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/clockchips.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 static unsigned char lapic_detected_unstable; 45 static unsigned char lapic_marked_unstable; 46 47 static void power_saving_mwait_init(void) 48 { 49 unsigned int eax, ebx, ecx, edx; 50 unsigned int highest_cstate = 0; 51 unsigned int highest_subcstate = 0; 52 int i; 53 54 if (!boot_cpu_has(X86_FEATURE_MWAIT)) 55 return; 56 if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF) 57 return; 58 59 cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx); 60 61 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) || 62 !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) 63 return; 64 65 edx >>= MWAIT_SUBSTATE_SIZE; 66 for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) { 67 if (edx & MWAIT_SUBSTATE_MASK) { 68 highest_cstate = i; 69 highest_subcstate = edx & MWAIT_SUBSTATE_MASK; 70 } 71 } 72 power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) | 73 (highest_subcstate - 1); 74 75 #if defined(CONFIG_X86) 76 switch (boot_cpu_data.x86_vendor) { 77 case X86_VENDOR_AMD: 78 case X86_VENDOR_INTEL: 79 /* 80 * AMD Fam10h TSC will tick in all 81 * C/P/S0/S1 states when this bit is set. 82 */ 83 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC)) 84 tsc_detected_unstable = 1; 85 if (!boot_cpu_has(X86_FEATURE_ARAT)) 86 lapic_detected_unstable = 1; 87 break; 88 default: 89 /* TSC & LAPIC could halt in idle */ 90 tsc_detected_unstable = 1; 91 lapic_detected_unstable = 1; 92 } 93 #endif 94 } 95 96 static unsigned long cpu_weight[NR_CPUS]; 97 static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1}; 98 static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS); 99 static void round_robin_cpu(unsigned int tsk_index) 100 { 101 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); 102 cpumask_var_t tmp; 103 int cpu; 104 unsigned long min_weight = -1; 105 unsigned long uninitialized_var(preferred_cpu); 106 107 if (!alloc_cpumask_var(&tmp, GFP_KERNEL)) 108 return; 109 110 mutex_lock(&round_robin_lock); 111 cpumask_clear(tmp); 112 for_each_cpu(cpu, pad_busy_cpus) 113 cpumask_or(tmp, tmp, topology_thread_cpumask(cpu)); 114 cpumask_andnot(tmp, cpu_online_mask, tmp); 115 /* avoid HT sibilings if possible */ 116 if (cpumask_empty(tmp)) 117 cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus); 118 if (cpumask_empty(tmp)) { 119 mutex_unlock(&round_robin_lock); 120 return; 121 } 122 for_each_cpu(cpu, tmp) { 123 if (cpu_weight[cpu] < min_weight) { 124 min_weight = cpu_weight[cpu]; 125 preferred_cpu = cpu; 126 } 127 } 128 129 if (tsk_in_cpu[tsk_index] != -1) 130 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); 131 tsk_in_cpu[tsk_index] = preferred_cpu; 132 cpumask_set_cpu(preferred_cpu, pad_busy_cpus); 133 cpu_weight[preferred_cpu]++; 134 mutex_unlock(&round_robin_lock); 135 136 set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu)); 137 } 138 139 static void exit_round_robin(unsigned int tsk_index) 140 { 141 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); 142 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); 143 tsk_in_cpu[tsk_index] = -1; 144 } 145 146 static unsigned int idle_pct = 5; /* percentage */ 147 static unsigned int round_robin_time = 1; /* second */ 148 static int power_saving_thread(void *data) 149 { 150 struct sched_param param = {.sched_priority = 1}; 151 int do_sleep; 152 unsigned int tsk_index = (unsigned long)data; 153 u64 last_jiffies = 0; 154 155 sched_setscheduler(current, SCHED_RR, ¶m); 156 157 while (!kthread_should_stop()) { 158 int cpu; 159 unsigned long expire_time; 160 161 try_to_freeze(); 162 163 /* round robin to cpus */ 164 expire_time = last_jiffies + round_robin_time * HZ; 165 if (time_before(expire_time, jiffies)) { 166 last_jiffies = jiffies; 167 round_robin_cpu(tsk_index); 168 } 169 170 do_sleep = 0; 171 172 expire_time = jiffies + HZ * (100 - idle_pct) / 100; 173 174 while (!need_resched()) { 175 if (tsc_detected_unstable && !tsc_marked_unstable) { 176 /* TSC could halt in idle, so notify users */ 177 mark_tsc_unstable("TSC halts in idle"); 178 tsc_marked_unstable = 1; 179 } 180 if (lapic_detected_unstable && !lapic_marked_unstable) { 181 int i; 182 /* LAPIC could halt in idle, so notify users */ 183 for_each_online_cpu(i) 184 clockevents_notify( 185 CLOCK_EVT_NOTIFY_BROADCAST_ON, 186 &i); 187 lapic_marked_unstable = 1; 188 } 189 local_irq_disable(); 190 cpu = smp_processor_id(); 191 if (lapic_marked_unstable) 192 clockevents_notify( 193 CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu); 194 stop_critical_timings(); 195 196 mwait_idle_with_hints(power_saving_mwait_eax, 1); 197 198 start_critical_timings(); 199 if (lapic_marked_unstable) 200 clockevents_notify( 201 CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu); 202 local_irq_enable(); 203 204 if (time_before(expire_time, jiffies)) { 205 do_sleep = 1; 206 break; 207 } 208 } 209 210 /* 211 * current sched_rt has threshold for rt task running time. 212 * When a rt task uses 95% CPU time, the rt thread will be 213 * scheduled out for 5% CPU time to not starve other tasks. But 214 * the mechanism only works when all CPUs have RT task running, 215 * as if one CPU hasn't RT task, RT task from other CPUs will 216 * borrow CPU time from this CPU and cause RT task use > 95% 217 * CPU time. To make 'avoid starvation' work, takes a nap here. 218 */ 219 if (unlikely(do_sleep)) 220 schedule_timeout_killable(HZ * idle_pct / 100); 221 222 /* If an external event has set the need_resched flag, then 223 * we need to deal with it, or this loop will continue to 224 * spin without calling __mwait(). 225 */ 226 if (unlikely(need_resched())) 227 schedule(); 228 } 229 230 exit_round_robin(tsk_index); 231 return 0; 232 } 233 234 static struct task_struct *ps_tsks[NR_CPUS]; 235 static unsigned int ps_tsk_num; 236 static int create_power_saving_task(void) 237 { 238 int rc; 239 240 ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread, 241 (void *)(unsigned long)ps_tsk_num, 242 "acpi_pad/%d", ps_tsk_num); 243 244 if (IS_ERR(ps_tsks[ps_tsk_num])) { 245 rc = PTR_ERR(ps_tsks[ps_tsk_num]); 246 ps_tsks[ps_tsk_num] = NULL; 247 } else { 248 rc = 0; 249 ps_tsk_num++; 250 } 251 252 return rc; 253 } 254 255 static void destroy_power_saving_task(void) 256 { 257 if (ps_tsk_num > 0) { 258 ps_tsk_num--; 259 kthread_stop(ps_tsks[ps_tsk_num]); 260 ps_tsks[ps_tsk_num] = NULL; 261 } 262 } 263 264 static void set_power_saving_task_num(unsigned int num) 265 { 266 if (num > ps_tsk_num) { 267 while (ps_tsk_num < num) { 268 if (create_power_saving_task()) 269 return; 270 } 271 } else if (num < ps_tsk_num) { 272 while (ps_tsk_num > num) 273 destroy_power_saving_task(); 274 } 275 } 276 277 static void acpi_pad_idle_cpus(unsigned int num_cpus) 278 { 279 get_online_cpus(); 280 281 num_cpus = min_t(unsigned int, num_cpus, num_online_cpus()); 282 set_power_saving_task_num(num_cpus); 283 284 put_online_cpus(); 285 } 286 287 static uint32_t acpi_pad_idle_cpus_num(void) 288 { 289 return ps_tsk_num; 290 } 291 292 static ssize_t acpi_pad_rrtime_store(struct device *dev, 293 struct device_attribute *attr, const char *buf, size_t count) 294 { 295 unsigned long num; 296 if (kstrtoul(buf, 0, &num)) 297 return -EINVAL; 298 if (num < 1 || num >= 100) 299 return -EINVAL; 300 mutex_lock(&isolated_cpus_lock); 301 round_robin_time = num; 302 mutex_unlock(&isolated_cpus_lock); 303 return count; 304 } 305 306 static ssize_t acpi_pad_rrtime_show(struct device *dev, 307 struct device_attribute *attr, char *buf) 308 { 309 return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time); 310 } 311 static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR, 312 acpi_pad_rrtime_show, 313 acpi_pad_rrtime_store); 314 315 static ssize_t acpi_pad_idlepct_store(struct device *dev, 316 struct device_attribute *attr, const char *buf, size_t count) 317 { 318 unsigned long num; 319 if (kstrtoul(buf, 0, &num)) 320 return -EINVAL; 321 if (num < 1 || num >= 100) 322 return -EINVAL; 323 mutex_lock(&isolated_cpus_lock); 324 idle_pct = num; 325 mutex_unlock(&isolated_cpus_lock); 326 return count; 327 } 328 329 static ssize_t acpi_pad_idlepct_show(struct device *dev, 330 struct device_attribute *attr, char *buf) 331 { 332 return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct); 333 } 334 static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR, 335 acpi_pad_idlepct_show, 336 acpi_pad_idlepct_store); 337 338 static ssize_t acpi_pad_idlecpus_store(struct device *dev, 339 struct device_attribute *attr, const char *buf, size_t count) 340 { 341 unsigned long num; 342 if (kstrtoul(buf, 0, &num)) 343 return -EINVAL; 344 mutex_lock(&isolated_cpus_lock); 345 acpi_pad_idle_cpus(num); 346 mutex_unlock(&isolated_cpus_lock); 347 return count; 348 } 349 350 static ssize_t acpi_pad_idlecpus_show(struct device *dev, 351 struct device_attribute *attr, char *buf) 352 { 353 return cpumap_print_to_pagebuf(false, buf, 354 to_cpumask(pad_busy_cpus_bits)); 355 } 356 357 static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR, 358 acpi_pad_idlecpus_show, 359 acpi_pad_idlecpus_store); 360 361 static int acpi_pad_add_sysfs(struct acpi_device *device) 362 { 363 int result; 364 365 result = device_create_file(&device->dev, &dev_attr_idlecpus); 366 if (result) 367 return -ENODEV; 368 result = device_create_file(&device->dev, &dev_attr_idlepct); 369 if (result) { 370 device_remove_file(&device->dev, &dev_attr_idlecpus); 371 return -ENODEV; 372 } 373 result = device_create_file(&device->dev, &dev_attr_rrtime); 374 if (result) { 375 device_remove_file(&device->dev, &dev_attr_idlecpus); 376 device_remove_file(&device->dev, &dev_attr_idlepct); 377 return -ENODEV; 378 } 379 return 0; 380 } 381 382 static void acpi_pad_remove_sysfs(struct acpi_device *device) 383 { 384 device_remove_file(&device->dev, &dev_attr_idlecpus); 385 device_remove_file(&device->dev, &dev_attr_idlepct); 386 device_remove_file(&device->dev, &dev_attr_rrtime); 387 } 388 389 /* 390 * Query firmware how many CPUs should be idle 391 * return -1 on failure 392 */ 393 static int acpi_pad_pur(acpi_handle handle) 394 { 395 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL}; 396 union acpi_object *package; 397 int num = -1; 398 399 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer))) 400 return num; 401 402 if (!buffer.length || !buffer.pointer) 403 return num; 404 405 package = buffer.pointer; 406 407 if (package->type == ACPI_TYPE_PACKAGE && 408 package->package.count == 2 && 409 package->package.elements[0].integer.value == 1) /* rev 1 */ 410 411 num = package->package.elements[1].integer.value; 412 413 kfree(buffer.pointer); 414 return num; 415 } 416 417 static void acpi_pad_handle_notify(acpi_handle handle) 418 { 419 int num_cpus; 420 uint32_t idle_cpus; 421 struct acpi_buffer param = { 422 .length = 4, 423 .pointer = (void *)&idle_cpus, 424 }; 425 426 mutex_lock(&isolated_cpus_lock); 427 num_cpus = acpi_pad_pur(handle); 428 if (num_cpus < 0) { 429 mutex_unlock(&isolated_cpus_lock); 430 return; 431 } 432 acpi_pad_idle_cpus(num_cpus); 433 idle_cpus = acpi_pad_idle_cpus_num(); 434 acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, ¶m); 435 mutex_unlock(&isolated_cpus_lock); 436 } 437 438 static void acpi_pad_notify(acpi_handle handle, u32 event, 439 void *data) 440 { 441 struct acpi_device *device = data; 442 443 switch (event) { 444 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY: 445 acpi_pad_handle_notify(handle); 446 acpi_bus_generate_netlink_event(device->pnp.device_class, 447 dev_name(&device->dev), event, 0); 448 break; 449 default: 450 pr_warn("Unsupported event [0x%x]\n", event); 451 break; 452 } 453 } 454 455 static int acpi_pad_add(struct acpi_device *device) 456 { 457 acpi_status status; 458 459 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME); 460 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS); 461 462 if (acpi_pad_add_sysfs(device)) 463 return -ENODEV; 464 465 status = acpi_install_notify_handler(device->handle, 466 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device); 467 if (ACPI_FAILURE(status)) { 468 acpi_pad_remove_sysfs(device); 469 return -ENODEV; 470 } 471 472 return 0; 473 } 474 475 static int acpi_pad_remove(struct acpi_device *device) 476 { 477 mutex_lock(&isolated_cpus_lock); 478 acpi_pad_idle_cpus(0); 479 mutex_unlock(&isolated_cpus_lock); 480 481 acpi_remove_notify_handler(device->handle, 482 ACPI_DEVICE_NOTIFY, acpi_pad_notify); 483 acpi_pad_remove_sysfs(device); 484 return 0; 485 } 486 487 static const struct acpi_device_id pad_device_ids[] = { 488 {"ACPI000C", 0}, 489 {"", 0}, 490 }; 491 MODULE_DEVICE_TABLE(acpi, pad_device_ids); 492 493 static struct acpi_driver acpi_pad_driver = { 494 .name = "processor_aggregator", 495 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS, 496 .ids = pad_device_ids, 497 .ops = { 498 .add = acpi_pad_add, 499 .remove = acpi_pad_remove, 500 }, 501 }; 502 503 static int __init acpi_pad_init(void) 504 { 505 power_saving_mwait_init(); 506 if (power_saving_mwait_eax == 0) 507 return -EINVAL; 508 509 return acpi_bus_register_driver(&acpi_pad_driver); 510 } 511 512 static void __exit acpi_pad_exit(void) 513 { 514 acpi_bus_unregister_driver(&acpi_pad_driver); 515 } 516 517 module_init(acpi_pad_init); 518 module_exit(acpi_pad_exit); 519 MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>"); 520 MODULE_DESCRIPTION("ACPI Processor Aggregator Driver"); 521 MODULE_LICENSE("GPL"); 522