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From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
	Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@elte.hu>,
	"Ted Ts'o" <tytso@mit.edu>, Thomas Gleixner <tglx@linutronix.de>,
	LKML <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Arjan van de Ven <arjan@infradead.org>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Tom Zanussi <tzanussi@gmail.com>, Li Zefan <lizf@cn.fujitsu.com>,
	Jason Baron <jbaron@redhat.com>,
	"David S. Miller" <davem@davemloft.net>,
	Christoph Hellwig <hch@lst.de>, Pekka Enberg <penberg@kernel.org>,
	Lai Jiangshan <laijs@cn.fujitsu.com>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	2nddept-manager@sdl.hitachi.co.jp
Subject: Re: [ANNOUNCE] New utility: 'trace'
Date: Thu, 18 Nov 2010 14:58:41 +0900	[thread overview]
Message-ID: <4CE4C091.8060306@hitachi.com> (raw)
In-Reply-To: <20101117182344.GD13717@Krystal>

(2010/11/18 3:23), Mathieu Desnoyers wrote:
> Amongst others, Ericsson rely on this kind of feature. The case where we're
> filtering "out" should be really, really fast (even if it makes the recording
> slightly slower). If there is a race modifying the data underneath between the
> filter execution and the copy to the buffers, I really don't think it matters.
> If the tracepoint caller context don't provide data consistency guarantees for
> the parameters it passes, we should not expect 100% perfect consistency between
> filter and what is actually saved in the trace. The trace analysis tools should
> just be able to cope with that, but I really don't think anyone should care.
> 
> So I would recommend no copy, filter directly on the source data, stop the
> filter chain as soon as a non-match is observed. Copy the data into the buffers
> if the filter passes.

Indeed, so that we can eliminate memory write accesses. :)

Thanks,

-- 
Masami HIRAMATSU
2nd Dept. Linux Technology Center
Hitachi, Ltd., Systems Development Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com

  reply	other threads:[~2010-11-18  5:58 UTC|newest]

Thread overview: 88+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-11-16 21:04 [ANNOUNCE] New utility: 'trace' Thomas Gleixner
2010-11-16 21:27 ` Darren Hart
2010-11-16 21:59   ` Ingo Molnar
2010-11-16 22:03     ` Peter Zijlstra
2010-11-16 22:08       ` Ingo Molnar
2010-11-16 22:09       ` Darren Hart
2010-11-16 22:48         ` Darren Hart
2010-11-16 22:07     ` Darren Hart
2010-11-16 22:17   ` Frederic Weisbecker
2010-11-17  8:30     ` Ingo Molnar
2010-11-17 11:35       ` Peter Zijlstra
2010-11-17 12:53         ` Frederic Weisbecker
2010-11-17 13:02           ` Peter Zijlstra
2010-11-17 13:10             ` Ingo Molnar
2010-11-17 13:36               ` Peter Zijlstra
2010-11-17 13:43                 ` Frederic Weisbecker
2010-11-17 13:53                   ` Peter Zijlstra
2010-11-17 14:10                     ` Frederic Weisbecker
2010-11-17 15:02                       ` Steven Rostedt
2010-11-17 18:13                       ` Ted Ts'o
2010-11-17 18:29                         ` Frederic Weisbecker
2010-11-17 18:30                           ` Darren Hart
2010-11-17 16:49             ` Darren Hart
2010-11-18 23:23       ` Joe Perches
2010-11-16 21:35 ` Ingo Molnar
2010-11-17  1:37 ` Ted Ts'o
2010-11-17  1:47   ` Steven Rostedt
2010-11-17  3:16     ` Ted Ts'o
2010-11-17  3:34       ` Steven Rostedt
2010-11-17 19:00         ` Bob Copeland
2010-11-17 13:24   ` Ingo Molnar
2010-11-17 13:38     ` Peter Zijlstra
2010-11-17 14:00       ` Ingo Molnar
2010-11-17 14:11         ` Peter Zijlstra
2010-11-17 14:18           ` Peter Zijlstra
2010-11-17 14:37             ` Thomas Gleixner
2010-11-17 14:41               ` Peter Zijlstra
2010-11-17 15:41               ` Tom Zanussi
2010-11-17 15:55                 ` Avi Kivity
2010-11-17 15:58                   ` Thomas Gleixner
2010-11-17 16:20                     ` Avi Kivity
2010-11-17 15:59                   ` Peter Zijlstra
2010-11-17 16:08                     ` Avi Kivity
2010-11-17 15:10           ` Steven Rostedt
2010-11-17 15:43             ` Peter Zijlstra
2010-11-17 16:04               ` Steven Rostedt
2010-11-17 16:15               ` Steven Rostedt
2010-11-17 19:40                 ` Darren Hart
2010-11-17 18:23               ` Mathieu Desnoyers
2010-11-18  5:58                 ` Masami Hiramatsu [this message]
2010-11-18  6:00               ` Masami Hiramatsu
2010-11-17 15:33           ` Tom Zanussi
2010-11-17 18:36             ` Mathieu Desnoyers
2010-11-17 18:53               ` Tom Zanussi
2010-11-17 19:02                 ` Mathieu Desnoyers
2010-11-17 19:25                   ` Tom Zanussi
2010-11-17 19:25               ` Steven Rostedt
2010-11-17  9:49 ` Philipp Marek
     [not found] ` <4CE38C53.8090606@kernel.org>
2010-11-17 12:07   ` [patch] trace: Add user-space event tracing/injection Ingo Molnar
2010-11-17 12:17     ` Pekka Enberg
2010-11-17 12:30       ` Ingo Molnar
2010-11-17 12:33         ` Pekka Enberg
2010-11-17 12:42           ` Peter Zijlstra
2010-11-17 12:58             ` Ingo Molnar
2010-11-17 13:09               ` Peter Zijlstra
2010-11-17 13:36                 ` Ingo Molnar
2010-11-17 12:24     ` Ingo Molnar
2010-11-17 12:30       ` Pekka Enberg
2010-11-17 12:29     ` Peter Zijlstra
2010-11-17 12:37       ` Peter Zijlstra
2010-11-17 13:10       ` Frederic Weisbecker
2010-11-17 13:31         ` Peter Zijlstra
2010-11-17 13:33           ` Frederic Weisbecker
2010-11-18  1:18     ` Darren Hart
2010-11-18  8:55       ` Ingo Molnar
2010-11-18 16:25         ` hp
2010-11-18 18:56           ` Ingo Molnar
2010-11-18 19:13             ` AW: " Reichert, Hans-Peter
2010-11-18 17:06         ` Darren Hart
2010-11-17 12:47 ` [ANNOUNCE] New utility: 'trace' Török Edwin
2010-11-17 12:51   ` Peter Zijlstra
2010-11-17 13:05     ` Török Edwin
2010-11-17 13:10       ` Peter Zijlstra
2010-11-17 13:32   ` Frederic Weisbecker
2010-11-18  0:47 ` Ian Munsie
     [not found]   ` <20101118151141.GA3368@redhat.com>
2010-11-19  2:32     ` Ian Munsie
2010-11-19 15:23       ` Jason Baron
     [not found]       ` <4CECACF9.3080907@linux.vnet.ibm.com>
     [not found]         ` <4CFD7182.4060206@linux.vnet.ibm.com>
2010-12-07  4:03           ` PowerPC, ftrace: Add PPC raw syscall tracepoints & ftrace fixes Ian Munsie

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