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

Ingo Molnar
2009-08-27T07:32:27Z

* 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