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.shared->policy;
  51         struct dbs_data *dbs_data = policy->governor_data;
  52         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
  53
  54         /*
  55          * break out if we 'cannot' reduce the speed as the user might
  56          * want freq_step to be zero
  57          */
  58         if (cs_tuners->freq_step == 0)
  59                 return;
  60
  61         /* Check for frequency increase */
  62         if (load > cs_tuners->up_threshold) {
  63                 dbs_info->down_skip = 0;
  64
  65                 /* if we are already at full speed then break out early */
  66                 if (dbs_info->requested_freq == policy->max)
  67                         return;
  68
  69                 dbs_info->requested_freq += get_freq_target(cs_tuners, policy);
  70
  71                 if (dbs_info->requested_freq > policy->max)
  72                         dbs_info->requested_freq = policy->max;
  73
  74                 __cpufreq_driver_target(policy, dbs_info->requested_freq,
  75                         CPUFREQ_RELATION_H);
  76                 return;
  77         }
  78
  79         /* if sampling_down_factor is active break out early */
  80         if (++dbs_info->down_skip < cs_tuners->sampling_down_factor)
  81                 return;
  82         dbs_info->down_skip = 0;
  83
  84         /* Check for frequency decrease */
  85         if (load < cs_tuners->down_threshold) {
  86                 unsigned int freq_target;
  87                 /*
  88                  * if we cannot reduce the frequency anymore, break out early
  89                  */
  90                 if (policy->cur == policy->min)
  91                         return;
  92
  93                 freq_target = get_freq_target(cs_tuners, policy);
  94                 if (dbs_info->requested_freq > freq_target)
  95                         dbs_info->requested_freq -= freq_target;
  96                 else
  97                         dbs_info->requested_freq = policy->min;
  98
  99                 __cpufreq_driver_target(policy, dbs_info->requested_freq,
 100                                 CPUFREQ_RELATION_L);
 101                 return;
 102         }
 103 }
 104
 105 static unsigned int cs_dbs_timer(struct cpufreq_policy *policy)
 106 {
 107         struct dbs_data *dbs_data = policy->governor_data;
 108         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 109
 110         dbs_check_cpu(policy, policy->cpu);
 111         return delay_for_sampling_rate(cs_tuners->sampling_rate);
 112 }
 113
 114 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 115                                 void *data);
 116
 117 static struct notifier_block cs_cpufreq_notifier_block = {
 118         .notifier_call = dbs_cpufreq_notifier,
 119 };
 120
 121 /************************** sysfs interface ************************/
 122 static struct dbs_governor cs_dbs_gov;
 123
 124 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data,
 125                 const char *buf, size_t count)
 126 {
 127         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 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         cs_tuners->sampling_down_factor = input;
 136         return count;
 137 }
 138
 139 static ssize_t store_sampling_rate(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)
 148                 return -EINVAL;
 149
 150         cs_tuners->sampling_rate = max(input, dbs_data->min_sampling_rate);
 151         return count;
 152 }
 153
 154 static ssize_t store_up_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         if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold)
 163                 return -EINVAL;
 164
 165         cs_tuners->up_threshold = input;
 166         return count;
 167 }
 168
 169 static ssize_t store_down_threshold(struct dbs_data *dbs_data, const char *buf,
 170                 size_t count)
 171 {
 172         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 173         unsigned int input;
 174         int ret;
 175         ret = sscanf(buf, "%u", &input);
 176
 177         /* cannot be lower than 11 otherwise freq will not fall */
 178         if (ret != 1 || input < 11 || input > 100 ||
 179                         input >= cs_tuners->up_threshold)
 180                 return -EINVAL;
 181
 182         cs_tuners->down_threshold = input;
 183         return count;
 184 }
 185
 186 static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data,
 187                 const char *buf, size_t count)
 188 {
 189         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 190         unsigned int input, j;
 191         int ret;
 192
 193         ret = sscanf(buf, "%u", &input);
 194         if (ret != 1)
 195                 return -EINVAL;
 196
 197         if (input > 1)
 198                 input = 1;
 199
 200         if (input == cs_tuners->ignore_nice_load) /* nothing to do */
 201                 return count;
 202
 203         cs_tuners->ignore_nice_load = input;
 204
 205         /* we need to re-evaluate prev_cpu_idle */
 206         for_each_online_cpu(j) {
 207                 struct cs_cpu_dbs_info_s *dbs_info;
 208                 dbs_info = &per_cpu(cs_cpu_dbs_info, j);
 209                 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j,
 210                                         &dbs_info->cdbs.prev_cpu_wall, 0);
 211                 if (cs_tuners->ignore_nice_load)
 212                         dbs_info->cdbs.prev_cpu_nice =
 213                                 kcpustat_cpu(j).cpustat[CPUTIME_NICE];
 214         }
 215         return count;
 216 }
 217
 218 static ssize_t store_freq_step(struct dbs_data *dbs_data, const char *buf,
 219                 size_t count)
 220 {
 221         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 222         unsigned int input;
 223         int ret;
 224         ret = sscanf(buf, "%u", &input);
 225
 226         if (ret != 1)
 227                 return -EINVAL;
 228
 229         if (input > 100)
 230                 input = 100;
 231
 232         /*
 233          * no need to test here if freq_step is zero as the user might actually
 234          * want this, they would be crazy though :)
 235          */
 236         cs_tuners->freq_step = input;
 237         return count;
 238 }
 239
 240 show_store_one(cs, sampling_rate);
 241 show_store_one(cs, sampling_down_factor);
 242 show_store_one(cs, up_threshold);
 243 show_store_one(cs, down_threshold);
 244 show_store_one(cs, ignore_nice_load);
 245 show_store_one(cs, freq_step);
 246 declare_show_sampling_rate_min(cs);
 247
 248 gov_sys_pol_attr_rw(sampling_rate);
 249 gov_sys_pol_attr_rw(sampling_down_factor);
 250 gov_sys_pol_attr_rw(up_threshold);
 251 gov_sys_pol_attr_rw(down_threshold);
 252 gov_sys_pol_attr_rw(ignore_nice_load);
 253 gov_sys_pol_attr_rw(freq_step);
 254 gov_sys_pol_attr_ro(sampling_rate_min);
 255
 256 static struct attribute *dbs_attributes_gov_sys[] = {
 257         &sampling_rate_min_gov_sys.attr,
 258         &sampling_rate_gov_sys.attr,
 259         &sampling_down_factor_gov_sys.attr,
 260         &up_threshold_gov_sys.attr,
 261         &down_threshold_gov_sys.attr,
 262         &ignore_nice_load_gov_sys.attr,
 263         &freq_step_gov_sys.attr,
 264         NULL
 265 };
 266
 267 static struct attribute_group cs_attr_group_gov_sys = {
 268         .attrs = dbs_attributes_gov_sys,
 269         .name = "conservative",
 270 };
 271
 272 static struct attribute *dbs_attributes_gov_pol[] = {
 273         &sampling_rate_min_gov_pol.attr,
 274         &sampling_rate_gov_pol.attr,
 275         &sampling_down_factor_gov_pol.attr,
 276         &up_threshold_gov_pol.attr,
 277         &down_threshold_gov_pol.attr,
 278         &ignore_nice_load_gov_pol.attr,
 279         &freq_step_gov_pol.attr,
 280         NULL
 281 };
 282
 283 static struct attribute_group cs_attr_group_gov_pol = {
 284         .attrs = dbs_attributes_gov_pol,
 285         .name = "conservative",
 286 };
 287
 288 /************************** sysfs end ************************/
 289
 290 static int cs_init(struct dbs_data *dbs_data, bool notify)
 291 {
 292         struct cs_dbs_tuners *tuners;
 293
 294         tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 295         if (!tuners) {
 296                 pr_err("%s: kzalloc failed\n", __func__);
 297                 return -ENOMEM;
 298         }
 299
 300         tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 301         tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
 302         tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 303         tuners->ignore_nice_load = 0;
 304         tuners->freq_step = DEF_FREQUENCY_STEP;
 305
 306         dbs_data->tuners = tuners;
 307         dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO *
 308                 jiffies_to_usecs(10);
 309
 310         if (notify)
 311                 cpufreq_register_notifier(&cs_cpufreq_notifier_block,
 312                                           CPUFREQ_TRANSITION_NOTIFIER);
 313
 314         return 0;
 315 }
 316
 317 static void cs_exit(struct dbs_data *dbs_data, bool notify)
 318 {
 319         if (notify)
 320                 cpufreq_unregister_notifier(&cs_cpufreq_notifier_block,
 321                                             CPUFREQ_TRANSITION_NOTIFIER);
 322
 323         kfree(dbs_data->tuners);
 324 }
 325
 326 define_get_cpu_dbs_routines(cs_cpu_dbs_info);
 327
 328 static struct dbs_governor cs_dbs_gov = {
 329         .gov = {
 330                 .name = "conservative",
 331                 .governor = cpufreq_governor_dbs,
 332                 .max_transition_latency = TRANSITION_LATENCY_LIMIT,
 333                 .owner = THIS_MODULE,
 334         },
 335         .governor = GOV_CONSERVATIVE,
 336         .attr_group_gov_sys = &cs_attr_group_gov_sys,
 337         .attr_group_gov_pol = &cs_attr_group_gov_pol,
 338         .get_cpu_cdbs = get_cpu_cdbs,
 339         .get_cpu_dbs_info_s = get_cpu_dbs_info_s,
 340         .gov_dbs_timer = cs_dbs_timer,
 341         .gov_check_cpu = cs_check_cpu,
 342         .init = cs_init,
 343         .exit = cs_exit,
 344 };
 345
 346 #define CPU_FREQ_GOV_CONSERVATIVE       (&cs_dbs_gov.gov)
 347
 348 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
 349                                 void *data)
 350 {
 351         struct cpufreq_freqs *freq = data;
 352         struct cs_cpu_dbs_info_s *dbs_info =
 353                                         &per_cpu(cs_cpu_dbs_info, freq->cpu);
 354         struct cpufreq_policy *policy = cpufreq_cpu_get_raw(freq->cpu);
 355
 356         if (!policy)
 357                 return 0;
 358
 359         /* policy isn't governed by conservative governor */
 360         if (policy->governor != CPU_FREQ_GOV_CONSERVATIVE)
 361                 return 0;
 362
 363         /*
 364          * we only care if our internally tracked freq moves outside the 'valid'
 365          * ranges of frequency available to us otherwise we do not change it
 366         */
 367         if (dbs_info->requested_freq > policy->max
 368                         || dbs_info->requested_freq < policy->min)
 369                 dbs_info->requested_freq = freq->new;
 370
 371         return 0;
 372 }
 373
 374 static int __init cpufreq_gov_dbs_init(void)
 375 {
 376         return cpufreq_register_governor(CPU_FREQ_GOV_CONSERVATIVE);
 377 }
 378
 379 static void __exit cpufreq_gov_dbs_exit(void)
 380 {
 381         cpufreq_unregister_governor(CPU_FREQ_GOV_CONSERVATIVE);
 382 }
 383
 384 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
 385 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
 386                 "Low Latency Frequency Transition capable processors "
 387                 "optimised for use in a battery environment");
 388 MODULE_LICENSE("GPL");
 389
 390 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 391 struct cpufreq_governor *cpufreq_default_governor(void)
 392 {
 393         return CPU_FREQ_GOV_CONSERVATIVE;
 394 }
 395
 396 fs_initcall(cpufreq_gov_dbs_init);
 397 #else
 398 module_init(cpufreq_gov_dbs_init);
 399 #endif
 400 module_exit(cpufreq_gov_dbs_exit);