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Re: [PATCH tracing/kprobes 0/7] tracing/kprobes: kprobe-based event tracer update and perf support
- From: fche at redhat dot com (Frank Ch. Eigler)
- To: Frederic Weisbecker <fweisbec at gmail dot com>
- Cc: 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>, Christoph Hellwig <hch at infradead dot org>, "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 15:03:35 -0400
- 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>
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.
It is also too easy to stress the low-level machinery beyond its
humble origins, in this case meaning putting probes in all kinds of
tender spots that go "ouch". The kprobes robustness patches coming in
are great and will benefit all of our efforts, but it will be awhile
until the kernel can survive a fuzz/crashme type stress test on that
subsystem. So expect ongoing effort there.
- FChE