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 u64 expire_time; 160 161 try_to_freeze(); 162 163 /* round robin to cpus */ 164 if (last_jiffies + round_robin_time * HZ < jiffies) { 165 last_jiffies = jiffies; 166 round_robin_cpu(tsk_index); 167 } 168 169 do_sleep = 0; 170 171 expire_time = jiffies + HZ * (100 - idle_pct) / 100; 172 173 while (!need_resched()) { 174 if (tsc_detected_unstable && !tsc_marked_unstable) { 175 /* TSC could halt in idle, so notify users */ 176 mark_tsc_unstable("TSC halts in idle"); 177 tsc_marked_unstable = 1; 178 } 179 if (lapic_detected_unstable && !lapic_marked_unstable) { 180 int i; 181 /* LAPIC could halt in idle, so notify users */ 182 for_each_online_cpu(i) 183 clockevents_notify( 184 CLOCK_EVT_NOTIFY_BROADCAST_ON, 185 &i); 186 lapic_marked_unstable = 1; 187 } 188 local_irq_disable(); 189 cpu = smp_processor_id(); 190 if (lapic_marked_unstable) 191 clockevents_notify( 192 CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu); 193 stop_critical_timings(); 194 195 mwait_idle_with_hints(power_saving_mwait_eax, 1); 196 197 start_critical_timings(); 198 if (lapic_marked_unstable) 199 clockevents_notify( 200 CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu); 201 local_irq_enable(); 202 203 if (jiffies > expire_time) { 204 do_sleep = 1; 205 break; 206 } 207 } 208 209 /* 210 * current sched_rt has threshold for rt task running time. 211 * When a rt task uses 95% CPU time, the rt thread will be 212 * scheduled out for 5% CPU time to not starve other tasks. But 213 * the mechanism only works when all CPUs have RT task running, 214 * as if one CPU hasn't RT task, RT task from other CPUs will 215 * borrow CPU time from this CPU and cause RT task use > 95% 216 * CPU time. To make 'avoid starvation' work, takes a nap here. 217 */ 218 if (do_sleep) 219 schedule_timeout_killable(HZ * idle_pct / 100); 220 } 221 222 exit_round_robin(tsk_index); 223 return 0; 224 } 225 226 static struct task_struct *ps_tsks[NR_CPUS]; 227 static unsigned int ps_tsk_num; 228 static int create_power_saving_task(void) 229 { 230 int rc; 231 232 ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread, 233 (void *)(unsigned long)ps_tsk_num, 234 "acpi_pad/%d", ps_tsk_num); 235 236 if (IS_ERR(ps_tsks[ps_tsk_num])) { 237 rc = PTR_ERR(ps_tsks[ps_tsk_num]); 238 ps_tsks[ps_tsk_num] = NULL; 239 } else { 240 rc = 0; 241 ps_tsk_num++; 242 } 243 244 return rc; 245 } 246 247 static void destroy_power_saving_task(void) 248 { 249 if (ps_tsk_num > 0) { 250 ps_tsk_num--; 251 kthread_stop(ps_tsks[ps_tsk_num]); 252 ps_tsks[ps_tsk_num] = NULL; 253 } 254 } 255 256 static void set_power_saving_task_num(unsigned int num) 257 { 258 if (num > ps_tsk_num) { 259 while (ps_tsk_num < num) { 260 if (create_power_saving_task()) 261 return; 262 } 263 } else if (num < ps_tsk_num) { 264 while (ps_tsk_num > num) 265 destroy_power_saving_task(); 266 } 267 } 268 269 static void acpi_pad_idle_cpus(unsigned int num_cpus) 270 { 271 get_online_cpus(); 272 273 num_cpus = min_t(unsigned int, num_cpus, num_online_cpus()); 274 set_power_saving_task_num(num_cpus); 275 276 put_online_cpus(); 277 } 278 279 static uint32_t acpi_pad_idle_cpus_num(void) 280 { 281 return ps_tsk_num; 282 } 283 284 static ssize_t acpi_pad_rrtime_store(struct device *dev, 285 struct device_attribute *attr, const char *buf, size_t count) 286 { 287 unsigned long num; 288 if (kstrtoul(buf, 0, &num)) 289 return -EINVAL; 290 if (num < 1 || num >= 100) 291 return -EINVAL; 292 mutex_lock(&isolated_cpus_lock); 293 round_robin_time = num; 294 mutex_unlock(&isolated_cpus_lock); 295 return count; 296 } 297 298 static ssize_t acpi_pad_rrtime_show(struct device *dev, 299 struct device_attribute *attr, char *buf) 300 { 301 return scnprintf(buf, PAGE_SIZE, "%d\n", round_robin_time); 302 } 303 static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR, 304 acpi_pad_rrtime_show, 305 acpi_pad_rrtime_store); 306 307 static ssize_t acpi_pad_idlepct_store(struct device *dev, 308 struct device_attribute *attr, const char *buf, size_t count) 309 { 310 unsigned long num; 311 if (kstrtoul(buf, 0, &num)) 312 return -EINVAL; 313 if (num < 1 || num >= 100) 314 return -EINVAL; 315 mutex_lock(&isolated_cpus_lock); 316 idle_pct = num; 317 mutex_unlock(&isolated_cpus_lock); 318 return count; 319 } 320 321 static ssize_t acpi_pad_idlepct_show(struct device *dev, 322 struct device_attribute *attr, char *buf) 323 { 324 return scnprintf(buf, PAGE_SIZE, "%d\n", idle_pct); 325 } 326 static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR, 327 acpi_pad_idlepct_show, 328 acpi_pad_idlepct_store); 329 330 static ssize_t acpi_pad_idlecpus_store(struct device *dev, 331 struct device_attribute *attr, const char *buf, size_t count) 332 { 333 unsigned long num; 334 if (kstrtoul(buf, 0, &num)) 335 return -EINVAL; 336 mutex_lock(&isolated_cpus_lock); 337 acpi_pad_idle_cpus(num); 338 mutex_unlock(&isolated_cpus_lock); 339 return count; 340 } 341 342 static ssize_t acpi_pad_idlecpus_show(struct device *dev, 343 struct device_attribute *attr, char *buf) 344 { 345 int n = 0; 346 n = cpumask_scnprintf(buf, PAGE_SIZE-2, to_cpumask(pad_busy_cpus_bits)); 347 buf[n++] = '\n'; 348 buf[n] = '\0'; 349 return n; 350 } 351 static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR, 352 acpi_pad_idlecpus_show, 353 acpi_pad_idlecpus_store); 354 355 static int acpi_pad_add_sysfs(struct acpi_device *device) 356 { 357 int result; 358 359 result = device_create_file(&device->dev, &dev_attr_idlecpus); 360 if (result) 361 return -ENODEV; 362 result = device_create_file(&device->dev, &dev_attr_idlepct); 363 if (result) { 364 device_remove_file(&device->dev, &dev_attr_idlecpus); 365 return -ENODEV; 366 } 367 result = device_create_file(&device->dev, &dev_attr_rrtime); 368 if (result) { 369 device_remove_file(&device->dev, &dev_attr_idlecpus); 370 device_remove_file(&device->dev, &dev_attr_idlepct); 371 return -ENODEV; 372 } 373 return 0; 374 } 375 376 static void acpi_pad_remove_sysfs(struct acpi_device *device) 377 { 378 device_remove_file(&device->dev, &dev_attr_idlecpus); 379 device_remove_file(&device->dev, &dev_attr_idlepct); 380 device_remove_file(&device->dev, &dev_attr_rrtime); 381 } 382 383 /* 384 * Query firmware how many CPUs should be idle 385 * return -1 on failure 386 */ 387 static int acpi_pad_pur(acpi_handle handle) 388 { 389 struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL}; 390 union acpi_object *package; 391 int num = -1; 392 393 if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer))) 394 return num; 395 396 if (!buffer.length || !buffer.pointer) 397 return num; 398 399 package = buffer.pointer; 400 401 if (package->type == ACPI_TYPE_PACKAGE && 402 package->package.count == 2 && 403 package->package.elements[0].integer.value == 1) /* rev 1 */ 404 405 num = package->package.elements[1].integer.value; 406 407 kfree(buffer.pointer); 408 return num; 409 } 410 411 static void acpi_pad_handle_notify(acpi_handle handle) 412 { 413 int num_cpus; 414 uint32_t idle_cpus; 415 struct acpi_buffer param = { 416 .length = 4, 417 .pointer = (void *)&idle_cpus, 418 }; 419 420 mutex_lock(&isolated_cpus_lock); 421 num_cpus = acpi_pad_pur(handle); 422 if (num_cpus < 0) { 423 mutex_unlock(&isolated_cpus_lock); 424 return; 425 } 426 acpi_pad_idle_cpus(num_cpus); 427 idle_cpus = acpi_pad_idle_cpus_num(); 428 acpi_evaluate_ost(handle, ACPI_PROCESSOR_AGGREGATOR_NOTIFY, 0, ¶m); 429 mutex_unlock(&isolated_cpus_lock); 430 } 431 432 static void acpi_pad_notify(acpi_handle handle, u32 event, 433 void *data) 434 { 435 struct acpi_device *device = data; 436 437 switch (event) { 438 case ACPI_PROCESSOR_AGGREGATOR_NOTIFY: 439 acpi_pad_handle_notify(handle); 440 acpi_bus_generate_netlink_event(device->pnp.device_class, 441 dev_name(&device->dev), event, 0); 442 break; 443 default: 444 pr_warn("Unsupported event [0x%x]\n", event); 445 break; 446 } 447 } 448 449 static int acpi_pad_add(struct acpi_device *device) 450 { 451 acpi_status status; 452 453 strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME); 454 strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS); 455 456 if (acpi_pad_add_sysfs(device)) 457 return -ENODEV; 458 459 status = acpi_install_notify_handler(device->handle, 460 ACPI_DEVICE_NOTIFY, acpi_pad_notify, device); 461 if (ACPI_FAILURE(status)) { 462 acpi_pad_remove_sysfs(device); 463 return -ENODEV; 464 } 465 466 return 0; 467 } 468 469 static int acpi_pad_remove(struct acpi_device *device) 470 { 471 mutex_lock(&isolated_cpus_lock); 472 acpi_pad_idle_cpus(0); 473 mutex_unlock(&isolated_cpus_lock); 474 475 acpi_remove_notify_handler(device->handle, 476 ACPI_DEVICE_NOTIFY, acpi_pad_notify); 477 acpi_pad_remove_sysfs(device); 478 return 0; 479 } 480 481 static const struct acpi_device_id pad_device_ids[] = { 482 {"ACPI000C", 0}, 483 {"", 0}, 484 }; 485 MODULE_DEVICE_TABLE(acpi, pad_device_ids); 486 487 static struct acpi_driver acpi_pad_driver = { 488 .name = "processor_aggregator", 489 .class = ACPI_PROCESSOR_AGGREGATOR_CLASS, 490 .ids = pad_device_ids, 491 .ops = { 492 .add = acpi_pad_add, 493 .remove = acpi_pad_remove, 494 }, 495 }; 496 497 static int __init acpi_pad_init(void) 498 { 499 power_saving_mwait_init(); 500 if (power_saving_mwait_eax == 0) 501 return -EINVAL; 502 503 return acpi_bus_register_driver(&acpi_pad_driver); 504 } 505 506 static void __exit acpi_pad_exit(void) 507 { 508 acpi_bus_unregister_driver(&acpi_pad_driver); 509 } 510 511 module_init(acpi_pad_init); 512 module_exit(acpi_pad_exit); 513 MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>"); 514 MODULE_DESCRIPTION("ACPI Processor Aggregator Driver"); 515 MODULE_LICENSE("GPL"); 516