From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
To: Andi Kleen <andi@firstfloor.org>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
Sandeepa Prabhu <sandeepa.prabhu@linaro.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
x86@kernel.org, Steven Rostedt <rostedt@goodmis.org>,
fche@redhat.com, mingo@redhat.com, systemtap@sourceware.org,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH -tip v7 24/26] kprobes: Enlarge hash table to 4096 entries
Date: Tue, 04 Mar 2014 10:54:42 +0900 [thread overview]
Message-ID: <53153262.6080804@hitachi.com> (raw)
In-Reply-To: <20140303172050.GZ22728@two.firstfloor.org>
(2014/03/04 2:20), Andi Kleen wrote:
>> So, we can see the hash table larger than 2^9 (512 entries,
>> which consumes 4KB) has no performance improvement.
>> Would you think 4kB is still big for kprobes? :)
>
> 4KB should be fine. Thanks for evaluating.
>
Ah, I mistook. There are other tables(for kretprobes and locks)
enlarged by this change too. To minimize the memory impact,
I decided to decouple those tables, because the hash of the
kretprobe tables are calculated by the task structure,
whereas kprobe table's hash comes from the probed address.
This means that the kretprobe has a different scalability issue,
and should be solved by a different way.
Thank you,
--
Masami HIRAMATSU
IT Management Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com
next prev parent reply other threads:[~2014-03-04 1:54 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-27 7:33 [PATCH -tip v7 00/26] kprobes: introduce NOKPROBE_SYMBOL, bugfixes and scalbility efforts Masami Hiramatsu
2014-02-27 7:33 ` [PATCH -tip v7 01/26] [BUGFIX]kprobes/x86: Fix page-fault handling logic Masami Hiramatsu
2014-02-27 7:33 ` [PATCH -tip v7 02/26] kprobes/x86: Allow to handle reentered kprobe on singlestepping Masami Hiramatsu
2014-02-27 7:33 ` [PATCH -tip v7 03/26] kprobes: Prohibit probing on .entry.text code Masami Hiramatsu
2014-02-27 7:33 ` [PATCH -tip v7 04/26] kprobes: Introduce NOKPROBE_SYMBOL() macro for blacklist Masami Hiramatsu
2014-02-27 7:33 ` [PATCH -tip v7 05/26] [BUGFIX] kprobes/x86: Prohibit probing on debug_stack_* Masami Hiramatsu
2014-02-27 7:33 ` [PATCH -tip v7 06/26] [BUGFIX] x86: Prohibit probing on native_set_debugreg/load_idt Masami Hiramatsu
2014-02-27 7:33 ` [PATCH -tip v7 07/26] [BUGFIX] x86: Prohibit probing on thunk functions and restore Masami Hiramatsu
2014-02-27 7:33 ` [PATCH -tip v7 08/26] kprobes/x86: Call exception handlers directly from do_int3/do_debug Masami Hiramatsu
2014-02-27 7:33 ` [PATCH -tip v7 09/26] x86: Call exception_enter after kprobes handled Masami Hiramatsu
2014-02-27 7:33 ` [PATCH -tip v7 10/26] kprobes/x86: Allow probe on some kprobe preparation functions Masami Hiramatsu
2014-02-27 7:33 ` [PATCH -tip v7 11/26] kprobes: Allow probe on some kprobe functions Masami Hiramatsu
2014-02-27 7:33 ` [PATCH -tip v7 12/26] ftrace/*probes: Allow probing on some functions Masami Hiramatsu
2014-02-27 7:33 ` [PATCH -tip v7 13/26] x86: Allow kprobes on text_poke/hw_breakpoint Masami Hiramatsu
2014-02-27 7:33 ` [PATCH -tip v7 14/26] x86: Use NOKPROBE_SYMBOL() instead of __kprobes annotation Masami Hiramatsu
2014-02-27 7:33 ` [PATCH -tip v7 15/26] kprobes: Use NOKPROBE_SYMBOL macro instead of __kprobes Masami Hiramatsu
2014-02-27 7:33 ` [PATCH -tip v7 16/26] ftrace/kprobes: Use NOKPROBE_SYMBOL macro in ftrace Masami Hiramatsu
2014-02-27 7:33 ` [PATCH -tip v7 17/26] notifier: Use NOKPROBE_SYMBOL macro in notifier Masami Hiramatsu
2014-02-27 7:33 ` [PATCH -tip v7 18/26] sched: Use NOKPROBE_SYMBOL macro in sched Masami Hiramatsu
2014-02-27 7:34 ` [PATCH -tip v7 19/26] kprobes: Show blacklist entries via debugfs Masami Hiramatsu
2014-02-27 7:34 ` [PATCH -tip v7 20/26] kprobes: Support blacklist functions in module Masami Hiramatsu
2014-02-27 7:34 ` [PATCH -tip v7 21/26] kprobes: Use NOKPROBE_SYMBOL() in sample modules Masami Hiramatsu
2014-02-27 7:34 ` [PATCH -tip v7 22/26] kprobes/x86: Use kprobe_blacklist for .kprobes.text and .entry.text Masami Hiramatsu
2014-02-27 7:34 ` [PATCH -tip v7 23/26] kprobes/x86: Remove unneeded preempt_disable/enable in interrupt handlers Masami Hiramatsu
2014-02-27 7:34 ` [PATCH -tip v7 24/26] kprobes: Enlarge hash table to 4096 entries Masami Hiramatsu
2014-02-27 21:45 ` Andi Kleen
2014-02-27 22:22 ` Masami Hiramatsu
2014-03-03 9:31 ` Masami Hiramatsu
2014-03-03 17:20 ` Andi Kleen
2014-03-04 1:54 ` Masami Hiramatsu [this message]
2014-02-27 7:34 ` [PATCH -tip v7 25/26] kprobes: Introduce kprobe cache to reduce cache misshits Masami Hiramatsu
2014-02-27 7:34 ` [PATCH -tip v7 26/26] ftrace: Introduce FTRACE_OPS_FL_SELF_FILTER for ftrace-kprobe Masami Hiramatsu
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