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