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Date: Tue, 24 Mar 2015 08:30:26 +0900
From: Namhyung Kim <namhyung@kernel.org>
To: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>, Arnaldo Carvalho de Melo <acme@kernel.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>, Jiri Olsa <jolsa@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Stephane Eranian <eranian@google.com>
Subject: Re: [RFC/PATCH] perf record: Save build-id of DSO in callchains
Message-ID: <20150323233026.GF2782@sejong>
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Hi David,

On Mon, Mar 23, 2015 at 07:44:37AM -0600, David Ahern wrote:
> On 3/23/15 2:18 AM, Namhyung Kim wrote:
> >>Just curious, could you try to measure the performance impact of this
> >>change?
> >
> >   $ time perf record --call-graph dwarf -o kbuild.xxx -a -- sleep 30
> >   [ perf record: Woken up 34674 times to write data ]
> >   [ perf record: Captured and wrote 9538.729 MB kbuild.xxx (1211997 samples) ]
> >
> >   real   0m32.244s
> >   user   0m1.097s
> >   sys    0m8.997s
> >
> >   $ time perf record --call-graph dwarf -o kbuild.yyy --buildid-callchain -a -- sleep 30
> >   [ perf record: Woken up 40902 times to write data ]
> >   [ perf record: Captured and wrote 11208.500 MB kbuild.yyy (1433922 samples) ]
> >
> >   real   2m21.695s
> >   user   1m33.127s
> >   sys    0m22.077s
> >
> 
> How many CPUs and processes?

I was running kbuild with allyesconfig on 12-cpu box.

Thanks,
Namhyung