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 struct cs_policy_dbs_info { 18 struct policy_dbs_info policy_dbs; 19 unsigned int down_skip; 20 unsigned int requested_freq; 21 }; 22 23 static inline struct cs_policy_dbs_info *to_dbs_info(struct policy_dbs_info *policy_dbs) 24 { 25 return container_of(policy_dbs, struct cs_policy_dbs_info, policy_dbs); 26 } 27 28 struct cs_dbs_tuners { 29 unsigned int down_threshold; 30 unsigned int freq_step; 31 }; 32 33 /* Conservative governor macros */ 34 #define DEF_FREQUENCY_UP_THRESHOLD (80) 35 #define DEF_FREQUENCY_DOWN_THRESHOLD (20) 36 #define DEF_FREQUENCY_STEP (5) 37 #define DEF_SAMPLING_DOWN_FACTOR (1) 38 #define MAX_SAMPLING_DOWN_FACTOR (10) 39 40 static inline unsigned int get_freq_target(struct cs_dbs_tuners *cs_tuners, 41 struct cpufreq_policy *policy) 42 { 43 unsigned int freq_target = (cs_tuners->freq_step * policy->max) / 100; 44 45 /* max freq cannot be less than 100. But who knows... */ 46 if (unlikely(freq_target == 0)) 47 freq_target = DEF_FREQUENCY_STEP; 48 49 return freq_target; 50 } 51 52 /* 53 * Every sampling_rate, we check, if current idle time is less than 20% 54 * (default), then we try to increase frequency. Every sampling_rate * 55 * sampling_down_factor, we check, if current idle time is more than 80% 56 * (default), then we try to decrease frequency 57 * 58 * Any frequency increase takes it to the maximum frequency. Frequency reduction 59 * happens at minimum steps of 5% (default) of maximum frequency 60 */ 61 static unsigned int cs_dbs_timer(struct cpufreq_policy *policy) 62 { 63 struct policy_dbs_info *policy_dbs = policy->governor_data; 64 struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs); 65 struct dbs_data *dbs_data = policy_dbs->dbs_data; 66 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 67 unsigned int load = dbs_update(policy); 68 69 /* 70 * break out if we 'cannot' reduce the speed as the user might 71 * want freq_step to be zero 72 */ 73 if (cs_tuners->freq_step == 0) 74 goto out; 75 76 /* Check for frequency increase */ 77 if (load > dbs_data->up_threshold) { 78 dbs_info->down_skip = 0; 79 80 /* if we are already at full speed then break out early */ 81 if (dbs_info->requested_freq == policy->max) 82 goto out; 83 84 dbs_info->requested_freq += get_freq_target(cs_tuners, policy); 85 86 if (dbs_info->requested_freq > policy->max) 87 dbs_info->requested_freq = policy->max; 88 89 __cpufreq_driver_target(policy, dbs_info->requested_freq, 90 CPUFREQ_RELATION_H); 91 goto out; 92 } 93 94 /* if sampling_down_factor is active break out early */ 95 if (++dbs_info->down_skip < dbs_data->sampling_down_factor) 96 goto out; 97 dbs_info->down_skip = 0; 98 99 /* Check for frequency decrease */ 100 if (load < cs_tuners->down_threshold) { 101 unsigned int freq_target; 102 /* 103 * if we cannot reduce the frequency anymore, break out early 104 */ 105 if (policy->cur == policy->min) 106 goto out; 107 108 freq_target = get_freq_target(cs_tuners, policy); 109 if (dbs_info->requested_freq > freq_target) 110 dbs_info->requested_freq -= freq_target; 111 else 112 dbs_info->requested_freq = policy->min; 113 114 __cpufreq_driver_target(policy, dbs_info->requested_freq, 115 CPUFREQ_RELATION_L); 116 } 117 118 out: 119 return dbs_data->sampling_rate; 120 } 121 122 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val, 123 void *data); 124 125 static struct notifier_block cs_cpufreq_notifier_block = { 126 .notifier_call = dbs_cpufreq_notifier, 127 }; 128 129 /************************** sysfs interface ************************/ 130 131 static ssize_t store_sampling_down_factor(struct gov_attr_set *attr_set, 132 const char *buf, size_t count) 133 { 134 struct dbs_data *dbs_data = to_dbs_data(attr_set); 135 unsigned int input; 136 int ret; 137 ret = sscanf(buf, "%u", &input); 138 139 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1) 140 return -EINVAL; 141 142 dbs_data->sampling_down_factor = input; 143 return count; 144 } 145 146 static ssize_t store_up_threshold(struct gov_attr_set *attr_set, 147 const char *buf, size_t count) 148 { 149 struct dbs_data *dbs_data = to_dbs_data(attr_set); 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 > 100 || input <= cs_tuners->down_threshold) 156 return -EINVAL; 157 158 dbs_data->up_threshold = input; 159 return count; 160 } 161 162 static ssize_t store_down_threshold(struct gov_attr_set *attr_set, 163 const char *buf, size_t count) 164 { 165 struct dbs_data *dbs_data = to_dbs_data(attr_set); 166 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 167 unsigned int input; 168 int ret; 169 ret = sscanf(buf, "%u", &input); 170 171 /* cannot be lower than 11 otherwise freq will not fall */ 172 if (ret != 1 || input < 11 || input > 100 || 173 input >= dbs_data->up_threshold) 174 return -EINVAL; 175 176 cs_tuners->down_threshold = input; 177 return count; 178 } 179 180 static ssize_t store_ignore_nice_load(struct gov_attr_set *attr_set, 181 const char *buf, size_t count) 182 { 183 struct dbs_data *dbs_data = to_dbs_data(attr_set); 184 unsigned int input; 185 int ret; 186 187 ret = sscanf(buf, "%u", &input); 188 if (ret != 1) 189 return -EINVAL; 190 191 if (input > 1) 192 input = 1; 193 194 if (input == dbs_data->ignore_nice_load) /* nothing to do */ 195 return count; 196 197 dbs_data->ignore_nice_load = input; 198 199 /* we need to re-evaluate prev_cpu_idle */ 200 gov_update_cpu_data(dbs_data); 201 202 return count; 203 } 204 205 static ssize_t store_freq_step(struct gov_attr_set *attr_set, const char *buf, 206 size_t count) 207 { 208 struct dbs_data *dbs_data = to_dbs_data(attr_set); 209 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 210 unsigned int input; 211 int ret; 212 ret = sscanf(buf, "%u", &input); 213 214 if (ret != 1) 215 return -EINVAL; 216 217 if (input > 100) 218 input = 100; 219 220 /* 221 * no need to test here if freq_step is zero as the user might actually 222 * want this, they would be crazy though :) 223 */ 224 cs_tuners->freq_step = input; 225 return count; 226 } 227 228 gov_show_one_common(sampling_rate); 229 gov_show_one_common(sampling_down_factor); 230 gov_show_one_common(up_threshold); 231 gov_show_one_common(ignore_nice_load); 232 gov_show_one_common(min_sampling_rate); 233 gov_show_one(cs, down_threshold); 234 gov_show_one(cs, freq_step); 235 236 gov_attr_rw(sampling_rate); 237 gov_attr_rw(sampling_down_factor); 238 gov_attr_rw(up_threshold); 239 gov_attr_rw(ignore_nice_load); 240 gov_attr_ro(min_sampling_rate); 241 gov_attr_rw(down_threshold); 242 gov_attr_rw(freq_step); 243 244 static struct attribute *cs_attributes[] = { 245 &min_sampling_rate.attr, 246 &sampling_rate.attr, 247 &sampling_down_factor.attr, 248 &up_threshold.attr, 249 &down_threshold.attr, 250 &ignore_nice_load.attr, 251 &freq_step.attr, 252 NULL 253 }; 254 255 /************************** sysfs end ************************/ 256 257 struct cs_governor { 258 struct dbs_governor dbs_gov; 259 unsigned int usage_count; 260 }; 261 262 static struct cs_governor cs_gov; 263 264 static struct policy_dbs_info *cs_alloc(void) 265 { 266 struct cs_policy_dbs_info *dbs_info; 267 268 dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL); 269 return dbs_info ? &dbs_info->policy_dbs : NULL; 270 } 271 272 static void cs_free(struct policy_dbs_info *policy_dbs) 273 { 274 kfree(to_dbs_info(policy_dbs)); 275 } 276 277 static int cs_init(struct dbs_data *dbs_data) 278 { 279 struct cs_dbs_tuners *tuners; 280 281 tuners = kzalloc(sizeof(*tuners), GFP_KERNEL); 282 if (!tuners) 283 return -ENOMEM; 284 285 tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD; 286 tuners->freq_step = DEF_FREQUENCY_STEP; 287 dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD; 288 dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR; 289 dbs_data->ignore_nice_load = 0; 290 291 dbs_data->tuners = tuners; 292 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO * 293 jiffies_to_usecs(10); 294 295 /* 296 * This function and cs_exit() are only called under gov_dbs_data_mutex 297 * which is global, so the cs_gov.usage_count accesses are guaranteed 298 * to be serialized. 299 */ 300 if (!cs_gov.usage_count++) 301 cpufreq_register_notifier(&cs_cpufreq_notifier_block, 302 CPUFREQ_TRANSITION_NOTIFIER); 303 304 return 0; 305 } 306 307 static void cs_exit(struct dbs_data *dbs_data) 308 { 309 /* Protected by gov_dbs_data_mutex - see the comment in cs_init(). */ 310 if (!--cs_gov.usage_count) 311 cpufreq_unregister_notifier(&cs_cpufreq_notifier_block, 312 CPUFREQ_TRANSITION_NOTIFIER); 313 314 kfree(dbs_data->tuners); 315 } 316 317 static void cs_start(struct cpufreq_policy *policy) 318 { 319 struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data); 320 321 dbs_info->down_skip = 0; 322 dbs_info->requested_freq = policy->cur; 323 } 324 325 static struct cs_governor cs_gov = { 326 .dbs_gov = { 327 .gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("conservative"), 328 .kobj_type = { .default_attrs = cs_attributes }, 329 .gov_dbs_timer = cs_dbs_timer, 330 .alloc = cs_alloc, 331 .free = cs_free, 332 .init = cs_init, 333 .exit = cs_exit, 334 .start = cs_start, 335 }, 336 }; 337 338 #define CPU_FREQ_GOV_CONSERVATIVE (&cs_gov.dbs_gov.gov) 339 340 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val, 341 void *data) 342 { 343 struct cpufreq_freqs *freq = data; 344 struct cpufreq_policy *policy = cpufreq_cpu_get_raw(freq->cpu); 345 struct cs_policy_dbs_info *dbs_info; 346 347 if (!policy) 348 return 0; 349 350 /* policy isn't governed by conservative governor */ 351 if (policy->governor != CPU_FREQ_GOV_CONSERVATIVE) 352 return 0; 353 354 dbs_info = to_dbs_info(policy->governor_data); 355 /* 356 * we only care if our internally tracked freq moves outside the 'valid' 357 * ranges of frequency available to us otherwise we do not change it 358 */ 359 if (dbs_info->requested_freq > policy->max 360 || dbs_info->requested_freq < policy->min) 361 dbs_info->requested_freq = freq->new; 362 363 return 0; 364 } 365 366 static int __init cpufreq_gov_dbs_init(void) 367 { 368 return cpufreq_register_governor(CPU_FREQ_GOV_CONSERVATIVE); 369 } 370 371 static void __exit cpufreq_gov_dbs_exit(void) 372 { 373 cpufreq_unregister_governor(CPU_FREQ_GOV_CONSERVATIVE); 374 } 375 376 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>"); 377 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for " 378 "Low Latency Frequency Transition capable processors " 379 "optimised for use in a battery environment"); 380 MODULE_LICENSE("GPL"); 381 382 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE 383 struct cpufreq_governor *cpufreq_default_governor(void) 384 { 385 return CPU_FREQ_GOV_CONSERVATIVE; 386 } 387 388 fs_initcall(cpufreq_gov_dbs_init); 389 #else 390 module_init(cpufreq_gov_dbs_init); 391 #endif 392 module_exit(cpufreq_gov_dbs_exit); 393