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_move_tail(&sibling
->list_entry
, &ctx
->counter_list
);
93 sibling
->group_leader
= sibling
;
98 counter_sched_out(struct perf_counter
*counter
,
99 struct perf_cpu_context
*cpuctx
,
100 struct perf_counter_context
*ctx
)
102 if (counter
->state
!= PERF_COUNTER_STATE_ACTIVE
)
105 counter
->state
= PERF_COUNTER_STATE_INACTIVE
;
106 counter
->hw_ops
->disable(counter
);
109 if (!is_software_counter(counter
))
110 cpuctx
->active_oncpu
--;
112 if (counter
->hw_event
.exclusive
|| !cpuctx
->active_oncpu
)
113 cpuctx
->exclusive
= 0;
117 group_sched_out(struct perf_counter
*group_counter
,
118 struct perf_cpu_context
*cpuctx
,
119 struct perf_counter_context
*ctx
)
121 struct perf_counter
*counter
;
123 if (group_counter
->state
!= PERF_COUNTER_STATE_ACTIVE
)
126 counter_sched_out(group_counter
, cpuctx
, ctx
);
129 * Schedule out siblings (if any):
131 list_for_each_entry(counter
, &group_counter
->sibling_list
, list_entry
)
132 counter_sched_out(counter
, cpuctx
, ctx
);
134 if (group_counter
->hw_event
.exclusive
)
135 cpuctx
->exclusive
= 0;
139 * Cross CPU call to remove a performance counter
141 * We disable the counter on the hardware level first. After that we
142 * remove it from the context list.
144 static void __perf_counter_remove_from_context(void *info
)
146 struct perf_cpu_context
*cpuctx
= &__get_cpu_var(perf_cpu_context
);
147 struct perf_counter
*counter
= info
;
148 struct perf_counter_context
*ctx
= counter
->ctx
;
153 * If this is a task context, we need to check whether it is
154 * the current task context of this cpu. If not it has been
155 * scheduled out before the smp call arrived.
157 if (ctx
->task
&& cpuctx
->task_ctx
!= ctx
)
160 curr_rq_lock_irq_save(&flags
);
161 spin_lock(&ctx
->lock
);
163 counter_sched_out(counter
, cpuctx
, ctx
);
165 counter
->task
= NULL
;
169 * Protect the list operation against NMI by disabling the
170 * counters on a global level. NOP for non NMI based counters.
172 perf_flags
= hw_perf_save_disable();
173 list_del_counter(counter
, ctx
);
174 hw_perf_restore(perf_flags
);
178 * Allow more per task counters with respect to the
181 cpuctx
->max_pertask
=
182 min(perf_max_counters
- ctx
->nr_counters
,
183 perf_max_counters
- perf_reserved_percpu
);
186 spin_unlock(&ctx
->lock
);
187 curr_rq_unlock_irq_restore(&flags
);
192 * Remove the counter from a task's (or a CPU's) list of counters.
194 * Must be called with counter->mutex and ctx->mutex held.
196 * CPU counters are removed with a smp call. For task counters we only
197 * call when the task is on a CPU.
199 static void perf_counter_remove_from_context(struct perf_counter
*counter
)
201 struct perf_counter_context
*ctx
= counter
->ctx
;
202 struct task_struct
*task
= ctx
->task
;
206 * Per cpu counters are removed via an smp call and
207 * the removal is always sucessful.
209 smp_call_function_single(counter
->cpu
,
210 __perf_counter_remove_from_context
,
216 task_oncpu_function_call(task
, __perf_counter_remove_from_context
,
219 spin_lock_irq(&ctx
->lock
);
221 * If the context is active we need to retry the smp call.
223 if (ctx
->nr_active
&& !list_empty(&counter
->list_entry
)) {
224 spin_unlock_irq(&ctx
->lock
);
229 * The lock prevents that this context is scheduled in so we
230 * can remove the counter safely, if the call above did not
233 if (!list_empty(&counter
->list_entry
)) {
235 list_del_counter(counter
, ctx
);
236 counter
->task
= NULL
;
238 spin_unlock_irq(&ctx
->lock
);
242 * Cross CPU call to disable a performance counter
244 static void __perf_counter_disable(void *info
)
246 struct perf_counter
*counter
= info
;
247 struct perf_cpu_context
*cpuctx
= &__get_cpu_var(perf_cpu_context
);
248 struct perf_counter_context
*ctx
= counter
->ctx
;
252 * If this is a per-task counter, need to check whether this
253 * counter's task is the current task on this cpu.
255 if (ctx
->task
&& cpuctx
->task_ctx
!= ctx
)
258 curr_rq_lock_irq_save(&flags
);
259 spin_lock(&ctx
->lock
);
262 * If the counter is on, turn it off.
263 * If it is in error state, leave it in error state.
265 if (counter
->state
>= PERF_COUNTER_STATE_INACTIVE
) {
266 if (counter
== counter
->group_leader
)
267 group_sched_out(counter
, cpuctx
, ctx
);
269 counter_sched_out(counter
, cpuctx
, ctx
);
270 counter
->state
= PERF_COUNTER_STATE_OFF
;
273 spin_unlock(&ctx
->lock
);
274 curr_rq_unlock_irq_restore(&flags
);
280 static void perf_counter_disable(struct perf_counter
*counter
)
282 struct perf_counter_context
*ctx
= counter
->ctx
;
283 struct task_struct
*task
= ctx
->task
;
287 * Disable the counter on the cpu that it's on
289 smp_call_function_single(counter
->cpu
, __perf_counter_disable
,
295 task_oncpu_function_call(task
, __perf_counter_disable
, counter
);
297 spin_lock_irq(&ctx
->lock
);
299 * If the counter is still active, we need to retry the cross-call.
301 if (counter
->state
== PERF_COUNTER_STATE_ACTIVE
) {
302 spin_unlock_irq(&ctx
->lock
);
307 * Since we have the lock this context can't be scheduled
308 * in, so we can change the state safely.
310 if (counter
->state
== PERF_COUNTER_STATE_INACTIVE
)
311 counter
->state
= PERF_COUNTER_STATE_OFF
;
313 spin_unlock_irq(&ctx
->lock
);
317 * Disable a counter and all its children.
319 static void perf_counter_disable_family(struct perf_counter
*counter
)
321 struct perf_counter
*child
;
323 perf_counter_disable(counter
);
326 * Lock the mutex to protect the list of children
328 mutex_lock(&counter
->mutex
);
329 list_for_each_entry(child
, &counter
->child_list
, child_list
)
330 perf_counter_disable(child
);
331 mutex_unlock(&counter
->mutex
);
335 counter_sched_in(struct perf_counter
*counter
,
336 struct perf_cpu_context
*cpuctx
,
337 struct perf_counter_context
*ctx
,
340 if (counter
->state
<= PERF_COUNTER_STATE_OFF
)
343 counter
->state
= PERF_COUNTER_STATE_ACTIVE
;
344 counter
->oncpu
= cpu
; /* TODO: put 'cpu' into cpuctx->cpu */
346 * The new state must be visible before we turn it on in the hardware:
350 if (counter
->hw_ops
->enable(counter
)) {
351 counter
->state
= PERF_COUNTER_STATE_INACTIVE
;
356 if (!is_software_counter(counter
))
357 cpuctx
->active_oncpu
++;
360 if (counter
->hw_event
.exclusive
)
361 cpuctx
->exclusive
= 1;
367 * Return 1 for a group consisting entirely of software counters,
368 * 0 if the group contains any hardware counters.
370 static int is_software_only_group(struct perf_counter
*leader
)
372 struct perf_counter
*counter
;
374 if (!is_software_counter(leader
))
376 list_for_each_entry(counter
, &leader
->sibling_list
, list_entry
)
377 if (!is_software_counter(counter
))
383 * Work out whether we can put this counter group on the CPU now.
385 static int group_can_go_on(struct perf_counter
*counter
,
386 struct perf_cpu_context
*cpuctx
,
390 * Groups consisting entirely of software counters can always go on.
392 if (is_software_only_group(counter
))
395 * If an exclusive group is already on, no other hardware
396 * counters can go on.
398 if (cpuctx
->exclusive
)
401 * If this group is exclusive and there are already
402 * counters on the CPU, it can't go on.
404 if (counter
->hw_event
.exclusive
&& cpuctx
->active_oncpu
)
407 * Otherwise, try to add it if all previous groups were able
414 * Cross CPU call to install and enable a performance counter
416 static void __perf_install_in_context(void *info
)
418 struct perf_cpu_context
*cpuctx
= &__get_cpu_var(perf_cpu_context
);
419 struct perf_counter
*counter
= info
;
420 struct perf_counter_context
*ctx
= counter
->ctx
;
421 struct perf_counter
*leader
= counter
->group_leader
;
422 int cpu
= smp_processor_id();
428 * If this is a task context, we need to check whether it is
429 * the current task context of this cpu. If not it has been
430 * scheduled out before the smp call arrived.
432 if (ctx
->task
&& cpuctx
->task_ctx
!= ctx
)
435 curr_rq_lock_irq_save(&flags
);
436 spin_lock(&ctx
->lock
);
439 * Protect the list operation against NMI by disabling the
440 * counters on a global level. NOP for non NMI based counters.
442 perf_flags
= hw_perf_save_disable();
444 list_add_counter(counter
, ctx
);
446 counter
->prev_state
= PERF_COUNTER_STATE_OFF
;
449 * Don't put the counter on if it is disabled or if
450 * it is in a group and the group isn't on.
452 if (counter
->state
!= PERF_COUNTER_STATE_INACTIVE
||
453 (leader
!= counter
&& leader
->state
!= PERF_COUNTER_STATE_ACTIVE
))
457 * An exclusive counter can't go on if there are already active
458 * hardware counters, and no hardware counter can go on if there
459 * is already an exclusive counter on.
461 if (!group_can_go_on(counter
, cpuctx
, 1))
464 err
= counter_sched_in(counter
, cpuctx
, ctx
, cpu
);
468 * This counter couldn't go on. If it is in a group
469 * then we have to pull the whole group off.
470 * If the counter group is pinned then put it in error state.
472 if (leader
!= counter
)
473 group_sched_out(leader
, cpuctx
, ctx
);
474 if (leader
->hw_event
.pinned
)
475 leader
->state
= PERF_COUNTER_STATE_ERROR
;
478 if (!err
&& !ctx
->task
&& cpuctx
->max_pertask
)
479 cpuctx
->max_pertask
--;
482 hw_perf_restore(perf_flags
);
484 spin_unlock(&ctx
->lock
);
485 curr_rq_unlock_irq_restore(&flags
);
489 * Attach a performance counter to a context
491 * First we add the counter to the list with the hardware enable bit
492 * in counter->hw_config cleared.
494 * If the counter is attached to a task which is on a CPU we use a smp
495 * call to enable it in the task context. The task might have been
496 * scheduled away, but we check this in the smp call again.
498 * Must be called with ctx->mutex held.
501 perf_install_in_context(struct perf_counter_context
*ctx
,
502 struct perf_counter
*counter
,
505 struct task_struct
*task
= ctx
->task
;
509 * Per cpu counters are installed via an smp call and
510 * the install is always sucessful.
512 smp_call_function_single(cpu
, __perf_install_in_context
,
517 counter
->task
= task
;
519 task_oncpu_function_call(task
, __perf_install_in_context
,
522 spin_lock_irq(&ctx
->lock
);
524 * we need to retry the smp call.
526 if (ctx
->is_active
&& list_empty(&counter
->list_entry
)) {
527 spin_unlock_irq(&ctx
->lock
);
532 * The lock prevents that this context is scheduled in so we
533 * can add the counter safely, if it the call above did not
536 if (list_empty(&counter
->list_entry
)) {
537 list_add_counter(counter
, ctx
);
540 spin_unlock_irq(&ctx
->lock
);
544 * Cross CPU call to enable a performance counter
546 static void __perf_counter_enable(void *info
)
548 struct perf_counter
*counter
= info
;
549 struct perf_cpu_context
*cpuctx
= &__get_cpu_var(perf_cpu_context
);
550 struct perf_counter_context
*ctx
= counter
->ctx
;
551 struct perf_counter
*leader
= counter
->group_leader
;
556 * If this is a per-task counter, need to check whether this
557 * counter's task is the current task on this cpu.
559 if (ctx
->task
&& cpuctx
->task_ctx
!= ctx
)
562 curr_rq_lock_irq_save(&flags
);
563 spin_lock(&ctx
->lock
);
565 counter
->prev_state
= counter
->state
;
566 if (counter
->state
>= PERF_COUNTER_STATE_INACTIVE
)
568 counter
->state
= PERF_COUNTER_STATE_INACTIVE
;
571 * If the counter is in a group and isn't the group leader,
572 * then don't put it on unless the group is on.
574 if (leader
!= counter
&& leader
->state
!= PERF_COUNTER_STATE_ACTIVE
)
577 if (!group_can_go_on(counter
, cpuctx
, 1))
580 err
= counter_sched_in(counter
, cpuctx
, ctx
,
585 * If this counter can't go on and it's part of a
586 * group, then the whole group has to come off.
588 if (leader
!= counter
)
589 group_sched_out(leader
, cpuctx
, ctx
);
590 if (leader
->hw_event
.pinned
)
591 leader
->state
= PERF_COUNTER_STATE_ERROR
;
595 spin_unlock(&ctx
->lock
);
596 curr_rq_unlock_irq_restore(&flags
);
602 static void perf_counter_enable(struct perf_counter
*counter
)
604 struct perf_counter_context
*ctx
= counter
->ctx
;
605 struct task_struct
*task
= ctx
->task
;
609 * Enable the counter on the cpu that it's on
611 smp_call_function_single(counter
->cpu
, __perf_counter_enable
,
616 spin_lock_irq(&ctx
->lock
);
617 if (counter
->state
>= PERF_COUNTER_STATE_INACTIVE
)
621 * If the counter is in error state, clear that first.
622 * That way, if we see the counter in error state below, we
623 * know that it has gone back into error state, as distinct
624 * from the task having been scheduled away before the
625 * cross-call arrived.
627 if (counter
->state
== PERF_COUNTER_STATE_ERROR
)
628 counter
->state
= PERF_COUNTER_STATE_OFF
;
631 spin_unlock_irq(&ctx
->lock
);
632 task_oncpu_function_call(task
, __perf_counter_enable
, counter
);
634 spin_lock_irq(&ctx
->lock
);
637 * If the context is active and the counter is still off,
638 * we need to retry the cross-call.
640 if (ctx
->is_active
&& counter
->state
== PERF_COUNTER_STATE_OFF
)
644 * Since we have the lock this context can't be scheduled
645 * in, so we can change the state safely.
647 if (counter
->state
== PERF_COUNTER_STATE_OFF
)
648 counter
->state
= PERF_COUNTER_STATE_INACTIVE
;
650 spin_unlock_irq(&ctx
->lock
);
654 * Enable a counter and all its children.
656 static void perf_counter_enable_family(struct perf_counter
*counter
)
658 struct perf_counter
*child
;
660 perf_counter_enable(counter
);
663 * Lock the mutex to protect the list of children
665 mutex_lock(&counter
->mutex
);
666 list_for_each_entry(child
, &counter
->child_list
, child_list
)
667 perf_counter_enable(child
);
668 mutex_unlock(&counter
->mutex
);
671 void __perf_counter_sched_out(struct perf_counter_context
*ctx
,
672 struct perf_cpu_context
*cpuctx
)
674 struct perf_counter
*counter
;
677 spin_lock(&ctx
->lock
);
679 if (likely(!ctx
->nr_counters
))
682 flags
= hw_perf_save_disable();
683 if (ctx
->nr_active
) {
684 list_for_each_entry(counter
, &ctx
->counter_list
, list_entry
)
685 group_sched_out(counter
, cpuctx
, ctx
);
687 hw_perf_restore(flags
);
689 spin_unlock(&ctx
->lock
);
693 * Called from scheduler to remove the counters of the current task,
694 * with interrupts disabled.
696 * We stop each counter and update the counter value in counter->count.
698 * This does not protect us against NMI, but disable()
699 * sets the disabled bit in the control field of counter _before_
700 * accessing the counter control register. If a NMI hits, then it will
701 * not restart the counter.
703 void perf_counter_task_sched_out(struct task_struct
*task
, int cpu
)
705 struct perf_cpu_context
*cpuctx
= &per_cpu(perf_cpu_context
, cpu
);
706 struct perf_counter_context
*ctx
= &task
->perf_counter_ctx
;
708 if (likely(!cpuctx
->task_ctx
))
711 __perf_counter_sched_out(ctx
, cpuctx
);
713 cpuctx
->task_ctx
= NULL
;
716 static void perf_counter_cpu_sched_out(struct perf_cpu_context
*cpuctx
)
718 __perf_counter_sched_out(&cpuctx
->ctx
, cpuctx
);
722 group_sched_in(struct perf_counter
*group_counter
,
723 struct perf_cpu_context
*cpuctx
,
724 struct perf_counter_context
*ctx
,
727 struct perf_counter
*counter
, *partial_group
;
730 if (group_counter
->state
== PERF_COUNTER_STATE_OFF
)
733 ret
= hw_perf_group_sched_in(group_counter
, cpuctx
, ctx
, cpu
);
735 return ret
< 0 ? ret
: 0;
737 group_counter
->prev_state
= group_counter
->state
;
738 if (counter_sched_in(group_counter
, cpuctx
, ctx
, cpu
))
742 * Schedule in siblings as one group (if any):
744 list_for_each_entry(counter
, &group_counter
->sibling_list
, list_entry
) {
745 counter
->prev_state
= counter
->state
;
746 if (counter_sched_in(counter
, cpuctx
, ctx
, cpu
)) {
747 partial_group
= counter
;
756 * Groups can be scheduled in as one unit only, so undo any
757 * partial group before returning:
759 list_for_each_entry(counter
, &group_counter
->sibling_list
, list_entry
) {
760 if (counter
== partial_group
)
762 counter_sched_out(counter
, cpuctx
, ctx
);
764 counter_sched_out(group_counter
, cpuctx
, ctx
);
770 __perf_counter_sched_in(struct perf_counter_context
*ctx
,
771 struct perf_cpu_context
*cpuctx
, int cpu
)
773 struct perf_counter
*counter
;
777 spin_lock(&ctx
->lock
);
779 if (likely(!ctx
->nr_counters
))
782 flags
= hw_perf_save_disable();
785 * First go through the list and put on any pinned groups
786 * in order to give them the best chance of going on.
788 list_for_each_entry(counter
, &ctx
->counter_list
, list_entry
) {
789 if (counter
->state
<= PERF_COUNTER_STATE_OFF
||
790 !counter
->hw_event
.pinned
)
792 if (counter
->cpu
!= -1 && counter
->cpu
!= cpu
)
795 if (group_can_go_on(counter
, cpuctx
, 1))
796 group_sched_in(counter
, cpuctx
, ctx
, cpu
);
799 * If this pinned group hasn't been scheduled,
800 * put it in error state.
802 if (counter
->state
== PERF_COUNTER_STATE_INACTIVE
)
803 counter
->state
= PERF_COUNTER_STATE_ERROR
;
806 list_for_each_entry(counter
, &ctx
->counter_list
, list_entry
) {
808 * Ignore counters in OFF or ERROR state, and
809 * ignore pinned counters since we did them already.
811 if (counter
->state
<= PERF_COUNTER_STATE_OFF
||
812 counter
->hw_event
.pinned
)
816 * Listen to the 'cpu' scheduling filter constraint
819 if (counter
->cpu
!= -1 && counter
->cpu
!= cpu
)
822 if (group_can_go_on(counter
, cpuctx
, can_add_hw
)) {
823 if (group_sched_in(counter
, cpuctx
, ctx
, cpu
))
827 hw_perf_restore(flags
);
829 spin_unlock(&ctx
->lock
);
833 * Called from scheduler to add the counters of the current task
834 * with interrupts disabled.
836 * We restore the counter value and then enable it.
838 * This does not protect us against NMI, but enable()
839 * sets the enabled bit in the control field of counter _before_
840 * accessing the counter control register. If a NMI hits, then it will
841 * keep the counter running.
843 void perf_counter_task_sched_in(struct task_struct
*task
, int cpu
)
845 struct perf_cpu_context
*cpuctx
= &per_cpu(perf_cpu_context
, cpu
);
846 struct perf_counter_context
*ctx
= &task
->perf_counter_ctx
;
848 __perf_counter_sched_in(ctx
, cpuctx
, cpu
);
849 cpuctx
->task_ctx
= ctx
;
852 static void perf_counter_cpu_sched_in(struct perf_cpu_context
*cpuctx
, int cpu
)
854 struct perf_counter_context
*ctx
= &cpuctx
->ctx
;
856 __perf_counter_sched_in(ctx
, cpuctx
, cpu
);
859 int perf_counter_task_disable(void)
861 struct task_struct
*curr
= current
;
862 struct perf_counter_context
*ctx
= &curr
->perf_counter_ctx
;
863 struct perf_counter
*counter
;
868 if (likely(!ctx
->nr_counters
))
871 curr_rq_lock_irq_save(&flags
);
872 cpu
= smp_processor_id();
874 /* force the update of the task clock: */
875 __task_delta_exec(curr
, 1);
877 perf_counter_task_sched_out(curr
, cpu
);
879 spin_lock(&ctx
->lock
);
882 * Disable all the counters:
884 perf_flags
= hw_perf_save_disable();
886 list_for_each_entry(counter
, &ctx
->counter_list
, list_entry
) {
887 if (counter
->state
!= PERF_COUNTER_STATE_ERROR
)
888 counter
->state
= PERF_COUNTER_STATE_OFF
;
891 hw_perf_restore(perf_flags
);
893 spin_unlock(&ctx
->lock
);
895 curr_rq_unlock_irq_restore(&flags
);
900 int perf_counter_task_enable(void)
902 struct task_struct
*curr
= current
;
903 struct perf_counter_context
*ctx
= &curr
->perf_counter_ctx
;
904 struct perf_counter
*counter
;
909 if (likely(!ctx
->nr_counters
))
912 curr_rq_lock_irq_save(&flags
);
913 cpu
= smp_processor_id();
915 /* force the update of the task clock: */
916 __task_delta_exec(curr
, 1);
918 perf_counter_task_sched_out(curr
, cpu
);
920 spin_lock(&ctx
->lock
);
923 * Disable all the counters:
925 perf_flags
= hw_perf_save_disable();
927 list_for_each_entry(counter
, &ctx
->counter_list
, list_entry
) {
928 if (counter
->state
> PERF_COUNTER_STATE_OFF
)
930 counter
->state
= PERF_COUNTER_STATE_INACTIVE
;
931 counter
->hw_event
.disabled
= 0;
933 hw_perf_restore(perf_flags
);
935 spin_unlock(&ctx
->lock
);
937 perf_counter_task_sched_in(curr
, cpu
);
939 curr_rq_unlock_irq_restore(&flags
);
945 * Round-robin a context's counters:
947 static void rotate_ctx(struct perf_counter_context
*ctx
)
949 struct perf_counter
*counter
;
952 if (!ctx
->nr_counters
)
955 spin_lock(&ctx
->lock
);
957 * Rotate the first entry last (works just fine for group counters too):
959 perf_flags
= hw_perf_save_disable();
960 list_for_each_entry(counter
, &ctx
->counter_list
, list_entry
) {
961 list_move_tail(&counter
->list_entry
, &ctx
->counter_list
);
964 hw_perf_restore(perf_flags
);
966 spin_unlock(&ctx
->lock
);
969 void perf_counter_task_tick(struct task_struct
*curr
, int cpu
)
971 struct perf_cpu_context
*cpuctx
= &per_cpu(perf_cpu_context
, cpu
);
972 struct perf_counter_context
*ctx
= &curr
->perf_counter_ctx
;
973 const int rotate_percpu
= 0;
976 perf_counter_cpu_sched_out(cpuctx
);
977 perf_counter_task_sched_out(curr
, cpu
);
980 rotate_ctx(&cpuctx
->ctx
);
984 perf_counter_cpu_sched_in(cpuctx
, cpu
);
985 perf_counter_task_sched_in(curr
, cpu
);
989 * Cross CPU call to read the hardware counter
991 static void __read(void *info
)
993 struct perf_counter
*counter
= info
;
996 curr_rq_lock_irq_save(&flags
);
997 counter
->hw_ops
->read(counter
);
998 curr_rq_unlock_irq_restore(&flags
);
1001 static u64
perf_counter_read(struct perf_counter
*counter
)
1004 * If counter is enabled and currently active on a CPU, update the
1005 * value in the counter structure:
1007 if (counter
->state
== PERF_COUNTER_STATE_ACTIVE
) {
1008 smp_call_function_single(counter
->oncpu
,
1009 __read
, counter
, 1);
1012 return atomic64_read(&counter
->count
);
1016 * Cross CPU call to switch performance data pointers
1018 static void __perf_switch_irq_data(void *info
)
1020 struct perf_cpu_context
*cpuctx
= &__get_cpu_var(perf_cpu_context
);
1021 struct perf_counter
*counter
= info
;
1022 struct perf_counter_context
*ctx
= counter
->ctx
;
1023 struct perf_data
*oldirqdata
= counter
->irqdata
;
1026 * If this is a task context, we need to check whether it is
1027 * the current task context of this cpu. If not it has been
1028 * scheduled out before the smp call arrived.
1031 if (cpuctx
->task_ctx
!= ctx
)
1033 spin_lock(&ctx
->lock
);
1036 /* Change the pointer NMI safe */
1037 atomic_long_set((atomic_long_t
*)&counter
->irqdata
,
1038 (unsigned long) counter
->usrdata
);
1039 counter
->usrdata
= oldirqdata
;
1042 spin_unlock(&ctx
->lock
);
1045 static struct perf_data
*perf_switch_irq_data(struct perf_counter
*counter
)
1047 struct perf_counter_context
*ctx
= counter
->ctx
;
1048 struct perf_data
*oldirqdata
= counter
->irqdata
;
1049 struct task_struct
*task
= ctx
->task
;
1052 smp_call_function_single(counter
->cpu
,
1053 __perf_switch_irq_data
,
1055 return counter
->usrdata
;
1059 spin_lock_irq(&ctx
->lock
);
1060 if (counter
->state
!= PERF_COUNTER_STATE_ACTIVE
) {
1061 counter
->irqdata
= counter
->usrdata
;
1062 counter
->usrdata
= oldirqdata
;
1063 spin_unlock_irq(&ctx
->lock
);
1066 spin_unlock_irq(&ctx
->lock
);
1067 task_oncpu_function_call(task
, __perf_switch_irq_data
, counter
);
1068 /* Might have failed, because task was scheduled out */
1069 if (counter
->irqdata
== oldirqdata
)
1072 return counter
->usrdata
;
1075 static void put_context(struct perf_counter_context
*ctx
)
1078 put_task_struct(ctx
->task
);
1081 static struct perf_counter_context
*find_get_context(pid_t pid
, int cpu
)
1083 struct perf_cpu_context
*cpuctx
;
1084 struct perf_counter_context
*ctx
;
1085 struct task_struct
*task
;
1088 * If cpu is not a wildcard then this is a percpu counter:
1091 /* Must be root to operate on a CPU counter: */
1092 if (!capable(CAP_SYS_ADMIN
))
1093 return ERR_PTR(-EACCES
);
1095 if (cpu
< 0 || cpu
> num_possible_cpus())
1096 return ERR_PTR(-EINVAL
);
1099 * We could be clever and allow to attach a counter to an
1100 * offline CPU and activate it when the CPU comes up, but
1103 if (!cpu_isset(cpu
, cpu_online_map
))
1104 return ERR_PTR(-ENODEV
);
1106 cpuctx
= &per_cpu(perf_cpu_context
, cpu
);
1116 task
= find_task_by_vpid(pid
);
1118 get_task_struct(task
);
1122 return ERR_PTR(-ESRCH
);
1124 ctx
= &task
->perf_counter_ctx
;
1127 /* Reuse ptrace permission checks for now. */
1128 if (!ptrace_may_access(task
, PTRACE_MODE_READ
)) {
1130 return ERR_PTR(-EACCES
);
1137 * Called when the last reference to the file is gone.
1139 static int perf_release(struct inode
*inode
, struct file
*file
)
1141 struct perf_counter
*counter
= file
->private_data
;
1142 struct perf_counter_context
*ctx
= counter
->ctx
;
1144 file
->private_data
= NULL
;
1146 mutex_lock(&ctx
->mutex
);
1147 mutex_lock(&counter
->mutex
);
1149 perf_counter_remove_from_context(counter
);
1151 mutex_unlock(&counter
->mutex
);
1152 mutex_unlock(&ctx
->mutex
);
1161 * Read the performance counter - simple non blocking version for now
1164 perf_read_hw(struct perf_counter
*counter
, char __user
*buf
, size_t count
)
1168 if (count
!= sizeof(cntval
))
1172 * Return end-of-file for a read on a counter that is in
1173 * error state (i.e. because it was pinned but it couldn't be
1174 * scheduled on to the CPU at some point).
1176 if (counter
->state
== PERF_COUNTER_STATE_ERROR
)
1179 mutex_lock(&counter
->mutex
);
1180 cntval
= perf_counter_read(counter
);
1181 mutex_unlock(&counter
->mutex
);
1183 return put_user(cntval
, (u64 __user
*) buf
) ? -EFAULT
: sizeof(cntval
);
1187 perf_copy_usrdata(struct perf_data
*usrdata
, char __user
*buf
, size_t count
)
1192 count
= min(count
, (size_t)usrdata
->len
);
1193 if (copy_to_user(buf
, usrdata
->data
+ usrdata
->rd_idx
, count
))
1196 /* Adjust the counters */
1197 usrdata
->len
-= count
;
1199 usrdata
->rd_idx
= 0;
1201 usrdata
->rd_idx
+= count
;
1207 perf_read_irq_data(struct perf_counter
*counter
,
1212 struct perf_data
*irqdata
, *usrdata
;
1213 DECLARE_WAITQUEUE(wait
, current
);
1216 irqdata
= counter
->irqdata
;
1217 usrdata
= counter
->usrdata
;
1219 if (usrdata
->len
+ irqdata
->len
>= count
)
1225 spin_lock_irq(&counter
->waitq
.lock
);
1226 __add_wait_queue(&counter
->waitq
, &wait
);
1228 set_current_state(TASK_INTERRUPTIBLE
);
1229 if (usrdata
->len
+ irqdata
->len
>= count
)
1232 if (signal_pending(current
))
1235 if (counter
->state
== PERF_COUNTER_STATE_ERROR
)
1238 spin_unlock_irq(&counter
->waitq
.lock
);
1240 spin_lock_irq(&counter
->waitq
.lock
);
1242 __remove_wait_queue(&counter
->waitq
, &wait
);
1243 __set_current_state(TASK_RUNNING
);
1244 spin_unlock_irq(&counter
->waitq
.lock
);
1246 if (usrdata
->len
+ irqdata
->len
< count
&&
1247 counter
->state
!= PERF_COUNTER_STATE_ERROR
)
1248 return -ERESTARTSYS
;
1250 mutex_lock(&counter
->mutex
);
1252 /* Drain pending data first: */
1253 res
= perf_copy_usrdata(usrdata
, buf
, count
);
1254 if (res
< 0 || res
== count
)
1257 /* Switch irq buffer: */
1258 usrdata
= perf_switch_irq_data(counter
);
1259 res2
= perf_copy_usrdata(usrdata
, buf
+ res
, count
- res
);
1267 mutex_unlock(&counter
->mutex
);
1273 perf_read(struct file
*file
, char __user
*buf
, size_t count
, loff_t
*ppos
)
1275 struct perf_counter
*counter
= file
->private_data
;
1277 switch (counter
->hw_event
.record_type
) {
1278 case PERF_RECORD_SIMPLE
:
1279 return perf_read_hw(counter
, buf
, count
);
1281 case PERF_RECORD_IRQ
:
1282 case PERF_RECORD_GROUP
:
1283 return perf_read_irq_data(counter
, buf
, count
,
1284 file
->f_flags
& O_NONBLOCK
);
1289 static unsigned int perf_poll(struct file
*file
, poll_table
*wait
)
1291 struct perf_counter
*counter
= file
->private_data
;
1292 unsigned int events
= 0;
1293 unsigned long flags
;
1295 poll_wait(file
, &counter
->waitq
, wait
);
1297 spin_lock_irqsave(&counter
->waitq
.lock
, flags
);
1298 if (counter
->usrdata
->len
|| counter
->irqdata
->len
)
1300 spin_unlock_irqrestore(&counter
->waitq
.lock
, flags
);
1305 static long perf_ioctl(struct file
*file
, unsigned int cmd
, unsigned long arg
)
1307 struct perf_counter
*counter
= file
->private_data
;
1311 case PERF_COUNTER_IOC_ENABLE
:
1312 perf_counter_enable_family(counter
);
1314 case PERF_COUNTER_IOC_DISABLE
:
1315 perf_counter_disable_family(counter
);
1323 static const struct file_operations perf_fops
= {
1324 .release
= perf_release
,
1327 .unlocked_ioctl
= perf_ioctl
,
1328 .compat_ioctl
= perf_ioctl
,
1332 * Generic software counter infrastructure
1335 static void perf_swcounter_update(struct perf_counter
*counter
)
1337 struct hw_perf_counter
*hwc
= &counter
->hw
;
1342 prev
= atomic64_read(&hwc
->prev_count
);
1343 now
= atomic64_read(&hwc
->count
);
1344 if (atomic64_cmpxchg(&hwc
->prev_count
, prev
, now
) != prev
)
1349 atomic64_add(delta
, &counter
->count
);
1350 atomic64_sub(delta
, &hwc
->period_left
);
1353 static void perf_swcounter_set_period(struct perf_counter
*counter
)
1355 struct hw_perf_counter
*hwc
= &counter
->hw
;
1356 s64 left
= atomic64_read(&hwc
->period_left
);
1357 s64 period
= hwc
->irq_period
;
1359 if (unlikely(left
<= -period
)) {
1361 atomic64_set(&hwc
->period_left
, left
);
1364 if (unlikely(left
<= 0)) {
1366 atomic64_add(period
, &hwc
->period_left
);
1369 atomic64_set(&hwc
->prev_count
, -left
);
1370 atomic64_set(&hwc
->count
, -left
);
1373 static void perf_swcounter_save_and_restart(struct perf_counter
*counter
)
1375 perf_swcounter_update(counter
);
1376 perf_swcounter_set_period(counter
);
1379 static void perf_swcounter_store_irq(struct perf_counter
*counter
, u64 data
)
1381 struct perf_data
*irqdata
= counter
->irqdata
;
1383 if (irqdata
->len
> PERF_DATA_BUFLEN
- sizeof(u64
)) {
1386 u64
*p
= (u64
*) &irqdata
->data
[irqdata
->len
];
1389 irqdata
->len
+= sizeof(u64
);
1393 static void perf_swcounter_handle_group(struct perf_counter
*sibling
)
1395 struct perf_counter
*counter
, *group_leader
= sibling
->group_leader
;
1397 list_for_each_entry(counter
, &group_leader
->sibling_list
, list_entry
) {
1398 perf_swcounter_update(counter
);
1399 perf_swcounter_store_irq(sibling
, counter
->hw_event
.type
);
1400 perf_swcounter_store_irq(sibling
, atomic64_read(&counter
->count
));
1404 static void perf_swcounter_interrupt(struct perf_counter
*counter
,
1405 int nmi
, struct pt_regs
*regs
)
1407 perf_swcounter_save_and_restart(counter
);
1409 switch (counter
->hw_event
.record_type
) {
1410 case PERF_RECORD_SIMPLE
:
1413 case PERF_RECORD_IRQ
:
1414 perf_swcounter_store_irq(counter
, instruction_pointer(regs
));
1417 case PERF_RECORD_GROUP
:
1418 perf_swcounter_handle_group(counter
);
1423 counter
->wakeup_pending
= 1;
1424 set_tsk_thread_flag(current
, TIF_PERF_COUNTERS
);
1426 wake_up(&counter
->waitq
);
1429 static int perf_swcounter_match(struct perf_counter
*counter
,
1430 enum hw_event_types event
,
1431 struct pt_regs
*regs
)
1433 if (counter
->state
!= PERF_COUNTER_STATE_ACTIVE
)
1436 if (counter
->hw_event
.raw
)
1439 if (counter
->hw_event
.type
!= event
)
1442 if (counter
->hw_event
.exclude_user
&& user_mode(regs
))
1445 if (counter
->hw_event
.exclude_kernel
&& !user_mode(regs
))
1451 static void perf_swcounter_ctx_event(struct perf_counter_context
*ctx
,
1452 enum hw_event_types event
, u64 nr
,
1453 int nmi
, struct pt_regs
*regs
)
1455 struct perf_counter
*counter
;
1456 unsigned long flags
;
1459 if (list_empty(&ctx
->counter_list
))
1462 spin_lock_irqsave(&ctx
->lock
, flags
);
1465 * XXX: make counter_list RCU safe
1467 list_for_each_entry(counter
, &ctx
->counter_list
, list_entry
) {
1468 if (perf_swcounter_match(counter
, event
, regs
)) {
1469 neg
= atomic64_add_negative(nr
, &counter
->hw
.count
);
1470 if (counter
->hw
.irq_period
&& !neg
)
1471 perf_swcounter_interrupt(counter
, nmi
, regs
);
1475 spin_unlock_irqrestore(&ctx
->lock
, flags
);
1478 void perf_swcounter_event(enum hw_event_types event
, u64 nr
,
1479 int nmi
, struct pt_regs
*regs
)
1481 struct perf_cpu_context
*cpuctx
= &get_cpu_var(perf_cpu_context
);
1483 perf_swcounter_ctx_event(&cpuctx
->ctx
, event
, nr
, nmi
, regs
);
1484 if (cpuctx
->task_ctx
)
1485 perf_swcounter_ctx_event(cpuctx
->task_ctx
, event
, nr
, nmi
, regs
);
1487 put_cpu_var(perf_cpu_context
);
1490 static void perf_swcounter_read(struct perf_counter
*counter
)
1492 perf_swcounter_update(counter
);
1495 static int perf_swcounter_enable(struct perf_counter
*counter
)
1497 perf_swcounter_set_period(counter
);
1501 static void perf_swcounter_disable(struct perf_counter
*counter
)
1503 perf_swcounter_update(counter
);
1506 static const struct hw_perf_counter_ops perf_ops_generic
= {
1507 .enable
= perf_swcounter_enable
,
1508 .disable
= perf_swcounter_disable
,
1509 .read
= perf_swcounter_read
,
1513 * Software counter: cpu wall time clock
1516 static int cpu_clock_perf_counter_enable(struct perf_counter
*counter
)
1518 int cpu
= raw_smp_processor_id();
1520 atomic64_set(&counter
->hw
.prev_count
, cpu_clock(cpu
));
1524 static void cpu_clock_perf_counter_update(struct perf_counter
*counter
)
1526 int cpu
= raw_smp_processor_id();
1530 now
= cpu_clock(cpu
);
1531 prev
= atomic64_read(&counter
->hw
.prev_count
);
1532 atomic64_set(&counter
->hw
.prev_count
, now
);
1533 atomic64_add(now
- prev
, &counter
->count
);
1536 static void cpu_clock_perf_counter_disable(struct perf_counter
*counter
)
1538 cpu_clock_perf_counter_update(counter
);
1541 static void cpu_clock_perf_counter_read(struct perf_counter
*counter
)
1543 cpu_clock_perf_counter_update(counter
);
1546 static const struct hw_perf_counter_ops perf_ops_cpu_clock
= {
1547 .enable
= cpu_clock_perf_counter_enable
,
1548 .disable
= cpu_clock_perf_counter_disable
,
1549 .read
= cpu_clock_perf_counter_read
,
1553 * Software counter: task time clock
1557 * Called from within the scheduler:
1559 static u64
task_clock_perf_counter_val(struct perf_counter
*counter
, int update
)
1561 struct task_struct
*curr
= counter
->task
;
1564 delta
= __task_delta_exec(curr
, update
);
1566 return curr
->se
.sum_exec_runtime
+ delta
;
1569 static void task_clock_perf_counter_update(struct perf_counter
*counter
, u64 now
)
1574 prev
= atomic64_read(&counter
->hw
.prev_count
);
1576 atomic64_set(&counter
->hw
.prev_count
, now
);
1580 atomic64_add(delta
, &counter
->count
);
1583 static void task_clock_perf_counter_read(struct perf_counter
*counter
)
1585 u64 now
= task_clock_perf_counter_val(counter
, 1);
1587 task_clock_perf_counter_update(counter
, now
);
1590 static int task_clock_perf_counter_enable(struct perf_counter
*counter
)
1592 if (counter
->prev_state
<= PERF_COUNTER_STATE_OFF
)
1593 atomic64_set(&counter
->hw
.prev_count
,
1594 task_clock_perf_counter_val(counter
, 0));
1599 static void task_clock_perf_counter_disable(struct perf_counter
*counter
)
1601 u64 now
= task_clock_perf_counter_val(counter
, 0);
1603 task_clock_perf_counter_update(counter
, now
);
1606 static const struct hw_perf_counter_ops perf_ops_task_clock
= {
1607 .enable
= task_clock_perf_counter_enable
,
1608 .disable
= task_clock_perf_counter_disable
,
1609 .read
= task_clock_perf_counter_read
,
1613 * Software counter: context switches
1616 static u64
get_context_switches(struct perf_counter
*counter
)
1618 struct task_struct
*curr
= counter
->ctx
->task
;
1621 return curr
->nvcsw
+ curr
->nivcsw
;
1622 return cpu_nr_switches(smp_processor_id());
1625 static void context_switches_perf_counter_update(struct perf_counter
*counter
)
1630 prev
= atomic64_read(&counter
->hw
.prev_count
);
1631 now
= get_context_switches(counter
);
1633 atomic64_set(&counter
->hw
.prev_count
, now
);
1637 atomic64_add(delta
, &counter
->count
);
1640 static void context_switches_perf_counter_read(struct perf_counter
*counter
)
1642 context_switches_perf_counter_update(counter
);
1645 static int context_switches_perf_counter_enable(struct perf_counter
*counter
)
1647 if (counter
->prev_state
<= PERF_COUNTER_STATE_OFF
)
1648 atomic64_set(&counter
->hw
.prev_count
,
1649 get_context_switches(counter
));
1653 static void context_switches_perf_counter_disable(struct perf_counter
*counter
)
1655 context_switches_perf_counter_update(counter
);
1658 static const struct hw_perf_counter_ops perf_ops_context_switches
= {
1659 .enable
= context_switches_perf_counter_enable
,
1660 .disable
= context_switches_perf_counter_disable
,
1661 .read
= context_switches_perf_counter_read
,
1665 * Software counter: cpu migrations
1668 static inline u64
get_cpu_migrations(struct perf_counter
*counter
)
1670 struct task_struct
*curr
= counter
->ctx
->task
;
1673 return curr
->se
.nr_migrations
;
1674 return cpu_nr_migrations(smp_processor_id());
1677 static void cpu_migrations_perf_counter_update(struct perf_counter
*counter
)
1682 prev
= atomic64_read(&counter
->hw
.prev_count
);
1683 now
= get_cpu_migrations(counter
);
1685 atomic64_set(&counter
->hw
.prev_count
, now
);
1689 atomic64_add(delta
, &counter
->count
);
1692 static void cpu_migrations_perf_counter_read(struct perf_counter
*counter
)
1694 cpu_migrations_perf_counter_update(counter
);
1697 static int cpu_migrations_perf_counter_enable(struct perf_counter
*counter
)
1699 if (counter
->prev_state
<= PERF_COUNTER_STATE_OFF
)
1700 atomic64_set(&counter
->hw
.prev_count
,
1701 get_cpu_migrations(counter
));
1705 static void cpu_migrations_perf_counter_disable(struct perf_counter
*counter
)
1707 cpu_migrations_perf_counter_update(counter
);
1710 static const struct hw_perf_counter_ops perf_ops_cpu_migrations
= {
1711 .enable
= cpu_migrations_perf_counter_enable
,
1712 .disable
= cpu_migrations_perf_counter_disable
,
1713 .read
= cpu_migrations_perf_counter_read
,
1716 static const struct hw_perf_counter_ops
*
1717 sw_perf_counter_init(struct perf_counter
*counter
)
1719 struct perf_counter_hw_event
*hw_event
= &counter
->hw_event
;
1720 const struct hw_perf_counter_ops
*hw_ops
= NULL
;
1721 struct hw_perf_counter
*hwc
= &counter
->hw
;
1724 * Software counters (currently) can't in general distinguish
1725 * between user, kernel and hypervisor events.
1726 * However, context switches and cpu migrations are considered
1727 * to be kernel events, and page faults are never hypervisor
1730 switch (counter
->hw_event
.type
) {
1731 case PERF_COUNT_CPU_CLOCK
:
1732 if (!(counter
->hw_event
.exclude_user
||
1733 counter
->hw_event
.exclude_kernel
||
1734 counter
->hw_event
.exclude_hv
))
1735 hw_ops
= &perf_ops_cpu_clock
;
1737 case PERF_COUNT_TASK_CLOCK
:
1738 if (counter
->hw_event
.exclude_user
||
1739 counter
->hw_event
.exclude_kernel
||
1740 counter
->hw_event
.exclude_hv
)
1743 * If the user instantiates this as a per-cpu counter,
1744 * use the cpu_clock counter instead.
1746 if (counter
->ctx
->task
)
1747 hw_ops
= &perf_ops_task_clock
;
1749 hw_ops
= &perf_ops_cpu_clock
;
1751 case PERF_COUNT_PAGE_FAULTS
:
1752 case PERF_COUNT_PAGE_FAULTS_MIN
:
1753 case PERF_COUNT_PAGE_FAULTS_MAJ
:
1754 hw_ops
= &perf_ops_generic
;
1756 case PERF_COUNT_CONTEXT_SWITCHES
:
1757 if (!counter
->hw_event
.exclude_kernel
)
1758 hw_ops
= &perf_ops_context_switches
;
1760 case PERF_COUNT_CPU_MIGRATIONS
:
1761 if (!counter
->hw_event
.exclude_kernel
)
1762 hw_ops
= &perf_ops_cpu_migrations
;
1769 hwc
->irq_period
= hw_event
->irq_period
;
1775 * Allocate and initialize a counter structure
1777 static struct perf_counter
*
1778 perf_counter_alloc(struct perf_counter_hw_event
*hw_event
,
1780 struct perf_counter_context
*ctx
,
1781 struct perf_counter
*group_leader
,
1784 const struct hw_perf_counter_ops
*hw_ops
;
1785 struct perf_counter
*counter
;
1787 counter
= kzalloc(sizeof(*counter
), gfpflags
);
1792 * Single counters are their own group leaders, with an
1793 * empty sibling list:
1796 group_leader
= counter
;
1798 mutex_init(&counter
->mutex
);
1799 INIT_LIST_HEAD(&counter
->list_entry
);
1800 INIT_LIST_HEAD(&counter
->sibling_list
);
1801 init_waitqueue_head(&counter
->waitq
);
1803 INIT_LIST_HEAD(&counter
->child_list
);
1805 counter
->irqdata
= &counter
->data
[0];
1806 counter
->usrdata
= &counter
->data
[1];
1808 counter
->hw_event
= *hw_event
;
1809 counter
->wakeup_pending
= 0;
1810 counter
->group_leader
= group_leader
;
1811 counter
->hw_ops
= NULL
;
1814 counter
->state
= PERF_COUNTER_STATE_INACTIVE
;
1815 if (hw_event
->disabled
)
1816 counter
->state
= PERF_COUNTER_STATE_OFF
;
1819 if (!hw_event
->raw
&& hw_event
->type
< 0)
1820 hw_ops
= sw_perf_counter_init(counter
);
1822 hw_ops
= hw_perf_counter_init(counter
);
1828 counter
->hw_ops
= hw_ops
;
1834 * sys_perf_counter_open - open a performance counter, associate it to a task/cpu
1836 * @hw_event_uptr: event type attributes for monitoring/sampling
1839 * @group_fd: group leader counter fd
1841 SYSCALL_DEFINE5(perf_counter_open
,
1842 const struct perf_counter_hw_event __user
*, hw_event_uptr
,
1843 pid_t
, pid
, int, cpu
, int, group_fd
, unsigned long, flags
)
1845 struct perf_counter
*counter
, *group_leader
;
1846 struct perf_counter_hw_event hw_event
;
1847 struct perf_counter_context
*ctx
;
1848 struct file
*counter_file
= NULL
;
1849 struct file
*group_file
= NULL
;
1850 int fput_needed
= 0;
1851 int fput_needed2
= 0;
1854 /* for future expandability... */
1858 if (copy_from_user(&hw_event
, hw_event_uptr
, sizeof(hw_event
)) != 0)
1862 * Get the target context (task or percpu):
1864 ctx
= find_get_context(pid
, cpu
);
1866 return PTR_ERR(ctx
);
1869 * Look up the group leader (we will attach this counter to it):
1871 group_leader
= NULL
;
1872 if (group_fd
!= -1) {
1874 group_file
= fget_light(group_fd
, &fput_needed
);
1876 goto err_put_context
;
1877 if (group_file
->f_op
!= &perf_fops
)
1878 goto err_put_context
;
1880 group_leader
= group_file
->private_data
;
1882 * Do not allow a recursive hierarchy (this new sibling
1883 * becoming part of another group-sibling):
1885 if (group_leader
->group_leader
!= group_leader
)
1886 goto err_put_context
;
1888 * Do not allow to attach to a group in a different
1889 * task or CPU context:
1891 if (group_leader
->ctx
!= ctx
)
1892 goto err_put_context
;
1894 * Only a group leader can be exclusive or pinned
1896 if (hw_event
.exclusive
|| hw_event
.pinned
)
1897 goto err_put_context
;
1901 counter
= perf_counter_alloc(&hw_event
, cpu
, ctx
, group_leader
,
1904 goto err_put_context
;
1906 ret
= anon_inode_getfd("[perf_counter]", &perf_fops
, counter
, 0);
1908 goto err_free_put_context
;
1910 counter_file
= fget_light(ret
, &fput_needed2
);
1912 goto err_free_put_context
;
1914 counter
->filp
= counter_file
;
1915 mutex_lock(&ctx
->mutex
);
1916 perf_install_in_context(ctx
, counter
, cpu
);
1917 mutex_unlock(&ctx
->mutex
);
1919 fput_light(counter_file
, fput_needed2
);
1922 fput_light(group_file
, fput_needed
);
1926 err_free_put_context
:
1936 * Initialize the perf_counter context in a task_struct:
1939 __perf_counter_init_context(struct perf_counter_context
*ctx
,
1940 struct task_struct
*task
)
1942 memset(ctx
, 0, sizeof(*ctx
));
1943 spin_lock_init(&ctx
->lock
);
1944 mutex_init(&ctx
->mutex
);
1945 INIT_LIST_HEAD(&ctx
->counter_list
);
1950 * inherit a counter from parent task to child task:
1952 static struct perf_counter
*
1953 inherit_counter(struct perf_counter
*parent_counter
,
1954 struct task_struct
*parent
,
1955 struct perf_counter_context
*parent_ctx
,
1956 struct task_struct
*child
,
1957 struct perf_counter
*group_leader
,
1958 struct perf_counter_context
*child_ctx
)
1960 struct perf_counter
*child_counter
;
1963 * Instead of creating recursive hierarchies of counters,
1964 * we link inherited counters back to the original parent,
1965 * which has a filp for sure, which we use as the reference
1968 if (parent_counter
->parent
)
1969 parent_counter
= parent_counter
->parent
;
1971 child_counter
= perf_counter_alloc(&parent_counter
->hw_event
,
1972 parent_counter
->cpu
, child_ctx
,
1973 group_leader
, GFP_KERNEL
);
1978 * Link it up in the child's context:
1980 child_counter
->task
= child
;
1981 list_add_counter(child_counter
, child_ctx
);
1982 child_ctx
->nr_counters
++;
1984 child_counter
->parent
= parent_counter
;
1986 * inherit into child's child as well:
1988 child_counter
->hw_event
.inherit
= 1;
1991 * Get a reference to the parent filp - we will fput it
1992 * when the child counter exits. This is safe to do because
1993 * we are in the parent and we know that the filp still
1994 * exists and has a nonzero count:
1996 atomic_long_inc(&parent_counter
->filp
->f_count
);
1999 * Link this into the parent counter's child list
2001 mutex_lock(&parent_counter
->mutex
);
2002 list_add_tail(&child_counter
->child_list
, &parent_counter
->child_list
);
2005 * Make the child state follow the state of the parent counter,
2006 * not its hw_event.disabled bit. We hold the parent's mutex,
2007 * so we won't race with perf_counter_{en,dis}able_family.
2009 if (parent_counter
->state
>= PERF_COUNTER_STATE_INACTIVE
)
2010 child_counter
->state
= PERF_COUNTER_STATE_INACTIVE
;
2012 child_counter
->state
= PERF_COUNTER_STATE_OFF
;
2014 mutex_unlock(&parent_counter
->mutex
);
2016 return child_counter
;
2019 static int inherit_group(struct perf_counter
*parent_counter
,
2020 struct task_struct
*parent
,
2021 struct perf_counter_context
*parent_ctx
,
2022 struct task_struct
*child
,
2023 struct perf_counter_context
*child_ctx
)
2025 struct perf_counter
*leader
;
2026 struct perf_counter
*sub
;
2028 leader
= inherit_counter(parent_counter
, parent
, parent_ctx
,
2029 child
, NULL
, child_ctx
);
2032 list_for_each_entry(sub
, &parent_counter
->sibling_list
, list_entry
) {
2033 if (!inherit_counter(sub
, parent
, parent_ctx
,
2034 child
, leader
, child_ctx
))
2040 static void sync_child_counter(struct perf_counter
*child_counter
,
2041 struct perf_counter
*parent_counter
)
2043 u64 parent_val
, child_val
;
2045 parent_val
= atomic64_read(&parent_counter
->count
);
2046 child_val
= atomic64_read(&child_counter
->count
);
2049 * Add back the child's count to the parent's count:
2051 atomic64_add(child_val
, &parent_counter
->count
);
2054 * Remove this counter from the parent's list
2056 mutex_lock(&parent_counter
->mutex
);
2057 list_del_init(&child_counter
->child_list
);
2058 mutex_unlock(&parent_counter
->mutex
);
2061 * Release the parent counter, if this was the last
2064 fput(parent_counter
->filp
);
2068 __perf_counter_exit_task(struct task_struct
*child
,
2069 struct perf_counter
*child_counter
,
2070 struct perf_counter_context
*child_ctx
)
2072 struct perf_counter
*parent_counter
;
2073 struct perf_counter
*sub
, *tmp
;
2076 * If we do not self-reap then we have to wait for the
2077 * child task to unschedule (it will happen for sure),
2078 * so that its counter is at its final count. (This
2079 * condition triggers rarely - child tasks usually get
2080 * off their CPU before the parent has a chance to
2081 * get this far into the reaping action)
2083 if (child
!= current
) {
2084 wait_task_inactive(child
, 0);
2085 list_del_init(&child_counter
->list_entry
);
2087 struct perf_cpu_context
*cpuctx
;
2088 unsigned long flags
;
2092 * Disable and unlink this counter.
2094 * Be careful about zapping the list - IRQ/NMI context
2095 * could still be processing it:
2097 curr_rq_lock_irq_save(&flags
);
2098 perf_flags
= hw_perf_save_disable();
2100 cpuctx
= &__get_cpu_var(perf_cpu_context
);
2102 group_sched_out(child_counter
, cpuctx
, child_ctx
);
2104 list_del_init(&child_counter
->list_entry
);
2106 child_ctx
->nr_counters
--;
2108 hw_perf_restore(perf_flags
);
2109 curr_rq_unlock_irq_restore(&flags
);
2112 parent_counter
= child_counter
->parent
;
2114 * It can happen that parent exits first, and has counters
2115 * that are still around due to the child reference. These
2116 * counters need to be zapped - but otherwise linger.
2118 if (parent_counter
) {
2119 sync_child_counter(child_counter
, parent_counter
);
2120 list_for_each_entry_safe(sub
, tmp
, &child_counter
->sibling_list
,
2123 sync_child_counter(sub
, sub
->parent
);
2127 kfree(child_counter
);
2132 * When a child task exits, feed back counter values to parent counters.
2134 * Note: we may be running in child context, but the PID is not hashed
2135 * anymore so new counters will not be added.
2137 void perf_counter_exit_task(struct task_struct
*child
)
2139 struct perf_counter
*child_counter
, *tmp
;
2140 struct perf_counter_context
*child_ctx
;
2142 child_ctx
= &child
->perf_counter_ctx
;
2144 if (likely(!child_ctx
->nr_counters
))
2147 list_for_each_entry_safe(child_counter
, tmp
, &child_ctx
->counter_list
,
2149 __perf_counter_exit_task(child
, child_counter
, child_ctx
);
2153 * Initialize the perf_counter context in task_struct
2155 void perf_counter_init_task(struct task_struct
*child
)
2157 struct perf_counter_context
*child_ctx
, *parent_ctx
;
2158 struct perf_counter
*counter
;
2159 struct task_struct
*parent
= current
;
2161 child_ctx
= &child
->perf_counter_ctx
;
2162 parent_ctx
= &parent
->perf_counter_ctx
;
2164 __perf_counter_init_context(child_ctx
, child
);
2167 * This is executed from the parent task context, so inherit
2168 * counters that have been marked for cloning:
2171 if (likely(!parent_ctx
->nr_counters
))
2175 * Lock the parent list. No need to lock the child - not PID
2176 * hashed yet and not running, so nobody can access it.
2178 mutex_lock(&parent_ctx
->mutex
);
2181 * We dont have to disable NMIs - we are only looking at
2182 * the list, not manipulating it:
2184 list_for_each_entry(counter
, &parent_ctx
->counter_list
, list_entry
) {
2185 if (!counter
->hw_event
.inherit
)
2188 if (inherit_group(counter
, parent
,
2189 parent_ctx
, child
, child_ctx
))
2193 mutex_unlock(&parent_ctx
->mutex
);
2196 static void __cpuinit
perf_counter_init_cpu(int cpu
)
2198 struct perf_cpu_context
*cpuctx
;
2200 cpuctx
= &per_cpu(perf_cpu_context
, cpu
);
2201 __perf_counter_init_context(&cpuctx
->ctx
, NULL
);
2203 mutex_lock(&perf_resource_mutex
);
2204 cpuctx
->max_pertask
= perf_max_counters
- perf_reserved_percpu
;
2205 mutex_unlock(&perf_resource_mutex
);
2207 hw_perf_counter_setup(cpu
);
2210 #ifdef CONFIG_HOTPLUG_CPU
2211 static void __perf_counter_exit_cpu(void *info
)
2213 struct perf_cpu_context
*cpuctx
= &__get_cpu_var(perf_cpu_context
);
2214 struct perf_counter_context
*ctx
= &cpuctx
->ctx
;
2215 struct perf_counter
*counter
, *tmp
;
2217 list_for_each_entry_safe(counter
, tmp
, &ctx
->counter_list
, list_entry
)
2218 __perf_counter_remove_from_context(counter
);
2220 static void perf_counter_exit_cpu(int cpu
)
2222 struct perf_cpu_context
*cpuctx
= &per_cpu(perf_cpu_context
, cpu
);
2223 struct perf_counter_context
*ctx
= &cpuctx
->ctx
;
2225 mutex_lock(&ctx
->mutex
);
2226 smp_call_function_single(cpu
, __perf_counter_exit_cpu
, NULL
, 1);
2227 mutex_unlock(&ctx
->mutex
);
2230 static inline void perf_counter_exit_cpu(int cpu
) { }
2233 static int __cpuinit
2234 perf_cpu_notify(struct notifier_block
*self
, unsigned long action
, void *hcpu
)
2236 unsigned int cpu
= (long)hcpu
;
2240 case CPU_UP_PREPARE
:
2241 case CPU_UP_PREPARE_FROZEN
:
2242 perf_counter_init_cpu(cpu
);
2245 case CPU_DOWN_PREPARE
:
2246 case CPU_DOWN_PREPARE_FROZEN
:
2247 perf_counter_exit_cpu(cpu
);
2257 static struct notifier_block __cpuinitdata perf_cpu_nb
= {
2258 .notifier_call
= perf_cpu_notify
,
2261 static int __init
perf_counter_init(void)
2263 perf_cpu_notify(&perf_cpu_nb
, (unsigned long)CPU_UP_PREPARE
,
2264 (void *)(long)smp_processor_id());
2265 register_cpu_notifier(&perf_cpu_nb
);
2269 early_initcall(perf_counter_init
);
2271 static ssize_t
perf_show_reserve_percpu(struct sysdev_class
*class, char *buf
)
2273 return sprintf(buf
, "%d\n", perf_reserved_percpu
);
2277 perf_set_reserve_percpu(struct sysdev_class
*class,
2281 struct perf_cpu_context
*cpuctx
;
2285 err
= strict_strtoul(buf
, 10, &val
);
2288 if (val
> perf_max_counters
)
2291 mutex_lock(&perf_resource_mutex
);
2292 perf_reserved_percpu
= val
;
2293 for_each_online_cpu(cpu
) {
2294 cpuctx
= &per_cpu(perf_cpu_context
, cpu
);
2295 spin_lock_irq(&cpuctx
->ctx
.lock
);
2296 mpt
= min(perf_max_counters
- cpuctx
->ctx
.nr_counters
,
2297 perf_max_counters
- perf_reserved_percpu
);
2298 cpuctx
->max_pertask
= mpt
;
2299 spin_unlock_irq(&cpuctx
->ctx
.lock
);
2301 mutex_unlock(&perf_resource_mutex
);
2306 static ssize_t
perf_show_overcommit(struct sysdev_class
*class, char *buf
)
2308 return sprintf(buf
, "%d\n", perf_overcommit
);
2312 perf_set_overcommit(struct sysdev_class
*class, const char *buf
, size_t count
)
2317 err
= strict_strtoul(buf
, 10, &val
);
2323 mutex_lock(&perf_resource_mutex
);
2324 perf_overcommit
= val
;
2325 mutex_unlock(&perf_resource_mutex
);
2330 static SYSDEV_CLASS_ATTR(
2333 perf_show_reserve_percpu
,
2334 perf_set_reserve_percpu
2337 static SYSDEV_CLASS_ATTR(
2340 perf_show_overcommit
,
2344 static struct attribute
*perfclass_attrs
[] = {
2345 &attr_reserve_percpu
.attr
,
2346 &attr_overcommit
.attr
,
2350 static struct attribute_group perfclass_attr_group
= {
2351 .attrs
= perfclass_attrs
,
2352 .name
= "perf_counters",
2355 static int __init
perf_counter_sysfs_init(void)
2357 return sysfs_create_group(&cpu_sysdev_class
.kset
.kobj
,
2358 &perfclass_attr_group
);
2360 device_initcall(perf_counter_sysfs_init
);