Message-ID: <4B1DAC6E.8000605@cn.fujitsu.com>
Date: Tue, 08 Dec 2009 09:31:26 +0800
From: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
User-Agent: Thunderbird 2.0.0.6 (Windows/20070728)
MIME-Version: 1.0
To: Frederic Weisbecker <fweisbec@gmail.com>
CC: Ingo Molnar <mingo@elte.hu>, 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
References: <20091115022135.GA5427@nowhere> <1260156884-8474-2-git-send-email-mitake@dcl.info.waseda.ac.jp> <20091207044125.GB5262@nowhere> <20091207072752.GG10868@elte.hu> <4B1CBEEB.3090800@cn.fujitsu.com> <20091207194802.GB5049@nowhere>
In-Reply-To: <20091207194802.GB5049@nowhere>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1380
Lines: 53

Hi Frederic,

Frederic Weisbecker wrote:

> This profile has been done using ftrace with perf right?

We not use perf, just operate it by debugfs, the test procedure
is like below:

case 1: disable all trace events:
echo nop > debugfs/tracing/current_tracer
echo > debugfs/tracing/set_event
run benchmarks
...

case 2: enable all trace events except lockdep:
echo nop > debugfs/tracing/current_tracer
echo *:* > debugfs/tracing/set_event
echo 0 >  debugfs/tracing/events/lockdep/enable
run benchmarks
...

> In one of your previous mails, you showed us the difference
> of the size of perf.data by capturing either scheduler events
> or lock events.
> 

It's not my work :-)

Thanks,
Xiao

> And IIRC, the case of lock events resulted in a 100 MB perf.data
> whereas it was a small file for sched events.
> 
> The overhead in the pagefault and mmap latency could then
> result in the fact we have much more events to save, walking
> through much more pages in perf buffer, then faulting more often,
> etc.
> 
> Plus the fact various locks are taken in mmap and fault path,
> generating more lock events.
> 
> Just a guess...
> 
> 
> 

--
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/