[PATCH 1/5] ftrace perf: Check sample types only for sampling events

Jiri Olsa
2016-03-16T14:34:49Z

Currently we check sample type for ftrace:function event
even if it's not created as sampling event. That prevents
creating ftrace_function event in counting mode.

Making sure we check sample types only for sampling events.

Before:
$ sudo perf stat -e ftrace:function ls
...

Performance counter stats for 'ls':

<not supported> ftrace:function

0.001983662 seconds time elapsed

After:
$ sudo perf stat -e ftrace:function ls
...

Performance counter stats for 'ls':

44,498 ftrace:function

0.037534722 seconds time elapsed

Suggested-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
kernel/trace/trace_event_perf.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 00df25fd86ef..e11108f1d197 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -47,6 +47,9 @@ static int perf_trace_event_perm(struct trace_event_call *tp_event,
if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
return -EPERM;

+ if (!is_sampling_event(p_event))
+ return 0;
+
/*
* We don't allow user space callchains for function trace
* event, due to issues with page faults while tracing page
--
2.4.3