On Wed, May 20, 2020 at 06:11:01PM -0300, Arnaldo Carvalho de Melo wrote:
> Em Sun, May 10, 2020 at 11:06:24PM +0800, Changbin Du escreveu:
> > This makes perf-ftrace display column header before printing trace.
>
> [acme@five perf]$ perf report -h header
>
> Usage: perf report [<options>]
>
> --header Show data header.
> --header-only Show only data header.
>
> [acme@five perf]$
>
> Perhaps there is value in --header-only to show the default that will be
> setup when using some set of options.
>
Arnaldo, what is the '--header-only' option used for? As for ftrace, the header
format is different for different trace options.
> - Arnaldo
>
> > $ 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 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
> >
>
> --
>
> - Arnaldo
--
Cheers,
Changbin Du
