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) 116 { 117 struct dbs_data *dbs_data = policy->governor_data; 118 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 119 120 dbs_check_cpu(dbs_data, policy->cpu); 121 return delay_for_sampling_rate(cs_tuners->sampling_rate); 122 } 123 124 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val, 125 void *data) 126 { 127 struct cpufreq_freqs *freq = data; 128 struct cs_cpu_dbs_info_s *dbs_info = 129 &per_cpu(cs_cpu_dbs_info, freq->cpu); 130 struct cpufreq_policy *policy = cpufreq_cpu_get_raw(freq->cpu); 131 132 if (!policy) 133 return 0; 134 135 /* policy isn't governed by conservative governor */ 136 if (policy->governor != &cpufreq_gov_conservative) 137 return 0; 138 139 /* 140 * we only care if our internally tracked freq moves outside the 'valid' 141 * ranges of frequency available to us otherwise we do not change it 142 */ 143 if (dbs_info->requested_freq > policy->max 144 || dbs_info->requested_freq < policy->min) 145 dbs_info->requested_freq = freq->new; 146 147 return 0; 148 } 149 150 static struct notifier_block cs_cpufreq_notifier_block = { 151 .notifier_call = dbs_cpufreq_notifier, 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_load(struct dbs_data *dbs_data, 220 const char *buf, 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_load) /* nothing to do */ 234 return count; 235 236 cs_tuners->ignore_nice_load = 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_load) 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_load); 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_load); 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_load_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_load_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, bool notify) 324 { 325 struct cs_dbs_tuners *tuners; 326 327 tuners = kzalloc(sizeof(*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_load = 0; 337 tuners->freq_step = DEF_FREQUENCY_STEP; 338 339 dbs_data->tuners = tuners; 340 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO * 341 jiffies_to_usecs(10); 342 343 if (notify) 344 cpufreq_register_notifier(&cs_cpufreq_notifier_block, 345 CPUFREQ_TRANSITION_NOTIFIER); 346 347 return 0; 348 } 349 350 static void cs_exit(struct dbs_data *dbs_data, bool notify) 351 { 352 if (notify) 353 cpufreq_unregister_notifier(&cs_cpufreq_notifier_block, 354 CPUFREQ_TRANSITION_NOTIFIER); 355 356 kfree(dbs_data->tuners); 357 } 358 359 define_get_cpu_dbs_routines(cs_cpu_dbs_info); 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 .init = cs_init, 370 .exit = cs_exit, 371 .mutex = __MUTEX_INITIALIZER(cs_dbs_cdata.mutex), 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 static int __init cpufreq_gov_dbs_init(void) 381 { 382 return cpufreq_register_governor(&cpufreq_gov_conservative); 383 } 384 385 static void __exit cpufreq_gov_dbs_exit(void) 386 { 387 cpufreq_unregister_governor(&cpufreq_gov_conservative); 388 } 389 390 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>"); 391 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for " 392 "Low Latency Frequency Transition capable processors " 393 "optimised for use in a battery environment"); 394 MODULE_LICENSE("GPL"); 395 396 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE 397 struct cpufreq_governor *cpufreq_default_governor(void) 398 { 399 return &cpufreq_gov_conservative; 400 } 401 402 fs_initcall(cpufreq_gov_dbs_init); 403 #else 404 module_init(cpufreq_gov_dbs_init); 405 #endif 406 module_exit(cpufreq_gov_dbs_exit); 407