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_step(struct cs_dbs_tuners *cs_tuners, 41 struct cpufreq_policy *policy) 42 { 43 unsigned int freq_step = (cs_tuners->freq_step * policy->max) / 100; 44 45 /* max freq cannot be less than 100. But who knows... */ 46 if (unlikely(freq_step == 0)) 47 freq_step = DEF_FREQUENCY_STEP; 48 49 return freq_step; 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 * Frequency updates happen at minimum steps of 5% (default) of maximum 59 * frequency 60 */ 61 static unsigned int cs_dbs_update(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 unsigned int requested_freq = dbs_info->requested_freq; 66 struct dbs_data *dbs_data = policy_dbs->dbs_data; 67 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 68 unsigned int load = dbs_update(policy); 69 unsigned int freq_step; 70 71 /* 72 * break out if we 'cannot' reduce the speed as the user might 73 * want freq_step to be zero 74 */ 75 if (cs_tuners->freq_step == 0) 76 goto out; 77 78 /* 79 * If requested_freq is out of range, it is likely that the limits 80 * changed in the meantime, so fall back to current frequency in that 81 * case. 82 */ 83 if (requested_freq > policy->max || requested_freq < policy->min) 84 requested_freq = policy->cur; 85 86 freq_step = get_freq_step(cs_tuners, policy); 87 88 /* 89 * Decrease requested_freq one freq_step for each idle period that 90 * we didn't update the frequency. 91 */ 92 if (policy_dbs->idle_periods < UINT_MAX) { 93 unsigned int freq_steps = policy_dbs->idle_periods * freq_step; 94 95 if (requested_freq > freq_steps) 96 requested_freq -= freq_steps; 97 else 98 requested_freq = policy->min; 99 100 policy_dbs->idle_periods = UINT_MAX; 101 } 102 103 /* Check for frequency increase */ 104 if (load > dbs_data->up_threshold) { 105 dbs_info->down_skip = 0; 106 107 /* if we are already at full speed then break out early */ 108 if (requested_freq == policy->max) 109 goto out; 110 111 requested_freq += freq_step; 112 if (requested_freq > policy->max) 113 requested_freq = policy->max; 114 115 __cpufreq_driver_target(policy, requested_freq, CPUFREQ_RELATION_H); 116 dbs_info->requested_freq = requested_freq; 117 goto out; 118 } 119 120 /* if sampling_down_factor is active break out early */ 121 if (++dbs_info->down_skip < dbs_data->sampling_down_factor) 122 goto out; 123 dbs_info->down_skip = 0; 124 125 /* Check for frequency decrease */ 126 if (load < cs_tuners->down_threshold) { 127 /* 128 * if we cannot reduce the frequency anymore, break out early 129 */ 130 if (requested_freq == policy->min) 131 goto out; 132 133 if (requested_freq > freq_step) 134 requested_freq -= freq_step; 135 else 136 requested_freq = policy->min; 137 138 __cpufreq_driver_target(policy, requested_freq, CPUFREQ_RELATION_L); 139 dbs_info->requested_freq = requested_freq; 140 } 141 142 out: 143 return dbs_data->sampling_rate; 144 } 145 146 /************************** sysfs interface ************************/ 147 148 static ssize_t store_sampling_down_factor(struct gov_attr_set *attr_set, 149 const char *buf, size_t count) 150 { 151 struct dbs_data *dbs_data = to_dbs_data(attr_set); 152 unsigned int input; 153 int ret; 154 ret = sscanf(buf, "%u", &input); 155 156 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1) 157 return -EINVAL; 158 159 dbs_data->sampling_down_factor = input; 160 return count; 161 } 162 163 static ssize_t store_up_threshold(struct gov_attr_set *attr_set, 164 const char *buf, size_t count) 165 { 166 struct dbs_data *dbs_data = to_dbs_data(attr_set); 167 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 168 unsigned int input; 169 int ret; 170 ret = sscanf(buf, "%u", &input); 171 172 if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold) 173 return -EINVAL; 174 175 dbs_data->up_threshold = input; 176 return count; 177 } 178 179 static ssize_t store_down_threshold(struct gov_attr_set *attr_set, 180 const char *buf, size_t count) 181 { 182 struct dbs_data *dbs_data = to_dbs_data(attr_set); 183 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 184 unsigned int input; 185 int ret; 186 ret = sscanf(buf, "%u", &input); 187 188 /* cannot be lower than 11 otherwise freq will not fall */ 189 if (ret != 1 || input < 11 || input > 100 || 190 input >= dbs_data->up_threshold) 191 return -EINVAL; 192 193 cs_tuners->down_threshold = input; 194 return count; 195 } 196 197 static ssize_t store_ignore_nice_load(struct gov_attr_set *attr_set, 198 const char *buf, size_t count) 199 { 200 struct dbs_data *dbs_data = to_dbs_data(attr_set); 201 unsigned int input; 202 int ret; 203 204 ret = sscanf(buf, "%u", &input); 205 if (ret != 1) 206 return -EINVAL; 207 208 if (input > 1) 209 input = 1; 210 211 if (input == dbs_data->ignore_nice_load) /* nothing to do */ 212 return count; 213 214 dbs_data->ignore_nice_load = input; 215 216 /* we need to re-evaluate prev_cpu_idle */ 217 gov_update_cpu_data(dbs_data); 218 219 return count; 220 } 221 222 static ssize_t store_freq_step(struct gov_attr_set *attr_set, const char *buf, 223 size_t count) 224 { 225 struct dbs_data *dbs_data = to_dbs_data(attr_set); 226 struct cs_dbs_tuners *cs_tuners = dbs_data->tuners; 227 unsigned int input; 228 int ret; 229 ret = sscanf(buf, "%u", &input); 230 231 if (ret != 1) 232 return -EINVAL; 233 234 if (input > 100) 235 input = 100; 236 237 /* 238 * no need to test here if freq_step is zero as the user might actually 239 * want this, they would be crazy though :) 240 */ 241 cs_tuners->freq_step = input; 242 return count; 243 } 244 245 gov_show_one_common(sampling_rate); 246 gov_show_one_common(sampling_down_factor); 247 gov_show_one_common(up_threshold); 248 gov_show_one_common(ignore_nice_load); 249 gov_show_one_common(min_sampling_rate); 250 gov_show_one(cs, down_threshold); 251 gov_show_one(cs, freq_step); 252 253 gov_attr_rw(sampling_rate); 254 gov_attr_rw(sampling_down_factor); 255 gov_attr_rw(up_threshold); 256 gov_attr_rw(ignore_nice_load); 257 gov_attr_ro(min_sampling_rate); 258 gov_attr_rw(down_threshold); 259 gov_attr_rw(freq_step); 260 261 static struct attribute *cs_attributes[] = { 262 &min_sampling_rate.attr, 263 &sampling_rate.attr, 264 &sampling_down_factor.attr, 265 &up_threshold.attr, 266 &down_threshold.attr, 267 &ignore_nice_load.attr, 268 &freq_step.attr, 269 NULL 270 }; 271 272 /************************** sysfs end ************************/ 273 274 static struct policy_dbs_info *cs_alloc(void) 275 { 276 struct cs_policy_dbs_info *dbs_info; 277 278 dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL); 279 return dbs_info ? &dbs_info->policy_dbs : NULL; 280 } 281 282 static void cs_free(struct policy_dbs_info *policy_dbs) 283 { 284 kfree(to_dbs_info(policy_dbs)); 285 } 286 287 static int cs_init(struct dbs_data *dbs_data) 288 { 289 struct cs_dbs_tuners *tuners; 290 291 tuners = kzalloc(sizeof(*tuners), GFP_KERNEL); 292 if (!tuners) 293 return -ENOMEM; 294 295 tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD; 296 tuners->freq_step = DEF_FREQUENCY_STEP; 297 dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD; 298 dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR; 299 dbs_data->ignore_nice_load = 0; 300 301 dbs_data->tuners = tuners; 302 dbs_data->min_sampling_rate = MIN_SAMPLING_RATE_RATIO * 303 jiffies_to_usecs(10); 304 305 return 0; 306 } 307 308 static void cs_exit(struct dbs_data *dbs_data) 309 { 310 kfree(dbs_data->tuners); 311 } 312 313 static void cs_start(struct cpufreq_policy *policy) 314 { 315 struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data); 316 317 dbs_info->down_skip = 0; 318 dbs_info->requested_freq = policy->cur; 319 } 320 321 static struct dbs_governor cs_governor = { 322 .gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("conservative"), 323 .kobj_type = { .default_attrs = cs_attributes }, 324 .gov_dbs_update = cs_dbs_update, 325 .alloc = cs_alloc, 326 .free = cs_free, 327 .init = cs_init, 328 .exit = cs_exit, 329 .start = cs_start, 330 }; 331 332 #define CPU_FREQ_GOV_CONSERVATIVE (&cs_governor.gov) 333 334 static int __init cpufreq_gov_dbs_init(void) 335 { 336 return cpufreq_register_governor(CPU_FREQ_GOV_CONSERVATIVE); 337 } 338 339 static void __exit cpufreq_gov_dbs_exit(void) 340 { 341 cpufreq_unregister_governor(CPU_FREQ_GOV_CONSERVATIVE); 342 } 343 344 MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>"); 345 MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for " 346 "Low Latency Frequency Transition capable processors " 347 "optimised for use in a battery environment"); 348 MODULE_LICENSE("GPL"); 349 350 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE 351 struct cpufreq_governor *cpufreq_default_governor(void) 352 { 353 return CPU_FREQ_GOV_CONSERVATIVE; 354 } 355 356 fs_initcall(cpufreq_gov_dbs_init); 357 #else 358 module_init(cpufreq_gov_dbs_init); 359 #endif 360 module_exit(cpufreq_gov_dbs_exit); 361