drivers/cpufreq/cpufreq_conservative.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  drivers/cpufreq/cpufreq_conservative.c
   4  *
   5  *  Copyright (C)  2001 Russell King
   6  *            (C)  2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
   7  *                      Jun Nakajima <jun.nakajima@intel.com>
   8  *            (C)  2009 Alexander Clouter <alex@digriz.org.uk>
   9  */
  10
  11 #include <linux/slab.h>
  12 #include "cpufreq_governor.h"
  13
  14 struct cs_policy_dbs_info {
  15         struct policy_dbs_info policy_dbs;
  16         unsigned int down_skip;
  17         unsigned int requested_freq;
  18 };
  19
  20 static inline struct cs_policy_dbs_info *to_dbs_info(struct policy_dbs_info *policy_dbs)
  21 {
  22         return container_of(policy_dbs, struct cs_policy_dbs_info, policy_dbs);
  23 }
  24
  25 struct cs_dbs_tuners {
  26         unsigned int down_threshold;
  27         unsigned int freq_step;
  28 };
  29
  30 /* Conservative governor macros */
  31 #define DEF_FREQUENCY_UP_THRESHOLD              (80)
  32 #define DEF_FREQUENCY_DOWN_THRESHOLD            (20)
  33 #define DEF_FREQUENCY_STEP                      (5)
  34 #define DEF_SAMPLING_DOWN_FACTOR                (1)
  35 #define MAX_SAMPLING_DOWN_FACTOR                (10)
  36
  37 static inline unsigned int get_freq_step(struct cs_dbs_tuners *cs_tuners,
  38                                          struct cpufreq_policy *policy)
  39 {
  40         unsigned int freq_step = (cs_tuners->freq_step * policy->max) / 100;
  41
  42         /* max freq cannot be less than 100. But who knows... */
  43         if (unlikely(freq_step == 0))
  44                 freq_step = DEF_FREQUENCY_STEP;
  45
  46         return freq_step;
  47 }
  48
  49 /*
  50  * Every sampling_rate, we check, if current idle time is less than 20%
  51  * (default), then we try to increase frequency. Every sampling_rate *
  52  * sampling_down_factor, we check, if current idle time is more than 80%
  53  * (default), then we try to decrease frequency
  54  *
  55  * Frequency updates happen at minimum steps of 5% (default) of maximum
  56  * frequency
  57  */
  58 static unsigned int cs_dbs_update(struct cpufreq_policy *policy)
  59 {
  60         struct policy_dbs_info *policy_dbs = policy->governor_data;
  61         struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
  62         unsigned int requested_freq = dbs_info->requested_freq;
  63         struct dbs_data *dbs_data = policy_dbs->dbs_data;
  64         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
  65         unsigned int load = dbs_update(policy);
  66         unsigned int freq_step;
  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         /*
  76          * If requested_freq is out of range, it is likely that the limits
  77          * changed in the meantime, so fall back to current frequency in that
  78          * case.
  79          */
  80         if (requested_freq > policy->max || requested_freq < policy->min) {
  81                 requested_freq = policy->cur;
  82                 dbs_info->requested_freq = requested_freq;
  83         }
  84
  85         freq_step = get_freq_step(cs_tuners, policy);
  86
  87         /*
  88          * Decrease requested_freq one freq_step for each idle period that
  89          * we didn't update the frequency.
  90          */
  91         if (policy_dbs->idle_periods < UINT_MAX) {
  92                 unsigned int freq_steps = policy_dbs->idle_periods * freq_step;
  93
  94                 if (requested_freq > policy->min + freq_steps)
  95                         requested_freq -= freq_steps;
  96                 else
  97                         requested_freq = policy->min;
  98
  99                 policy_dbs->idle_periods = UINT_MAX;
 100         }
 101
 102         /* Check for frequency increase */
 103         if (load > dbs_data->up_threshold) {
 104                 dbs_info->down_skip = 0;
 105
 106                 /* if we are already at full speed then break out early */
 107                 if (requested_freq == policy->max)
 108                         goto out;
 109
 110                 requested_freq += freq_step;
 111                 if (requested_freq > policy->max)
 112                         requested_freq = policy->max;
 113
 114                 __cpufreq_driver_target(policy, requested_freq,
 115                                         CPUFREQ_RELATION_HE);
 116                 dbs_info->requested_freq = requested_freq;
 117                 goto out;
 118         }
 119
 120         /* if sampling_down_factor is active break out early */
 121         if (++dbs_info->down_skip < dbs_data->sampling_down_factor)
 122                 goto out;
 123         dbs_info->down_skip = 0;
 124
 125         /* Check for frequency decrease */
 126         if (load < cs_tuners->down_threshold) {
 127                 /*
 128                  * if we cannot reduce the frequency anymore, break out early
 129                  */
 130                 if (requested_freq == policy->min)
 131                         goto out;
 132
 133                 if (requested_freq > freq_step)
 134                         requested_freq -= freq_step;
 135                 else
 136                         requested_freq = policy->min;
 137
 138                 __cpufreq_driver_target(policy, requested_freq,
 139                                         CPUFREQ_RELATION_LE);
 140                 dbs_info->requested_freq = requested_freq;
 141         }
 142
 143  out:
 144         return dbs_data->sampling_rate;
 145 }
 146
 147 /************************** sysfs interface ************************/
 148
 149 static ssize_t sampling_down_factor_store(struct gov_attr_set *attr_set,
 150                                           const char *buf, size_t count)
 151 {
 152         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 153         unsigned int input;
 154         int ret;
 155         ret = sscanf(buf, "%u", &input);
 156
 157         if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
 158                 return -EINVAL;
 159
 160         dbs_data->sampling_down_factor = input;
 161         return count;
 162 }
 163
 164 static ssize_t up_threshold_store(struct gov_attr_set *attr_set,
 165                                   const char *buf, size_t count)
 166 {
 167         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 168         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 169         unsigned int input;
 170         int ret;
 171         ret = sscanf(buf, "%u", &input);
 172
 173         if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold)
 174                 return -EINVAL;
 175
 176         dbs_data->up_threshold = input;
 177         return count;
 178 }
 179
 180 static ssize_t down_threshold_store(struct gov_attr_set *attr_set,
 181                                     const char *buf, size_t count)
 182 {
 183         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 184         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 185         unsigned int input;
 186         int ret;
 187         ret = sscanf(buf, "%u", &input);
 188
 189         /* cannot be lower than 1 otherwise freq will not fall */
 190         if (ret != 1 || input < 1 || input > 100 ||
 191                         input >= dbs_data->up_threshold)
 192                 return -EINVAL;
 193
 194         cs_tuners->down_threshold = input;
 195         return count;
 196 }
 197
 198 static ssize_t ignore_nice_load_store(struct gov_attr_set *attr_set,
 199                                       const char *buf, size_t count)
 200 {
 201         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 202         unsigned int input;
 203         int ret;
 204
 205         ret = sscanf(buf, "%u", &input);
 206         if (ret != 1)
 207                 return -EINVAL;
 208
 209         if (input > 1)
 210                 input = 1;
 211
 212         if (input == dbs_data->ignore_nice_load) /* nothing to do */
 213                 return count;
 214
 215         dbs_data->ignore_nice_load = input;
 216
 217         /* we need to re-evaluate prev_cpu_idle */
 218         gov_update_cpu_data(dbs_data);
 219
 220         return count;
 221 }
 222
 223 static ssize_t freq_step_store(struct gov_attr_set *attr_set, const char *buf,
 224                                size_t count)
 225 {
 226         struct dbs_data *dbs_data = to_dbs_data(attr_set);
 227         struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
 228         unsigned int input;
 229         int ret;
 230         ret = sscanf(buf, "%u", &input);
 231
 232         if (ret != 1)
 233                 return -EINVAL;
 234
 235         if (input > 100)
 236                 input = 100;
 237
 238         /*
 239          * no need to test here if freq_step is zero as the user might actually
 240          * want this, they would be crazy though :)
 241          */
 242         cs_tuners->freq_step = input;
 243         return count;
 244 }
 245
 246 gov_show_one_common(sampling_rate);
 247 gov_show_one_common(sampling_down_factor);
 248 gov_show_one_common(up_threshold);
 249 gov_show_one_common(ignore_nice_load);
 250 gov_show_one(cs, down_threshold);
 251 gov_show_one(cs, freq_step);
 252
 253 gov_attr_rw(sampling_rate);
 254 gov_attr_rw(sampling_down_factor);
 255 gov_attr_rw(up_threshold);
 256 gov_attr_rw(ignore_nice_load);
 257 gov_attr_rw(down_threshold);
 258 gov_attr_rw(freq_step);
 259
 260 static struct attribute *cs_attrs[] = {
 261         &sampling_rate.attr,
 262         &sampling_down_factor.attr,
 263         &up_threshold.attr,
 264         &down_threshold.attr,
 265         &ignore_nice_load.attr,
 266         &freq_step.attr,
 267         NULL
 268 };
 269 ATTRIBUTE_GROUPS(cs);
 270
 271 /************************** sysfs end ************************/
 272
 273 static struct policy_dbs_info *cs_alloc(void)
 274 {
 275         struct cs_policy_dbs_info *dbs_info;
 276
 277         dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL);
 278         return dbs_info ? &dbs_info->policy_dbs : NULL;
 279 }
 280
 281 static void cs_free(struct policy_dbs_info *policy_dbs)
 282 {
 283         kfree(to_dbs_info(policy_dbs));
 284 }
 285
 286 static int cs_init(struct dbs_data *dbs_data)
 287 {
 288         struct cs_dbs_tuners *tuners;
 289
 290         tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 291         if (!tuners)
 292                 return -ENOMEM;
 293
 294         tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
 295         tuners->freq_step = DEF_FREQUENCY_STEP;
 296         dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
 297         dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
 298         dbs_data->ignore_nice_load = 0;
 299         dbs_data->tuners = tuners;
 300
 301         return 0;
 302 }
 303
 304 static void cs_exit(struct dbs_data *dbs_data)
 305 {
 306         kfree(dbs_data->tuners);
 307 }
 308
 309 static void cs_start(struct cpufreq_policy *policy)
 310 {
 311         struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
 312
 313         dbs_info->down_skip = 0;
 314         dbs_info->requested_freq = policy->cur;
 315 }
 316
 317 static struct dbs_governor cs_governor = {
 318         .gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("conservative"),
 319         .kobj_type = { .default_groups = cs_groups },
 320         .gov_dbs_update = cs_dbs_update,
 321         .alloc = cs_alloc,
 322         .free = cs_free,
 323         .init = cs_init,
 324         .exit = cs_exit,
 325         .start = cs_start,
 326 };
 327
 328 #define CPU_FREQ_GOV_CONSERVATIVE       (cs_governor.gov)
 329
 330 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
 331 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
 332                 "Low Latency Frequency Transition capable processors "
 333                 "optimised for use in a battery environment");
 334 MODULE_LICENSE("GPL");
 335
 336 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 337 struct cpufreq_governor *cpufreq_default_governor(void)
 338 {
 339         return &CPU_FREQ_GOV_CONSERVATIVE;
 340 }
 341 #endif
 342
 343 cpufreq_governor_init(CPU_FREQ_GOV_CONSERVATIVE);
 344 cpufreq_governor_exit(CPU_FREQ_GOV_CONSERVATIVE);