linux-kernel - Re: [PATCH v5 02/17] perf ftrace: add option '-F/--funcs' to list available functions

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Message-ID: <20200718070600.6ptgpxtj5xmcwckt@mail.google.com>
Date:   Sat, 18 Jul 2020 15:06:00 +0800
From:   Changbin Du <changbin.du@...il.com>
To:     Steven Rostedt <rostedt@...dmis.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>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-kernel@...r.kernel.org,
        "linux-trace-devel@...r.kernel.org" 
        <linux-trace-devel@...r.kernel.org>
Subject: Re: [PATCH v5 02/17] perf ftrace: add option '-F/--funcs' to list
 available functions

On Fri, Jul 17, 2020 at 11:05:04AM -0400, Steven Rostedt wrote:
> On Sat, 11 Jul 2020 20:40:20 +0800
> Changbin Du <changbin.du@...il.com> wrote:
> 
> > This adds an option '-F/--funcs' to list all available functions to trace,
> > which is read from tracing file 'available_filter_functions'.
> > 
> > $ sudo ./perf ftrace -F | head
> > trace_initcall_finish_cb
> > initcall_blacklisted
> > do_one_initcall
> > do_one_initcall
> > trace_initcall_start_cb
> > run_init_process
> > try_to_run_init_process
> > match_dev_by_label
> > match_dev_by_uuid
> > rootfs_init_fs_context
> > 
> > Signed-off-by: Changbin Du <changbin.du@...il.com>
> > 
> > ---
> > v2: option name '-l/--list-functions' -> '-F/--funcs'
> > ---
> >  tools/perf/Documentation/perf-ftrace.txt |  4 +++
> >  tools/perf/builtin-ftrace.c              | 43 ++++++++++++++++++++++++
> >  2 files changed, 47 insertions(+)
> > 
> > diff --git a/tools/perf/Documentation/perf-ftrace.txt b/tools/perf/Documentation/perf-ftrace.txt
> > index 952e46669168..d79560dea19f 100644
> > --- a/tools/perf/Documentation/perf-ftrace.txt
> > +++ b/tools/perf/Documentation/perf-ftrace.txt
> > @@ -30,6 +30,10 @@ OPTIONS
> >  --verbose=::
> >          Verbosity level.
> >  
> > +-F::
> > +--funcs::
> > +        List all available functions to trace.
> > +
> >  -p::
> >  --pid=::
> >  	Trace on existing process id (comma separated list).
> > diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> > index 5f53da87040d..244cc8e6bd60 100644
> > --- a/tools/perf/builtin-ftrace.c
> > +++ b/tools/perf/builtin-ftrace.c
> > @@ -32,6 +32,7 @@ struct perf_ftrace {
> >  	struct evlist		*evlist;
> >  	struct target		target;
> >  	const char		*tracer;
> > +	bool			list_avail_functions;
> >  	struct list_head	filters;
> >  	struct list_head	notrace;
> >  	struct list_head	graph_funcs;
> > @@ -127,6 +128,43 @@ static int append_tracing_file(const char *name, const char *val)
> >  	return __write_tracing_file(name, val, true);
> >  }
> >  
> > +static int read_tracing_file_to_stdout(const char *name)
> > +{
> 
> All this is looking like its duplicating code that we are working on
> for libtracefs. 
> 
> Would you like to start contributing to that, and when we get the
> libtracefs.so packed in distributions, we can easily create the
> perf ftrace without having to rewrite the wheel 10 times?
> 
> -- Steve
Yes, I'd like to join the development of libtracefs. But honestly speaking,
I am not sure whether I can get enough time on it since I have to take care
of my little baby :).

I have the same opinion with Arnaldo that we can merge what we'v already
done here. Then consider to migrate to libtracefs instead before adding
more new features.

-- 
Cheers,
Changbin Du