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/cpufreq.h> 15 #include <linux/init.h> 16 #include <linux/kernel.h> 17 #include <linux/kernel_stat.h> 18 #include <linux/kobject.h> 19 #include <linux/module.h> 20 #include <linux/mutex.h> 21 #include <linux/notifier.h> 22 #include <linux/percpu-defs.h> 23 #include <linux/sysfs.h> 24 #include <linux/types.h> 25 26 #include "cpufreq_governor.h" 27 28 /* Conservative governor macros */ 29 #define DEF_FREQUENCY_UP_THRESHOLD (80) 30 #define DEF_FREQUENCY_DOWN_THRESHOLD (20) 31 #define DEF_SAMPLING_DOWN_FACTOR (1) 32 #define MAX_SAMPLING_DOWN_FACTOR (10) 33 34 static struct dbs_data cs_dbs_data; 35 static DEFINE_PER_CPU(struct cs_cpu_dbs_info_s, cs_cpu_dbs_info); 36 37 static struct cs_dbs_tuners cs_tuners = { 38 .up_threshold = DEF_FREQUENCY_UP_THRESHOLD, 39 .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD, 40 .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR, 41 .ignore_nice = 0, 42 .freq_step = 5, 43 }; 44 45 /* 46 * Every sampling_rate, we check, if current idle time is less than 20% 47 * (default), then we try to increase frequency Every sampling_rate * 48 * sampling_down_factor, we check, if current idle time is more than 80%, then 49 * we try to decrease frequency 50 * 51 * Any frequency increase takes it to the maximum frequency. Frequency reduction 52 * happens at minimum steps of 5% (default) of maximum frequency 53 */ 54 static void cs_check_cpu(int cpu, unsigned int load) 55 { 56 struct cs_cpu_dbs_info_s *dbs_info = &per_cpu(cs_cpu_dbs_info, cpu); 57 struct cpufreq_policy *policy = dbs_info->cdbs.cur_policy; 58 unsigned int freq_target; 59 60 /* 61 * break out if we 'cannot' reduce the speed as the user might 62 * want freq_step to be zero 63 */ 64 if (cs_tuners.freq_step == 0) 65 return; 66 67 /* Check for frequency increase */ 68 if (load > cs_tuners.up_threshold) { 69 dbs_info->down_skip = 0; 70 71 /* if we are already at full speed then break out early */ 72 if (dbs_info->requested_freq == policy->max) 73 return; 74 75 freq_target = (cs_tuners.freq_step * policy->max) / 100; 76 77 /* max freq cannot be less than 100. But who knows.... */ 78 if (unlikely(freq_target == 0)) 79 freq_target = 5; 80 81 dbs_info->requested_freq += freq_target; 82 if (dbs_info->requested_freq > policy->max) 83 dbs_info->requested_freq = policy->max; 84 85 __cpufreq_driver_target(policy, dbs_info->requested_freq, 86 CPUFREQ_RELATION_H); 87 return; 88 } 89 90 /* 91 * The optimal frequency is the frequency that is the lowest that can 92 * support the current CPU usage without triggering the up policy. To be 93 * safe, we focus 10 points under the threshold. 94 */ 95 if (load < (cs_tuners.down_threshold - 10)) { 96 freq_target = (cs_tuners.freq_step * policy->max) / 100; 97 98 dbs_info->requested_freq -= freq_target; 99 if (dbs_info->requested_freq < policy->min) 100 dbs_info->requested_freq = policy->min; 101 102 /* 103 * if we cannot reduce the frequency anymore, break out early 104 */ 105 if (policy->cur == policy->min) 106 return; 107 108 __cpufreq_driver_target(policy, dbs_info->requested_freq, 109 CPUFREQ_RELATION_H); 110 return; 111 } 112 } 113 114 static void cs_dbs_timer(struct work_struct *work) 115 { 116 struct delayed_work *dw = to_delayed_work(work); 117 struct cs_cpu_dbs_info_s *dbs_info = container_of(work, 118 struct cs_cpu_dbs_info_s, cdbs.work.work); 119 unsigned int cpu = dbs_info->cdbs.cur_policy->cpu; 120 struct cs_cpu_dbs_info_s *core_dbs_info = &per_cpu(cs_cpu_dbs_info, 121 cpu); 122 int delay = delay_for_sampling_rate(cs_tuners.sampling_rate); 123 124 mutex_lock(&core_dbs_info->cdbs.timer_mutex); 125 if (need_load_eval(&core_dbs_info->cdbs, cs_tuners.sampling_rate)) 126 dbs_check_cpu(&cs_dbs_data, cpu); 127 128 schedule_delayed_work_on(smp_processor_id(), dw, delay); 129 mutex_unlock(&core_dbs_info->cdbs.timer_mutex); 130 } 131 132 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val, 133 void *data) 134 { 135 struct cpufreq_freqs *freq = data; 136 struct cs_cpu_dbs_info_s *dbs_info = 137 &per_cpu(cs_cpu_dbs_info, freq->cpu); 138 struct cpufreq_policy *policy; 139 140 if (!dbs_info->enable) 141 return 0; 142 143 policy = dbs_info->cdbs.cur_policy; 144 145 /* 146 * we only care if our internally tracked freq moves outside the 'valid' 147 * ranges of frequency available to us otherwise we do not change it 148 */ 149 if (dbs_info->requested_freq > policy->max 150 || dbs_info->requested_freq < policy->min) 151 dbs_info->requested_freq = freq->new; 152 153 return 0; 154 } 155 156 /************************** sysfs interface ************************/ 157 static ssize_t show_sampling_rate_min(struct kobject *kobj, 158 struct attribute *attr, char *buf) 159 { 160 return sprintf(buf, "%u\n", cs_dbs_data.min_sampling_rate); 161 } 162 163 static ssize_t store_sampling_down_factor(struct kobject *a, 164 struct attribute *b, 165 const char *buf, size_t count) 166 { 167 unsigned int input; 168 int ret; 169 ret = sscanf(buf, "%u", &input); 170 171 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1) 172 return -EINVAL; 173 174 cs_tuners.sampling_down_factor = input; 175 return count; 176 } 177 178 static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b, 179 const char *buf, size_t count) 180 { 181 unsigned int input; 182 int ret; 183 ret = sscanf(buf, "%u", &input); 184 185 if (ret != 1) 186 return -EINVAL; 187 188 cs_tuners.sampling_rate = max(input, cs_dbs_data.min_sampling_rate); 189 return count; 190 } 191 192 static ssize_t store_up_threshold(struct kobject *a, struct attribute *b, 193 const char *buf, size_t count) 194 { 195 unsigned int input; 196 int ret; 197 ret = sscanf(buf, "%u", &input); 198 199 if (ret != 1 || input > 100 || input <= cs_tuners.down_threshold) 200 return -EINVAL; 201 202 cs_tuners.up_threshold = input; 203 return count; 204 } 205 206 static ssize_t store_down_threshold(struct kobject *a, struct attribute *b, 207 const char *buf, size_t count) 208 { 209 unsigned int input; 210 int ret; 211 ret = sscanf(buf, "%u", &input); 212 213 /* cannot be lower than 11 otherwise freq will not fall */ 214 if (ret != 1 || input < 11 || input > 100 || 215 input >= cs_tuners.up_threshold) 216 return -EINVAL; 217 218 cs_tuners.down_threshold = input; 219 return count; 220 } 221 222 static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b, 223 const char *buf, size_t count) 224 { 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) /* nothing to do */ 236 return count; 237 238 cs_tuners.ignore_nice = 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); 246 if (cs_tuners.ignore_nice) 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 kobject *a, struct attribute *b, 254 const char *buf, size_t count) 255 { 256 unsigned int input; 257 int ret; 258 ret = sscanf(buf, "%u", &input); 259 260 if (ret != 1) 261 return -EINVAL; 262 263 if (input > 100) 264 input = 100; 265 266 /* 267 * no need to test here if freq_step is zero as the user might actually 268 * want this, they would be crazy though :) 269 */ 270 cs_tuners.freq_step = input; 271 return count; 272 } 273 274 show_one(cs, sampling_rate, sampling_rate); 275 show_one(cs, sampling_down_factor, sampling_down_factor); 276 show_one(cs, up_threshold, up_threshold); 277 show_one(cs, down_threshold, down_threshold); 278 show_one(cs, ignore_nice_load, ignore_nice); 279 show_one(cs, freq_step, freq_step); 280 281 define_one_global_rw(sampling_rate); 282 define_one_global_rw(sampling_down_factor); 283 define_one_global_rw(up_threshold); 284 define_one_global_rw(down_threshold); 285 define_one_global_rw(ignore_nice_load); 286 define_one_global_rw(freq_step); 287 define_one_global_ro(sampling_rate_min); 288 289 static struct attribute *dbs_attributes[] = { 290 &sampling_rate_min.attr, 291 &sampling_rate.attr, 292 &sampling_down_factor.attr, 293 &up_threshold.attr, 294 &down_threshold.attr, 295 &ignore_nice_load.attr, 296 &freq_step.attr, 297 NULL 298 }; 299 300 static struct attribute_group cs_attr_group = { 301 .attrs = dbs_attributes, 302 .name = "conservative", 303 }; 304 305 /************************** sysfs end ************************/ 306 307 define_get_cpu_dbs_routines(cs_cpu_dbs_info); 308 309 static struct notifier_block cs_cpufreq_notifier_block = { 310 .notifier_call = dbs_cpufreq_notifier, 311 }; 312 313 static struct cs_ops cs_ops = { 314 .notifier_block = &cs_cpufreq_notifier_block, 315 }; 316 317 static struct dbs_data cs_dbs_data = { 318 .governor = GOV_CONSERVATIVE, 319 .attr_group = &cs_attr_group, 320 .tuners = &cs_tuners, 321 .get_cpu_cdbs = get_cpu_cdbs, 322 .get_cpu_dbs_info_s = get_cpu_dbs_info_s, 323 .gov_dbs_timer = cs_dbs_timer, 324 .gov_check_cpu = cs_check_cpu, 325 .gov_ops = &cs_ops, 326 }; 327 328 static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy, 329 unsigned int event) 330 { 331 return cpufreq_governor_dbs(&cs_dbs_data, policy, event); 332 } 333 334 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE 335 static 336 #endif 337 struct cpufreq_governor cpufreq_gov_conservative = { 338 .name = "conservative", 339 .governor = cs_cpufreq_governor_dbs, 340 .max_transition_latency = TRANSITION_LATENCY_LIMIT, 341 .owner = THIS_MODULE, 342 }; 343 344 static int __init cpufreq_gov_dbs_init(void) 345 { 346 mutex_init(&cs_dbs_data.mutex); 347 return cpufreq_register_governor(&cpufreq_gov_conservative); 348 } 349 350 static void __exit cpufreq_gov_dbs_exit(void) 351 { 352 cpufreq_unregister_governor(&cpufreq_gov_conservative); 353 } 354 355 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>"); 356 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for " 357 "Low Latency Frequency Transition capable processors " 358 "optimised for use in a battery environment"); 359 MODULE_LICENSE("GPL"); 360 361 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE 362 fs_initcall(cpufreq_gov_dbs_init); 363 #else 364 module_init(cpufreq_gov_dbs_init); 365 #endif 366 module_exit(cpufreq_gov_dbs_exit); 367