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Re: [PATCH tracing/kprobes 0/7] tracing/kprobes: kprobe-based event tracer update and perf support
- From: Mark Wielaard <mjw at redhat dot com>
- To: Christoph Hellwig <hch at infradead dot org>
- Cc: "Frank Ch. Eigler" <fche at redhat dot com>, Frederic Weisbecker <fweisbec at gmail dot com>, Masami Hiramatsu <mhiramat at redhat dot com>, Steven Rostedt <rostedt at goodmis dot org>, Ingo Molnar <mingo at elte dot hu>, lkml <linux-kernel at vger dot kernel dot org>, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Andi Kleen <ak at linux dot intel dot com>, "H. Peter Anvin" <hpa at zytor dot com>, Jason Baron <jbaron at redhat dot com>, Jim Keniston <jkenisto at us dot ibm dot com>, "K.Prasad" <prasad at linux dot vnet dot ibm dot com>, Lai Jiangshan <laijs at cn dot fujitsu dot com>, Li Zefan <lizf at cn dot fujitsu dot com>, Peter Zijlstra <peterz at infradead dot org>, Srikar Dronamraju <srikar at linux dot vnet dot ibm dot com>, Tom Zanussi <tzanussi at gmail dot com>, systemtap <systemtap at sources dot redhat dot com>, DLE <dle-develop at lists dot sourceforge dot net>
- Date: Fri, 11 Sep 2009 21:50:13 +0200
- Subject: Re: [PATCH tracing/kprobes 0/7] tracing/kprobes: kprobe-based event tracer update and perf support
- References: <20090910235258.22412.29317.stgit@dhcp-100-2-132.bos.redhat.com> <20090911013332.GB16396@nowhere> <y0mr5udjoc8.fsf@fche.csb> <20090911190651.GA22065@infradead.org>
On Fri, 2009-09-11 at 15:06 -0400, Christoph Hellwig wrote:
> On Fri, Sep 11, 2009 at 03:03:35PM -0400, Frank Ch. Eigler wrote:
> > Frederic Weisbecker <fweisbec@gmail.com> writes:
> >
> > > [...] I'm really looking forward seeing this C expression-like
> > > kprobe creation tool. It seems powerful enough to replace printk +
> > > kernel rebuild. No need anymore to write some printk to debug,
> > > worrying, [...]
> >
> > To a large extent, systemtap had delivered this already some years
> > ago, including the cushy ponies dancing in the sunlight. While such
> > low-level machinery is fine, some of our experience indicates that it
> > is dramatically easier to use if high-level, symbolic, debugging data
> > is used to compute probe locations and variable names/types/locations.
>
> No, systemtap has been for years failing to delivers this in a way that
> it could be usefully integrated into the kernel.
You are saying "No" to a claim Frank didn't even make.
> Masami's patches are
> exactly the kind of low-level functionality we absolutely need in the
> kernel tree so that we can built more useful higherlevel tools ontop
> of this.
And nobody is denying that either. I think everybody agrees that Masami
is doing some really wonderful work and improving the kprobes
foundations in a way that any higher level tracing tool will benefit
from it.
Cheers,
Mark