[tip:perf/urgent] perf: Generate EXIT event only once per task context

tip-bot for Namhyung Kim
2013-03-18T11:09:12Z

Commit-ID: d610d98b5de6860feb21539726e9af7c9094151c
Gitweb: http://git.kernel.org/tip/d610d98b5de6860feb21539726e9af7c9094151c
Author: Namhyung Kim <namhyung.kim@lge.com>
AuthorDate: Fri, 15 Mar 2013 16:27:13 +0900
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 18 Mar 2013 09:47:33 +0100

perf: Generate EXIT event only once per task context

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>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung.kim@lge.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1363332433-7637-1-git-send-email-namhyung@kernel.org
Signed-off-by: Ingo Molnar <mingo@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 fa79c37..59412d0 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4434,12 +4434,15 @@ 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();
}