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Re: [RFC][ PATCH -tip v2 0/7] kprobes: Kprobes jump optimization support
- From: Masami Hiramatsu <mhiramat at redhat dot com>
- To: Ingo Molnar <mingo at elte dot hu>
- Cc: Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, lkml <linux-kernel at vger dot kernel dot org>, "H. Peter Anvin" <hpa at zytor dot com>, Frederic Weisbecker <fweisbec at gmail dot com>, Jim Keniston <jkenisto at us dot ibm dot com>, Srikar Dronamraju <srikar at linux dot vnet dot ibm dot com>, Christoph Hellwig <hch at infradead dot org>, Steven Rostedt <rostedt at goodmis dot org>, Anders Kaseorg <andersk at ksplice dot com>, Tim Abbott <tabbott at ksplice dot com>, systemtap <systemtap at sources dot redhat dot com>, DLE <dle-develop at lists dot sourceforge dot net>
- Date: Tue, 23 Jun 2009 17:54:21 -0400
- Subject: Re: [RFC][ PATCH -tip v2 0/7] kprobes: Kprobes jump optimization support
- References: <20090622212255.5384.53732.stgit@localhost.localdomain> <20090623114252.GB9497@elte.hu> <4A40E153.9030704@redhat.com> <20090623194009.GA8777@elte.hu>
Ingo Molnar wrote:
>> Ingo Molnar wrote:
>>> * Masami Hiramatsu <mhiramat@redhat.com> wrote:
>>>
>>>> o Usage
>>>> Set CONFIG_OPTPROBES=y when building a kernel, then all *probes will be
>>>> optimized if possible.
>>> Should be default-y if KPROBES is enabled. I.e. we really only want
>>> to disable it to debug potential issues.
>> Sure, thanks!
>
> Plus i'd suggest a runtime control (a sysctl) as well - if it's not
> too intrusive. Since this is an optional speedup feature, distros
> can have this enabled and if there's some problem with it then it
> can still be disabled in sysctl.conf, without having to rebuild the
> kernel.
The runtime control is a good idea. Btw, current kprobes already has
a runtime disable interface under sysfs. Is there any reason that we'd
better to use sysctl instead of sysfs?
Thank you,
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division
e-mail: mhiramat@redhat.com