Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756032Ab1BXPrI (ORCPT ); Thu, 24 Feb 2011 10:47:08 -0500 Received: from ns.dcl.info.waseda.ac.jp ([133.9.216.194]:61264 "EHLO ns.dcl.info.waseda.ac.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755237Ab1BXPrE (ORCPT ); Thu, 24 Feb 2011 10:47:04 -0500 Message-ID: <4D667D60.5010903@dcl.info.waseda.ac.jp> Date: Fri, 25 Feb 2011 00:46:40 +0900 From: Hitoshi Mitake User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:2.0b10pre) Gecko/20110114 Thunderbird/3.3a2 MIME-Version: 1.0 To: Frederic Weisbecker CC: Peter Zijlstra , linux-kernel@vger.kernel.org, h.mitake@gmail.com, Paul Mackerras , Ingo Molnar , Arnaldo Carvalho de Melo , Steven Rostedt Subject: Re: [PATCH] perf lock: clean the options for perf record References: <1298388507-19774-1-git-send-email-mitake@dcl.info.waseda.ac.jp> <4D63D685.2010401@dcl.info.waseda.ac.jp> <1298389415.2217.243.camel@twins> <20110222182206.GB1799@nowhere> <4D648A65.2040107@dcl.info.waseda.ac.jp> In-Reply-To: <4D648A65.2040107@dcl.info.waseda.ac.jp> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2516 Lines: 65 On 2011年02月23日 13:17, Hitoshi Mitake wrote: > On 2011年02月23日 03:22, Frederic Weisbecker wrote: >> On Tue, Feb 22, 2011 at 04:43:35PM +0100, Peter Zijlstra wrote: >>> On Wed, 2011-02-23 at 00:30 +0900, Hitoshi Mitake wrote: >>>> How do you think about it? >>> >>> Most of the lock code (esp the spinlock stuff) is already way over the >>> threshold of sanity, adding to that for some dubious reasons doesn't >>> seem like a good idea. >>> >>> I'm still not at all sure why people want all this lock tracing. >> >> Right, well I can imagine many usecases that could make lock >> tracing bring more value than what lockstat already provides, >> through a tool like perf lock if we enhance it. >> >> We should probably first focus on developing the tooling side >> and make it useful enough that optimizations in the kernel >> side become desirable. >> > > Yes, lockstat only provides the lock usage statistics of > entire of the system. perf lock will be able to provide the partial > information of specified term, or the degree of dependency > between locks. > For trial, I created new tracepoint for rwsem and tested. Names of events are rwsem_{acquire, contended, acquired, release}, their meanings are similar to lock_{...}. I traced perf bench sched messaging and result was, mitake@x201i:~/linux/.../tools/perf% ./perf bench sched messaging # Running sched/messaging benchmark... # 20 sender and receiver processes per group # 10 groups == 400 processes run Total time: 1.252 [sec] mitake@x201i:~/linux/.../tools/perf% sudo ./perf record -R -m 1024 -c 1 -e rwsem:rwsem_acquire -e rwsem:rwsem_release,rwsem:rwsem_contended,rwsem:rwsem_acquired ./perf bench sched messaging # Running sched/messaging benchmark... # 20 sender and receiver processes per group # 10 groups == 400 processes run Total time: 1.332 [sec] [ perf record: Woken up 4 times to write data ] [ perf record: Captured and wrote 13.495 MB perf.data (~589597 samples) ] raw execution of sched messaging was 1.252 sec, and traced version was 1.332 sec. This overhead is far smaller than the overhead of current lock tracepoints. I think that it is possible to write some meaningful tools like reader/writer ratio measuring. If something can be written, I'll post it. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/