linux-kernel - Re: [PATCH v2 07/15] perf ftrace: show trace column header

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Date:   Tue, 7 Jul 2020 22:06:10 +0800
From:   Changbin Du <changbin.du@...il.com>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Changbin Du <changbin.du@...il.com>, Jiri Olsa <jolsa@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 07/15] perf ftrace: show trace column header

On Fri, Jul 03, 2020 at 03:20:15PM +0900, Namhyung Kim wrote:
> On Sat, Jun 27, 2020 at 10:38 PM Changbin Du <changbin.du@...il.com> wrote:
> >
> > 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
> 
> You'd better indent the example output by 2 spaces to prevent
> the # signs commented out.
>
okay. I even didn't know this recipe befoe so I add a '\' :).  Thanks.

> Thanks
> Namhyung
> 
> 
> >
> > Signed-off-by: Changbin Du <changbin.du@...il.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 e45496012611..686d744d5025 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 (!ftrace->initial_delay) {
> >                 if (write_tracing_file("tracing_on", "1") < 0) {
> >                         pr_err("can't enable tracing\n");
> > --
> > 2.25.1
> >

-- 
Cheers,
Changbin Du