2 * Performance counter core code
4 * Copyright(C) 2008 Thomas Gleixner <tglx@linutronix.de>
5 * Copyright(C) 2008 Red Hat, Inc., Ingo Molnar
7 * For licencing details see kernel-base/COPYING
11 #include <linux/cpu.h>
12 #include <linux/smp.h>
13 #include <linux/file.h>
14 #include <linux/poll.h>
15 #include <linux/sysfs.h>
16 #include <linux/ptrace.h>
17 #include <linux/percpu.h>
18 #include <linux/uaccess.h>
19 #include <linux/syscalls.h>
20 #include <linux/anon_inodes.h>
21 #include <linux/kernel_stat.h>
22 #include <linux/perf_counter.h>
24 #include <linux/vmstat.h>
27 * Each CPU has a list of per CPU counters:
29 DEFINE_PER_CPU(struct perf_cpu_context
, perf_cpu_context
);
31 int perf_max_counters __read_mostly
= 1;
32 static int perf_reserved_percpu __read_mostly
;
33 static int perf_overcommit __read_mostly
= 1;
36 * Mutex for (sysadmin-configurable) counter reservations:
38 static DEFINE_MUTEX(perf_resource_mutex
);
41 * Architecture provided APIs - weak aliases:
43 extern __weak
const struct hw_perf_counter_ops
*
44 hw_perf_counter_init(struct perf_counter
*counter
)
49 u64 __weak
hw_perf_save_disable(void) { return 0; }
50 void __weak
hw_perf_restore(u64 ctrl
) { barrier(); }
51 void __weak
hw_perf_counter_setup(int cpu
) { barrier(); }
52 int __weak
hw_perf_group_sched_in(struct perf_counter
*group_leader
,
53 struct perf_cpu_context
*cpuctx
,
54 struct perf_counter_context
*ctx
, int cpu
)
59 void __weak
perf_counter_print_debug(void) { }
62 list_add_counter(struct perf_counter
*counter
, struct perf_counter_context
*ctx
)
64 struct perf_counter
*group_leader
= counter
->group_leader
;
67 * Depending on whether it is a standalone or sibling counter,
68 * add it straight to the context's counter list, or to the group
69 * leader's sibling list:
71 if (counter
->group_leader
== counter
)
72 list_add_tail(&counter
->list_entry
, &ctx
->counter_list
);
74 list_add_tail(&counter
->list_entry
, &group_leader
->sibling_list
);
78 list_del_counter(struct perf_counter
*counter
, struct perf_counter_context
*ctx
)
80 struct perf_counter
*sibling
, *tmp
;
82 list_del_init(&counter
->list_entry
);
85 * If this was a group counter with sibling counters then
86 * upgrade the siblings to singleton counters by adding them
87 * to the context list directly:
89 list_for_each_entry_safe(sibling
, tmp
,
90 &counter
->sibling_list
, list_entry
) {
92 list_del_init(&sibling
->list_entry
);
93 list_add_tail(&sibling
->list_entry
, &ctx
->counter_list
);
94 sibling
->group_leader
= sibling
;
99 counter_sched_out(struct perf_counter
*counter
,
100 struct perf_cpu_context
*cpuctx
,
101 struct perf_counter_context
*ctx
)
103 if (counter
->state
!= PERF_COUNTER_STATE_ACTIVE
)
106 counter
->state
= PERF_COUNTER_STATE_INACTIVE
;
107 counter
->hw_ops
->disable(counter
);
110 if (!is_software_counter(counter
))
111 cpuctx
->active_oncpu
--;
113 if (counter
->hw_event
.exclusive
|| !cpuctx
->active_oncpu
)
114 cpuctx
->exclusive
= 0;
118 group_sched_out(struct perf_counter
*group_counter
,
119 struct perf_cpu_context
*cpuctx
,
120 struct perf_counter_context
*ctx
)
122 struct perf_counter
*counter
;
124 if (group_counter
->state
!= PERF_COUNTER_STATE_ACTIVE
)
127 counter_sched_out(group_counter
, cpuctx
, ctx
);
130 * Schedule out siblings (if any):
132 list_for_each_entry(counter
, &group_counter
->sibling_list
, list_entry
)
133 counter_sched_out(counter
, cpuctx
, ctx
);
135 if (group_counter
->hw_event
.exclusive
)
136 cpuctx
->exclusive
= 0;
140 * Cross CPU call to remove a performance counter
142 * We disable the counter on the hardware level first. After that we
143 * remove it from the context list.
145 static void __perf_counter_remove_from_context(void *info
)
147 struct perf_cpu_context
*cpuctx
= &__get_cpu_var(perf_cpu_context
);
148 struct perf_counter
*counter
= info
;
149 struct perf_counter_context
*ctx
= counter
->ctx
;
154 * If this is a task context, we need to check whether it is
155 * the current task context of this cpu. If not it has been
156 * scheduled out before the smp call arrived.
158 if (ctx
->task
&& cpuctx
->task_ctx
!= ctx
)
161 curr_rq_lock_irq_save(&flags
);
162 spin_lock(&ctx
->lock
);
164 counter_sched_out(counter
, cpuctx
, ctx
);
166 counter
->task
= NULL
;
170 * Protect the list operation against NMI by disabling the
171 * counters on a global level. NOP for non NMI based counters.
173 perf_flags
= hw_perf_save_disable();
174 list_del_counter(counter
, ctx
);
175 hw_perf_restore(perf_flags
);
179 * Allow more per task counters with respect to the
182 cpuctx
->max_pertask
=
183 min(perf_max_counters
- ctx
->nr_counters
,
184 perf_max_counters
- perf_reserved_percpu
);
187 spin_unlock(&ctx
->lock
);
188 curr_rq_unlock_irq_restore(&flags
);
193 * Remove the counter from a task's (or a CPU's) list of counters.
195 * Must be called with counter->mutex and ctx->mutex held.
197 * CPU counters are removed with a smp call. For task counters we only
198 * call when the task is on a CPU.
200 static void perf_counter_remove_from_context(struct perf_counter
*counter
)
202 struct perf_counter_context
*ctx
= counter
->ctx
;
203 struct task_struct
*task
= ctx
->task
;
207 * Per cpu counters are removed via an smp call and
208 * the removal is always sucessful.
210 smp_call_function_single(counter
->cpu
,
211 __perf_counter_remove_from_context
,
217 task_oncpu_function_call(task
, __perf_counter_remove_from_context
,
220 spin_lock_irq(&ctx
->lock
);
222 * If the context is active we need to retry the smp call.
224 if (ctx
->nr_active
&& !list_empty(&counter
->list_entry
)) {
225 spin_unlock_irq(&ctx
->lock
);
230 * The lock prevents that this context is scheduled in so we
231 * can remove the counter safely, if the call above did not
234 if (!list_empty(&counter
->list_entry
)) {
236 list_del_counter(counter
, ctx
);
237 counter
->task
= NULL
;
239 spin_unlock_irq(&ctx
->lock
);
243 * Cross CPU call to disable a performance counter
245 static void __perf_counter_disable(void *info
)
247 struct perf_counter
*counter
= info
;
248 struct perf_cpu_context
*cpuctx
= &__get_cpu_var(perf_cpu_context
);
249 struct perf_counter_context
*ctx
= counter
->ctx
;
253 * If this is a per-task counter, need to check whether this
254 * counter's task is the current task on this cpu.
256 if (ctx
->task
&& cpuctx
->task_ctx
!= ctx
)
259 curr_rq_lock_irq_save(&flags
);
260 spin_lock(&ctx
->lock
);
263 * If the counter is on, turn it off.
264 * If it is in error state, leave it in error state.
266 if (counter
->state
>= PERF_COUNTER_STATE_INACTIVE
) {
267 if (counter
== counter
->group_leader
)
268 group_sched_out(counter
, cpuctx
, ctx
);
270 counter_sched_out(counter
, cpuctx
, ctx
);
271 counter
->state
= PERF_COUNTER_STATE_OFF
;
274 spin_unlock(&ctx
->lock
);
275 curr_rq_unlock_irq_restore(&flags
);
281 static void perf_counter_disable(struct perf_counter
*counter
)
283 struct perf_counter_context
*ctx
= counter
->ctx
;
284 struct task_struct
*task
= ctx
->task
;
288 * Disable the counter on the cpu that it's on
290 smp_call_function_single(counter
->cpu
, __perf_counter_disable
,
296 task_oncpu_function_call(task
, __perf_counter_disable
, counter
);
298 spin_lock_irq(&ctx
->lock
);
300 * If the counter is still active, we need to retry the cross-call.
302 if (counter
->state
== PERF_COUNTER_STATE_ACTIVE
) {
303 spin_unlock_irq(&ctx
->lock
);
308 * Since we have the lock this context can't be scheduled
309 * in, so we can change the state safely.
311 if (counter
->state
== PERF_COUNTER_STATE_INACTIVE
)
312 counter
->state
= PERF_COUNTER_STATE_OFF
;
314 spin_unlock_irq(&ctx
->lock
);
318 * Disable a counter and all its children.
320 static void perf_counter_disable_family(struct perf_counter
*counter
)
322 struct perf_counter
*child
;
324 perf_counter_disable(counter
);
327 * Lock the mutex to protect the list of children
329 mutex_lock(&counter
->mutex
);
330 list_for_each_entry(child
, &counter
->child_list
, child_list
)
331 perf_counter_disable(child
);
332 mutex_unlock(&counter
->mutex
);
336 counter_sched_in(struct perf_counter
*counter
,
337 struct perf_cpu_context
*cpuctx
,
338 struct perf_counter_context
*ctx
,
341 if (counter
->state
<= PERF_COUNTER_STATE_OFF
)
344 counter
->state
= PERF_COUNTER_STATE_ACTIVE
;
345 counter
->oncpu
= cpu
; /* TODO: put 'cpu' into cpuctx->cpu */
347 * The new state must be visible before we turn it on in the hardware:
351 if (counter
->hw_ops
->enable(counter
)) {
352 counter
->state
= PERF_COUNTER_STATE_INACTIVE
;
357 if (!is_software_counter(counter
))
358 cpuctx
->active_oncpu
++;
361 if (counter
->hw_event
.exclusive
)
362 cpuctx
->exclusive
= 1;
368 * Return 1 for a group consisting entirely of software counters,
369 * 0 if the group contains any hardware counters.
371 static int is_software_only_group(struct perf_counter
*leader
)
373 struct perf_counter
*counter
;
375 if (!is_software_counter(leader
))
377 list_for_each_entry(counter
, &leader
->sibling_list
, list_entry
)
378 if (!is_software_counter(counter
))
384 * Work out whether we can put this counter group on the CPU now.
386 static int group_can_go_on(struct perf_counter
*counter
,
387 struct perf_cpu_context
*cpuctx
,
391 * Groups consisting entirely of software counters can always go on.
393 if (is_software_only_group(counter
))
396 * If an exclusive group is already on, no other hardware
397 * counters can go on.
399 if (cpuctx
->exclusive
)
402 * If this group is exclusive and there are already
403 * counters on the CPU, it can't go on.
405 if (counter
->hw_event
.exclusive
&& cpuctx
->active_oncpu
)
408 * Otherwise, try to add it if all previous groups were able
415 * Cross CPU call to install and enable a performance counter
417 static void __perf_install_in_context(void *info
)
419 struct perf_cpu_context
*cpuctx
= &__get_cpu_var(perf_cpu_context
);
420 struct perf_counter
*counter
= info
;
421 struct perf_counter_context
*ctx
= counter
->ctx
;
422 struct perf_counter
*leader
= counter
->group_leader
;
423 int cpu
= smp_processor_id();
429 * If this is a task context, we need to check whether it is
430 * the current task context of this cpu. If not it has been
431 * scheduled out before the smp call arrived.
433 if (ctx
->task
&& cpuctx
->task_ctx
!= ctx
)
436 curr_rq_lock_irq_save(&flags
);
437 spin_lock(&ctx
->lock
);
440 * Protect the list operation against NMI by disabling the
441 * counters on a global level. NOP for non NMI based counters.
443 perf_flags
= hw_perf_save_disable();
445 list_add_counter(counter
, ctx
);
447 counter
->prev_state
= PERF_COUNTER_STATE_OFF
;
450 * Don't put the counter on if it is disabled or if
451 * it is in a group and the group isn't on.
453 if (counter
->state
!= PERF_COUNTER_STATE_INACTIVE
||
454 (leader
!= counter
&& leader
->state
!= PERF_COUNTER_STATE_ACTIVE
))
458 * An exclusive counter can't go on if there are already active
459 * hardware counters, and no hardware counter can go on if there
460 * is already an exclusive counter on.
462 if (!group_can_go_on(counter
, cpuctx
, 1))
465 err
= counter_sched_in(counter
, cpuctx
, ctx
, cpu
);
469 * This counter couldn't go on. If it is in a group
470 * then we have to pull the whole group off.
471 * If the counter group is pinned then put it in error state.
473 if (leader
!= counter
)
474 group_sched_out(leader
, cpuctx
, ctx
);
475 if (leader
->hw_event
.pinned
)
476 leader
->state
= PERF_COUNTER_STATE_ERROR
;
479 if (!err
&& !ctx
->task
&& cpuctx
->max_pertask
)
480 cpuctx
->max_pertask
--;
483 hw_perf_restore(perf_flags
);
485 spin_unlock(&ctx
->lock
);
486 curr_rq_unlock_irq_restore(&flags
);
490 * Attach a performance counter to a context
492 * First we add the counter to the list with the hardware enable bit
493 * in counter->hw_config cleared.
495 * If the counter is attached to a task which is on a CPU we use a smp
496 * call to enable it in the task context. The task might have been
497 * scheduled away, but we check this in the smp call again.
499 * Must be called with ctx->mutex held.
502 perf_install_in_context(struct perf_counter_context
*ctx
,
503 struct perf_counter
*counter
,
506 struct task_struct
*task
= ctx
->task
;
510 * Per cpu counters are installed via an smp call and
511 * the install is always sucessful.
513 smp_call_function_single(cpu
, __perf_install_in_context
,
518 counter
->task
= task
;
520 task_oncpu_function_call(task
, __perf_install_in_context
,
523 spin_lock_irq(&ctx
->lock
);
525 * we need to retry the smp call.
527 if (ctx
->is_active
&& list_empty(&counter
->list_entry
)) {
528 spin_unlock_irq(&ctx
->lock
);
533 * The lock prevents that this context is scheduled in so we
534 * can add the counter safely, if it the call above did not
537 if (list_empty(&counter
->list_entry
)) {
538 list_add_counter(counter
, ctx
);
541 spin_unlock_irq(&ctx
->lock
);
545 * Cross CPU call to enable a performance counter
547 static void __perf_counter_enable(void *info
)
549 struct perf_counter
*counter
= info
;
550 struct perf_cpu_context
*cpuctx
= &__get_cpu_var(perf_cpu_context
);
551 struct perf_counter_context
*ctx
= counter
->ctx
;
552 struct perf_counter
*leader
= counter
->group_leader
;
557 * If this is a per-task counter, need to check whether this
558 * counter's task is the current task on this cpu.
560 if (ctx
->task
&& cpuctx
->task_ctx
!= ctx
)
563 curr_rq_lock_irq_save(&flags
);
564 spin_lock(&ctx
->lock
);
566 counter
->prev_state
= counter
->state
;
567 if (counter
->state
>= PERF_COUNTER_STATE_INACTIVE
)
569 counter
->state
= PERF_COUNTER_STATE_INACTIVE
;
572 * If the counter is in a group and isn't the group leader,
573 * then don't put it on unless the group is on.
575 if (leader
!= counter
&& leader
->state
!= PERF_COUNTER_STATE_ACTIVE
)
578 if (!group_can_go_on(counter
, cpuctx
, 1))
581 err
= counter_sched_in(counter
, cpuctx
, ctx
,
586 * If this counter can't go on and it's part of a
587 * group, then the whole group has to come off.
589 if (leader
!= counter
)
590 group_sched_out(leader
, cpuctx
, ctx
);
591 if (leader
->hw_event
.pinned
)
592 leader
->state
= PERF_COUNTER_STATE_ERROR
;
596 spin_unlock(&ctx
->lock
);
597 curr_rq_unlock_irq_restore(&flags
);
603 static void perf_counter_enable(struct perf_counter
*counter
)
605 struct perf_counter_context
*ctx
= counter
->ctx
;
606 struct task_struct
*task
= ctx
->task
;
610 * Enable the counter on the cpu that it's on
612 smp_call_function_single(counter
->cpu
, __perf_counter_enable
,
617 spin_lock_irq(&ctx
->lock
);
618 if (counter
->state
>= PERF_COUNTER_STATE_INACTIVE
)
622 * If the counter is in error state, clear that first.
623 * That way, if we see the counter in error state below, we
624 * know that it has gone back into error state, as distinct
625 * from the task having been scheduled away before the
626 * cross-call arrived.
628 if (counter
->state
== PERF_COUNTER_STATE_ERROR
)
629 counter
->state
= PERF_COUNTER_STATE_OFF
;
632 spin_unlock_irq(&ctx
->lock
);
633 task_oncpu_function_call(task
, __perf_counter_enable
, counter
);
635 spin_lock_irq(&ctx
->lock
);
638 * If the context is active and the counter is still off,
639 * we need to retry the cross-call.
641 if (ctx
->is_active
&& counter
->state
== PERF_COUNTER_STATE_OFF
)
645 * Since we have the lock this context can't be scheduled
646 * in, so we can change the state safely.
648 if (counter
->state
== PERF_COUNTER_STATE_OFF
)
649 counter
->state
= PERF_COUNTER_STATE_INACTIVE
;
651 spin_unlock_irq(&ctx
->lock
);
655 * Enable a counter and all its children.
657 static void perf_counter_enable_family(struct perf_counter
*counter
)
659 struct perf_counter
*child
;
661 perf_counter_enable(counter
);
664 * Lock the mutex to protect the list of children
666 mutex_lock(&counter
->mutex
);
667 list_for_each_entry(child
, &counter
->child_list
, child_list
)
668 perf_counter_enable(child
);
669 mutex_unlock(&counter
->mutex
);
672 void __perf_counter_sched_out(struct perf_counter_context
*ctx
,
673 struct perf_cpu_context
*cpuctx
)
675 struct perf_counter
*counter
;
678 spin_lock(&ctx
->lock
);
680 if (likely(!ctx
->nr_counters
))
683 flags
= hw_perf_save_disable();
684 if (ctx
->nr_active
) {
685 list_for_each_entry(counter
, &ctx
->counter_list
, list_entry
)
686 group_sched_out(counter
, cpuctx
, ctx
);
688 hw_perf_restore(flags
);
690 spin_unlock(&ctx
->lock
);
694 * Called from scheduler to remove the counters of the current task,
695 * with interrupts disabled.
697 * We stop each counter and update the counter value in counter->count.
699 * This does not protect us against NMI, but disable()
700 * sets the disabled bit in the control field of counter _before_
701 * accessing the counter control register. If a NMI hits, then it will
702 * not restart the counter.
704 void perf_counter_task_sched_out(struct task_struct
*task
, int cpu
)
706 struct perf_cpu_context
*cpuctx
= &per_cpu(perf_cpu_context
, cpu
);
707 struct perf_counter_context
*ctx
= &task
->perf_counter_ctx
;
709 if (likely(!cpuctx
->task_ctx
))
712 __perf_counter_sched_out(ctx
, cpuctx
);
714 cpuctx
->task_ctx
= NULL
;
717 static void perf_counter_cpu_sched_out(struct perf_cpu_context
*cpuctx
)
719 __perf_counter_sched_out(&cpuctx
->ctx
, cpuctx
);
723 group_sched_in(struct perf_counter
*group_counter
,
724 struct perf_cpu_context
*cpuctx
,
725 struct perf_counter_context
*ctx
,
728 struct perf_counter
*counter
, *partial_group
;
731 if (group_counter
->state
== PERF_COUNTER_STATE_OFF
)
734 ret
= hw_perf_group_sched_in(group_counter
, cpuctx
, ctx
, cpu
);
736 return ret
< 0 ? ret
: 0;
738 group_counter
->prev_state
= group_counter
->state
;
739 if (counter_sched_in(group_counter
, cpuctx
, ctx
, cpu
))
743 * Schedule in siblings as one group (if any):
745 list_for_each_entry(counter
, &group_counter
->sibling_list
, list_entry
) {
746 counter
->prev_state
= counter
->state
;
747 if (counter_sched_in(counter
, cpuctx
, ctx
, cpu
)) {
748 partial_group
= counter
;
757 * Groups can be scheduled in as one unit only, so undo any
758 * partial group before returning:
760 list_for_each_entry(counter
, &group_counter
->sibling_list
, list_entry
) {
761 if (counter
== partial_group
)
763 counter_sched_out(counter
, cpuctx
, ctx
);
765 counter_sched_out(group_counter
, cpuctx
, ctx
);
771 __perf_counter_sched_in(struct perf_counter_context
*ctx
,
772 struct perf_cpu_context
*cpuctx
, int cpu
)
774 struct perf_counter
*counter
;
778 spin_lock(&ctx
->lock
);
780 if (likely(!ctx
->nr_counters
))
783 flags
= hw_perf_save_disable();
786 * First go through the list and put on any pinned groups
787 * in order to give them the best chance of going on.
789 list_for_each_entry(counter
, &ctx
->counter_list
, list_entry
) {
790 if (counter
->state
<= PERF_COUNTER_STATE_OFF
||
791 !counter
->hw_event
.pinned
)
793 if (counter
->cpu
!= -1 && counter
->cpu
!= cpu
)
796 if (group_can_go_on(counter
, cpuctx
, 1))
797 group_sched_in(counter
, cpuctx
, ctx
, cpu
);
800 * If this pinned group hasn't been scheduled,
801 * put it in error state.
803 if (counter
->state
== PERF_COUNTER_STATE_INACTIVE
)
804 counter
->state
= PERF_COUNTER_STATE_ERROR
;
807 list_for_each_entry(counter
, &ctx
->counter_list
, list_entry
) {
809 * Ignore counters in OFF or ERROR state, and
810 * ignore pinned counters since we did them already.
812 if (counter
->state
<= PERF_COUNTER_STATE_OFF
||
813 counter
->hw_event
.pinned
)
817 * Listen to the 'cpu' scheduling filter constraint
820 if (counter
->cpu
!= -1 && counter
->cpu
!= cpu
)
823 if (group_can_go_on(counter
, cpuctx
, can_add_hw
)) {
824 if (group_sched_in(counter
, cpuctx
, ctx
, cpu
))
828 hw_perf_restore(flags
);
830 spin_unlock(&ctx
->lock
);
834 * Called from scheduler to add the counters of the current task
835 * with interrupts disabled.
837 * We restore the counter value and then enable it.
839 * This does not protect us against NMI, but enable()
840 * sets the enabled bit in the control field of counter _before_
841 * accessing the counter control register. If a NMI hits, then it will
842 * keep the counter running.
844 void perf_counter_task_sched_in(struct task_struct
*task
, int cpu
)
846 struct perf_cpu_context
*cpuctx
= &per_cpu(perf_cpu_context
, cpu
);
847 struct perf_counter_context
*ctx
= &task
->perf_counter_ctx
;
849 __perf_counter_sched_in(ctx
, cpuctx
, cpu
);
850 cpuctx
->task_ctx
= ctx
;
853 static void perf_counter_cpu_sched_in(struct perf_cpu_context
*cpuctx
, int cpu
)
855 struct perf_counter_context
*ctx
= &cpuctx
->ctx
;
857 __perf_counter_sched_in(ctx
, cpuctx
, cpu
);
860 int perf_counter_task_disable(void)
862 struct task_struct
*curr
= current
;
863 struct perf_counter_context
*ctx
= &curr
->perf_counter_ctx
;
864 struct perf_counter
*counter
;
869 if (likely(!ctx
->nr_counters
))
872 curr_rq_lock_irq_save(&flags
);
873 cpu
= smp_processor_id();
875 /* force the update of the task clock: */
876 __task_delta_exec(curr
, 1);
878 perf_counter_task_sched_out(curr
, cpu
);
880 spin_lock(&ctx
->lock
);
883 * Disable all the counters:
885 perf_flags
= hw_perf_save_disable();
887 list_for_each_entry(counter
, &ctx
->counter_list
, list_entry
) {
888 if (counter
->state
!= PERF_COUNTER_STATE_ERROR
)
889 counter
->state
= PERF_COUNTER_STATE_OFF
;
892 hw_perf_restore(perf_flags
);
894 spin_unlock(&ctx
->lock
);
896 curr_rq_unlock_irq_restore(&flags
);
901 int perf_counter_task_enable(void)
903 struct task_struct
*curr
= current
;
904 struct perf_counter_context
*ctx
= &curr
->perf_counter_ctx
;
905 struct perf_counter
*counter
;
910 if (likely(!ctx
->nr_counters
))
913 curr_rq_lock_irq_save(&flags
);
914 cpu
= smp_processor_id();
916 /* force the update of the task clock: */
917 __task_delta_exec(curr
, 1);
919 perf_counter_task_sched_out(curr
, cpu
);
921 spin_lock(&ctx
->lock
);
924 * Disable all the counters:
926 perf_flags
= hw_perf_save_disable();
928 list_for_each_entry(counter
, &ctx
->counter_list
, list_entry
) {
929 if (counter
->state
> PERF_COUNTER_STATE_OFF
)
931 counter
->state
= PERF_COUNTER_STATE_INACTIVE
;
932 counter
->hw_event
.disabled
= 0;
934 hw_perf_restore(perf_flags
);
936 spin_unlock(&ctx
->lock
);
938 perf_counter_task_sched_in(curr
, cpu
);
940 curr_rq_unlock_irq_restore(&flags
);
946 * Round-robin a context's counters:
948 static void rotate_ctx(struct perf_counter_context
*ctx
)
950 struct perf_counter
*counter
;
953 if (!ctx
->nr_counters
)
956 spin_lock(&ctx
->lock
);
958 * Rotate the first entry last (works just fine for group counters too):
960 perf_flags
= hw_perf_save_disable();
961 list_for_each_entry(counter
, &ctx
->counter_list
, list_entry
) {
962 list_del(&counter
->list_entry
);
963 list_add_tail(&counter
->list_entry
, &ctx
->counter_list
);
966 hw_perf_restore(perf_flags
);
968 spin_unlock(&ctx
->lock
);
971 void perf_counter_task_tick(struct task_struct
*curr
, int cpu
)
973 struct perf_cpu_context
*cpuctx
= &per_cpu(perf_cpu_context
, cpu
);
974 struct perf_counter_context
*ctx
= &curr
->perf_counter_ctx
;
975 const int rotate_percpu
= 0;
978 perf_counter_cpu_sched_out(cpuctx
);
979 perf_counter_task_sched_out(curr
, cpu
);
982 rotate_ctx(&cpuctx
->ctx
);
986 perf_counter_cpu_sched_in(cpuctx
, cpu
);
987 perf_counter_task_sched_in(curr
, cpu
);
991 * Cross CPU call to read the hardware counter
993 static void __read(void *info
)
995 struct perf_counter
*counter
= info
;
998 curr_rq_lock_irq_save(&flags
);
999 counter
->hw_ops
->read(counter
);
1000 curr_rq_unlock_irq_restore(&flags
);
1003 static u64
perf_counter_read(struct perf_counter
*counter
)
1006 * If counter is enabled and currently active on a CPU, update the
1007 * value in the counter structure:
1009 if (counter
->state
== PERF_COUNTER_STATE_ACTIVE
) {
1010 smp_call_function_single(counter
->oncpu
,
1011 __read
, counter
, 1);
1014 return atomic64_read(&counter
->count
);
1018 * Cross CPU call to switch performance data pointers
1020 static void __perf_switch_irq_data(void *info
)
1022 struct perf_cpu_context
*cpuctx
= &__get_cpu_var(perf_cpu_context
);
1023 struct perf_counter
*counter
= info
;
1024 struct perf_counter_context
*ctx
= counter
->ctx
;
1025 struct perf_data
*oldirqdata
= counter
->irqdata
;
1028 * If this is a task context, we need to check whether it is
1029 * the current task context of this cpu. If not it has been
1030 * scheduled out before the smp call arrived.
1033 if (cpuctx
->task_ctx
!= ctx
)
1035 spin_lock(&ctx
->lock
);
1038 /* Change the pointer NMI safe */
1039 atomic_long_set((atomic_long_t
*)&counter
->irqdata
,
1040 (unsigned long) counter
->usrdata
);
1041 counter
->usrdata
= oldirqdata
;
1044 spin_unlock(&ctx
->lock
);
1047 static struct perf_data
*perf_switch_irq_data(struct perf_counter
*counter
)
1049 struct perf_counter_context
*ctx
= counter
->ctx
;
1050 struct perf_data
*oldirqdata
= counter
->irqdata
;
1051 struct task_struct
*task
= ctx
->task
;
1054 smp_call_function_single(counter
->cpu
,
1055 __perf_switch_irq_data
,
1057 return counter
->usrdata
;
1061 spin_lock_irq(&ctx
->lock
);
1062 if (counter
->state
!= PERF_COUNTER_STATE_ACTIVE
) {
1063 counter
->irqdata
= counter
->usrdata
;
1064 counter
->usrdata
= oldirqdata
;
1065 spin_unlock_irq(&ctx
->lock
);
1068 spin_unlock_irq(&ctx
->lock
);
1069 task_oncpu_function_call(task
, __perf_switch_irq_data
, counter
);
1070 /* Might have failed, because task was scheduled out */
1071 if (counter
->irqdata
== oldirqdata
)
1074 return counter
->usrdata
;
1077 static void put_context(struct perf_counter_context
*ctx
)
1080 put_task_struct(ctx
->task
);
1083 static struct perf_counter_context
*find_get_context(pid_t pid
, int cpu
)
1085 struct perf_cpu_context
*cpuctx
;
1086 struct perf_counter_context
*ctx
;
1087 struct task_struct
*task
;
1090 * If cpu is not a wildcard then this is a percpu counter:
1093 /* Must be root to operate on a CPU counter: */
1094 if (!capable(CAP_SYS_ADMIN
))
1095 return ERR_PTR(-EACCES
);
1097 if (cpu
< 0 || cpu
> num_possible_cpus())
1098 return ERR_PTR(-EINVAL
);
1101 * We could be clever and allow to attach a counter to an
1102 * offline CPU and activate it when the CPU comes up, but
1105 if (!cpu_isset(cpu
, cpu_online_map
))
1106 return ERR_PTR(-ENODEV
);
1108 cpuctx
= &per_cpu(perf_cpu_context
, cpu
);
1118 task
= find_task_by_vpid(pid
);
1120 get_task_struct(task
);
1124 return ERR_PTR(-ESRCH
);
1126 ctx
= &task
->perf_counter_ctx
;
1129 /* Reuse ptrace permission checks for now. */
1130 if (!ptrace_may_access(task
, PTRACE_MODE_READ
)) {
1132 return ERR_PTR(-EACCES
);
1139 * Called when the last reference to the file is gone.
1141 static int perf_release(struct inode
*inode
, struct file
*file
)
1143 struct perf_counter
*counter
= file
->private_data
;
1144 struct perf_counter_context
*ctx
= counter
->ctx
;
1146 file
->private_data
= NULL
;
1148 mutex_lock(&ctx
->mutex
);
1149 mutex_lock(&counter
->mutex
);
1151 perf_counter_remove_from_context(counter
);
1153 mutex_unlock(&counter
->mutex
);
1154 mutex_unlock(&ctx
->mutex
);
1163 * Read the performance counter - simple non blocking version for now
1166 perf_read_hw(struct perf_counter
*counter
, char __user
*buf
, size_t count
)
1170 if (count
!= sizeof(cntval
))
1174 * Return end-of-file for a read on a counter that is in
1175 * error state (i.e. because it was pinned but it couldn't be
1176 * scheduled on to the CPU at some point).
1178 if (counter
->state
== PERF_COUNTER_STATE_ERROR
)
1181 mutex_lock(&counter
->mutex
);
1182 cntval
= perf_counter_read(counter
);
1183 mutex_unlock(&counter
->mutex
);
1185 return put_user(cntval
, (u64 __user
*) buf
) ? -EFAULT
: sizeof(cntval
);
1189 perf_copy_usrdata(struct perf_data
*usrdata
, char __user
*buf
, size_t count
)
1194 count
= min(count
, (size_t)usrdata
->len
);
1195 if (copy_to_user(buf
, usrdata
->data
+ usrdata
->rd_idx
, count
))
1198 /* Adjust the counters */
1199 usrdata
->len
-= count
;
1201 usrdata
->rd_idx
= 0;
1203 usrdata
->rd_idx
+= count
;
1209 perf_read_irq_data(struct perf_counter
*counter
,
1214 struct perf_data
*irqdata
, *usrdata
;
1215 DECLARE_WAITQUEUE(wait
, current
);
1218 irqdata
= counter
->irqdata
;
1219 usrdata
= counter
->usrdata
;
1221 if (usrdata
->len
+ irqdata
->len
>= count
)
1227 spin_lock_irq(&counter
->waitq
.lock
);
1228 __add_wait_queue(&counter
->waitq
, &wait
);
1230 set_current_state(TASK_INTERRUPTIBLE
);
1231 if (usrdata
->len
+ irqdata
->len
>= count
)
1234 if (signal_pending(current
))
1237 if (counter
->state
== PERF_COUNTER_STATE_ERROR
)
1240 spin_unlock_irq(&counter
->waitq
.lock
);
1242 spin_lock_irq(&counter
->waitq
.lock
);
1244 __remove_wait_queue(&counter
->waitq
, &wait
);
1245 __set_current_state(TASK_RUNNING
);
1246 spin_unlock_irq(&counter
->waitq
.lock
);
1248 if (usrdata
->len
+ irqdata
->len
< count
&&
1249 counter
->state
!= PERF_COUNTER_STATE_ERROR
)
1250 return -ERESTARTSYS
;
1252 mutex_lock(&counter
->mutex
);
1254 /* Drain pending data first: */
1255 res
= perf_copy_usrdata(usrdata
, buf
, count
);
1256 if (res
< 0 || res
== count
)
1259 /* Switch irq buffer: */
1260 usrdata
= perf_switch_irq_data(counter
);
1261 res2
= perf_copy_usrdata(usrdata
, buf
+ res
, count
- res
);
1269 mutex_unlock(&counter
->mutex
);
1275 perf_read(struct file
*file
, char __user
*buf
, size_t count
, loff_t
*ppos
)
1277 struct perf_counter
*counter
= file
->private_data
;
1279 switch (counter
->hw_event
.record_type
) {
1280 case PERF_RECORD_SIMPLE
:
1281 return perf_read_hw(counter
, buf
, count
);
1283 case PERF_RECORD_IRQ
:
1284 case PERF_RECORD_GROUP
:
1285 return perf_read_irq_data(counter
, buf
, count
,
1286 file
->f_flags
& O_NONBLOCK
);
1291 static unsigned int perf_poll(struct file
*file
, poll_table
*wait
)
1293 struct perf_counter
*counter
= file
->private_data
;
1294 unsigned int events
= 0;
1295 unsigned long flags
;
1297 poll_wait(file
, &counter
->waitq
, wait
);
1299 spin_lock_irqsave(&counter
->waitq
.lock
, flags
);
1300 if (counter
->usrdata
->len
|| counter
->irqdata
->len
)
1302 spin_unlock_irqrestore(&counter
->waitq
.lock
, flags
);
1307 static long perf_ioctl(struct file
*file
, unsigned int cmd
, unsigned long arg
)
1309 struct perf_counter
*counter
= file
->private_data
;
1313 case PERF_COUNTER_IOC_ENABLE
:
1314 perf_counter_enable_family(counter
);
1316 case PERF_COUNTER_IOC_DISABLE
:
1317 perf_counter_disable_family(counter
);
1325 static const struct file_operations perf_fops
= {
1326 .release
= perf_release
,
1329 .unlocked_ioctl
= perf_ioctl
,
1330 .compat_ioctl
= perf_ioctl
,
1333 static int cpu_clock_perf_counter_enable(struct perf_counter
*counter
)
1335 int cpu
= raw_smp_processor_id();
1337 atomic64_set(&counter
->hw
.prev_count
, cpu_clock(cpu
));
1341 static void cpu_clock_perf_counter_update(struct perf_counter
*counter
)
1343 int cpu
= raw_smp_processor_id();
1347 now
= cpu_clock(cpu
);
1348 prev
= atomic64_read(&counter
->hw
.prev_count
);
1349 atomic64_set(&counter
->hw
.prev_count
, now
);
1350 atomic64_add(now
- prev
, &counter
->count
);
1353 static void cpu_clock_perf_counter_disable(struct perf_counter
*counter
)
1355 cpu_clock_perf_counter_update(counter
);
1358 static void cpu_clock_perf_counter_read(struct perf_counter
*counter
)
1360 cpu_clock_perf_counter_update(counter
);
1363 static const struct hw_perf_counter_ops perf_ops_cpu_clock
= {
1364 .enable
= cpu_clock_perf_counter_enable
,
1365 .disable
= cpu_clock_perf_counter_disable
,
1366 .read
= cpu_clock_perf_counter_read
,
1370 * Called from within the scheduler:
1372 static u64
task_clock_perf_counter_val(struct perf_counter
*counter
, int update
)
1374 struct task_struct
*curr
= counter
->task
;
1377 delta
= __task_delta_exec(curr
, update
);
1379 return curr
->se
.sum_exec_runtime
+ delta
;
1382 static void task_clock_perf_counter_update(struct perf_counter
*counter
, u64 now
)
1387 prev
= atomic64_read(&counter
->hw
.prev_count
);
1389 atomic64_set(&counter
->hw
.prev_count
, now
);
1393 atomic64_add(delta
, &counter
->count
);
1396 static void task_clock_perf_counter_read(struct perf_counter
*counter
)
1398 u64 now
= task_clock_perf_counter_val(counter
, 1);
1400 task_clock_perf_counter_update(counter
, now
);
1403 static int task_clock_perf_counter_enable(struct perf_counter
*counter
)
1405 if (counter
->prev_state
<= PERF_COUNTER_STATE_OFF
)
1406 atomic64_set(&counter
->hw
.prev_count
,
1407 task_clock_perf_counter_val(counter
, 0));
1412 static void task_clock_perf_counter_disable(struct perf_counter
*counter
)
1414 u64 now
= task_clock_perf_counter_val(counter
, 0);
1416 task_clock_perf_counter_update(counter
, now
);
1419 static const struct hw_perf_counter_ops perf_ops_task_clock
= {
1420 .enable
= task_clock_perf_counter_enable
,
1421 .disable
= task_clock_perf_counter_disable
,
1422 .read
= task_clock_perf_counter_read
,
1425 #ifdef CONFIG_VM_EVENT_COUNTERS
1426 #define cpu_page_faults() __get_cpu_var(vm_event_states).event[PGFAULT]
1428 #define cpu_page_faults() 0
1431 static u64
get_page_faults(struct perf_counter
*counter
)
1433 struct task_struct
*curr
= counter
->ctx
->task
;
1436 return curr
->maj_flt
+ curr
->min_flt
;
1437 return cpu_page_faults();
1440 static void page_faults_perf_counter_update(struct perf_counter
*counter
)
1445 prev
= atomic64_read(&counter
->hw
.prev_count
);
1446 now
= get_page_faults(counter
);
1448 atomic64_set(&counter
->hw
.prev_count
, now
);
1452 atomic64_add(delta
, &counter
->count
);
1455 static void page_faults_perf_counter_read(struct perf_counter
*counter
)
1457 page_faults_perf_counter_update(counter
);
1460 static int page_faults_perf_counter_enable(struct perf_counter
*counter
)
1462 if (counter
->prev_state
<= PERF_COUNTER_STATE_OFF
)
1463 atomic64_set(&counter
->hw
.prev_count
, get_page_faults(counter
));
1467 static void page_faults_perf_counter_disable(struct perf_counter
*counter
)
1469 page_faults_perf_counter_update(counter
);
1472 static const struct hw_perf_counter_ops perf_ops_page_faults
= {
1473 .enable
= page_faults_perf_counter_enable
,
1474 .disable
= page_faults_perf_counter_disable
,
1475 .read
= page_faults_perf_counter_read
,
1478 static u64
get_context_switches(struct perf_counter
*counter
)
1480 struct task_struct
*curr
= counter
->ctx
->task
;
1483 return curr
->nvcsw
+ curr
->nivcsw
;
1484 return cpu_nr_switches(smp_processor_id());
1487 static void context_switches_perf_counter_update(struct perf_counter
*counter
)
1492 prev
= atomic64_read(&counter
->hw
.prev_count
);
1493 now
= get_context_switches(counter
);
1495 atomic64_set(&counter
->hw
.prev_count
, now
);
1499 atomic64_add(delta
, &counter
->count
);
1502 static void context_switches_perf_counter_read(struct perf_counter
*counter
)
1504 context_switches_perf_counter_update(counter
);
1507 static int context_switches_perf_counter_enable(struct perf_counter
*counter
)
1509 if (counter
->prev_state
<= PERF_COUNTER_STATE_OFF
)
1510 atomic64_set(&counter
->hw
.prev_count
,
1511 get_context_switches(counter
));
1515 static void context_switches_perf_counter_disable(struct perf_counter
*counter
)
1517 context_switches_perf_counter_update(counter
);
1520 static const struct hw_perf_counter_ops perf_ops_context_switches
= {
1521 .enable
= context_switches_perf_counter_enable
,
1522 .disable
= context_switches_perf_counter_disable
,
1523 .read
= context_switches_perf_counter_read
,
1526 static inline u64
get_cpu_migrations(struct perf_counter
*counter
)
1528 struct task_struct
*curr
= counter
->ctx
->task
;
1531 return curr
->se
.nr_migrations
;
1532 return cpu_nr_migrations(smp_processor_id());
1535 static void cpu_migrations_perf_counter_update(struct perf_counter
*counter
)
1540 prev
= atomic64_read(&counter
->hw
.prev_count
);
1541 now
= get_cpu_migrations(counter
);
1543 atomic64_set(&counter
->hw
.prev_count
, now
);
1547 atomic64_add(delta
, &counter
->count
);
1550 static void cpu_migrations_perf_counter_read(struct perf_counter
*counter
)
1552 cpu_migrations_perf_counter_update(counter
);
1555 static int cpu_migrations_perf_counter_enable(struct perf_counter
*counter
)
1557 if (counter
->prev_state
<= PERF_COUNTER_STATE_OFF
)
1558 atomic64_set(&counter
->hw
.prev_count
,
1559 get_cpu_migrations(counter
));
1563 static void cpu_migrations_perf_counter_disable(struct perf_counter
*counter
)
1565 cpu_migrations_perf_counter_update(counter
);
1568 static const struct hw_perf_counter_ops perf_ops_cpu_migrations
= {
1569 .enable
= cpu_migrations_perf_counter_enable
,
1570 .disable
= cpu_migrations_perf_counter_disable
,
1571 .read
= cpu_migrations_perf_counter_read
,
1574 static const struct hw_perf_counter_ops
*
1575 sw_perf_counter_init(struct perf_counter
*counter
)
1577 const struct hw_perf_counter_ops
*hw_ops
= NULL
;
1580 * Software counters (currently) can't in general distinguish
1581 * between user, kernel and hypervisor events.
1582 * However, context switches and cpu migrations are considered
1583 * to be kernel events, and page faults are never hypervisor
1586 switch (counter
->hw_event
.type
) {
1587 case PERF_COUNT_CPU_CLOCK
:
1588 if (!(counter
->hw_event
.exclude_user
||
1589 counter
->hw_event
.exclude_kernel
||
1590 counter
->hw_event
.exclude_hv
))
1591 hw_ops
= &perf_ops_cpu_clock
;
1593 case PERF_COUNT_TASK_CLOCK
:
1594 if (counter
->hw_event
.exclude_user
||
1595 counter
->hw_event
.exclude_kernel
||
1596 counter
->hw_event
.exclude_hv
)
1599 * If the user instantiates this as a per-cpu counter,
1600 * use the cpu_clock counter instead.
1602 if (counter
->ctx
->task
)
1603 hw_ops
= &perf_ops_task_clock
;
1605 hw_ops
= &perf_ops_cpu_clock
;
1607 case PERF_COUNT_PAGE_FAULTS
:
1608 if (!(counter
->hw_event
.exclude_user
||
1609 counter
->hw_event
.exclude_kernel
))
1610 hw_ops
= &perf_ops_page_faults
;
1612 case PERF_COUNT_CONTEXT_SWITCHES
:
1613 if (!counter
->hw_event
.exclude_kernel
)
1614 hw_ops
= &perf_ops_context_switches
;
1616 case PERF_COUNT_CPU_MIGRATIONS
:
1617 if (!counter
->hw_event
.exclude_kernel
)
1618 hw_ops
= &perf_ops_cpu_migrations
;
1627 * Allocate and initialize a counter structure
1629 static struct perf_counter
*
1630 perf_counter_alloc(struct perf_counter_hw_event
*hw_event
,
1632 struct perf_counter_context
*ctx
,
1633 struct perf_counter
*group_leader
,
1636 const struct hw_perf_counter_ops
*hw_ops
;
1637 struct perf_counter
*counter
;
1639 counter
= kzalloc(sizeof(*counter
), gfpflags
);
1644 * Single counters are their own group leaders, with an
1645 * empty sibling list:
1648 group_leader
= counter
;
1650 mutex_init(&counter
->mutex
);
1651 INIT_LIST_HEAD(&counter
->list_entry
);
1652 INIT_LIST_HEAD(&counter
->sibling_list
);
1653 init_waitqueue_head(&counter
->waitq
);
1655 INIT_LIST_HEAD(&counter
->child_list
);
1657 counter
->irqdata
= &counter
->data
[0];
1658 counter
->usrdata
= &counter
->data
[1];
1660 counter
->hw_event
= *hw_event
;
1661 counter
->wakeup_pending
= 0;
1662 counter
->group_leader
= group_leader
;
1663 counter
->hw_ops
= NULL
;
1666 counter
->state
= PERF_COUNTER_STATE_INACTIVE
;
1667 if (hw_event
->disabled
)
1668 counter
->state
= PERF_COUNTER_STATE_OFF
;
1671 if (!hw_event
->raw
&& hw_event
->type
< 0)
1672 hw_ops
= sw_perf_counter_init(counter
);
1674 hw_ops
= hw_perf_counter_init(counter
);
1680 counter
->hw_ops
= hw_ops
;
1686 * sys_perf_counter_open - open a performance counter, associate it to a task/cpu
1688 * @hw_event_uptr: event type attributes for monitoring/sampling
1691 * @group_fd: group leader counter fd
1693 SYSCALL_DEFINE5(perf_counter_open
,
1694 const struct perf_counter_hw_event __user
*, hw_event_uptr
,
1695 pid_t
, pid
, int, cpu
, int, group_fd
, unsigned long, flags
)
1697 struct perf_counter
*counter
, *group_leader
;
1698 struct perf_counter_hw_event hw_event
;
1699 struct perf_counter_context
*ctx
;
1700 struct file
*counter_file
= NULL
;
1701 struct file
*group_file
= NULL
;
1702 int fput_needed
= 0;
1703 int fput_needed2
= 0;
1706 /* for future expandability... */
1710 if (copy_from_user(&hw_event
, hw_event_uptr
, sizeof(hw_event
)) != 0)
1714 * Get the target context (task or percpu):
1716 ctx
= find_get_context(pid
, cpu
);
1718 return PTR_ERR(ctx
);
1721 * Look up the group leader (we will attach this counter to it):
1723 group_leader
= NULL
;
1724 if (group_fd
!= -1) {
1726 group_file
= fget_light(group_fd
, &fput_needed
);
1728 goto err_put_context
;
1729 if (group_file
->f_op
!= &perf_fops
)
1730 goto err_put_context
;
1732 group_leader
= group_file
->private_data
;
1734 * Do not allow a recursive hierarchy (this new sibling
1735 * becoming part of another group-sibling):
1737 if (group_leader
->group_leader
!= group_leader
)
1738 goto err_put_context
;
1740 * Do not allow to attach to a group in a different
1741 * task or CPU context:
1743 if (group_leader
->ctx
!= ctx
)
1744 goto err_put_context
;
1746 * Only a group leader can be exclusive or pinned
1748 if (hw_event
.exclusive
|| hw_event
.pinned
)
1749 goto err_put_context
;
1753 counter
= perf_counter_alloc(&hw_event
, cpu
, ctx
, group_leader
,
1756 goto err_put_context
;
1758 ret
= anon_inode_getfd("[perf_counter]", &perf_fops
, counter
, 0);
1760 goto err_free_put_context
;
1762 counter_file
= fget_light(ret
, &fput_needed2
);
1764 goto err_free_put_context
;
1766 counter
->filp
= counter_file
;
1767 mutex_lock(&ctx
->mutex
);
1768 perf_install_in_context(ctx
, counter
, cpu
);
1769 mutex_unlock(&ctx
->mutex
);
1771 fput_light(counter_file
, fput_needed2
);
1774 fput_light(group_file
, fput_needed
);
1778 err_free_put_context
:
1788 * Initialize the perf_counter context in a task_struct:
1791 __perf_counter_init_context(struct perf_counter_context
*ctx
,
1792 struct task_struct
*task
)
1794 memset(ctx
, 0, sizeof(*ctx
));
1795 spin_lock_init(&ctx
->lock
);
1796 mutex_init(&ctx
->mutex
);
1797 INIT_LIST_HEAD(&ctx
->counter_list
);
1802 * inherit a counter from parent task to child task:
1804 static struct perf_counter
*
1805 inherit_counter(struct perf_counter
*parent_counter
,
1806 struct task_struct
*parent
,
1807 struct perf_counter_context
*parent_ctx
,
1808 struct task_struct
*child
,
1809 struct perf_counter
*group_leader
,
1810 struct perf_counter_context
*child_ctx
)
1812 struct perf_counter
*child_counter
;
1815 * Instead of creating recursive hierarchies of counters,
1816 * we link inherited counters back to the original parent,
1817 * which has a filp for sure, which we use as the reference
1820 if (parent_counter
->parent
)
1821 parent_counter
= parent_counter
->parent
;
1823 child_counter
= perf_counter_alloc(&parent_counter
->hw_event
,
1824 parent_counter
->cpu
, child_ctx
,
1825 group_leader
, GFP_KERNEL
);
1830 * Link it up in the child's context:
1832 child_counter
->task
= child
;
1833 list_add_counter(child_counter
, child_ctx
);
1834 child_ctx
->nr_counters
++;
1836 child_counter
->parent
= parent_counter
;
1838 * inherit into child's child as well:
1840 child_counter
->hw_event
.inherit
= 1;
1843 * Get a reference to the parent filp - we will fput it
1844 * when the child counter exits. This is safe to do because
1845 * we are in the parent and we know that the filp still
1846 * exists and has a nonzero count:
1848 atomic_long_inc(&parent_counter
->filp
->f_count
);
1851 * Link this into the parent counter's child list
1853 mutex_lock(&parent_counter
->mutex
);
1854 list_add_tail(&child_counter
->child_list
, &parent_counter
->child_list
);
1857 * Make the child state follow the state of the parent counter,
1858 * not its hw_event.disabled bit. We hold the parent's mutex,
1859 * so we won't race with perf_counter_{en,dis}able_family.
1861 if (parent_counter
->state
>= PERF_COUNTER_STATE_INACTIVE
)
1862 child_counter
->state
= PERF_COUNTER_STATE_INACTIVE
;
1864 child_counter
->state
= PERF_COUNTER_STATE_OFF
;
1866 mutex_unlock(&parent_counter
->mutex
);
1868 return child_counter
;
1871 static int inherit_group(struct perf_counter
*parent_counter
,
1872 struct task_struct
*parent
,
1873 struct perf_counter_context
*parent_ctx
,
1874 struct task_struct
*child
,
1875 struct perf_counter_context
*child_ctx
)
1877 struct perf_counter
*leader
;
1878 struct perf_counter
*sub
;
1880 leader
= inherit_counter(parent_counter
, parent
, parent_ctx
,
1881 child
, NULL
, child_ctx
);
1884 list_for_each_entry(sub
, &parent_counter
->sibling_list
, list_entry
) {
1885 if (!inherit_counter(sub
, parent
, parent_ctx
,
1886 child
, leader
, child_ctx
))
1892 static void sync_child_counter(struct perf_counter
*child_counter
,
1893 struct perf_counter
*parent_counter
)
1895 u64 parent_val
, child_val
;
1897 parent_val
= atomic64_read(&parent_counter
->count
);
1898 child_val
= atomic64_read(&child_counter
->count
);
1901 * Add back the child's count to the parent's count:
1903 atomic64_add(child_val
, &parent_counter
->count
);
1906 * Remove this counter from the parent's list
1908 mutex_lock(&parent_counter
->mutex
);
1909 list_del_init(&child_counter
->child_list
);
1910 mutex_unlock(&parent_counter
->mutex
);
1913 * Release the parent counter, if this was the last
1916 fput(parent_counter
->filp
);
1920 __perf_counter_exit_task(struct task_struct
*child
,
1921 struct perf_counter
*child_counter
,
1922 struct perf_counter_context
*child_ctx
)
1924 struct perf_counter
*parent_counter
;
1925 struct perf_counter
*sub
, *tmp
;
1928 * If we do not self-reap then we have to wait for the
1929 * child task to unschedule (it will happen for sure),
1930 * so that its counter is at its final count. (This
1931 * condition triggers rarely - child tasks usually get
1932 * off their CPU before the parent has a chance to
1933 * get this far into the reaping action)
1935 if (child
!= current
) {
1936 wait_task_inactive(child
, 0);
1937 list_del_init(&child_counter
->list_entry
);
1939 struct perf_cpu_context
*cpuctx
;
1940 unsigned long flags
;
1944 * Disable and unlink this counter.
1946 * Be careful about zapping the list - IRQ/NMI context
1947 * could still be processing it:
1949 curr_rq_lock_irq_save(&flags
);
1950 perf_flags
= hw_perf_save_disable();
1952 cpuctx
= &__get_cpu_var(perf_cpu_context
);
1954 group_sched_out(child_counter
, cpuctx
, child_ctx
);
1956 list_del_init(&child_counter
->list_entry
);
1958 child_ctx
->nr_counters
--;
1960 hw_perf_restore(perf_flags
);
1961 curr_rq_unlock_irq_restore(&flags
);
1964 parent_counter
= child_counter
->parent
;
1966 * It can happen that parent exits first, and has counters
1967 * that are still around due to the child reference. These
1968 * counters need to be zapped - but otherwise linger.
1970 if (parent_counter
) {
1971 sync_child_counter(child_counter
, parent_counter
);
1972 list_for_each_entry_safe(sub
, tmp
, &child_counter
->sibling_list
,
1975 sync_child_counter(sub
, sub
->parent
);
1979 kfree(child_counter
);
1984 * When a child task exits, feed back counter values to parent counters.
1986 * Note: we may be running in child context, but the PID is not hashed
1987 * anymore so new counters will not be added.
1989 void perf_counter_exit_task(struct task_struct
*child
)
1991 struct perf_counter
*child_counter
, *tmp
;
1992 struct perf_counter_context
*child_ctx
;
1994 child_ctx
= &child
->perf_counter_ctx
;
1996 if (likely(!child_ctx
->nr_counters
))
1999 list_for_each_entry_safe(child_counter
, tmp
, &child_ctx
->counter_list
,
2001 __perf_counter_exit_task(child
, child_counter
, child_ctx
);
2005 * Initialize the perf_counter context in task_struct
2007 void perf_counter_init_task(struct task_struct
*child
)
2009 struct perf_counter_context
*child_ctx
, *parent_ctx
;
2010 struct perf_counter
*counter
;
2011 struct task_struct
*parent
= current
;
2013 child_ctx
= &child
->perf_counter_ctx
;
2014 parent_ctx
= &parent
->perf_counter_ctx
;
2016 __perf_counter_init_context(child_ctx
, child
);
2019 * This is executed from the parent task context, so inherit
2020 * counters that have been marked for cloning:
2023 if (likely(!parent_ctx
->nr_counters
))
2027 * Lock the parent list. No need to lock the child - not PID
2028 * hashed yet and not running, so nobody can access it.
2030 mutex_lock(&parent_ctx
->mutex
);
2033 * We dont have to disable NMIs - we are only looking at
2034 * the list, not manipulating it:
2036 list_for_each_entry(counter
, &parent_ctx
->counter_list
, list_entry
) {
2037 if (!counter
->hw_event
.inherit
)
2040 if (inherit_group(counter
, parent
,
2041 parent_ctx
, child
, child_ctx
))
2045 mutex_unlock(&parent_ctx
->mutex
);
2048 static void __cpuinit
perf_counter_init_cpu(int cpu
)
2050 struct perf_cpu_context
*cpuctx
;
2052 cpuctx
= &per_cpu(perf_cpu_context
, cpu
);
2053 __perf_counter_init_context(&cpuctx
->ctx
, NULL
);
2055 mutex_lock(&perf_resource_mutex
);
2056 cpuctx
->max_pertask
= perf_max_counters
- perf_reserved_percpu
;
2057 mutex_unlock(&perf_resource_mutex
);
2059 hw_perf_counter_setup(cpu
);
2062 #ifdef CONFIG_HOTPLUG_CPU
2063 static void __perf_counter_exit_cpu(void *info
)
2065 struct perf_cpu_context
*cpuctx
= &__get_cpu_var(perf_cpu_context
);
2066 struct perf_counter_context
*ctx
= &cpuctx
->ctx
;
2067 struct perf_counter
*counter
, *tmp
;
2069 list_for_each_entry_safe(counter
, tmp
, &ctx
->counter_list
, list_entry
)
2070 __perf_counter_remove_from_context(counter
);
2072 static void perf_counter_exit_cpu(int cpu
)
2074 struct perf_cpu_context
*cpuctx
= &per_cpu(perf_cpu_context
, cpu
);
2075 struct perf_counter_context
*ctx
= &cpuctx
->ctx
;
2077 mutex_lock(&ctx
->mutex
);
2078 smp_call_function_single(cpu
, __perf_counter_exit_cpu
, NULL
, 1);
2079 mutex_unlock(&ctx
->mutex
);
2082 static inline void perf_counter_exit_cpu(int cpu
) { }
2085 static int __cpuinit
2086 perf_cpu_notify(struct notifier_block
*self
, unsigned long action
, void *hcpu
)
2088 unsigned int cpu
= (long)hcpu
;
2092 case CPU_UP_PREPARE
:
2093 case CPU_UP_PREPARE_FROZEN
:
2094 perf_counter_init_cpu(cpu
);
2097 case CPU_DOWN_PREPARE
:
2098 case CPU_DOWN_PREPARE_FROZEN
:
2099 perf_counter_exit_cpu(cpu
);
2109 static struct notifier_block __cpuinitdata perf_cpu_nb
= {
2110 .notifier_call
= perf_cpu_notify
,
2113 static int __init
perf_counter_init(void)
2115 perf_cpu_notify(&perf_cpu_nb
, (unsigned long)CPU_UP_PREPARE
,
2116 (void *)(long)smp_processor_id());
2117 register_cpu_notifier(&perf_cpu_nb
);
2121 early_initcall(perf_counter_init
);
2123 static ssize_t
perf_show_reserve_percpu(struct sysdev_class
*class, char *buf
)
2125 return sprintf(buf
, "%d\n", perf_reserved_percpu
);
2129 perf_set_reserve_percpu(struct sysdev_class
*class,
2133 struct perf_cpu_context
*cpuctx
;
2137 err
= strict_strtoul(buf
, 10, &val
);
2140 if (val
> perf_max_counters
)
2143 mutex_lock(&perf_resource_mutex
);
2144 perf_reserved_percpu
= val
;
2145 for_each_online_cpu(cpu
) {
2146 cpuctx
= &per_cpu(perf_cpu_context
, cpu
);
2147 spin_lock_irq(&cpuctx
->ctx
.lock
);
2148 mpt
= min(perf_max_counters
- cpuctx
->ctx
.nr_counters
,
2149 perf_max_counters
- perf_reserved_percpu
);
2150 cpuctx
->max_pertask
= mpt
;
2151 spin_unlock_irq(&cpuctx
->ctx
.lock
);
2153 mutex_unlock(&perf_resource_mutex
);
2158 static ssize_t
perf_show_overcommit(struct sysdev_class
*class, char *buf
)
2160 return sprintf(buf
, "%d\n", perf_overcommit
);
2164 perf_set_overcommit(struct sysdev_class
*class, const char *buf
, size_t count
)
2169 err
= strict_strtoul(buf
, 10, &val
);
2175 mutex_lock(&perf_resource_mutex
);
2176 perf_overcommit
= val
;
2177 mutex_unlock(&perf_resource_mutex
);
2182 static SYSDEV_CLASS_ATTR(
2185 perf_show_reserve_percpu
,
2186 perf_set_reserve_percpu
2189 static SYSDEV_CLASS_ATTR(
2192 perf_show_overcommit
,
2196 static struct attribute
*perfclass_attrs
[] = {
2197 &attr_reserve_percpu
.attr
,
2198 &attr_overcommit
.attr
,
2202 static struct attribute_group perfclass_attr_group
= {
2203 .attrs
= perfclass_attrs
,
2204 .name
= "perf_counters",
2207 static int __init
perf_counter_sysfs_init(void)
2209 return sysfs_create_group(&cpu_sysdev_class
.kset
.kobj
,
2210 &perfclass_attr_group
);
2212 device_initcall(perf_counter_sysfs_init
);