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Date: Tue, 4 May 2010 12:56:40 +0100
From: Eric B Munson <ebmunson@us.ibm.com>
To: Anton Blanchard <anton@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>, Paul Mackerras <paulus@samba.org>,
       Ingo Molnar <mingo@elte.hu>, Arnaldo Carvalho de Melo <acme@redhat.com>,
       Frederic Weisbecker <fweisbec@gmail.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] perf: Fix performance issue with perf report
Message-ID: <20100504115640.GA6380@us.ibm.com>
References: <20100504111915.GB14636@kryten>
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On Tue, 04 May 2010, Anton Blanchard wrote:

>=20
> On a large machine we spend a lot of time in perf_header__find_attr when
> running perf report.=20
>=20
> If we are parsing a file without PERF_SAMPLE_ID then for each sample we c=
all
> perf_header__find_attr and loop through all counter IDs, never finding a =
match.
> As the machine gets larger there are more per cpu counters and we spend an
> awful lot of time in there.
>=20
> The patch below initialises each sample id to -1ULL and checks for this in
> perf_header__find_attr. We may need to do something more intelligent even=
tually
> (eg a hash lookup from counter id to attr) but this at least fixes the mo=
st
> common usage of perf report.
>=20
> Signed-off-by: Anton Blanchard <anton@samba.org>

Acked-by: Eric B Munson <ebmunson@us.ibm.com>

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