linux-kernel - Re: [PATCH 2/2] perf lock: New subcommand "lock" to perf for analyzing lock statistics

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 07 Dec 2009 16:38:03 +0800
From:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>
To:	Ingo Molnar <mingo@...e.hu>
CC:	Frederic Weisbecker <fweisbec@...il.com>,
	Hitoshi Mitake <mitake@....info.waseda.ac.jp>,
	linux-kernel@...r.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Tom Zanussi <tzanussi@...il.com>,
	Steven Rostedt <srostedt@...hat.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Subject: Re: [PATCH 2/2] perf lock: New subcommand "lock" to perf for analyzing
 lock statistics



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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/