Re: [PATCH 00/15] [git pull] for tip/tracing/ftrace

Ingo Molnar
2009-02-17T10:42:51Z

* Steven Rostedt <rostedt@goodmis.org> wrote:

> Ingo,
>
> This is a patch series that offers a variety of features.
>
> The first is to add:
>
> #### all functions enabled ####
>
> to set_ftrace_filter when all functions will be traced when function
> tracing is on.
>
> The next is to add a :command: interface, and the module command:
>
> echo '*:mod:ext4' > set_ftrace_filter
>
> Will select all functions in the ext4 module.
>
> echo '!*write*:mod:ext4' > set_ftrace_filter
>
> will remove all functions with the characters 'write' and are
> in ext4.

Very nice feature!

I'm wondering, would it be possible to somehow extend this to
built-in drivers too, so that we get symmetry of usage
independently of whether something is built in or a module? I
suspect it needs some extensions to kbuild though ...

> Next we extend the :command: interface as well as add a way to
> hook tracers to specific functions. Instead of tracing all functions
> the same, this patch series adds a hash to be able to trace different
> functions differently.

That's a nice extension too!

Small naming detail: instead of calling it a 'hook' (which
really has a bad sound to it for various reasons), how about
calling it a 'trigger' and/or a 'callback'?

> I implement a 'traceon' and 'traceoff' to have a function
> start or stop tracing when it is hit. It also includes a
> counter for the number of times to implement the trace on/off.
>
> echo '*_lock:traceon:4' > set_ftrace_filter
> echo '*_unlock:traceoff:5' > set_ftrace_filter

if there's no counter specified, does it default to 1
[single-shot trigger] or infinity?

> This will have all functions that end with _lock turn on
> tracing and all that end with _unlock disable it, 4 times
> each.
>
> The following patches are in:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace.git
>
> branch: tip/tracing/ftrace
>
>
> Steven Rostedt (15):
> ftrace: state that all functions are enabled in set_ftrace_filter
> ftrace: add do_for_each_ftrace_rec and while_for_each_ftrace_rec
> ftrace: rename ftrace_match to ftrace_match_records
> ftrace: break up ftrace_match_records into smaller components
> ftrace: add module command function filter selection
> ftrace: enable filtering only when a function is filtered on
> ftrace: add command interface for function selection
> ftrace: convert ftrace_lock from a spinlock to mutex
> ftrace: consolidate mutexes
> ftrace: trace different functions with a different tracer
> ring-buffer: add tracing_is_on to test if ring buffer is enabled
> ftrace: add traceon traceoff commands to enable/disable the buffers
> ftrace: show selected functions in set_ftrace_filter
> ftrace: add pretty print to selected fuction traces
> ftrace: add pretty print function for traceon and traceoff hooks
>
> ----
> include/linux/ftrace.h | 40 ++
> include/linux/ring_buffer.h | 2 +
> kernel/trace/ftrace.c | 929 +++++++++++++++++++++++++++++++---------
> kernel/trace/ring_buffer.c | 9 +
> kernel/trace/trace_functions.c | 163 +++++++
> 5 files changed, 946 insertions(+), 197 deletions(-)

Pulled into tip:tracing/ftrace, thanks Steve!

Ingo