Re: [PATCH][GIT PULL] ftrace: add kernel command line functionfiltering

From: Thomas Gleixner
Date: Thu May 28 2009 - 16:55:42 EST


On Thu, 28 May 2009, Steven Rostedt wrote:
> ----
> Documentation/kernel-parameters.txt | 17 ++++++++++++-
> kernel/trace/ftrace.c | 42 +++++++++++++++++++++++++++++++++++
> 2 files changed, 57 insertions(+), 2 deletions(-)
> ---------------------------
> commit 3481535dc7351d3a45f67d8016bd78fc5c537628
> Author: Steven Rostedt <srostedt@xxxxxxxxxx>
> Date: Thu May 28 13:37:24 2009 -0400
>
> ftrace: add kernel command line function filtering
>
> When using ftrace=function on the command line to trace functions
> on boot up, one can not filter out functions that are commonly called.
>
> This patch adds two new ftrace command line commands.
>
> ftrace_notrace=function-list
> ftrace_filter=function-list
>
> Where function-list is a comma separated list of functions to filter.
> The ftrace_notrace will make the functions listed not be included
> in the function tracing, and ftrace_filter will only trace the functions
> listed.
>
> These two act the same as the debugfs/tracing/set_ftrace_notrace and
> debugfs/tracing/set_ftrace_filter respectively.
>
> The simple glob expressions that are allowed by the filter files can also
> be used by the command line interface.
>
> ftrace_notrace=rcu*,*lock,*spin*
>
> Will not trace any function that starts with rcu, ends with lock, or has
> the word spin in it.

That's enough to filter out most of the annoyance during boot

> Note, if the self tests are enabled, they may interfere with the filtering
> set by the command lines.
>
> [ Imact: allow filtering of function tracing at boot up ]

Is "Imact" an attempt to distract Linus ?

Thanks,

tglx
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