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