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