "%u", &input);
 137
 138         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 139                 return -EINVAL;
 140
 141         dbs_data->sampling_down_factor = input;
 142         return count;
 143 }
 144
 145 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
 146                 size_t count)
 147 {
 148         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 149         unsigned int input;
 150         int ret;
 151         ret = sscanf(buf, "%u", &input);
 152
 153         if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold)
 154                 return -EINVAL;
 155
 156         dbs_data->up_threshold = input;
 157         return count;
 158 }
 159
 160 static ssize_t store_down_threshold(struct dbs_data *dbs_data, const char *buf,
 161                 size_t count)
 162 {
 163         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 164         unsigned int input;
 165         int ret;
 166         ret = sscanf(buf, "%u", &input);
 167
 168         /* cannot be lower than 11 otherwise freq will not fall */
 169         if (ret != 1 || input < 11 || input > 100 ||
 170                         input >= dbs_data->up_threshold)
 171                 return -EINVAL;
 172
 173         cs_tuners->down_threshold = input;
 174         return count;
 175 }
 176
 177 static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data,
 178                 const char *buf, size_t count)
 179 {
 180         unsigned int input;
 181         int ret;
 182
 183         ret = sscanf(buf, "%u", &input);
 184         if (ret != 1)
 185                 return -EINVAL;
 186
 187         if (input > 1)
 188                 input = 1;
 189
 190         if (input == dbs_data->ignore_nice_load) /* nothing to do */
 191                 return count;
 192
 193         dbs_data->ignore_nice_load = input;
 194
 195         /* we need to re-evaluate prev_cpu_idle */
 196         gov_update_cpu_data(&cs_dbs_gov, dbs_data);
 197
 198         return count;
 199 }
 200
 201 static ssize_t store_freq_step(struct dbs_data *dbs_data, const char *buf,
 202                 size_t count)
 203 {
 204         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 205         unsigned int input;
 206         int ret;
 207         ret = sscanf(buf, "%u", &input);
 208
 209         if (ret != 1)
 210                 return -EINVAL;
 211
 212         if (input > 100)
 213                 input = 100;
 214
 215         /*
 216          * no need to test here if freq_step is zero as the user might actually
 217          * want this, they would be crazy though :)
 218          */
 219         cs_tuners->freq_step = input;
 220         return count;
 221 }
 222
 223 gov_show_one_common(sampling_rate);
 224 gov_show_one_common(sampling_down_factor);
 225 gov_show_one_common(up_threshold);
 226 gov_show_one_common(ignore_nice_load);
 227 gov_show_one_common(min_sampling_rate);
 228 gov_show_one(cs, down_threshold);
 229 gov_show_one(cs, freq_step);
 230
 231 gov_attr_rw(sampling_rate);
 232 gov_attr_rw(sampling_down_factor);
 233 gov_attr_rw(up_threshold);
 234 gov_attr_rw(ignore_nice_load);
 235 gov_attr_ro(min_sampling_rate);
 236 gov_attr_rw(down_threshold);
 237 gov_attr_rw(freq_step);
 238
 239 static struct attribute *cs_attributes[] = {
 240         &min_sampling_rate.attr,
 241         &sampling_rate.attr,
 242         &sampling_down_factor.attr,
 243         &up_threshold.attr,
 244         &down_threshold.attr,
 245         &ignore_nice_load.attr,
 246         &freq_step.attr,
 247         NULL
 248 };
 249
 250 /************************** sysfs end ************************/
 251
 252 static struct policy_dbs_info *cs_alloc(void)
 253 {
 254         struct cs_policy_dbs_info *dbs_info;
 255
 256         dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL);
 257         return dbs_info ? &dbs_info->policy_dbs : NULL;
 258 }
 259
 260 static void cs_free(struct policy_dbs_info *policy_dbs)
 261 {
 262         kfree(to_dbs_info(policy_dbs));
 263 }
 264
 265 static int cs_init(struct dbs_data *dbs_data, bool notify)
 266 {
 267         struct cs_dbs_tuners *tuners;
 268
 269         tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 270         if (!tuners) {
 271                 pr_err("%s: kzalloc failed\n", __func__);
 272                 return -ENOMEM;
 273         }
 274
 275         tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
 276         tuners->freq_step = DEF_FREQUENCY_STEP;
 277         dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 278         dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 279         dbs_data->ignore_nice_load = 0;
 280
 281         dbs_data->tuners = tuners;
 282         dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 283                 jiffies_to_usecs(10);
 284
 285         if (notify)
 286                 cpufreq_register_notifier(&cs_cpufreq_notifier_block,
 287                                           CPUFREQ_TRANSITION_NOTIFIER);
 288
 289         return 0;
 290 }
 291
 292 static void cs_exit(struct dbs_data *dbs_data, bool notify)
 293 {
 294         if (notify)
 295                 cpufreq_unregister_notifier(&cs_cpufreq_notifier_block,
 296                                             CPUFREQ_TRANSITION_NOTIFIER);
 297
 298         kfree(dbs_data->tuners);
 299 }
 300
 301 static void cs_start(struct cpufreq_policy *policy)
 302 {
 303         struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
 304
 305         dbs_info->down_skip = 0;
 306         dbs_info->requested_freq = policy->cur;
 307 }
 308
 309 define_get_cpu_dbs_routines(cs_cpu_dbs_info);
 310
 311 static struct dbs_governor cs_dbs_gov = {
 312         .gov = {
 313                 .name = "conservative",
 314                 .governor = cpufreq_governor_dbs,
 315                 .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 316                 .owner = THIS_MODULE,
 317         },
 318         .kobj_type = { .default_attrs = cs_attributes },
 319         .get_cpu_cdbs = get_cpu_cdbs,
 320         .gov_dbs_timer = cs_dbs_timer,
 321         .alloc = cs_alloc,
 322         .free = cs_free,
 323         .init = cs_init,
 324         .exit = cs_exit,
 325         .start = cs_start,
 326 };
 327
 328 #define CPU_FREQ_GOV_CONSERVATIVE       (&cs_dbs_gov.gov)
 329
 330 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 331                                 void *data)
 332 {
 333         struct cpufreq_freqs *freq = data;
 334         struct cpufreq_policy *policy = cpufreq_cpu_get_raw(freq->cpu);
 335         struct cs_policy_dbs_info *dbs_info;
 336
 337         if (!policy)
 338                 return 0;
 339
 340         /* policy isn't governed by conservative governor */
 341         if (policy->governor != CPU_FREQ_GOV_CONSERVATIVE)
 342                 return 0;
 343
 344         dbs_info = to_dbs_info(policy->governor_data);
 345         /*
 346          * we only care if our internally tracked freq moves outside the 'valid'
 347          * ranges of frequency available to us otherwise we do not change it
 348         */
 349         if (dbs_info->requested_freq > policy->max
 350                         || dbs_info->requested_freq < policy->min)
 351                 dbs_info->requested_freq = freq->new;
 352
 353         return 0;
 354 }
 355
 356 static int __init cpufreq_gov_dbs_init(void)
 357 {
 358         return cpufreq_register_governor(CPU_FREQ_GOV_CONSERVATIVE);
 359 }
 360
 361 static void __exit cpufreq_gov_dbs_exit(void)
 362 {
 363         cpufreq_unregister_governor(CPU_FREQ_GOV_CONSERVATIVE);
 364 }
 365
 366 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
 367 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
 368                 "Low Latency Frequency Transition capable processors "
 369                 "optimised for use in a battery environment");
 370 MODULE_LICENSE("GPL");
 371
 372 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 373 struct cpufreq_governor *cpufreq_default_governor(void)
 374 {
 375         return CPU_FREQ_GOV_CONSERVATIVE;
 376 }
 377
 378 fs_initcall(cpufreq_gov_dbs_init);
 379 #else
 380 module_init(cpufreq_gov_dbs_init);
 381 #endif
 382 module_exit(cpufreq_gov_dbs_exit);