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Re: [PATCH -tip tracing/kprobes 0/9] tracing/kprobes, perf: perf probe and kprobe-tracer bugfixes
- From: Masami Hiramatsu <mhiramat at redhat dot com>
- To: Ingo Molnar <mingo at elte dot hu>
- Cc: Frederic Weisbecker <fweisbec at gmail dot com>, Steven Rostedt <rostedt at goodmis dot org>, lkml <linux-kernel at vger dot kernel dot org>, Thomas Gleixner <tglx at linutronix dot de>, Arnaldo Carvalho de Melo <acme at redhat dot com>, Mike Galbraith <efault at gmx dot de>, Paul Mackerras <paulus at samba dot org>, Peter Zijlstra <a dot p dot zijlstra at chello dot nl>, Christoph Hellwig <hch at infradead dot org>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Jim Keniston <jkenisto at us dot ibm dot com>, "Frank Ch. Eigler" <fche at redhat dot com>, "H. Peter Anvin" <hpa at zytor dot com>, systemtap <systemtap at sources dot redhat dot com>, DLE <dle-develop at lists dot sourceforge dot net>
- Date: Tue, 20 Oct 2009 10:38:14 -0400
- Subject: Re: [PATCH -tip tracing/kprobes 0/9] tracing/kprobes, perf: perf probe and kprobe-tracer bugfixes
- References: <20091017000711.16556.69935.stgit@dhcp-100-2-132.bos.redhat.com> <20091017080203.GA4155@elte.hu> <20091017103427.GA31238@elte.hu> <4ADAAF50.9040604@redhat.com> <20091019075103.GF17960@elte.hu> <20091019110055.GA5549@nowhere> <20091019112125.GA12829@elte.hu> <4ADCC348.2020800@redhat.com> <20091020065055.GL8550@elte.hu>
Ingo Molnar wrote:
>>> The point is to prefer intuitive, non-mechanic, fundamentally human
>>> expressions of information above mechanic ones (absolute line numbers,
>>> addresses, ways of probing, etc.) - and to have a rich variety of them.
>>>
>>> String based pattern matching and intuitive syntax that reuses existing
>>> paradigms of arithmetics and pattern-matching is good - limited syntax
>>> and extra, arbitrary syntactic hoops to jump through is bad.
>>>
>>> If we provide all that, people will start using this stuff - and i'd
>>> only like to merge this upstream once it's clear that people like me
>>> will (be able to) use this facility for ad-hoc probe insertion.
>>>
>>> In other words: this facility has to 'live within' our source code and
>>> has to be able to interact with it on a very broad basis - for it to be
>>> maximally useful for everyday development.
>>
>> Hmm, so you mean perf-probe should work with source-code? Without
>> source code (but with debuginfo), maybe we can't use string matching,
>> is that OK?
>
> Well most forms of debuginfo embedd the full source code in the
> debuginfo, right? If it's not there (or we dont know where it is) then
> we cannot use it, obviously.
Um, actually debuginfo doesn't have the full source code, but has
the source file path. So, only if there are source files,
we can use string-based matching. Even if there are no source files,
that means users can't change their kernel:-). So we don't care
about kernel-version dependency.
> But we obviously want the whole 'perf probe' workflow to primarily
> operate on source code - we are humans.
Sure :-)
Thank you,
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division
e-mail: mhiramat@redhat.com