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Re: [PATCH -tip v6 00/22] kprobes: introduce NOKPROBE_SYMBOL(), cleanup and fixes crash bugs
- From: fche at redhat dot com (Frank Ch. Eigler)
- To: Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>
- Cc: Ingo Molnar <mingo at kernel dot org>, linux-arch at vger dot kernel dot org, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Sandeepa Prabhu <sandeepa dot prabhu at linaro dot org>, x86 at kernel dot org, lkml <linux-kernel at vger dot kernel dot org>, "Steven Rostedt (Red Hat)" <rostedt at goodmis dot org>, systemtap at sourceware dot org, "David S. Miller" <davem at davemloft dot net>
- Date: Thu, 19 Dec 2013 15:46:02 -0500
- Subject: Re: [PATCH -tip v6 00/22] kprobes: introduce NOKPROBE_SYMBOL(), cleanup and fixes crash bugs
- Authentication-results: sourceware.org; auth=none
- References: <20131219090353 dot 14309 dot 15496 dot stgit at kbuild-fedora dot novalocal>
Hi, Masami -
masami.hiramatsu.pt wrote:
> Here is the version 6 of NOKPROBE_SYMBOL series. :)
> [...]
Some preliminary results from building these on top of tip/master on
x86-64.
# stap -te "probe kprobe.function("*") {}"
starts up OK, without crashes, which looks like great progress. But a
closer look indicates that the insertion of kprobes is taking about
three (!!) orders of magnitude longer than before, as judged by the
rate of increase of 'wc -l /sys/kernel/debug/kprobes/list'. So, one
has to let the thing run for several hours just to get all the kprobes
inserted, never mind letting stress-testing begin.
For reference, here's the steady-state "perf top" output during all this
insertion work:
54.81% [kernel] [k] _raw_spin_unlock_irqrestore
38.13% [kernel] [k] __slab_alloc
1.11% [kernel] [k] kprobe_ftrace_handler
0.88% [kernel] [k] _raw_spin_unlock_irq
More notes once the machine gets far enough to get to the robustness
testing phase.
- FChE