linux-kernel - [PATCH -tip v4 0/3] Kprobes/x86: Batch optimization support

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Date:	Fri, 19 Nov 2010 19:09:25 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Rusty Russell <rusty@...tcorp.com.au>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Jason Baron <jbaron@...hat.com>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	linux-kernel@...r.kernel.org, 2nddept-manager@....hitachi.co.jp
Subject: [PATCH -tip v4 0/3] Kprobes/x86: Batch optimization support

Hi,

Here is batch optimizing patch series version 4.

Since current kprobes jump optimization calls stop_machine() for each
probe, it can make a lot of latency noises when (un)registering a lot of
probes (~1000) at once. For example, on 4 core Xeon, 256 probes
optimization takes 770us in average (max 3.3ms).
This patch series introduces batch (un)optimization which modifies
code with just one stop_machine(), and it improves optimization time
to 90us in average (max 330us).

- Introduce text_poke_smp_batch() which modifies multiple
  codes with one stop_machine().
- Limit how many probes can be (un)optimized at once.
- Introduce delayed unoptimization for batch processing.

text_poke_smp_batch() will also help Jump label to reduce
its delay coming from text_poke_smp().

Changes in v4:
- Update to the latest tip tree.

Changes in v3:
- Set kp.addr = NULL according to Ananth's comment.

Changes in v2:
- Add kprobes selftest bugfix patch.
- Add some comments about locks according to Mathieu's comment.
- Allocate working buffers when initializing kprobes, instead of
  using static arraies.
- Merge max optimization limit patch into batch optimizing patch.

Thank you,

---

Masami Hiramatsu (3):
      kprobes: Support delayed unoptimization
      kprobes/x86: Use text_poke_smp_batch
      x86: Introduce text_poke_smp_batch() for batch-code modifying


 arch/x86/include/asm/alternative.h |    7 +
 arch/x86/include/asm/kprobes.h     |    4 
 arch/x86/kernel/alternative.c      |   49 +++-
 arch/x86/kernel/kprobes.c          |  114 +++++++++
 include/linux/kprobes.h            |    4 
 kernel/kprobes.c                   |  435 ++++++++++++++++++++++++------------
 6 files changed, 451 insertions(+), 162 deletions(-)

-- 
Masami HIRAMATSU
2nd Dept. Linux Technology Center
Hitachi, Ltd., Systems Development Laboratory
E-mail: masami.hiramatsu.pt@...achi.com

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