Re: [PATCH v2] events/core: fix acoount failure for event's total_enable_time
From: Peter Zijlstra
Date: Fri Dec 20 2024 - 10:29:31 EST
On Fri, Dec 20, 2024 at 04:14:14PM +0100, Peter Zijlstra wrote:
> On Fri, Dec 20, 2024 at 02:05:39PM +0000, Yeoreum Yun wrote:
> > the answer is in the perf_event_exit_event()'s
> > perf_remove_from_context(). in here
> > event_sched_out() is called via __perf_remove_from_context()
> > So above case, the enable time is fixed in here.
>
> OK, how's this then?
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 065f9188b44a..96a00034b26f 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -2406,7 +2406,8 @@ ctx_time_update_event(struct perf_event_context *ctx, struct perf_event *event)
#define DETACH_GROUP 0x01UL
#define DETACH_CHILD 0x02UL
-#define DETACH_DEAD 0x04UL
+#define DETACH_EXIT 0x04UL
+#define DETACH_DEAD 0x048L
/*
* Cross CPU call to remove a performance event
@@ -2421,6 +2422,7 @@ __perf_remove_from_context(struct perf_event *event,
void *info)
{
struct perf_event_pmu_context *pmu_ctx = event->pmu_ctx;
+ enum perf_event_state state = PERF_EVENT_STATE_OFF;
unsigned long flags = (unsigned long)info;
ctx_time_update(cpuctx, ctx);
@@ -2429,16 +2431,20 @@ __perf_remove_from_context(struct perf_event *event,
* Ensure event_sched_out() switches to OFF, at the very least
* this avoids raising perf_pending_task() at this time.
*/
- if (flags & DETACH_DEAD)
+ if (flags & DETACH_EXIT)
+ state = PERF_EVENT_STATE_EXIT;
+ if (flags & DETACH_DEAD) {
event->pending_disable = 1;
+ state = PERF_EVENT_STATE_DEAD;
+ }
event_sched_out(event, ctx);
if (flags & DETACH_GROUP)
perf_group_detach(event);
if (flags & DETACH_CHILD)
perf_child_detach(event);
list_del_event(event, ctx);
- if (flags & DETACH_DEAD)
- event->state = PERF_EVENT_STATE_DEAD;
+
+ perf_event_set_state(event, min(event->state, state));
if (!pmu_ctx->nr_events) {
pmu_ctx->rotate_necessary = 0;
@@ -13371,12 +13377,7 @@ perf_event_exit_event(struct perf_event *event, struct perf_event_context *ctx)
mutex_lock(&parent_event->child_mutex);
}
- perf_remove_from_context(event, detach_flags);
-
- raw_spin_lock_irq(&ctx->lock);
- if (event->state > PERF_EVENT_STATE_EXIT)
- perf_event_set_state(event, PERF_EVENT_STATE_EXIT);
- raw_spin_unlock_irq(&ctx->lock);
+ perf_remove_from_context(event, detach_flags | DETACH_EXIT);
/*
* Child events can be freed.