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