1 /* 2 * drivers/cpufreq/cpufreq_ondemand.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 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 */ 12 13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 14 15 #include <linux/cpu.h> 16 #include <linux/percpu-defs.h> 17 #include <linux/slab.h> 18 #include <linux/tick.h> 19 #include <linux/sched/cpufreq.h> 20 21 #include "cpufreq_ondemand.h" 22 23 /* On-demand governor macros */ 24 #define DEF_FREQUENCY_UP_THRESHOLD (80) 25 #define DEF_SAMPLING_DOWN_FACTOR (1) 26 #define MAX_SAMPLING_DOWN_FACTOR (100000) 27 #define MICRO_FREQUENCY_UP_THRESHOLD (95) 28 #define MICRO_FREQUENCY_MIN_SAMPLE_RATE (10000) 29 #define MIN_FREQUENCY_UP_THRESHOLD (1) 30 #define MAX_FREQUENCY_UP_THRESHOLD (100) 31 32 static struct od_ops od_ops; 33 34 static unsigned int default_powersave_bias; 35 36 /* 37 * Not all CPUs want IO time to be accounted as busy; this depends on how 38 * efficient idling at a higher frequency/voltage is. 39 * Pavel Machek says this is not so for various generations of AMD and old 40 * Intel systems. 41 * Mike Chan (android.com) claims this is also not true for ARM. 42 * Because of this, whitelist specific known (series) of CPUs by default, and 43 * leave all others up to the user. 44 */ 45 static int should_io_be_busy(void) 46 { 47 #if defined(CONFIG_X86) 48 /* 49 * For Intel, Core 2 (model 15) and later have an efficient idle. 50 */ 51 if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL && 52 boot_cpu_data.x86 == 6 && 53 boot_cpu_data.x86_model >= 15) 54 return 1; 55 #endif 56 return 0; 57 } 58 59 /* 60 * Find right freq to be set now with powersave_bias on. 61 * Returns the freq_hi to be used right now and will set freq_hi_delay_us, 62 * freq_lo, and freq_lo_delay_us in percpu area for averaging freqs. 63 */ 64 static unsigned int generic_powersave_bias_target(struct cpufreq_policy *policy, 65 unsigned int freq_next, unsigned int relation) 66 { 67 unsigned int freq_req, freq_reduc, freq_avg; 68 unsigned int freq_hi, freq_lo; 69 unsigned int index; 70 unsigned int delay_hi_us; 71 struct policy_dbs_info *policy_dbs = policy->governor_data; 72 struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs); 73 struct dbs_data *dbs_data = policy_dbs->dbs_data; 74 struct od_dbs_tuners *od_tuners = dbs_data->tuners; 75 struct cpufreq_frequency_table *freq_table = policy->freq_table; 76 77 if (!freq_table) { 78 dbs_info->freq_lo = 0; 79 dbs_info->freq_lo_delay_us = 0; 80 return freq_next; 81 } 82 83 index = cpufreq_frequency_table_target(policy, freq_next, relation); 84 freq_req = freq_table[index].frequency; 85 freq_reduc = freq_req * od_tuners->powersave_bias / 1000; 86 freq_avg = freq_req - freq_reduc; 87 88 /* Find freq bounds for freq_avg in freq_table */ 89 index = cpufreq_table_find_index_h(policy, freq_avg); 90 freq_lo = freq_table[index].frequency; 91 index = cpufreq_table_find_index_l(policy, freq_avg); 92 freq_hi = freq_table[index].frequency; 93 94 /* Find out how long we have to be in hi and lo freqs */ 95 if (freq_hi == freq_lo) { 96 dbs_info->freq_lo = 0; 97 dbs_info->freq_lo_delay_us = 0; 98 return freq_lo; 99 } 100 delay_hi_us = (freq_avg - freq_lo) * dbs_data->sampling_rate; 101 delay_hi_us += (freq_hi - freq_lo) / 2; 102 delay_hi_us /= freq_hi - freq_lo; 103 dbs_info->freq_hi_delay_us = delay_hi_us; 104 dbs_info->freq_lo = freq_lo; 105 dbs_info->freq_lo_delay_us = dbs_data->sampling_rate - delay_hi_us; 106 return freq_hi; 107 } 108 109 static void ondemand_powersave_bias_init(struct cpufreq_policy *policy) 110 { 111 struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data); 112 113 dbs_info->freq_lo = 0; 114 } 115 116 static void dbs_freq_increase(struct cpufreq_policy *policy, unsigned int freq) 117 { 118 struct policy_dbs_info *policy_dbs = policy->governor_data; 119 struct dbs_data *dbs_data = policy_dbs->dbs_data; 120 struct od_dbs_tuners *od_tuners = dbs_data->tuners; 121 122 if (od_tuners->powersave_bias) 123 freq = od_ops.powersave_bias_target(policy, freq, 124 CPUFREQ_RELATION_H); 125 else if (policy->cur == policy->max) 126 return; 127 128 __cpufreq_driver_target(policy, freq, od_tuners->powersave_bias ? 129 CPUFREQ_RELATION_L : CPUFREQ_RELATION_H); 130 } 131 132 /* 133 * Every sampling_rate, we check, if current idle time is less than 20% 134 * (default), then we try to increase frequency. Else, we adjust the frequency 135 * proportional to load. 136 */ 137 static void od_update(struct cpufreq_policy *policy) 138 { 139 struct policy_dbs_info *policy_dbs = policy->governor_data; 140 struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs); 141 struct dbs_data *dbs_data = policy_dbs->dbs_data; 142 struct od_dbs_tuners *od_tuners = dbs_data->tuners; 143 unsigned int load = dbs_update(policy); 144 145 dbs_info->freq_lo = 0; 146 147 /* Check for frequency increase */ 148 if (load > dbs_data->up_threshold) { 149 /* If switching to max speed, apply sampling_down_factor */ 150 if (policy->cur < policy->max) 151 policy_dbs->rate_mult = dbs_data->sampling_down_factor; 152 dbs_freq_increase(policy, policy->max); 153 } else { 154 /* Calculate the next frequency proportional to load */ 155 unsigned int freq_next, min_f, max_f; 156 157 min_f = policy->cpuinfo.min_freq; 158 max_f = policy->cpuinfo.max_freq; 159 freq_next = min_f + load * (max_f - min_f) / 100; 160 161 /* No longer fully busy, reset rate_mult */ 162 policy_dbs->rate_mult = 1; 163 164 if (od_tuners->powersave_bias) 165 freq_next = od_ops.powersave_bias_target(policy, 166 freq_next, 167 CPUFREQ_RELATION_L); 168 169 __cpufreq_driver_target(policy, freq_next, CPUFREQ_RELATION_C); 170 } 171 } 172 173 static unsigned int od_dbs_update(struct cpufreq_policy *policy) 174 { 175 struct policy_dbs_info *policy_dbs = policy->governor_data; 176 struct dbs_data *dbs_data = policy_dbs->dbs_data; 177 struct od_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs); 178 int sample_type = dbs_info->sample_type; 179 180 /* Common NORMAL_SAMPLE setup */ 181 dbs_info->sample_type = OD_NORMAL_SAMPLE; 182 /* 183 * OD_SUB_SAMPLE doesn't make sense if sample_delay_ns is 0, so ignore 184 * it then. 185 */ 186 if (sample_type == OD_SUB_SAMPLE && policy_dbs->sample_delay_ns > 0) { 187 __cpufreq_driver_target(policy, dbs_info->freq_lo, 188 CPUFREQ_RELATION_H); 189 return dbs_info->freq_lo_delay_us; 190 } 191 192 od_update(policy); 193 194 if (dbs_info->freq_lo) { 195 /* Setup SUB_SAMPLE */ 196 dbs_info->sample_type = OD_SUB_SAMPLE; 197 return dbs_info->freq_hi_delay_us; 198 } 199 200 return dbs_data->sampling_rate * policy_dbs->rate_mult; 201 } 202 203 /************************** sysfs interface ************************/ 204 static struct dbs_governor od_dbs_gov; 205 206 static ssize_t store_io_is_busy(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 unsigned int input; 211 int ret; 212 213 ret = sscanf(buf, "%u", &input); 214 if (ret != 1) 215 return -EINVAL; 216 dbs_data->io_is_busy = !!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_up_threshold(struct gov_attr_set *attr_set, 225 const char *buf, size_t count) 226 { 227 struct dbs_data *dbs_data = to_dbs_data(attr_set); 228 unsigned int input; 229 int ret; 230 ret = sscanf(buf, "%u", &input); 231 232 if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD || 233 input < MIN_FREQUENCY_UP_THRESHOLD) { 234 return -EINVAL; 235 } 236 237 dbs_data->up_threshold = input; 238 return count; 239 } 240 241 static ssize_t store_sampling_down_factor(struct gov_attr_set *attr_set, 242 const char *buf, size_t count) 243 { 244 struct dbs_data *dbs_data = to_dbs_data(attr_set); 245 struct policy_dbs_info *policy_dbs; 246 unsigned int input; 247 int ret; 248 ret = sscanf(buf, "%u", &input); 249 250 if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1) 251 return -EINVAL; 252 253 dbs_data->sampling_down_factor = input; 254 255 /* Reset down sampling multiplier in case it was active */ 256 list_for_each_entry(policy_dbs, &attr_set->policy_list, list) { 257 /* 258 * Doing this without locking might lead to using different 259 * rate_mult values in od_update() and od_dbs_update(). 260 */ 261 mutex_lock(&policy_dbs->update_mutex); 262 policy_dbs->rate_mult = 1; 263 mutex_unlock(&policy_dbs->update_mutex); 264 } 265 266 return count; 267 } 268 269 static ssize_t store_ignore_nice_load(struct gov_attr_set *attr_set, 270 const char *buf, size_t count) 271 { 272 struct dbs_data *dbs_data = to_dbs_data(attr_set); 273 unsigned int input; 274 int ret; 275 276 ret = sscanf(buf, "%u", &input); 277 if (ret != 1) 278 return -EINVAL; 279 280 if (input > 1) 281 input = 1; 282 283 if (input == dbs_data->ignore_nice_load) { /* nothing to do */ 284 return count; 285 } 286 dbs_data->ignore_nice_load = input; 287 288 /* we need to re-evaluate prev_cpu_idle */ 289 gov_update_cpu_data(dbs_data); 290 291 return count; 292 } 293 294 static ssize_t store_powersave_bias(struct gov_attr_set *attr_set, 295 const char *buf, size_t count) 296 { 297 struct dbs_data *dbs_data = to_dbs_data(attr_set); 298 struct od_dbs_tuners *od_tuners = dbs_data->tuners; 299 struct policy_dbs_info *policy_dbs; 300 unsigned int input; 301 int ret; 302 ret = sscanf(buf, "%u", &input); 303 304 if (ret != 1) 305 return -EINVAL; 306 307 if (input > 1000) 308 input = 1000; 309 310 od_tuners->powersave_bias = input; 311 312 list_for_each_entry(policy_dbs, &attr_set->policy_list, list) 313 ondemand_powersave_bias_init(policy_dbs->policy); 314 315 return count; 316 } 317 318 gov_show_one_common(sampling_rate); 319 gov_show_one_common(up_threshold); 320 gov_show_one_common(sampling_down_factor); 321 gov_show_one_common(ignore_nice_load); 322 gov_show_one_common(io_is_busy); 323 gov_show_one(od, powersave_bias); 324 325 gov_attr_rw(sampling_rate); 326 gov_attr_rw(io_is_busy); 327 gov_attr_rw(up_threshold); 328 gov_attr_rw(sampling_down_factor); 329 gov_attr_rw(ignore_nice_load); 330 gov_attr_rw(powersave_bias); 331 332 static struct attribute *od_attributes[] = { 333 &sampling_rate.attr, 334 &up_threshold.attr, 335 &sampling_down_factor.attr, 336 &ignore_nice_load.attr, 337 &powersave_bias.attr, 338 &io_is_busy.attr, 339 NULL 340 }; 341 342 /************************** sysfs end ************************/ 343 344 static struct policy_dbs_info *od_alloc(void) 345 { 346 struct od_policy_dbs_info *dbs_info; 347 348 dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL); 349 return dbs_info ? &dbs_info->policy_dbs : NULL; 350 } 351 352 static void od_free(struct policy_dbs_info *policy_dbs) 353 { 354 kfree(to_dbs_info(policy_dbs)); 355 } 356 357 static int od_init(struct dbs_data *dbs_data) 358 { 359 struct od_dbs_tuners *tuners; 360 u64 idle_time; 361 int cpu; 362 363 tuners = kzalloc(sizeof(*tuners), GFP_KERNEL); 364 if (!tuners) 365 return -ENOMEM; 366 367 cpu = get_cpu(); 368 idle_time = get_cpu_idle_time_us(cpu, NULL); 369 put_cpu(); 370 if (idle_time != -1ULL) { 371 /* Idle micro accounting is supported. Use finer thresholds */ 372 dbs_data->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD; 373 } else { 374 dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD; 375 } 376 377 dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR; 378 dbs_data->ignore_nice_load = 0; 379 tuners->powersave_bias = default_powersave_bias; 380 dbs_data->io_is_busy = should_io_be_busy(); 381 382 dbs_data->tuners = tuners; 383 return 0; 384 } 385 386 static void od_exit(struct dbs_data *dbs_data) 387 { 388 kfree(dbs_data->tuners); 389 } 390 391 static void od_start(struct cpufreq_policy *policy) 392 { 393 struct od_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data); 394 395 dbs_info->sample_type = OD_NORMAL_SAMPLE; 396 ondemand_powersave_bias_init(policy); 397 } 398 399 static struct od_ops od_ops = { 400 .powersave_bias_target = generic_powersave_bias_target, 401 }; 402 403 static struct dbs_governor od_dbs_gov = { 404 .gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("ondemand"), 405 .kobj_type = { .default_attrs = od_attributes }, 406 .gov_dbs_update = od_dbs_update, 407 .alloc = od_alloc, 408 .free = od_free, 409 .init = od_init, 410 .exit = od_exit, 411 .start = od_start, 412 }; 413 414 #define CPU_FREQ_GOV_ONDEMAND (&od_dbs_gov.gov) 415 416 static void od_set_powersave_bias(unsigned int powersave_bias) 417 { 418 unsigned int cpu; 419 cpumask_t done; 420 421 default_powersave_bias = powersave_bias; 422 cpumask_clear(&done); 423 424 get_online_cpus(); 425 for_each_online_cpu(cpu) { 426 struct cpufreq_policy *policy; 427 struct policy_dbs_info *policy_dbs; 428 struct dbs_data *dbs_data; 429 struct od_dbs_tuners *od_tuners; 430 431 if (cpumask_test_cpu(cpu, &done)) 432 continue; 433 434 policy = cpufreq_cpu_get_raw(cpu); 435 if (!policy || policy->governor != CPU_FREQ_GOV_ONDEMAND) 436 continue; 437 438 policy_dbs = policy->governor_data; 439 if (!policy_dbs) 440 continue; 441 442 cpumask_or(&done, &done, policy->cpus); 443 444 dbs_data = policy_dbs->dbs_data; 445 od_tuners = dbs_data->tuners; 446 od_tuners->powersave_bias = default_powersave_bias; 447 } 448 put_online_cpus(); 449 } 450 451 void od_register_powersave_bias_handler(unsigned int (*f) 452 (struct cpufreq_policy *, unsigned int, unsigned int), 453 unsigned int powersave_bias) 454 { 455 od_ops.powersave_bias_target = f; 456 od_set_powersave_bias(powersave_bias); 457 } 458 EXPORT_SYMBOL_GPL(od_register_powersave_bias_handler); 459 460 void od_unregister_powersave_bias_handler(void) 461 { 462 od_ops.powersave_bias_target = generic_powersave_bias_target; 463 od_set_powersave_bias(0); 464 } 465 EXPORT_SYMBOL_GPL(od_unregister_powersave_bias_handler); 466 467 static int __init cpufreq_gov_dbs_init(void) 468 { 469 return cpufreq_register_governor(CPU_FREQ_GOV_ONDEMAND); 470 } 471 472 static void __exit cpufreq_gov_dbs_exit(void) 473 { 474 cpufreq_unregister_governor(CPU_FREQ_GOV_ONDEMAND); 475 } 476 477 MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>"); 478 MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>"); 479 MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for " 480 "Low Latency Frequency Transition capable processors"); 481 MODULE_LICENSE("GPL"); 482 483 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND 484 struct cpufreq_governor *cpufreq_default_governor(void) 485 { 486 return CPU_FREQ_GOV_ONDEMAND; 487 } 488 489 fs_initcall(cpufreq_gov_dbs_init); 490 #else 491 module_init(cpufreq_gov_dbs_init); 492 #endif 493 module_exit(cpufreq_gov_dbs_exit); 494