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 unsigned int cs_dbs_timer(struct cpufreq_policy *policy)
  48 {
  49         struct cs_cpu_dbs_info_s *dbs_info = &per_cpu(cs_cpu_dbs_info, policy->cpu);
  50         struct policy_dbs_info *policy_dbs = policy->governor_data;
  51         struct dbs_data *dbs_data = policy_dbs->dbs_data;
  52         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
  53         unsigned int load = dbs_update(policy);
  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                 goto out;
  61
  62         /* Check for frequency increase */
  63         if (load > dbs_data->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                         goto out;
  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                 goto out;
  78         }
  79
  80         /* if sampling_down_factor is active break out early */
  81         if (++dbs_info->down_skip < dbs_data->sampling_down_factor)
  82                 goto out;
  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                         goto out;
  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         }
 103
 104  out:
 105         return dbs_data->sampling_rate;
 106 }
 107
 108 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 109                                 void *data);
 110
 111 static struct notifier_block cs_cpufreq_notifier_block = {
 112         .notifier_call = dbs_cpufreq_notifier,
 113 };
 114
 115 /************************** sysfs interface ************************/
 116 static struct dbs_governor cs_dbs_gov;
 117
 118 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 119                 const char *buf, size_t count)
 120 {
 121         unsigned int input;
 122         int ret;
 123         ret = sscanf(buf, "%u", &input);
 124
 125         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 126                 return -EINVAL;
 127
 128         dbs_data->sampling_down_factor = input;
 129         return count;
 130 }
 131
 132 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf,
 133                 size_t count)
 134 {
 135         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 136         unsigned int input;
 137         int ret;
 138         ret = sscanf(buf, "%u", &input);
 139
 140         if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold)
 141                 return -EINVAL;
 142
 143         dbs_data->up_threshold = input;
 144         return count;
 145 }
 146
 147 static ssize_t store_down_threshold(struct dbs_data *dbs_data, const char *buf,
 148                 size_t count)
 149 {
 150         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 151         unsigned int input;
 152         int ret;
 153         ret = sscanf(buf, "%u", &input);
 154
 155         /* cannot be lower than 11 otherwise freq will not fall */
 156         if (ret != 1 || input < 11 || input > 100 ||
 157                         input >= dbs_data->up_threshold)
 158                 return -EINVAL;
 159
 160         cs_tuners->down_threshold = input;
 161         return count;
 162 }
 163
 164 static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data,
 165                 const char *buf, size_t count)
 166 {
 167         unsigned int input, j;
 168         int ret;
 169
 170         ret = sscanf(buf, "%u", &input);
 171         if (ret != 1)
 172                 return -EINVAL;
 173
 174         if (input > 1)
 175                 input = 1;
 176
 177         if (input == dbs_data->ignore_nice_load) /* nothing to do */
 178                 return count;
 179
 180         dbs_data->ignore_nice_load = input;
 181
 182         /* we need to re-evaluate prev_cpu_idle */
 183         for_each_online_cpu(j) {
 184                 struct cs_cpu_dbs_info_s *dbs_info;
 185                 dbs_info = &per_cpu(cs_cpu_dbs_info, j);
 186                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 187                                         &dbs_info->cdbs.prev_cpu_wall, 0);
 188                 if (dbs_data->ignore_nice_load)
 189                         dbs_info->cdbs.prev_cpu_nice =
 190                                 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 191         }
 192         return count;
 193 }
 194
 195 static ssize_t store_freq_step(struct dbs_data *dbs_data, const char *buf,
 196                 size_t count)
 197 {
 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 int cs_init(struct dbs_data *dbs_data, bool notify)
 247 {
 248         struct cs_dbs_tuners *tuners;
 249
 250         tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 251         if (!tuners) {
 252                 pr_err("%s: kzalloc failed\n", __func__);
 253                 return -ENOMEM;
 254         }
 255
 256         tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
 257         tuners->freq_step = DEF_FREQUENCY_STEP;
 258         dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 259         dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 260         dbs_data->ignore_nice_load = 0;
 261
 262         dbs_data->tuners = tuners;
 263         dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 264                 jiffies_to_usecs(10);
 265
 266         if (notify)
 267                 cpufreq_register_notifier(&cs_cpufreq_notifier_block,
 268                                           CPUFREQ_TRANSITION_NOTIFIER);
 269
 270         return 0;
 271 }
 272
 273 static void cs_exit(struct dbs_data *dbs_data, bool notify)
 274 {
 275         if (notify)
 276                 cpufreq_unregister_notifier(&cs_cpufreq_notifier_block,
 277                                             CPUFREQ_TRANSITION_NOTIFIER);
 278
 279         kfree(dbs_data->tuners);
 280 }
 281
 282 static void cs_start(struct cpufreq_policy *policy)
 283 {
 284         struct cs_cpu_dbs_info_s *dbs_info = &per_cpu(cs_cpu_dbs_info, policy->cpu);
 285
 286         dbs_info->down_skip = 0;
 287         dbs_info->requested_freq = policy->cur;
 288 }
 289
 290 define_get_cpu_dbs_routines(cs_cpu_dbs_info);
 291
 292 static struct dbs_governor cs_dbs_gov = {
 293         .gov = {
 294                 .name = "conservative",
 295                 .governor = cpufreq_governor_dbs,
 296                 .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 297                 .owner = THIS_MODULE,
 298         },
 299         .kobj_type = { .default_attrs = cs_attributes },
 300         .get_cpu_cdbs = get_cpu_cdbs,
 301         .gov_dbs_timer = cs_dbs_timer,
 302         .init = cs_init,
 303         .exit = cs_exit,
 304         .start = cs_start,
 305 };
 306
 307 #define CPU_FREQ_GOV_CONSERVATIVE       (&cs_dbs_gov.gov)
 308
 309 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 310                                 void *data)
 311 {
 312         struct cpufreq_freqs *freq = data;
 313         struct cs_cpu_dbs_info_s *dbs_info =
 314                                         &per_cpu(cs_cpu_dbs_info, freq->cpu);
 315         struct cpufreq_policy *policy = cpufreq_cpu_get_raw(freq->cpu);
 316
 317         if (!policy)
 318                 return 0;
 319
 320         /* policy isn't governed by conservative governor */
 321         if (policy->governor != CPU_FREQ_GOV_CONSERVATIVE)
 322                 return 0;
 323
 324         /*
 325          * we only care if our internally tracked freq moves outside the 'valid'
 326          * ranges of frequency available to us otherwise we do not change it
 327         */
 328         if (dbs_info->requested_freq > policy->max
 329                         || dbs_info->requested_freq < policy->min)
 330                 dbs_info->requested_freq = freq->new;
 331
 332         return 0;
 333 }
 334
 335 static int __init cpufreq_gov_dbs_init(void)
 336 {
 337         return cpufreq_register_governor(CPU_FREQ_GOV_CONSERVATIVE);
 338 }
 339
 340 static void __exit cpufreq_gov_dbs_exit(void)
 341 {
 342         cpufreq_unregister_governor(CPU_FREQ_GOV_CONSERVATIVE);
 343 }
 344
 345 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
 346 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
 347                 "Low Latency Frequency Transition capable processors "
 348                 "optimised for use in a battery environment");
 349 MODULE_LICENSE("GPL");
 350
 351 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 352 struct cpufreq_governor *cpufreq_default_governor(void)
 353 {
 354         return CPU_FREQ_GOV_CONSERVATIVE;
 355 }
 356
 357 fs_initcall(cpufreq_gov_dbs_init);
 358 #else
 359 module_init(cpufreq_gov_dbs_init);
 360 #endif
 361 module_exit(cpufreq_gov_dbs_exit);