Re: [PATCH -tip v4 3/3] kprobes: Support delayed unoptimization

[Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>]

(2010/11/26 16:26), Ingo Molnar wrote:
> * Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> wrote:
> 
>> Unoptimization occurs when a probe is unregistered or disabled, and
>> is heavy because it recovers instructions by using stop_machine().
>> This patch delays unoptimization operations and unoptimize several
>> probes at once by using text_poke_smp_batch().
>> This can avoid unexpected system slowdown coming from stop_machine().
>>
>> Changes in v2:
>> - Use dynamic allocated buffers and params.
>>
>> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
>> Cc: Thomas Gleixner <tglx@linutronix.de>
>> Cc: Ingo Molnar <mingo@redhat.com>
>> Cc: "H. Peter Anvin" <hpa@zytor.com>
>> Cc: x86@kernel.org
>> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
>> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
>> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
>> Cc: Steven Rostedt <rostedt@goodmis.org>
>> Cc: linux-kernel@vger.kernel.org
>> Cc: Rusty Russell <rusty@rustcorp.com.au>
>> Cc: Frederic Weisbecker <fweisbec@gmail.com>
>> ---
>>
>>  arch/x86/include/asm/kprobes.h |    4 
>>  arch/x86/kernel/kprobes.c      |   45 ++++
>>  include/linux/kprobes.h        |    2 
>>  kernel/kprobes.c               |  434 +++++++++++++++++++++++++++-------------
>>  4 files changed, 344 insertions(+), 141 deletions(-)
> 
> Hm, this is a scary big patch with non-trivial effects - it should be broken up as 
> much as possible, into successive, bisectable steps. The end result looks mostly 
> fine - it's just this one huge step of a patch that is dangerous.

Agreed, then I'll break it down to several patches.
Thank you for your comment! :)

> 
> Thanks,
> 
> 	Ingo


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