linux-kernel - Re: [PATCH] tracing: print function names instead of just address

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Message-ID: <20190212025819.tremtds3coufd5ga@mail.google.com>
Date:   Tue, 12 Feb 2019 02:58:20 +0000
From:   Changbin Du <changbin.du@...il.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Changbin Du <changbin.du@...il.com>, mingo@...hat.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tracing: print function names instead of just address

On Mon, Feb 11, 2019 at 02:55:32PM -0500, Steven Rostedt wrote:
> On Sun, 10 Feb 2019 00:19:19 +0800
> Changbin Du <changbin.du@...il.com> wrote:
> 
> > Here is an example for this change.
> > 
> > $ sudo perf record -e 'ftrace:function' --filter='ip==schedule'
> > $ sudo perf report
> 
> I took this but changed the subject as it only affects perf (the kernel
> doesn't use the format field for output, and trace-cmd has an internal
> plugin that overrides it too).
>
Thanks. You explained why I can't find the usage for the other entries.
I was looking for it before... :)

> -- Steve
> 
> > 
> > The output of perf before this patch:
> > 
> > \# Samples: 100  of event 'ftrace:function'
> > \# Event count (approx.): 100
> > \#
> > \# Overhead  Trace output
> > \# ........  ......................................
> > \#
> >     51.00%   ffffffff81f6aaa0 <-- ffffffff81158e8d
> >     29.00%   ffffffff81f6aaa0 <-- ffffffff8116ccb2
> >      8.00%   ffffffff81f6aaa0 <-- ffffffff81f6f2ed
> >      4.00%   ffffffff81f6aaa0 <-- ffffffff811628db
> >      4.00%   ffffffff81f6aaa0 <-- ffffffff81f6ec5b
> >      2.00%   ffffffff81f6aaa0 <-- ffffffff81f6f21a
> >      1.00%   ffffffff81f6aaa0 <-- ffffffff811b04af
> >      1.00%   ffffffff81f6aaa0 <-- ffffffff8143ce17
> > 
> > After this patch:
> > 
> > \# Samples: 36  of event 'ftrace:function'
> > \# Event count (approx.): 36
> > \#
> > \# Overhead  Trace output
> > \# ........  ............................................
> > \#
> >     38.89%   schedule <-- schedule_hrtimeout_range_clock
> >     27.78%   schedule <-- worker_thread
> >     13.89%   schedule <-- schedule_timeout
> >     11.11%   schedule <-- smpboot_thread_fn
> >      5.56%   schedule <-- rcu_gp_kthread
> >      2.78%   schedule <-- exit_to_usermode_loop
> > 
> > Signed-off-by: Changbin Du <changbin.du@...il.com>
> > ---
> >  kernel/trace/trace_entries.h | 41 +++++++++++++++++-------------------
> >  1 file changed, 19 insertions(+), 22 deletions(-)
> > 
> > 

-- 
Cheers,
Changbin Du