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