Subject: Re: [RFC PATCH -tip 2/2 v2] add a scripts for pagecache usage per
 process
From: Peter Zijlstra <peterz@infradead.org>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tom Zanussi <tzanussi@gmail.com>, Ingo Molnar <mingo@elte.hu>,
       Paul Mackerras <paulus@samba.org>,
       Arnaldo Carvalho de Melo <acme@redhat.com>,
       Keiichi KII <k-keiichi@bx.jp.nec.com>, linux-kernel@vger.kernel.org,
       lwoodman@redhat.com, linux-mm@kvack.org, riel@redhat.com,
       rostedt@goodmis.org, akpm@linux-foundation.org,
       Munehiro Ikeda <m-ikeda@ds.jp.nec.com>,
       Atsushi Tsuji <a-tsuji@bk.jp.nec.com>
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Date: Tue, 23 Feb 2010 19:13:22 +0100
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On Tue, 2010-02-23 at 18:54 +0100, Frederic Weisbecker wrote:

> > [PATCH] perf record: filter out perf process tracepoint events
> > 
> > The perf process itself can generate a lot of trace data, which most
> > of the time isn't of any interest.  This patch adds a predicate to the
> > kernel tracepoint filter of each recorded event type which effectively
> > screens out any event generated by perf.
> > 
> > Assuming the common case would be to ignore perf, this makes it the
> > default; the old behavior can be selected by using 'perf record -P'.
> 
> 
> I think filtering out perf from the instrumentation is a very
> desirable features.
> 
> But I see two drawbacks with this patch.
> First of all, we want to keep perf as a part of the instrumentation
> as a default behaviour I think, as it is a true part of the system
> wide load. So I would rather suggest to keep it as a default and
> have an exclude_perf option instead of include_perf.

Agreed, excluding by default doesn't seem to be a sane idea.

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