Re: [PATCH 08/18] tracing: Add kprobe-based event tracer

Frederic Weisbecker
2009-08-27T13:48:14Z

On Thu, Aug 27, 2009 at 09:31:39AM +0200, Ingo Molnar wrote:
>
> * Frederic Weisbecker <fweisbec@gmail.com> wrote:
>
> > From: Masami Hiramatsu <mhiramat@redhat.com>
> >
> > Add kprobes-based event tracer on ftrace.
> >
> > This tracer is similar to the events tracer which is based on
> > Tracepoint infrastructure. Instead of Tracepoint, this tracer is
> > based on kprobes (kprobe and kretprobe). It probes anywhere where
> > kprobes can probe(this
> > means, all functions body except for __kprobes functions).
> >
> > Similar to the events tracer, this tracer doesn't need to be
> > activated via current_tracer, instead of that, just set probe
> > points via /sys/kernel/debug/tracing/kprobe_events. And you can
> > set filters on each probe events via
> > /sys/kernel/debug/tracing/events/kprobes/<EVENT>/filter.
>
> ok, one observation here: this should seemlessly merge into
> /debug/tracing/events/ and provide a record format descriptor in
> 'format' to allow the automated fetching of the results of the
> probe. The PERF_SAMPLE_RAW gateway should work as well.
>
> That way tooling that knows about /debug/tracing/events/ will
> automatically work with kprobes events as well. We can profile based
> on kprobes, etc. etc.
>
> The _setting_ of the probe is still a separate channel - but if
> existing installed probes are merged into existing tooling that's a
> big step forward in terms of utility.
>
> Ingo

It does already :)

But I've split out this patch that initially embeded the documentation.
If you look at the 9/10 patch, you can see how look like the format
files for kprobes.