[Fwd: [RFC][PATCH 0/3]Djprobe (Direct Jump Probe) for 2.6.14-rc5-mm1]

[Masami Hiramatsu]

Hi,

I posted latest djprobe patch to Linux-kernel ML.
But it seems that it was rejected by spam-filter on this ML...
So I send it again.

-------- Original Message --------
Subject: [RFC][PATCH 0/3]Djprobe (Direct Jump Probe) for 2.6.14-rc5-mm1
Date: Mon, 31 Oct 2005 20:04:04 +0900
From: Masami Hiramatsu <hiramatu@sdl.hitachi.co.jp>
To: linux-kernel@vger.kernel.org
CC: Satoshi Oshima <soshima@redhat.com>, Hideo Aoki <haoki@redhat.com>,  Yumiko Sugita <sugita@sdl.hitachi.co.jp>,  noboru.obata.ar@hitachi.com,  systemtap@sources.redhat.com

Hello,

I would like to propose djprobe (Direct Jump Probe) for low overhead
probing.
The djprobe is useful for the performance analysis function and the
kernel flight-recording function which constantly traces events in
the kernel. Because we should make their influence on performance as
small as possible.
Djprobe is a kind of probes in kernel like kprobes.
 It has some features:
- Jump instruction based probe. This is so fast.
- Non interruption.
- Safely code insertion on SMP.
- Lockless probe after registered.
I attached detailed document of djprobe to this mail. If you need
more information, please see it.

This djprobe is NOT a replacement of kprobes. Djprobe and kprobes
have complementary qualities. (ex: djprobe's overhead is low, and
kprobes can be inserted in anywhere.)
You can use both kprobes and djprobe as the situation demands.

I measured the overhead of the djprobe on Pentium4 3.06GHz PC by
using gtodbench (*). The result I got was about 100ns. In the view
of performance, I think djprobe is the best probe method. What would
you think about this?

(*)The gtodbench is micro benchmark which is included in published
djprobe source package. You can download it from LKST's web site:
http://prdownloads.sourceforge.net/lkst/djprobe-20050713.tar.bz2

The following three patches introduce djprobe (Direct Jump Probe)
to linux-2.6.14-rc5-mm1.
patch 1:    Introduce a instruction slot management structure to
            handle different size slots. (a patch for kprobes)
patch 2:    Djprobe core (arch-independant) patch.
patch 3:    Djprobe i386 (arch-dependant) patch.

Please try to use djprobe.

Any comments or suggestions are welcome.

Best regards,

-- 
Masami HIRAMATSU
2nd Research Dept.
Hitachi, Ltd., Systems Development Laboratory
E-mail: hiramatu@sdl.hitachi.co.jp
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