[PATCH 15/19] perf ftrace: show trace column header

[Changbin Du]

This makes perf-ftrace display column header before printing trace.

$ sudo perf ftrace
\# tracer: function
\#
\# entries-in-buffer/entries-written: 0/0   #P:8
\#
\#           TASK-PID     CPU#   TIMESTAMP  FUNCTION
\#              | |         |       |         |
           <...>-9246  [006]  10726.262760: mutex_unlock <-rb_simple_write
           <...>-9246  [006]  10726.262764: __fsnotify_parent <-vfs_write
           <...>-9246  [006]  10726.262765: fsnotify <-vfs_write
           <...>-9246  [006]  10726.262766: __sb_end_write <-vfs_write
           <...>-9246  [006]  10726.262767: fpregs_assert_state_consistent <-do_syscall_64

Signed-off-by: Changbin Du <changbin.du@xxxxxxxxx>
---
 tools/perf/builtin-ftrace.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
index 64c22f367ba2..0b39b6a88026 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -614,6 +614,9 @@ static int __cmd_ftrace(struct perf_ftrace *ftrace, int argc, const char **argv)
 	fcntl(trace_fd, F_SETFL, O_NONBLOCK);
 	pollfd.fd = trace_fd;
 
+	/* display column headers */
+	read_tracing_file_to_stdout("trace");
+
 	if (write_tracing_file("tracing_on", "1") < 0) {
 		pr_err("can't enable tracing\n");
 		goto out_close_fd;
-- 
2.25.1