From: Masami Hiramatsu <mhiramat@redhat.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Fr??d??ric Weisbecker <fweisbec@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
lkml <linux-kernel@vger.kernel.org>,
systemtap <systemtap@sources.redhat.com>,
DLE <dle-develop@lists.sourceforge.net>,
Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
Jim Keniston <jkenisto@us.ibm.com>,
Mathieu Desnoyers <compudj@krystal.dyndns.org>
Subject: Re: [PATCH tracing/kprobes] kprobes: Disable booster when CONFIG_PREEMPT=y
Date: Fri, 29 Jan 2010 09:52:13 -0500 [thread overview]
Message-ID: <4B62F61D.5060203@redhat.com> (raw)
In-Reply-To: <20100129092135.GE10878@elte.hu>
Ingo Molnar wrote:
>
> * Masami Hiramatsu <mhiramat@redhat.com> wrote:
>
>> Disable kprobe booster when CONFIG_PREEMPT=y, because it can't ensure that
>> all kernel threads preempted on kprobe's boosted slot run out from the slot
>> even using freeze_processes().
>
> hm, this really sucks as it makes preemptible kernels perform worse. Is there
> no better solution?
>
>> The booster on preemptive kernel will be resumed if synchronize_tasks() or
>> something like that is introduced.
>
> such as this one?
Yes, I think this synchronize_tasks(), which just (sleeping) wait until
all currently preempted tasks are wake up and scheduled, can ensure safety.
Thank you,
--
Masami Hiramatsu
Software Engineer
Hitachi Computer Products (America), Inc.
Software Solutions Division
e-mail: mhiramat@redhat.com
next prev parent reply other threads:[~2010-01-29 14:50 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-22 1:16 [RFC PATCH 00/10] Ftrace functions hashlist Frederic Weisbecker
2010-01-22 1:16 ` [RFC PATCH 01/10] ftrace: Generalize the function hashlist from function profiler Frederic Weisbecker
2010-01-22 1:16 ` [RFC PATCH 02/10] ftrace: Ensure tracing has really stopped before leaving unregister_ftrace_graph Frederic Weisbecker
2010-01-22 1:51 ` Steven Rostedt
2010-01-22 2:04 ` Frederic Weisbecker
2010-01-22 1:16 ` [RFC PATCH 03/10] ftrace: Drop the ftrace_profile_enabled checks in tracing hot path Frederic Weisbecker
2010-01-22 2:05 ` Steven Rostedt
2010-01-22 2:28 ` Mathieu Desnoyers
2010-01-22 3:12 ` Steven Rostedt
2010-01-22 4:09 ` Mathieu Desnoyers
2010-01-22 4:52 ` Steven Rostedt
2010-01-22 12:34 ` Mathieu Desnoyers
2010-01-22 14:54 ` Masami Hiramatsu
2010-01-25 20:58 ` Frederic Weisbecker
2010-01-25 22:14 ` Masami Hiramatsu
2010-01-26 0:41 ` Frederic Weisbecker
2010-01-26 1:13 ` Mathieu Desnoyers
2010-01-26 1:37 ` Masami Hiramatsu
2010-01-27 21:55 ` [PATCH tracing/kprobes] kprobes: Disable booster when CONFIG_PREEMPT=y Masami Hiramatsu
2010-01-28 1:08 ` Mathieu Desnoyers
2010-01-28 4:21 ` Ananth N Mavinakayanahalli
2010-01-29 9:21 ` Ingo Molnar
2010-01-29 11:30 ` Peter Zijlstra
2010-01-29 14:52 ` Masami Hiramatsu [this message]
2010-01-29 17:08 ` Mathieu Desnoyers
2010-01-29 17:15 ` Peter Zijlstra
2010-01-29 17:27 ` Mathieu Desnoyers
2010-01-29 17:32 ` Masami Hiramatsu
2010-01-22 2:43 ` [RFC PATCH 03/10] ftrace: Drop the ftrace_profile_enabled checks in tracing hot path Frederic Weisbecker
2010-01-22 3:05 ` Steven Rostedt
2010-01-25 20:52 ` Frederic Weisbecker
2010-01-22 1:16 ` [RFC PATCH 04/10] ftrace: Ensure buffers are visibles to tracing callbacks right away Frederic Weisbecker
2010-01-22 1:16 ` [RFC PATCH 05/10] ftrace: Drop buffer check in function profiler callbacks Frederic Weisbecker
2010-01-25 6:17 ` Lai Jiangshan
2010-01-30 20:47 ` Frederic Weisbecker
2010-01-22 1:16 ` [RFC PATCH 06/10] ftrace: Release the function hlist if we don't need it anymore Frederic Weisbecker
2010-01-25 6:41 ` Lai Jiangshan
2010-01-30 21:14 ` Frederic Weisbecker
2010-01-22 1:16 ` [RFC PATCH 07/10] ftrace: Make the function hashlist concurrently usable Frederic Weisbecker
2010-01-22 1:16 ` [PATCH 08/10] tracing: Simplify test for function_graph tracing Frederic Weisbecker
2010-01-22 1:16 ` [RFC PATCH 09/10] tracing: Use the hashlist for graph function Frederic Weisbecker
2010-01-25 8:50 ` Lai Jiangshan
2010-01-30 21:19 ` Frederic Weisbecker
2010-01-22 1:16 ` [RFC PATCH 10/10] ftrace: Factorize search and insertion in the function hashlist Frederic Weisbecker
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