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