Version:  2.0.40 2.2.26 2.4.37 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6

Linux/drivers/acpi/acpi_pad.c

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

This page was automatically generated by LXR 0.3.1 (source).  •  Linux is a registered trademark of Linus Torvalds  •  Contact us