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

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Message-ID: <20190211145532.75d82308@gandalf.local.home>
Date:   Mon, 11 Feb 2019 14:55:32 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Changbin Du <changbin.du@...il.com>
Cc:     mingo@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tracing: print function names instead of just address

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).

-- 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(-)
> 
>