[PATCH] perf: Generate EXIT event only once per task context

Namhyung Kim
2013-03-15T07:27:20Z

From: Namhyung Kim <namhyung.kim@lge.com>

perf_event_task_event() iterates pmu list and generate events for each
eligible pmu context. But if task_event has task_ctx like in EXIT
it'll generate events even though the pmu doesn't have an eligible one.
Fix it by moving the code to proper places.

Before this patch:

$ perf record -n true
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.006 MB perf.data (~248 samples) ]

$ perf report -D | tail
Aggregated stats:
TOTAL events: 73
MMAP events: 67
COMM events: 2
EXIT events: 4
cycles stats:
TOTAL events: 73
MMAP events: 67
COMM events: 2
EXIT events: 4

After this patch:

$ perf report -D | tail
Aggregated stats:
TOTAL events: 70
MMAP events: 67
COMM events: 2
EXIT events: 1
cycles stats:
TOTAL events: 70
MMAP events: 67
COMM events: 2
EXIT events: 1

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
kernel/events/core.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 53ac21cc4012..73ea6fcacf52 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4432,12 +4432,15 @@ static void perf_event_task_event(struct perf_task_event *task_event)
if (ctxn < 0)
goto next;
ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
+ if (ctx)
+ perf_event_task_ctx(ctx, task_event);
}
- if (ctx)
- perf_event_task_ctx(ctx, task_event);
next:
put_cpu_ptr(pmu->pmu_cpu_context);
}
+ if (task_event->task_ctx)
+ perf_event_task_ctx(task_event->task_ctx, task_event);
+
rcu_read_unlock();
}

--
1.7.11.7