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.shared->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 if (dbs_info->requested_freq > policy->max) 72 dbs_info->requested_freq = policy->max; 73 74 __cpufreq_driver_target(policy, dbs_info->requested_freq, 75 CPUFREQ_RELATION_H); 76 return; 77 } 78 79 /* if sampling_down_factor is active break out early */ 80 if (++dbs_info->down_skip < cs_tuners->sampling_down_factor) 81 return; 82 dbs_info->down_skip = 0; 83 84 /* Check for frequency decrease */ 85 if (load < cs_tuners->down_threshold) { 86 unsigned int freq_target; 87 /* 88 * if we cannot reduce the frequency anymore, break out early 89 */ 90 if (policy->cur == policy->min) 91 return; 92 93 freq_target = get_freq_target(cs_tuners, policy); 94 if (dbs_info->requested_freq > freq_target) 95 dbs_info->requested_freq -= freq_target; 96 else 97 dbs_info->requested_freq = policy->min; 98 99 __cpufreq_driver_target(policy, dbs_info->requested_freq, 100 CPUFREQ_RELATION_L); 101 return; 102 } 103 } 104 105 static unsigned int cs_dbs_timer(struct cpu_dbs_info *cdbs, 106 struct dbs_data *dbs_data, bool modify_all) 107 { 108 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 109 110 if (modify_all) 111 dbs_check_cpu(dbs_data, cdbs->shared->policy->cpu); 112 113 return delay_for_sampling_rate(cs_tuners->sampling_rate); 114 } 115 116 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val, 117 void *data) 118 { 119 struct cpufreq_freqs *freq = data; 120 struct cs_cpu_dbs_info_s *dbs_info = 121 &per_cpu(cs_cpu_dbs_info, freq->cpu); 122 struct cpufreq_policy *policy; 123 124 if (!dbs_info->enable) 125 return 0; 126 127 policy = dbs_info->cdbs.shared->policy; 128 129 /* 130 * we only care if our internally tracked freq moves outside the 'valid' 131 * ranges of frequency available to us otherwise we do not change it 132 */ 133 if (dbs_info->requested_freq > policy->max 134 || dbs_info->requested_freq < policy->min) 135 dbs_info->requested_freq = freq->new; 136 137 return 0; 138 } 139 140 static struct notifier_block cs_cpufreq_notifier_block = { 141 .notifier_call = dbs_cpufreq_notifier, 142 }; 143 144 /************************** sysfs interface ************************/ 145 static struct common_dbs_data cs_dbs_cdata; 146 147 static ssize_t store_sampling_down_factor(struct dbs_data *dbs_data, 148 const char *buf, size_t count) 149 { 150 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 151 unsigned int input; 152 int ret; 153 ret = sscanf(buf, "%u", &input); 154 155 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1) 156 return -EINVAL; 157 158 cs_tuners->sampling_down_factor = input; 159 return count; 160 } 161 162 static ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf, 163 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) 171 return -EINVAL; 172 173 cs_tuners->sampling_rate = max(input, dbs_data->min_sampling_rate); 174 return count; 175 } 176 177 static ssize_t store_up_threshold(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 || input > 100 || input <= cs_tuners->down_threshold) 186 return -EINVAL; 187 188 cs_tuners->up_threshold = input; 189 return count; 190 } 191 192 static ssize_t store_down_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 /* cannot be lower than 11 otherwise freq will not fall */ 201 if (ret != 1 || input < 11 || input > 100 || 202 input >= cs_tuners->up_threshold) 203 return -EINVAL; 204 205 cs_tuners->down_threshold = input; 206 return count; 207 } 208 209 static ssize_t store_ignore_nice_load(struct dbs_data *dbs_data, 210 const char *buf, size_t count) 211 { 212 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 213 unsigned int input, j; 214 int ret; 215 216 ret = sscanf(buf, "%u", &input); 217 if (ret != 1) 218 return -EINVAL; 219 220 if (input > 1) 221 input = 1; 222 223 if (input == cs_tuners->ignore_nice_load) /* nothing to do */ 224 return count; 225 226 cs_tuners->ignore_nice_load = input; 227 228 /* we need to re-evaluate prev_cpu_idle */ 229 for_each_online_cpu(j) { 230 struct cs_cpu_dbs_info_s *dbs_info; 231 dbs_info = &per_cpu(cs_cpu_dbs_info, j); 232 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j, 233 &dbs_info->cdbs.prev_cpu_wall, 0); 234 if (cs_tuners->ignore_nice_load) 235 dbs_info->cdbs.prev_cpu_nice = 236 kcpustat_cpu(j).cpustat[CPUTIME_NICE]; 237 } 238 return count; 239 } 240 241 static ssize_t store_freq_step(struct dbs_data *dbs_data, const char *buf, 242 size_t count) 243 { 244 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 245 unsigned int input; 246 int ret; 247 ret = sscanf(buf, "%u", &input); 248 249 if (ret != 1) 250 return -EINVAL; 251 252 if (input > 100) 253 input = 100; 254 255 /* 256 * no need to test here if freq_step is zero as the user might actually 257 * want this, they would be crazy though :) 258 */ 259 cs_tuners->freq_step = input; 260 return count; 261 } 262 263 show_store_one(cs, sampling_rate); 264 show_store_one(cs, sampling_down_factor); 265 show_store_one(cs, up_threshold); 266 show_store_one(cs, down_threshold); 267 show_store_one(cs, ignore_nice_load); 268 show_store_one(cs, freq_step); 269 declare_show_sampling_rate_min(cs); 270 271 gov_sys_pol_attr_rw(sampling_rate); 272 gov_sys_pol_attr_rw(sampling_down_factor); 273 gov_sys_pol_attr_rw(up_threshold); 274 gov_sys_pol_attr_rw(down_threshold); 275 gov_sys_pol_attr_rw(ignore_nice_load); 276 gov_sys_pol_attr_rw(freq_step); 277 gov_sys_pol_attr_ro(sampling_rate_min); 278 279 static struct attribute *dbs_attributes_gov_sys[] = { 280 &sampling_rate_min_gov_sys.attr, 281 &sampling_rate_gov_sys.attr, 282 &sampling_down_factor_gov_sys.attr, 283 &up_threshold_gov_sys.attr, 284 &down_threshold_gov_sys.attr, 285 &ignore_nice_load_gov_sys.attr, 286 &freq_step_gov_sys.attr, 287 NULL 288 }; 289 290 static struct attribute_group cs_attr_group_gov_sys = { 291 .attrs = dbs_attributes_gov_sys, 292 .name = "conservative", 293 }; 294 295 static struct attribute *dbs_attributes_gov_pol[] = { 296 &sampling_rate_min_gov_pol.attr, 297 &sampling_rate_gov_pol.attr, 298 &sampling_down_factor_gov_pol.attr, 299 &up_threshold_gov_pol.attr, 300 &down_threshold_gov_pol.attr, 301 &ignore_nice_load_gov_pol.attr, 302 &freq_step_gov_pol.attr, 303 NULL 304 }; 305 306 static struct attribute_group cs_attr_group_gov_pol = { 307 .attrs = dbs_attributes_gov_pol, 308 .name = "conservative", 309 }; 310 311 /************************** sysfs end ************************/ 312 313 static int cs_init(struct dbs_data *dbs_data, bool notify) 314 { 315 struct cs_dbs_tuners *tuners; 316 317 tuners = kzalloc(sizeof(*tuners), GFP_KERNEL); 318 if (!tuners) { 319 pr_err("%s: kzalloc failed\n", __func__); 320 return -ENOMEM; 321 } 322 323 tuners->up_threshold = DEF_FREQUENCY_UP_THRESHOLD; 324 tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD; 325 tuners->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR; 326 tuners->ignore_nice_load = 0; 327 tuners->freq_step = DEF_FREQUENCY_STEP; 328 329 dbs_data->tuners = tuners; 330 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO * 331 jiffies_to_usecs(10); 332 333 if (notify) 334 cpufreq_register_notifier(&cs_cpufreq_notifier_block, 335 CPUFREQ_TRANSITION_NOTIFIER); 336 337 return 0; 338 } 339 340 static void cs_exit(struct dbs_data *dbs_data, bool notify) 341 { 342 if (notify) 343 cpufreq_unregister_notifier(&cs_cpufreq_notifier_block, 344 CPUFREQ_TRANSITION_NOTIFIER); 345 346 kfree(dbs_data->tuners); 347 } 348 349 define_get_cpu_dbs_routines(cs_cpu_dbs_info); 350 351 static struct common_dbs_data cs_dbs_cdata = { 352 .governor = GOV_CONSERVATIVE, 353 .attr_group_gov_sys = &cs_attr_group_gov_sys, 354 .attr_group_gov_pol = &cs_attr_group_gov_pol, 355 .get_cpu_cdbs = get_cpu_cdbs, 356 .get_cpu_dbs_info_s = get_cpu_dbs_info_s, 357 .gov_dbs_timer = cs_dbs_timer, 358 .gov_check_cpu = cs_check_cpu, 359 .init = cs_init, 360 .exit = cs_exit, 361 .mutex = __MUTEX_INITIALIZER(cs_dbs_cdata.mutex), 362 }; 363 364 static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy, 365 unsigned int event) 366 { 367 return cpufreq_governor_dbs(policy, &cs_dbs_cdata, event); 368 } 369 370 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE 371 static 372 #endif 373 struct cpufreq_governor cpufreq_gov_conservative = { 374 .name = "conservative", 375 .governor = cs_cpufreq_governor_dbs, 376 .max_transition_latency = TRANSITION_LATENCY_LIMIT, 377 .owner = THIS_MODULE, 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 fs_initcall(cpufreq_gov_dbs_init); 398 #else 399 module_init(cpufreq_gov_dbs_init); 400 #endif 401 module_exit(cpufreq_gov_dbs_exit); 402