linux-kernel - Re: [PATCH 2/2] perf hist: Don't fprintf the callgraph unconditionally

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Date:	Sun, 14 Mar 2010 10:47:34 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Cc:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Mike Galbraith <efault@....de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>
Subject: Re: [PATCH 2/2] perf hist: Don't fprintf the callgraph
	unconditionally

On Fri, Mar 12, 2010 at 12:46:48PM -0300, Arnaldo Carvalho de Melo wrote:
> From: Arnaldo Carvalho de Melo <acme@...hat.com>
> 
>   [root@...pio ~]# perf report -i newt.data | head -10
>   # Samples: 11999679868
>   #
>   # Overhead  Command                  Shared Object  Symbol
>   # ........  .......  .............................  ......
>   #
>       63.61%     perf  libslang.so.2.1.4              [.] SLsmg_write_chars
>        6.30%     perf  perf                           [.] symbols__find
>        2.19%     perf  libnewt.so.0.52.10             [.] newtListboxAppendEntry
>        2.08%     perf  libslang.so.2.1.4              [.] SLsmg_write_chars@plt
>        1.99%     perf  libc-2.10.2.so                 [.] _IO_vfprintf_internal
>   [root@...pio ~]#
> 
> Not good, the newt form for report works, but slang has to eat the cost of the
> additional callgraph lines everytime it prints a line, and the callgraph
> doesn't appear on the screen, so move the callgraph printing to a separate
> function and don't use it in newt.c.
> 
> Newt tree widgets are being investigated to properly support callgraphs, but
> till that gets merged, lets remove this huge overhead and show at least the
> symbol overheads for a callgraph rich perf.data with good performance.
> 
> Cc: Frédéric Weisbecker <fweisbec@...il.com>
> Cc: Mike Galbraith <efault@....de>
> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> Cc: Paul Mackerras <paulus@...ba.org>
> Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>


Hmm, so for now the callchain won't work anymore until
it gets properly reimplemented right?

Not that much a problem as a necessary step if it really makes
easier for the newt integration.

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