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/cpufreq.h> 15 #include <linux/init.h> 16 #include <linux/kernel.h> 17 #include <linux/kernel_stat.h> 18 #include <linux/kobject.h> 19 #include <linux/module.h> 20 #include <linux/mutex.h> 21 #include <linux/notifier.h> 22 #include <linux/percpu-defs.h> 23 #include <linux/slab.h> 24 #include <linux/sysfs.h> 25 #include <linux/types.h> 26 27 #include "cpufreq_governor.h" 28 29 /* Conservative governor macros */ 30 #define DEF_FREQUENCY_UP_THRESHOLD (80) 31 #define DEF_FREQUENCY_DOWN_THRESHOLD (20) 32 #define DEF_FREQUENCY_STEP (5) 33 #define DEF_SAMPLING_DOWN_FACTOR (1) 34 #define MAX_SAMPLING_DOWN_FACTOR (10) 35 36 static DEFINE_PER_CPU(struct cs_cpu_dbs_info_s, cs_cpu_dbs_info); 37 38 static inline unsigned int get_freq_target(struct cs_dbs_tuners *cs_tuners, 39 struct cpufreq_policy *policy) 40 { 41 unsigned int freq_target = (cs_tuners->freq_step * policy->max) / 100; 42 43 /* max freq cannot be less than 100. But who knows... */ 44 if (unlikely(freq_target == 0)) 45 freq_target = DEF_FREQUENCY_STEP; 46 47 return freq_target; 48 } 49 50 /* 51 * Every sampling_rate, we check, if current idle time is less than 20% 52 * (default), then we try to increase frequency. Every sampling_rate * 53 * sampling_down_factor, we check, if current idle time is more than 80% 54 * (default), then we try to decrease frequency 55 * 56 * Any frequency increase takes it to the maximum frequency. Frequency reduction 57 * happens at minimum steps of 5% (default) of maximum frequency 58 */ 59 static void cs_check_cpu(int cpu, unsigned int load) 60 { 61 struct cs_cpu_dbs_info_s *dbs_info = &per_cpu(cs_cpu_dbs_info, cpu); 62 struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy; 63 struct dbs_data *dbs_data = policy->governor_data; 64 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 65 66 /* 67 * break out if we 'cannot' reduce the speed as the user might 68 * want freq_step to be zero 69 */ 70 if (cs_tuners->freq_step == 0) 71 return; 72 73 /* Check for frequency increase */ 74 if (load > cs_tuners->up_threshold) { 75 dbs_info->down_skip = 0; 76 77 /* if we are already at full speed then break out early */ 78 if (dbs_info->requested_freq == policy->max) 79 return; 80 81 dbs_info->requested_freq += get_freq_target(cs_tuners, policy); 82 if (dbs_info->requested_freq > policy->max) 83 dbs_info->requested_freq = policy->max; 84 85 __cpufreq_driver_target(policy, dbs_info->requested_freq, 86 CPUFREQ_RELATION_H); 87 return; 88 } 89 90 /* if sampling_down_factor is active break out early */ 91 if (++dbs_info->down_skip < cs_tuners->sampling_down_factor) 92 return; 93 dbs_info->down_skip = 0; 94 95 /* Check for frequency decrease */ 96 if (load < cs_tuners->down_threshold) { 97 /* 98 * if we cannot reduce the frequency anymore, break out early 99 */ 100 if (policy->cur == policy->min) 101 return; 102 103 dbs_info->requested_freq -= get_freq_target(cs_tuners, policy); 104 if (dbs_info->requested_freq < policy->min) 105 dbs_info->requested_freq = policy->min; 106 107 __cpufreq_driver_target(policy, dbs_info->requested_freq, 108 CPUFREQ_RELATION_L); 109 return; 110 } 111 } 112 113 static void cs_dbs_timer(struct work_struct *work) 114 { 115 struct cs_cpu_dbs_info_s *dbs_info = container_of(work, 116 struct cs_cpu_dbs_info_s, cdbs.work.work); 117 unsigned int cpu = dbs_info->cdbs.cur_policy->cpu; 118 struct cs_cpu_dbs_info_s *core_dbs_info = &per_cpu(cs_cpu_dbs_info, 119 cpu); 120 struct dbs_data *dbs_data = dbs_info->cdbs.cur_policy->governor_data; 121 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 122 int delay = delay_for_sampling_rate(cs_tuners->sampling_rate); 123 bool modify_all = true; 124 125 mutex_lock(&core_dbs_info->cdbs.timer_mutex); 126 if (!need_load_eval(&core_dbs_info->cdbs, cs_tuners->sampling_rate)) 127 modify_all = false; 128 else 129 dbs_check_cpu(dbs_data, cpu); 130 131 gov_queue_work(dbs_data, dbs_info->cdbs.cur_policy, delay, modify_all); 132 mutex_unlock(&core_dbs_info->cdbs.timer_mutex); 133 } 134 135 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val, 136 void *data) 137 { 138 struct cpufreq_freqs *freq = data; 139 struct cs_cpu_dbs_info_s *dbs_info = 140 &per_cpu(cs_cpu_dbs_info, freq->cpu); 141 struct cpufreq_policy *policy; 142 143 if (!dbs_info->enable) 144 return 0; 145 146 policy = dbs_info->cdbs.cur_policy; 147 148 /* 149 * we only care if our internally tracked freq moves outside the 'valid' 150 * ranges of frequency available to us otherwise we do not change it 151 */ 152 if (dbs_info->requested_freq > policy->max 153 || dbs_info->requested_freq < policy->min) 154 dbs_info->requested_freq = freq->new; 155 156 return 0; 157 } 158 159 /************************** sysfs interface ************************/ 160 static struct common_dbs_data cs_dbs_cdata; 161 162 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data, 163 const char *buf, size_t count) 164 { 165 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 166 unsigned int input; 167 int ret; 168 ret = sscanf(buf, "%u", &input); 169 170 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1) 171 return -EINVAL; 172 173 cs_tuners->sampling_down_factor = input; 174 return count; 175 } 176 177 static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf, 178 size_t count) 179 { 180 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 181 unsigned int input; 182 int ret; 183 ret = sscanf(buf, "%u", &input); 184 185 if (ret != 1) 186 return -EINVAL; 187 188 cs_tuners->sampling_rate = max(input, dbs_data->min_sampling_rate); 189 return count; 190 } 191 192 static ssize_t store_up_threshold(struct dbs_data *dbs_data, const char *buf, 193 size_t count) 194 { 195 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 196 unsigned int input; 197 int ret; 198 ret = sscanf(buf, "%u", &input); 199 200 if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold) 201 return -EINVAL; 202 203 cs_tuners->up_threshold = input; 204 return count; 205 } 206 207 static ssize_t store_down_threshold(struct dbs_data *dbs_data, const char *buf, 208 size_t count) 209 { 210 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 211 unsigned int input; 212 int ret; 213 ret = sscanf(buf, "%u", &input); 214 215 /* cannot be lower than 11 otherwise freq will not fall */ 216 if (ret != 1 || input < 11 || input > 100 || 217 input >= cs_tuners->up_threshold) 218 return -EINVAL; 219 220 cs_tuners->down_threshold = input; 221 return count; 222 } 223 224 static ssize_t store_ignore_nice(struct dbs_data *dbs_data, const char *buf, 225 size_t count) 226 { 227 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 228 unsigned int input, j; 229 int ret; 230 231 ret = sscanf(buf, "%u", &input); 232 if (ret != 1) 233 return -EINVAL; 234 235 if (input > 1) 236 input = 1; 237 238 if (input == cs_tuners->ignore_nice) /* nothing to do */ 239 return count; 240 241 cs_tuners->ignore_nice = input; 242 243 /* we need to re-evaluate prev_cpu_idle */ 244 for_each_online_cpu(j) { 245 struct cs_cpu_dbs_info_s *dbs_info; 246 dbs_info = &per_cpu(cs_cpu_dbs_info, j); 247 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j, 248 &dbs_info->cdbs.prev_cpu_wall, 0); 249 if (cs_tuners->ignore_nice) 250 dbs_info->cdbs.prev_cpu_nice = 251 kcpustat_cpu(j).cpustat[CPUTIME_NICE]; 252 } 253 return count; 254 } 255 256 static ssize_t store_freq_step(struct dbs_data *dbs_data, const char *buf, 257 size_t count) 258 { 259 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 260 unsigned int input; 261 int ret; 262 ret = sscanf(buf, "%u", &input); 263 264 if (ret != 1) 265 return -EINVAL; 266 267 if (input > 100) 268 input = 100; 269 270 /* 271 * no need to test here if freq_step is zero as the user might actually 272 * want this, they would be crazy though :) 273 */ 274 cs_tuners->freq_step = input; 275 return count; 276 } 277 278 show_store_one(cs, sampling_rate); 279 show_store_one(cs, sampling_down_factor); 280 show_store_one(cs, up_threshold); 281 show_store_one(cs, down_threshold); 282 show_store_one(cs, ignore_nice); 283 show_store_one(cs, freq_step); 284 declare_show_sampling_rate_min(cs); 285 286 gov_sys_pol_attr_rw(sampling_rate); 287 gov_sys_pol_attr_rw(sampling_down_factor); 288 gov_sys_pol_attr_rw(up_threshold); 289 gov_sys_pol_attr_rw(down_threshold); 290 gov_sys_pol_attr_rw(ignore_nice); 291 gov_sys_pol_attr_rw(freq_step); 292 gov_sys_pol_attr_ro(sampling_rate_min); 293 294 static struct attribute *dbs_attributes_gov_sys[] = { 295 &sampling_rate_min_gov_sys.attr, 296 &sampling_rate_gov_sys.attr, 297 &sampling_down_factor_gov_sys.attr, 298 &up_threshold_gov_sys.attr, 299 &down_threshold_gov_sys.attr, 300 &ignore_nice_gov_sys.attr, 301 &freq_step_gov_sys.attr, 302 NULL 303 }; 304 305 static struct attribute_group cs_attr_group_gov_sys = { 306 .attrs = dbs_attributes_gov_sys, 307 .name = "conservative", 308 }; 309 310 static struct attribute *dbs_attributes_gov_pol[] = { 311 &sampling_rate_min_gov_pol.attr, 312 &sampling_rate_gov_pol.attr, 313 &sampling_down_factor_gov_pol.attr, 314 &up_threshold_gov_pol.attr, 315 &down_threshold_gov_pol.attr, 316 &ignore_nice_gov_pol.attr, 317 &freq_step_gov_pol.attr, 318 NULL 319 }; 320 321 static struct attribute_group cs_attr_group_gov_pol = { 322 .attrs = dbs_attributes_gov_pol, 323 .name = "conservative", 324 }; 325 326 /************************** sysfs end ************************/ 327 328 static int cs_init(struct dbs_data *dbs_data) 329 { 330 struct cs_dbs_tuners *tuners; 331 332 tuners = kzalloc(sizeof(struct cs_dbs_tuners), GFP_KERNEL); 333 if (!tuners) { 334 pr_err("%s: kzalloc failed\n", __func__); 335 return -ENOMEM; 336 } 337 338 tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD; 339 tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD; 340 tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR; 341 tuners->ignore_nice = 0; 342 tuners->freq_step = DEF_FREQUENCY_STEP; 343 344 dbs_data->tuners = tuners; 345 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO * 346 jiffies_to_usecs(10); 347 mutex_init(&dbs_data->mutex); 348 return 0; 349 } 350 351 static void cs_exit(struct dbs_data *dbs_data) 352 { 353 kfree(dbs_data->tuners); 354 } 355 356 define_get_cpu_dbs_routines(cs_cpu_dbs_info); 357 358 static struct notifier_block cs_cpufreq_notifier_block = { 359 .notifier_call = dbs_cpufreq_notifier, 360 }; 361 362 static struct cs_ops cs_ops = { 363 .notifier_block = &cs_cpufreq_notifier_block, 364 }; 365 366 static struct common_dbs_data cs_dbs_cdata = { 367 .governor = GOV_CONSERVATIVE, 368 .attr_group_gov_sys = &cs_attr_group_gov_sys, 369 .attr_group_gov_pol = &cs_attr_group_gov_pol, 370 .get_cpu_cdbs = get_cpu_cdbs, 371 .get_cpu_dbs_info_s = get_cpu_dbs_info_s, 372 .gov_dbs_timer = cs_dbs_timer, 373 .gov_check_cpu = cs_check_cpu, 374 .gov_ops = &cs_ops, 375 .init = cs_init, 376 .exit = cs_exit, 377 }; 378 379 static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy, 380 unsigned int event) 381 { 382 return cpufreq_governor_dbs(policy, &cs_dbs_cdata, event); 383 } 384 385 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE 386 static 387 #endif 388 struct cpufreq_governor cpufreq_gov_conservative = { 389 .name = "conservative", 390 .governor = cs_cpufreq_governor_dbs, 391 .max_transition_latency = TRANSITION_LATENCY_LIMIT, 392 .owner = THIS_MODULE, 393 }; 394 395 static int __init cpufreq_gov_dbs_init(void) 396 { 397 return cpufreq_register_governor(&cpufreq_gov_conservative); 398 } 399 400 static void __exit cpufreq_gov_dbs_exit(void) 401 { 402 cpufreq_unregister_governor(&cpufreq_gov_conservative); 403 } 404 405 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>"); 406 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for " 407 "Low Latency Frequency Transition capable processors " 408 "optimised for use in a battery environment"); 409 MODULE_LICENSE("GPL"); 410 411 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE 412 fs_initcall(cpufreq_gov_dbs_init); 413 #else 414 module_init(cpufreq_gov_dbs_init); 415 #endif 416 module_exit(cpufreq_gov_dbs_exit); 417