Message-ID: <4CE3FB0D.30902@redhat.com>
Date: Wed, 17 Nov 2010 17:55:57 +0200
From: Avi Kivity <avi@redhat.com>
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To: Tom Zanussi <tzanussi@gmail.com>
CC: Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@elte.hu>,
        "Ted Ts'o" <tytso@mit.edu>, LKML <linux-kernel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Arjan van de Ven <arjan@infradead.org>,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.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>
Subject: Re: [ANNOUNCE] New utility: 'trace'
References: <alpine.LFD.2.00.1011162103580.2900@localhost6.localdomain6>	 <20101117013700.GA3290@thunk.org> <20101117132404.GF27063@elte.hu>	 <1290001128.2109.785.camel@laptop>  <20101117140002.GH27063@elte.hu>	 <1290003110.2109.822.camel@laptop> <1290003505.2109.833.camel@laptop>	 <alpine.LFD.2.00.1011171529120.2900@localhost6.localdomain6> <1290008466.1921.21.camel@elnicho>
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On 11/17/2010 05:41 PM, Tom Zanussi wrote:
>
>> The only reason why these filters might make sense is to reduce the
>> trace volume on system wide traces in production environments, but
>> that's a completely different story. These scenarios can do with the
>> dynamic tracepoint stuff and the custom filtering w/o putting the
>> burden on the majority of users.
>>
> Yeah, in my mind, the main point of the filters was to be a 'blunt
> force' instrument preventing userspace from being overwhelmed by events.
> The real filtering would happen in userspace with e.g. real scripting
> languages.
>

Filtering is also useful for fine-grained perf events; this cannot be 
done in userspace.

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