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