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

[Masami Hiramatsu]

Frederic Weisbecker wrote:
> On Thu, Aug 27, 2009 at 09:31:39AM +0200, Ingo Molnar wrote:
> > * Frederic Weisbecker<fweisbec@xxxxxxxxx>  wrote:
> >
> > > From: Masami Hiramatsu<mhiramat@xxxxxxxxxx>
> > >
> > > 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.

As far as I've tested, it just requires two changes for perf-tools.
- Support CONFIG_PROFILE_EVENT(profile_enable/disable) on kprobe-tracer.
- Ignore 'alias' tag(which is a special tag in kprobes event) while
  parsing format file.

Thank you,


--
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division

e-mail: mhiramat@xxxxxxxxxx

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