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