1 /* 2 * acpi_pad.c ACPI Processor Aggregator Driver 3 * 4 * Copyright (c) 2009, Intel Corporation. 5 * 6 * This program is free software; you can redistribute it and/or modify it 7 * under the terms and conditions of the GNU General Public License, 8 * version 2, as published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 13 * more details. 14 * 15 * You should have received a copy of the GNU General Public License along with 16 * this program; if not, write to the Free Software Foundation, Inc., 17 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 */ 20 21 #include <linux/kernel.h> 22 #include <linux/cpumask.h> 23 #include <linux/module.h> 24 #include <linux/init.h> 25 #include <linux/types.h> 26 #include <linux/kthread.h> 27 #include <linux/freezer.h> 28 #include <linux/cpu.h> 29 #include <linux/tick.h> 30 #include <linux/slab.h> 31 #include <linux/acpi.h> 32 #include <asm/mwait.h> 33 34 #define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad" 35 #define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator" 36 #define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80 37 static DEFINE_MUTEX(isolated_cpus_lock); 38 static DEFINE_MUTEX(round_robin_lock); 39 40 static unsigned long power_saving_mwait_eax; 41 42 static unsigned char tsc_detected_unstable; 43 static unsigned char tsc_marked_unstable; 44 45 static void power_saving_mwait_init(void) 46 { 47 unsigned int eax, ebx, ecx, edx; 48 unsigned int highest_cstate = 0; 49 unsigned int highest_subcstate = 0; 50 int i; 51 52 if (!boot_cpu_has(X86_FEATURE_MWAIT)) 53 return; 54 if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF) 55 return; 56 57 cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx); 58 59 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) || 60 !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) 61 return; 62 63 edx >>= MWAIT_SUBSTATE_SIZE; 64 for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) { 65 if (edx & MWAIT_SUBSTATE_MASK) { 66 highest_cstate = i; 67 highest_subcstate = edx & MWAIT_SUBSTATE_MASK; 68 } 69 } 70 power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) | 71 (highest_subcstate - 1); 72 73 #if defined(CONFIG_X86) 74 switch (boot_cpu_data.x86_vendor) { 75 case X86_VENDOR_AMD: 76 case X86_VENDOR_INTEL: 77 /* 78 * AMD Fam10h TSC will tick in all 79 * C/P/S0/S1 states when this bit is set. 80 */ 81 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC)) 82 tsc_detected_unstable = 1; 83 break; 84 default: 85 /* TSC could halt in idle */ 86 tsc_detected_unstable = 1; 87 } 88 #endif 89 } 90 91 static unsigned long cpu_weight[NR_CPUS]; 92 static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1}; 93 static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS); 94 static void round_robin_cpu(unsigned int tsk_index) 95 { 96 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); 97 cpumask_var_t tmp; 98 int cpu; 99 unsigned long min_weight = -1; 100 unsigned long uninitialized_var(preferred_cpu); 101 102 if (!alloc_cpumask_var(&tmp, GFP_KERNEL)) 103 return; 104 105 mutex_lock(&round_robin_lock); 106 cpumask_clear(tmp); 107 for_each_cpu(cpu, pad_busy_cpus) 108 cpumask_or(tmp, tmp, topology_sibling_cpumask(cpu)); 109 cpumask_andnot(tmp, cpu_online_mask, tmp); 110 /* avoid HT sibilings if possible */ 111 if (cpumask_empty(tmp)) 112 cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus); 113 if (cpumask_empty(tmp)) { 114 mutex_unlock(&round_robin_lock); 115 return; 116 } 117 for_each_cpu(cpu, tmp) { 118 if (cpu_weight[cpu] < min_weight) { 119 min_weight = cpu_weight[cpu]; 120 preferred_cpu = cpu; 121 } 122 } 123 124 if (tsk_in_cpu[tsk_index] != -1) 125 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); 126 tsk_in_cpu[tsk_index] = preferred_cpu; 127 cpumask_set_cpu(preferred_cpu, pad_busy_cpus); 128 cpu_weight[preferred_cpu]++; 129 mutex_unlock(&round_robin_lock); 130 131 set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu)); 132 } 133 134 static void exit_round_robin(unsigned int tsk_index) 135 { 136 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); 137 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); 138 tsk_in_cpu[tsk_index] = -1; 139 } 140 141 static unsigned int idle_pct = 5; /* percentage */ 142 static unsigned int round_robin_time = 1; /* second */ 143 static int power_saving_thread(void *data) 144 { 145 struct sched_param param = {.sched_priority = 1}; 146 int do_sleep; 147 unsigned int tsk_index = (unsigned long)data; 148 u64 last_jiffies = 0; 149 150 sched_setscheduler(current, SCHED_RR, ¶m); 151 152 while (!kthread_should_stop()) { 153 unsigned long expire_time; 154 155 try_to_freeze(); 156 157 /* round robin to cpus */ 158 expire_time = last_jiffies + round_robin_time * HZ; 159 if (time_before(expire_time, jiffies)) { 160 last_jiffies = jiffies; 161 round_robin_cpu(tsk_index); 162 } 163 164 do_sleep = 0; 165 166 expire_time = jiffies + HZ * (100 - idle_pct) / 100; 167 168 while (!need_resched()) { 169 if (tsc_detected_unstable && !tsc_marked_unstable) { 170 /* TSC could halt in idle, so notify users */ 171 mark_tsc_unstable("TSC halts in idle"); 172 tsc_marked_unstable = 1; 173 } 174 local_irq_disable(); 175 tick_broadcast_enable(); 176 tick_broadcast_enter(); 177 stop_critical_timings(); 178 179 mwait_idle_with_hints(power_saving_mwait_eax, 1); 180 181 start_critical_timings(); 182 tick_broadcast_exit(); 183 local_irq_enable(); 184 185 if (time_before(expire_time, jiffies)) { 186 do_sleep = 1; 187 break; 188 } 189 } 190 191 /* 192 * current sched_rt has threshold for rt task running time. 193 * When a rt task uses 95% CPU time, the rt thread will be 194 * scheduled out for 5% CPU time to not starve other tasks. But 195 * the mechanism only works when all CPUs have RT task running, 196 * as if one CPU hasn't RT task, RT task from other CPUs will 197 * borrow CPU time from this CPU and cause RT task use > 95% 198 * CPU time. To make 'avoid starvation' work, takes a nap here. 199 */ 200 if (unlikely(do_sleep)) 201 schedule_timeout_killable(HZ * idle_pct / 100); 202 203 /* If an external event has set the need_resched flag, then 204 * we need to deal with it, or this loop will continue to 205 * spin without calling __mwait(). 206 */ 207 if (unlikely(need_resched())) 208 schedule(); 209 } 210 211 exit_round_robin(tsk_index); 212 return 0; 213 } 214 215 static struct task_struct *ps_tsks[NR_CPUS]; 216 static unsigned int ps_tsk_num; 217 static int create_power_saving_task(void) 218 { 219 int rc; 220 221 ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread, 222 (void *)(unsigned long)ps_tsk_num, 223 "acpi_pad/%d", ps_tsk_num); 224 225 if (IS_ERR(ps_tsks[ps_tsk_num])) { 226 rc = PTR_ERR(ps_tsks[ps_tsk_num]); 227 ps_tsks[ps_tsk_num] = NULL; 228 } else { 229 rc = 0; 230 ps_tsk_num++; 231 } 232 233 return rc; 234 } 235 236 static void destroy_power_saving_task(void) 237 { 238 if (ps_tsk_num > 0) { 239 ps_tsk_num--; 240 kthread_stop(ps_tsks[ps_tsk_num]); 241 ps_tsks[ps_tsk_num] = NULL; 242 } 243 } 244 245 static void set_power_saving_task_num(unsigned int num) 246 { 247 if (num > ps_tsk_num) { 248 while (ps_tsk_num < num) { 249 if (create_power_saving_task()) 250 return; 251 } 252 } else if (num < ps_tsk_num) { 253 while (ps_tsk_num > num) 254 destroy_power_saving_task(); 255 } 256 } 257 258 static void acpi_pad_idle_cpus(unsigned int num_cpus) 259 { 260 get_online_cpus(); 261 262 num_cpus = min_t(unsigned int, num_cpus, num_online_cpus()); 263 set_power_saving_task_num(num_cpus); 264 265 put_online_cpus(); 266 } 267 268 static uint32_t acpi_pad_idle_cpus_num(void) 269 { 270 return ps_tsk_num; 271 } 272 273 static ssize_t acpi_pad_rrtime_store(struct device *dev, 274 struct device_attribute *attr, const char *buf, size_t count) 275 { 276 unsigned long num; 277 if (kstrtoul(buf, 0, &num)) 278 return -EINVAL; 279 if (num < 1 || num >= 100) 280 return -EINVAL; 281 mutex_lock(&isolated_cpus_lock); 282 round_robin_time = num; 283 mutex_unlock(&isolated_cpus_lock); 284 return count; 285 } 286 287 static ssize_t acpi_pad_rrtime_show(struct device *dev, 288 struct device_attribute *attr, char *buf) 289 { 290 return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time); 291 } 292 static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR, 293 acpi_pad_rrtime_show, 294 acpi_pad_rrtime_store); 295 296 static ssize_t acpi_pad_idlepct_store(struct device *dev, 297 struct device_attribute *attr, const char *buf, size_t count) 298 { 299 unsigned long num; 300 if (kstrtoul(buf, 0, &num)) 301 return -EINVAL; 302 if (num < 1 || num >= 100) 303 return -EINVAL; 304 mutex_lock(&isolated_cpus_lock); 305 idle_pct = num; 306 mutex_unlock(&isolated_cpus_lock); 307 return count; 308 } 309 310 static ssize_t acpi_pad_idlepct_show(struct device *dev, 311 struct device_attribute *attr, char *buf) 312 { 313 return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct); 314 } 315 static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR, 316 acpi_pad_idlepct_show, 317 acpi_pad_idlepct_store); 318 319 static ssize_t acpi_pad_idlecpus_store(struct device *dev, 320 struct device_attribute *attr, const char *buf, size_t count) 321 { 322 unsigned long num; 323 if (kstrtoul(buf, 0, &num)) 324 return -EINVAL; 325 mutex_lock(&isolated_cpus_lock); 326 acpi_pad_idle_cpus(num); 327 mutex_unlock(&isolated_cpus_lock); 328 return count; 329 } 330 331 static ssize_t acpi_pad_idlecpus_show(struct device *dev, 332 struct device_attribute *attr, char *buf) 333 { 334 return cpumap_print_to_pagebuf(false, buf, 335 to_cpumask(pad_busy_cpus_bits)); 336 } 337 338 static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR, 339 acpi_pad_idlecpus_show, 340 acpi_pad_idlecpus_store); 341 342 static int acpi_pad_add_sysfs(struct acpi_device *device) 343 { 344 int result; 345 346 result = device_create_file(&device->dev, &dev_attr_idlecpus); 347 if (result) 348 return -ENODEV; 349 result = device_create_file(&device->dev, &dev_attr_idlepct); 350 if (result) { 351 device_remove_file(&device->dev, &dev_attr_idlecpus); 352 return -ENODEV; 353 } 354 result = device_create_file(&device->dev, &dev_attr_rrtime); 355 if (result) { 356 device_remove_file(&device->dev, &dev_attr_idlecpus); 357 device_remove_file(&device->dev, &dev_attr_idlepct); 358 return -ENODEV; 359 } 360 return 0; 361 } 362 363 static void acpi_pad_remove_sysfs(struct acpi_device *device) 364 { 365 device_remove_file(&device->dev, &dev_attr_idlecpus); 366 device_remove_file(&device->dev, &dev_attr_idlepct); 367 device_remove_file(&device->dev, &dev_attr_rrtime); 368 } 369 370 /* 371 * Query firmware how many CPUs should be idle 372 * return -1 on failure 373 */ 374 static int acpi_pad_pur(acpi_handle handle) 375 { 376 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL}; 377 union acpi_object *package; 378 int num = -1; 379 380 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer))) 381 return num; 382 383 if (!buffer.length || !buffer.pointer) 384 return num; 385 386 package = buffer.pointer; 387 388 if (package->type == ACPI_TYPE_PACKAGE && 389 package->package.count == 2 && 390 package->package.elements[0].integer.value == 1) /* rev 1 */ 391 392 num = package->package.elements[1].integer.value; 393 394 kfree(buffer.pointer); 395 return num; 396 } 397 398 static void acpi_pad_handle_notify(acpi_handle handle) 399 { 400 int num_cpus; 401 uint32_t idle_cpus; 402 struct acpi_buffer param = { 403 .length = 4, 404 .pointer = (void *)&idle_cpus, 405 }; 406 407 mutex_lock(&isolated_cpus_lock); 408 num_cpus = acpi_pad_pur(handle); 409 if (num_cpus < 0) { 410 mutex_unlock(&isolated_cpus_lock); 411 return; 412 } 413 acpi_pad_idle_cpus(num_cpus); 414 idle_cpus = acpi_pad_idle_cpus_num(); 415 acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, ¶m); 416 mutex_unlock(&isolated_cpus_lock); 417 } 418 419 static void acpi_pad_notify(acpi_handle handle, u32 event, 420 void *data) 421 { 422 struct acpi_device *device = data; 423 424 switch (event) { 425 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY: 426 acpi_pad_handle_notify(handle); 427 acpi_bus_generate_netlink_event(device->pnp.device_class, 428 dev_name(&device->dev), event, 0); 429 break; 430 default: 431 pr_warn("Unsupported event [0x%x]\n", event); 432 break; 433 } 434 } 435 436 static int acpi_pad_add(struct acpi_device *device) 437 { 438 acpi_status status; 439 440 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME); 441 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS); 442 443 if (acpi_pad_add_sysfs(device)) 444 return -ENODEV; 445 446 status = acpi_install_notify_handler(device->handle, 447 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device); 448 if (ACPI_FAILURE(status)) { 449 acpi_pad_remove_sysfs(device); 450 return -ENODEV; 451 } 452 453 return 0; 454 } 455 456 static int acpi_pad_remove(struct acpi_device *device) 457 { 458 mutex_lock(&isolated_cpus_lock); 459 acpi_pad_idle_cpus(0); 460 mutex_unlock(&isolated_cpus_lock); 461 462 acpi_remove_notify_handler(device->handle, 463 ACPI_DEVICE_NOTIFY, acpi_pad_notify); 464 acpi_pad_remove_sysfs(device); 465 return 0; 466 } 467 468 static const struct acpi_device_id pad_device_ids[] = { 469 {"ACPI000C", 0}, 470 {"", 0}, 471 }; 472 MODULE_DEVICE_TABLE(acpi, pad_device_ids); 473 474 static struct acpi_driver acpi_pad_driver = { 475 .name = "processor_aggregator", 476 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS, 477 .ids = pad_device_ids, 478 .ops = { 479 .add = acpi_pad_add, 480 .remove = acpi_pad_remove, 481 }, 482 }; 483 484 static int __init acpi_pad_init(void) 485 { 486 power_saving_mwait_init(); 487 if (power_saving_mwait_eax == 0) 488 return -EINVAL; 489 490 return acpi_bus_register_driver(&acpi_pad_driver); 491 } 492 493 static void __exit acpi_pad_exit(void) 494 { 495 acpi_bus_unregister_driver(&acpi_pad_driver); 496 } 497 498 module_init(acpi_pad_init); 499 module_exit(acpi_pad_exit); 500 MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>"); 501 MODULE_DESCRIPTION("ACPI Processor Aggregator Driver"); 502 MODULE_LICENSE("GPL"); 503