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 <acpi/acpi_bus.h> 32 #include <acpi/acpi_drivers.h> 33 #include <asm/mwait.h> 34 35 #define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad" 36 #define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator" 37 #define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80 38 static DEFINE_MUTEX(isolated_cpus_lock); 39 static DEFINE_MUTEX(round_robin_lock); 40 41 static unsigned long power_saving_mwait_eax; 42 43 static unsigned char tsc_detected_unstable; 44 static unsigned char tsc_marked_unstable; 45 static unsigned char lapic_detected_unstable; 46 static unsigned char lapic_marked_unstable; 47 48 static void power_saving_mwait_init(void) 49 { 50 unsigned int eax, ebx, ecx, edx; 51 unsigned int highest_cstate = 0; 52 unsigned int highest_subcstate = 0; 53 int i; 54 55 if (!boot_cpu_has(X86_FEATURE_MWAIT)) 56 return; 57 if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF) 58 return; 59 60 cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx); 61 62 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) || 63 !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) 64 return; 65 66 edx >>= MWAIT_SUBSTATE_SIZE; 67 for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) { 68 if (edx & MWAIT_SUBSTATE_MASK) { 69 highest_cstate = i; 70 highest_subcstate = edx & MWAIT_SUBSTATE_MASK; 71 } 72 } 73 power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) | 74 (highest_subcstate - 1); 75 76 #if defined(CONFIG_X86) 77 switch (boot_cpu_data.x86_vendor) { 78 case X86_VENDOR_AMD: 79 case X86_VENDOR_INTEL: 80 /* 81 * AMD Fam10h TSC will tick in all 82 * C/P/S0/S1 states when this bit is set. 83 */ 84 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC)) 85 tsc_detected_unstable = 1; 86 if (!boot_cpu_has(X86_FEATURE_ARAT)) 87 lapic_detected_unstable = 1; 88 break; 89 default: 90 /* TSC & LAPIC could halt in idle */ 91 tsc_detected_unstable = 1; 92 lapic_detected_unstable = 1; 93 } 94 #endif 95 } 96 97 static unsigned long cpu_weight[NR_CPUS]; 98 static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1}; 99 static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS); 100 static void round_robin_cpu(unsigned int tsk_index) 101 { 102 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); 103 cpumask_var_t tmp; 104 int cpu; 105 unsigned long min_weight = -1; 106 unsigned long uninitialized_var(preferred_cpu); 107 108 if (!alloc_cpumask_var(&tmp, GFP_KERNEL)) 109 return; 110 111 mutex_lock(&round_robin_lock); 112 cpumask_clear(tmp); 113 for_each_cpu(cpu, pad_busy_cpus) 114 cpumask_or(tmp, tmp, topology_thread_cpumask(cpu)); 115 cpumask_andnot(tmp, cpu_online_mask, tmp); 116 /* avoid HT sibilings if possible */ 117 if (cpumask_empty(tmp)) 118 cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus); 119 if (cpumask_empty(tmp)) { 120 mutex_unlock(&round_robin_lock); 121 return; 122 } 123 for_each_cpu(cpu, tmp) { 124 if (cpu_weight[cpu] < min_weight) { 125 min_weight = cpu_weight[cpu]; 126 preferred_cpu = cpu; 127 } 128 } 129 130 if (tsk_in_cpu[tsk_index] != -1) 131 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); 132 tsk_in_cpu[tsk_index] = preferred_cpu; 133 cpumask_set_cpu(preferred_cpu, pad_busy_cpus); 134 cpu_weight[preferred_cpu]++; 135 mutex_unlock(&round_robin_lock); 136 137 set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu)); 138 } 139 140 static void exit_round_robin(unsigned int tsk_index) 141 { 142 struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits); 143 cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus); 144 tsk_in_cpu[tsk_index] = -1; 145 } 146 147 static unsigned int idle_pct = 5; /* percentage */ 148 static unsigned int round_robin_time = 1; /* second */ 149 static int power_saving_thread(void *data) 150 { 151 struct sched_param param = {.sched_priority = 1}; 152 int do_sleep; 153 unsigned int tsk_index = (unsigned long)data; 154 u64 last_jiffies = 0; 155 156 sched_setscheduler(current, SCHED_RR, ¶m); 157 158 while (!kthread_should_stop()) { 159 int cpu; 160 u64 expire_time; 161 162 try_to_freeze(); 163 164 /* round robin to cpus */ 165 if (last_jiffies + round_robin_time * HZ < 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 __monitor((void *)¤t_thread_info()->flags, 0, 0); 197 smp_mb(); 198 if (!need_resched()) 199 __mwait(power_saving_mwait_eax, 1); 200 201 start_critical_timings(); 202 if (lapic_marked_unstable) 203 clockevents_notify( 204 CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu); 205 local_irq_enable(); 206 207 if (jiffies > expire_time) { 208 do_sleep = 1; 209 break; 210 } 211 } 212 213 /* 214 * current sched_rt has threshold for rt task running time. 215 * When a rt task uses 95% CPU time, the rt thread will be 216 * scheduled out for 5% CPU time to not starve other tasks. But 217 * the mechanism only works when all CPUs have RT task running, 218 * as if one CPU hasn't RT task, RT task from other CPUs will 219 * borrow CPU time from this CPU and cause RT task use > 95% 220 * CPU time. To make 'avoid starvation' work, takes a nap here. 221 */ 222 if (do_sleep) 223 schedule_timeout_killable(HZ * idle_pct / 100); 224 } 225 226 exit_round_robin(tsk_index); 227 return 0; 228 } 229 230 static struct task_struct *ps_tsks[NR_CPUS]; 231 static unsigned int ps_tsk_num; 232 static int create_power_saving_task(void) 233 { 234 int rc = -ENOMEM; 235 236 ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread, 237 (void *)(unsigned long)ps_tsk_num, 238 "acpi_pad/%d", ps_tsk_num); 239 rc = IS_ERR(ps_tsks[ps_tsk_num]) ? PTR_ERR(ps_tsks[ps_tsk_num]) : 0; 240 if (!rc) 241 ps_tsk_num++; 242 else 243 ps_tsks[ps_tsk_num] = NULL; 244 245 return rc; 246 } 247 248 static void destroy_power_saving_task(void) 249 { 250 if (ps_tsk_num > 0) { 251 ps_tsk_num--; 252 kthread_stop(ps_tsks[ps_tsk_num]); 253 ps_tsks[ps_tsk_num] = NULL; 254 } 255 } 256 257 static void set_power_saving_task_num(unsigned int num) 258 { 259 if (num > ps_tsk_num) { 260 while (ps_tsk_num < num) { 261 if (create_power_saving_task()) 262 return; 263 } 264 } else if (num < ps_tsk_num) { 265 while (ps_tsk_num > num) 266 destroy_power_saving_task(); 267 } 268 } 269 270 static void acpi_pad_idle_cpus(unsigned int num_cpus) 271 { 272 get_online_cpus(); 273 274 num_cpus = min_t(unsigned int, num_cpus, num_online_cpus()); 275 set_power_saving_task_num(num_cpus); 276 277 put_online_cpus(); 278 } 279 280 static uint32_t acpi_pad_idle_cpus_num(void) 281 { 282 return ps_tsk_num; 283 } 284 285 static ssize_t acpi_pad_rrtime_store(struct device *dev, 286 struct device_attribute *attr, const char *buf, size_t count) 287 { 288 unsigned long num; 289 if (kstrtoul(buf, 0, &num)) 290 return -EINVAL; 291 if (num < 1 || num >= 100) 292 return -EINVAL; 293 mutex_lock(&isolated_cpus_lock); 294 round_robin_time = num; 295 mutex_unlock(&isolated_cpus_lock); 296 return count; 297 } 298 299 static ssize_t acpi_pad_rrtime_show(struct device *dev, 300 struct device_attribute *attr, char *buf) 301 { 302 return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time); 303 } 304 static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR, 305 acpi_pad_rrtime_show, 306 acpi_pad_rrtime_store); 307 308 static ssize_t acpi_pad_idlepct_store(struct device *dev, 309 struct device_attribute *attr, const char *buf, size_t count) 310 { 311 unsigned long num; 312 if (kstrtoul(buf, 0, &num)) 313 return -EINVAL; 314 if (num < 1 || num >= 100) 315 return -EINVAL; 316 mutex_lock(&isolated_cpus_lock); 317 idle_pct = num; 318 mutex_unlock(&isolated_cpus_lock); 319 return count; 320 } 321 322 static ssize_t acpi_pad_idlepct_show(struct device *dev, 323 struct device_attribute *attr, char *buf) 324 { 325 return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct); 326 } 327 static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR, 328 acpi_pad_idlepct_show, 329 acpi_pad_idlepct_store); 330 331 static ssize_t acpi_pad_idlecpus_store(struct device *dev, 332 struct device_attribute *attr, const char *buf, size_t count) 333 { 334 unsigned long num; 335 if (kstrtoul(buf, 0, &num)) 336 return -EINVAL; 337 mutex_lock(&isolated_cpus_lock); 338 acpi_pad_idle_cpus(num); 339 mutex_unlock(&isolated_cpus_lock); 340 return count; 341 } 342 343 static ssize_t acpi_pad_idlecpus_show(struct device *dev, 344 struct device_attribute *attr, char *buf) 345 { 346 int n = 0; 347 n = cpumask_scnprintf(buf, PAGE_SIZE-2, to_cpumask(pad_busy_cpus_bits)); 348 buf[n++] = '\n'; 349 buf[n] = '\0'; 350 return n; 351 } 352 static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR, 353 acpi_pad_idlecpus_show, 354 acpi_pad_idlecpus_store); 355 356 static int acpi_pad_add_sysfs(struct acpi_device *device) 357 { 358 int result; 359 360 result = device_create_file(&device->dev, &dev_attr_idlecpus); 361 if (result) 362 return -ENODEV; 363 result = device_create_file(&device->dev, &dev_attr_idlepct); 364 if (result) { 365 device_remove_file(&device->dev, &dev_attr_idlecpus); 366 return -ENODEV; 367 } 368 result = device_create_file(&device->dev, &dev_attr_rrtime); 369 if (result) { 370 device_remove_file(&device->dev, &dev_attr_idlecpus); 371 device_remove_file(&device->dev, &dev_attr_idlepct); 372 return -ENODEV; 373 } 374 return 0; 375 } 376 377 static void acpi_pad_remove_sysfs(struct acpi_device *device) 378 { 379 device_remove_file(&device->dev, &dev_attr_idlecpus); 380 device_remove_file(&device->dev, &dev_attr_idlepct); 381 device_remove_file(&device->dev, &dev_attr_rrtime); 382 } 383 384 /* 385 * Query firmware how many CPUs should be idle 386 * return -1 on failure 387 */ 388 static int acpi_pad_pur(acpi_handle handle) 389 { 390 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL}; 391 union acpi_object *package; 392 int num = -1; 393 394 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer))) 395 return num; 396 397 if (!buffer.length || !buffer.pointer) 398 return num; 399 400 package = buffer.pointer; 401 402 if (package->type == ACPI_TYPE_PACKAGE && 403 package->package.count == 2 && 404 package->package.elements[0].integer.value == 1) /* rev 1 */ 405 406 num = package->package.elements[1].integer.value; 407 408 kfree(buffer.pointer); 409 return num; 410 } 411 412 /* Notify firmware how many CPUs are idle */ 413 static void acpi_pad_ost(acpi_handle handle, int stat, 414 uint32_t idle_cpus) 415 { 416 union acpi_object params[3] = { 417 {.type = ACPI_TYPE_INTEGER,}, 418 {.type = ACPI_TYPE_INTEGER,}, 419 {.type = ACPI_TYPE_BUFFER,}, 420 }; 421 struct acpi_object_list arg_list = {3, params}; 422 423 params[0].integer.value = ACPI_PROCESSOR_AGGREGATOR_NOTIFY; 424 params[1].integer.value = stat; 425 params[2].buffer.length = 4; 426 params[2].buffer.pointer = (void *)&idle_cpus; 427 acpi_evaluate_object(handle, "_OST", &arg_list, NULL); 428 } 429 430 static void acpi_pad_handle_notify(acpi_handle handle) 431 { 432 int num_cpus; 433 uint32_t idle_cpus; 434 435 mutex_lock(&isolated_cpus_lock); 436 num_cpus = acpi_pad_pur(handle); 437 if (num_cpus < 0) { 438 mutex_unlock(&isolated_cpus_lock); 439 return; 440 } 441 acpi_pad_idle_cpus(num_cpus); 442 idle_cpus = acpi_pad_idle_cpus_num(); 443 acpi_pad_ost(handle, 0, idle_cpus); 444 mutex_unlock(&isolated_cpus_lock); 445 } 446 447 static void acpi_pad_notify(acpi_handle handle, u32 event, 448 void *data) 449 { 450 struct acpi_device *device = data; 451 452 switch (event) { 453 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY: 454 acpi_pad_handle_notify(handle); 455 acpi_bus_generate_proc_event(device, event, 0); 456 acpi_bus_generate_netlink_event(device->pnp.device_class, 457 dev_name(&device->dev), event, 0); 458 break; 459 default: 460 pr_warn("Unsupported event [0x%x]\n", event); 461 break; 462 } 463 } 464 465 static int acpi_pad_add(struct acpi_device *device) 466 { 467 acpi_status status; 468 469 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME); 470 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS); 471 472 if (acpi_pad_add_sysfs(device)) 473 return -ENODEV; 474 475 status = acpi_install_notify_handler(device->handle, 476 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device); 477 if (ACPI_FAILURE(status)) { 478 acpi_pad_remove_sysfs(device); 479 return -ENODEV; 480 } 481 482 return 0; 483 } 484 485 static int acpi_pad_remove(struct acpi_device *device, 486 int type) 487 { 488 mutex_lock(&isolated_cpus_lock); 489 acpi_pad_idle_cpus(0); 490 mutex_unlock(&isolated_cpus_lock); 491 492 acpi_remove_notify_handler(device->handle, 493 ACPI_DEVICE_NOTIFY, acpi_pad_notify); 494 acpi_pad_remove_sysfs(device); 495 return 0; 496 } 497 498 static const struct acpi_device_id pad_device_ids[] = { 499 {"ACPI000C", 0}, 500 {"", 0}, 501 }; 502 MODULE_DEVICE_TABLE(acpi, pad_device_ids); 503 504 static struct acpi_driver acpi_pad_driver = { 505 .name = "processor_aggregator", 506 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS, 507 .ids = pad_device_ids, 508 .ops = { 509 .add = acpi_pad_add, 510 .remove = acpi_pad_remove, 511 }, 512 }; 513 514 static int __init acpi_pad_init(void) 515 { 516 power_saving_mwait_init(); 517 if (power_saving_mwait_eax == 0) 518 return -EINVAL; 519 520 return acpi_bus_register_driver(&acpi_pad_driver); 521 } 522 523 static void __exit acpi_pad_exit(void) 524 { 525 acpi_bus_unregister_driver(&acpi_pad_driver); 526 } 527 528 module_init(acpi_pad_init); 529 module_exit(acpi_pad_exit); 530 MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>"); 531 MODULE_DESCRIPTION("ACPI Processor Aggregator Driver"); 532 MODULE_LICENSE("GPL"); 533