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From: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
	Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>,
	linux-kernel@vger.kernel.org,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Paul Mackerras <paulus@samba.org>,
	Tom Zanussi <tzanussi@gmail.com>,
	Steven Rostedt <srostedt@redhat.com>,
	KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Subject: Re: [PATCH 2/2] perf lock: New subcommand "lock" to perf for analyzing lock statistics
Date: Mon, 07 Dec 2009 16:38:03 +0800	[thread overview]
Message-ID: <4B1CBEEB.3090800@cn.fujitsu.com> (raw)
In-Reply-To: <20091207072752.GG10868@elte.hu>



Ingo Molnar wrote:

> Also, i agree that the performance aspect is probably the most pressing 
> issue. Note that 'perf bench sched messaging' is very locking intense so 
> a 10x slowdown is not entirely unexpected - we still ought to optimize 
> it all some more. 'perf lock' is an excellent testcase for this in any 
> case.
> 

Here are some test results to show the overhead of lockdep trace events:

                   select    pagefault   mmap    Memory par   Cont_SW
                   latency    latency   latency   R/W BD      latency

disable ftrace        0         0         0         0          0

enable all ftrace  -16.65%    -109.80%   -93.62%   0.14%      -6.94%

enable all ftrace  -2.67%      1.08%     -3.65%   -0.52%      -0.68%
except lockdep


We also found big overhead when using kernbench and fio, but we haven't
verified whether it's caused by lockdep events.

Thanks,
Xiao

  reply	other threads:[~2009-12-07  8:39 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-11-12  6:43 [PATCH][RFC] Measuring term of acquiring spinlock Hitoshi Mitake
2009-11-12  7:39 ` Ingo Molnar
2009-11-13  4:21   ` Hitoshi Mitake
2009-11-13  8:17     ` Ingo Molnar
2009-11-13  8:24       ` Peter Zijlstra
2009-11-13  8:40       ` Frederic Weisbecker
2009-11-13  8:51         ` Ingo Molnar
2009-11-13  9:06           ` [PATCH] tracing: Rename lockdep event subsystem into lock Frederic Weisbecker
2009-11-13  9:10             ` Peter Zijlstra
2009-11-13  9:26               ` Ingo Molnar
2009-11-13  9:36               ` Frederic Weisbecker
2009-11-13  9:31             ` [tip:perf/core] tracing: Rename 'lockdep' event subsystem into 'lock' tip-bot for Frederic Weisbecker
2009-11-13  9:57             ` tip-bot for Frederic Weisbecker
2009-11-13 10:51     ` [PATCH][RFC] Measuring term of acquiring spinlock Frederic Weisbecker
2009-11-15  1:20       ` Hitoshi Mitake
2009-11-15  2:21         ` Frederic Weisbecker
2009-11-15  8:38           ` Hitoshi Mitake
2009-12-07  3:34           ` [PATCH 1/2] Does raw_field_ptr() supports __data_loc? Hitoshi Mitake
2009-12-07  4:02             ` Frederic Weisbecker
2009-12-07 16:09             ` Steven Rostedt
2009-12-07  3:34           ` [PATCH 2/2] perf lock: New subcommand "lock" to perf for analyzing lock statistics Hitoshi Mitake
2009-12-07  4:41             ` Frederic Weisbecker
2009-12-07  7:27               ` Ingo Molnar
2009-12-07  8:38                 ` Xiao Guangrong [this message]
2009-12-07 15:00                   ` Hitoshi Mitake
2009-12-07 16:38                   ` Steven Rostedt
2009-12-07 19:48                   ` Frederic Weisbecker
2009-12-07 19:57                     ` Frederic Weisbecker
2009-12-08  1:31                     ` Xiao Guangrong
2009-12-07 14:57                 ` Hitoshi Mitake
2009-12-07 14:51               ` Hitoshi Mitake
2009-12-07 20:16                 ` Frederic Weisbecker

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