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 };
  21
  22 static inline struct cs_policy_dbs_info *to_dbs_info(struct policy_dbs_info *policy_dbs)
  23 {
  24         return container_of(policy_dbs, struct cs_policy_dbs_info, policy_dbs);
  25 }
  26
  27 struct cs_dbs_tuners {
  28         unsigned int down_threshold;
  29         unsigned int freq_step;
  30 };
  31
  32 /* Conservative governor macros */
  33 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
  34 #define DEF_FREQUENCY_DOWN_THRESHOLD            (20)
  35 #define DEF_FREQUENCY_STEP                      (5)
  36 #define DEF_SAMPLING_DOWN_FACTOR                (1)
  37 #define MAX_SAMPLING_DOWN_FACTOR                (10)
  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                 unsigned int requested_freq = policy->cur;
  78
  79                 dbs_info->down_skip = 0;
  80
  81                 /* if we are already at full speed then break out early */
  82                 if (requested_freq == policy->max)
  83                         goto out;
  84
  85                 requested_freq += get_freq_target(cs_tuners, policy);
  86
  87                 __cpufreq_driver_target(policy, requested_freq, CPUFREQ_RELATION_H);
  88                 goto out;
  89         }
  90
  91         /* if sampling_down_factor is active break out early */
  92         if (++dbs_info->down_skip < dbs_data->sampling_down_factor)
  93                 goto out;
  94         dbs_info->down_skip = 0;
  95
  96         /* Check for frequency decrease */
  97         if (load < cs_tuners->down_threshold) {
  98                 unsigned int freq_target, requested_freq = policy->cur;
  99                 /*
 100                  * if we cannot reduce the frequency anymore, break out early
 101                  */
 102                 if (requested_freq == policy->min)
 103                         goto out;
 104
 105                 freq_target = get_freq_target(cs_tuners, policy);
 106                 if (requested_freq > freq_target)
 107                         requested_freq -= freq_target;
 108                 else
 109                         requested_freq = policy->min;
 110
 111                 __cpufreq_driver_target(policy, requested_freq, CPUFREQ_RELATION_L);
 112         }
 113
 114  out:
 115         return dbs_data->sampling_rate;
 116 }
 117
 118 /************************** sysfs interface ************************/
 119
 120 static ssize_t store_sampling_down_factor(struct gov_attr_set *attr_set,
 121                                           const char *buf, size_t count)
 122 {
 123         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 124         unsigned int input;
 125         int ret;
 126         ret = sscanf(buf, "%u", &input);
 127
 128         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 129                 return -EINVAL;
 130
 131         dbs_data->sampling_down_factor = input;
 132         return count;
 133 }
 134
 135 static ssize_t store_up_threshold(struct gov_attr_set *attr_set,
 136                                   const char *buf, size_t count)
 137 {
 138         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 139         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 140         unsigned int input;
 141         int ret;
 142         ret = sscanf(buf, "%u", &input);
 143
 144         if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold)
 145                 return -EINVAL;
 146
 147         dbs_data->up_threshold = input;
 148         return count;
 149 }
 150
 151 static ssize_t store_down_threshold(struct gov_attr_set *attr_set,
 152                                     const char *buf, size_t count)
 153 {
 154         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 155         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 156         unsigned int input;
 157         int ret;
 158         ret = sscanf(buf, "%u", &input);
 159
 160         /* cannot be lower than 11 otherwise freq will not fall */
 161         if (ret != 1 || input < 11 || input > 100 ||
 162                         input >= dbs_data->up_threshold)
 163                 return -EINVAL;
 164
 165         cs_tuners->down_threshold = input;
 166         return count;
 167 }
 168
 169 static ssize_t store_ignore_nice_load(struct gov_attr_set *attr_set,
 170                                       const char *buf, size_t count)
 171 {
 172         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 173         unsigned int input;
 174         int ret;
 175
 176         ret = sscanf(buf, "%u", &input);
 177         if (ret != 1)
 178                 return -EINVAL;
 179
 180         if (input > 1)
 181                 input = 1;
 182
 183         if (input == dbs_data->ignore_nice_load) /* nothing to do */
 184                 return count;
 185
 186         dbs_data->ignore_nice_load = input;
 187
 188         /* we need to re-evaluate prev_cpu_idle */
 189         gov_update_cpu_data(dbs_data);
 190
 191         return count;
 192 }
 193
 194 static ssize_t store_freq_step(struct gov_attr_set *attr_set, const char *buf,
 195                                size_t count)
 196 {
 197         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 198         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 199         unsigned int input;
 200         int ret;
 201         ret = sscanf(buf, "%u", &input);
 202
 203         if (ret != 1)
 204                 return -EINVAL;
 205
 206         if (input > 100)
 207                 input = 100;
 208
 209         /*
 210          * no need to test here if freq_step is zero as the user might actually
 211          * want this, they would be crazy though :)
 212          */
 213         cs_tuners->freq_step = input;
 214         return count;
 215 }
 216
 217 gov_show_one_common(sampling_rate);
 218 gov_show_one_common(sampling_down_factor);
 219 gov_show_one_common(up_threshold);
 220 gov_show_one_common(ignore_nice_load);
 221 gov_show_one_common(min_sampling_rate);
 222 gov_show_one(cs, down_threshold);
 223 gov_show_one(cs, freq_step);
 224
 225 gov_attr_rw(sampling_rate);
 226 gov_attr_rw(sampling_down_factor);
 227 gov_attr_rw(up_threshold);
 228 gov_attr_rw(ignore_nice_load);
 229 gov_attr_ro(min_sampling_rate);
 230 gov_attr_rw(down_threshold);
 231 gov_attr_rw(freq_step);
 232
 233 static struct attribute *cs_attributes[] = {
 234         &min_sampling_rate.attr,
 235         &sampling_rate.attr,
 236         &sampling_down_factor.attr,
 237         &up_threshold.attr,
 238         &down_threshold.attr,
 239         &ignore_nice_load.attr,
 240         &freq_step.attr,
 241         NULL
 242 };
 243
 244 /************************** sysfs end ************************/
 245
 246 static struct policy_dbs_info *cs_alloc(void)
 247 {
 248         struct cs_policy_dbs_info *dbs_info;
 249
 250         dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL);
 251         return dbs_info ? &dbs_info->policy_dbs : NULL;
 252 }
 253
 254 static void cs_free(struct policy_dbs_info *policy_dbs)
 255 {
 256         kfree(to_dbs_info(policy_dbs));
 257 }
 258
 259 static int cs_init(struct dbs_data *dbs_data)
 260 {
 261         struct cs_dbs_tuners *tuners;
 262
 263         tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 264         if (!tuners)
 265                 return -ENOMEM;
 266
 267         tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
 268         tuners->freq_step = DEF_FREQUENCY_STEP;
 269         dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 270         dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 271         dbs_data->ignore_nice_load = 0;
 272
 273         dbs_data->tuners = tuners;
 274         dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 275                 jiffies_to_usecs(10);
 276
 277         return 0;
 278 }
 279
 280 static void cs_exit(struct dbs_data *dbs_data)
 281 {
 282         kfree(dbs_data->tuners);
 283 }
 284
 285 static void cs_start(struct cpufreq_policy *policy)
 286 {
 287         struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
 288
 289         dbs_info->down_skip = 0;
 290 }
 291
 292 static struct dbs_governor cs_governor = {
 293         .gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("conservative"),
 294         .kobj_type = { .default_attrs = cs_attributes },
 295         .gov_dbs_timer = cs_dbs_timer,
 296         .alloc = cs_alloc,
 297         .free = cs_free,
 298         .init = cs_init,
 299         .exit = cs_exit,
 300         .start = cs_start,
 301 };
 302
 303 #define CPU_FREQ_GOV_CONSERVATIVE       (&cs_governor.gov)
 304
 305 static int __init cpufreq_gov_dbs_init(void)
 306 {
 307         return cpufreq_register_governor(CPU_FREQ_GOV_CONSERVATIVE);
 308 }
 309
 310 static void __exit cpufreq_gov_dbs_exit(void)
 311 {
 312         cpufreq_unregister_governor(CPU_FREQ_GOV_CONSERVATIVE);
 313 }
 314
 315 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
 316 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
 317                 "Low Latency Frequency Transition capable processors "
 318                 "optimised for use in a battery environment");
 319 MODULE_LICENSE("GPL");
 320
 321 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 322 struct cpufreq_governor *cpufreq_default_governor(void)
 323 {
 324         return CPU_FREQ_GOV_CONSERVATIVE;
 325 }
 326
 327 fs_initcall(cpufreq_gov_dbs_init);
 328 #else
 329 module_init(cpufreq_gov_dbs_init);
 330 #endif
 331 module_exit(cpufreq_gov_dbs_exit);