[PATCH v4 06/17] 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...@gmail.com>
---
 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 348e2d960987..887e78b23a82 100644
--- a/tools/perf/builtin-ftrace.c
+++ b/tools/perf/builtin-ftrace.c
@@ -430,6 +430,9 @@ 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