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 macors */ 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 cs_cpu_dbs_info_s *dbs_info = container_of(work, 117 struct cs_cpu_dbs_info_s, cdbs.work.work); 118 unsigned int cpu = dbs_info->cdbs.cpu; 119 int delay = delay_for_sampling_rate(cs_tuners.sampling_rate); 120 121 mutex_lock(&dbs_info->cdbs.timer_mutex); 122 123 dbs_check_cpu(&cs_dbs_data, cpu); 124 125 schedule_delayed_work_on(cpu, &dbs_info->cdbs.work, delay); 126 mutex_unlock(&dbs_info->cdbs.timer_mutex); 127 } 128 129 static int dbs_cpufreq_notifier(struct notifier_block *nb, unsigned long val, 130 void *data) 131 { 132 struct cpufreq_freqs *freq = data; 133 struct cs_cpu_dbs_info_s *dbs_info = 134 &per_cpu(cs_cpu_dbs_info, freq->cpu); 135 struct cpufreq_policy *policy; 136 137 if (!dbs_info->enable) 138 return 0; 139 140 policy = dbs_info->cdbs.cur_policy; 141 142 /* 143 * we only care if our internally tracked freq moves outside the 'valid' 144 * ranges of freqency available to us otherwise we do not change it 145 */ 146 if (dbs_info->requested_freq > policy->max 147 || dbs_info->requested_freq < policy->min) 148 dbs_info->requested_freq = freq->new; 149 150 return 0; 151 } 152 153 /************************** sysfs interface ************************/ 154 static ssize_t show_sampling_rate_min(struct kobject *kobj, 155 struct attribute *attr, char *buf) 156 { 157 return sprintf(buf, "%u\n", cs_dbs_data.min_sampling_rate); 158 } 159 160 static ssize_t store_sampling_down_factor(struct kobject *a, 161 struct attribute *b, 162 const char *buf, size_t count) 163 { 164 unsigned int input; 165 int ret; 166 ret = sscanf(buf, "%u", &input); 167 168 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1) 169 return -EINVAL; 170 171 cs_tuners.sampling_down_factor = input; 172 return count; 173 } 174 175 static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b, 176 const char *buf, size_t count) 177 { 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, cs_dbs_data.min_sampling_rate); 186 return count; 187 } 188 189 static ssize_t store_up_threshold(struct kobject *a, struct attribute *b, 190 const char *buf, size_t count) 191 { 192 unsigned int input; 193 int ret; 194 ret = sscanf(buf, "%u", &input); 195 196 if (ret != 1 || input > 100 || input <= cs_tuners.down_threshold) 197 return -EINVAL; 198 199 cs_tuners.up_threshold = input; 200 return count; 201 } 202 203 static ssize_t store_down_threshold(struct kobject *a, struct attribute *b, 204 const char *buf, size_t count) 205 { 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 kobject *a, struct attribute *b, 220 const char *buf, size_t count) 221 { 222 unsigned int input, j; 223 int ret; 224 225 ret = sscanf(buf, "%u", &input); 226 if (ret != 1) 227 return -EINVAL; 228 229 if (input > 1) 230 input = 1; 231 232 if (input == cs_tuners.ignore_nice) /* nothing to do */ 233 return count; 234 235 cs_tuners.ignore_nice = input; 236 237 /* we need to re-evaluate prev_cpu_idle */ 238 for_each_online_cpu(j) { 239 struct cs_cpu_dbs_info_s *dbs_info; 240 dbs_info = &per_cpu(cs_cpu_dbs_info, j); 241 dbs_info->cdbs.prev_cpu_idle = get_cpu_idle_time(j, 242 &dbs_info->cdbs.prev_cpu_wall); 243 if (cs_tuners.ignore_nice) 244 dbs_info->cdbs.prev_cpu_nice = 245 kcpustat_cpu(j).cpustat[CPUTIME_NICE]; 246 } 247 return count; 248 } 249 250 static ssize_t store_freq_step(struct kobject *a, struct attribute *b, 251 const char *buf, size_t count) 252 { 253 unsigned int input; 254 int ret; 255 ret = sscanf(buf, "%u", &input); 256 257 if (ret != 1) 258 return -EINVAL; 259 260 if (input > 100) 261 input = 100; 262 263 /* 264 * no need to test here if freq_step is zero as the user might actually 265 * want this, they would be crazy though :) 266 */ 267 cs_tuners.freq_step = input; 268 return count; 269 } 270 271 show_one(cs, sampling_rate, sampling_rate); 272 show_one(cs, sampling_down_factor, sampling_down_factor); 273 show_one(cs, up_threshold, up_threshold); 274 show_one(cs, down_threshold, down_threshold); 275 show_one(cs, ignore_nice_load, ignore_nice); 276 show_one(cs, freq_step, freq_step); 277 278 define_one_global_rw(sampling_rate); 279 define_one_global_rw(sampling_down_factor); 280 define_one_global_rw(up_threshold); 281 define_one_global_rw(down_threshold); 282 define_one_global_rw(ignore_nice_load); 283 define_one_global_rw(freq_step); 284 define_one_global_ro(sampling_rate_min); 285 286 static struct attribute *dbs_attributes[] = { 287 &sampling_rate_min.attr, 288 &sampling_rate.attr, 289 &sampling_down_factor.attr, 290 &up_threshold.attr, 291 &down_threshold.attr, 292 &ignore_nice_load.attr, 293 &freq_step.attr, 294 NULL 295 }; 296 297 static struct attribute_group cs_attr_group = { 298 .attrs = dbs_attributes, 299 .name = "conservative", 300 }; 301 302 /************************** sysfs end ************************/ 303 304 define_get_cpu_dbs_routines(cs_cpu_dbs_info); 305 306 static struct notifier_block cs_cpufreq_notifier_block = { 307 .notifier_call = dbs_cpufreq_notifier, 308 }; 309 310 static struct cs_ops cs_ops = { 311 .notifier_block = &cs_cpufreq_notifier_block, 312 }; 313 314 static struct dbs_data cs_dbs_data = { 315 .governor = GOV_CONSERVATIVE, 316 .attr_group = &cs_attr_group, 317 .tuners = &cs_tuners, 318 .get_cpu_cdbs = get_cpu_cdbs, 319 .get_cpu_dbs_info_s = get_cpu_dbs_info_s, 320 .gov_dbs_timer = cs_dbs_timer, 321 .gov_check_cpu = cs_check_cpu, 322 .gov_ops = &cs_ops, 323 }; 324 325 static int cs_cpufreq_governor_dbs(struct cpufreq_policy *policy, 326 unsigned int event) 327 { 328 return cpufreq_governor_dbs(&cs_dbs_data, policy, event); 329 } 330 331 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE 332 static 333 #endif 334 struct cpufreq_governor cpufreq_gov_conservative = { 335 .name = "conservative", 336 .governor = cs_cpufreq_governor_dbs, 337 .max_transition_latency = TRANSITION_LATENCY_LIMIT, 338 .owner = THIS_MODULE, 339 }; 340 341 static int __init cpufreq_gov_dbs_init(void) 342 { 343 mutex_init(&cs_dbs_data.mutex); 344 return cpufreq_register_governor(&cpufreq_gov_conservative); 345 } 346 347 static void __exit cpufreq_gov_dbs_exit(void) 348 { 349 cpufreq_unregister_governor(&cpufreq_gov_conservative); 350 } 351 352 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>"); 353 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for " 354 "Low Latency Frequency Transition capable processors " 355 "optimised for use in a battery environment"); 356 MODULE_LICENSE("GPL"); 357 358 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE 359 fs_initcall(cpufreq_gov_dbs_init); 360 #else 361 module_init(cpufreq_gov_dbs_init); 362 #endif 363 module_exit(cpufreq_gov_dbs_exit); 364