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Re: [PATCH -tip v5 4/7] tracing: add kprobe-based event tracer
- From: Christoph Hellwig <hch at infradead dot org>
- To: Masami Hiramatsu <mhiramat at redhat dot com>
- Cc: Ingo Molnar <mingo at elte dot hu>, Steven Rostedt <rostedt at goodmis dot org>, lkml <linux-kernel at vger dot kernel dot org>, systemtap <systemtap at sources dot redhat dot com>, kvm <kvm at vger dot kernel dot org>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Frederic Weisbecker <fweisbec at gmail dot com>, Tom Zanussi <tzanussi at gmail dot com>
- Date: Mon, 11 May 2009 05:32:24 -0400
- Subject: Re: [PATCH -tip v5 4/7] tracing: add kprobe-based event tracer
- References: <20090509004829.5505.38720.stgit@localhost.localdomain> <20090509004859.5505.18729.stgit@localhost.localdomain>
On Fri, May 08, 2009 at 08:48:59PM -0400, Masami Hiramatsu wrote:
> 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).
That's some pretty cool functionality, especially together with patch 7.
But as with so many tracing bits in the kernel it's just lowlevel bits
without a good user interface. We'd really need some high-level way
for sysadmins/developers to use it. E.g. a version of the systemtap
compiler that doesn't build a kernel module but instead uses the event
tracer + the kprobes tracer.
Or a model like Tom's zedtrace where a perl script would do the dwarf
lookups and generates these probes in addition to the filtered event
traces.