linux-kernel - Re: [PROBLEM] perf report is broken in latest linus git

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Date:	Thu, 13 Aug 2009 12:47:17 +0300
From:	Pekka Enberg <penberg@...helsinki.fi>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	paulus@...ba.org, linux-kernel@...r.kernel.org
Subject: Re: [PROBLEM] perf report is broken in latest linus git

Hi Ingo,

On Thu, 2009-08-13 at 11:36 +0200, Ingo Molnar wrote:
> * Pekka Enberg <penberg@...helsinki.fi> wrote:
> 
> > Latest Linus git kernel with -rc4 perf userspace:
> > 
> >   penberg@...berg-laptop:~/testing/jato$ perf record -f jato HelloWorldSwing
> >   [ perf record: Captured and wrote 1.402 MB perf.data (~61261 samples) ]
> > 
> >   penberg@...berg-laptop:~/testing/jato$ perf report --sort comm,dso,symbol|head -30
> >   # Samples: 60457
> >   #
> >   # Overhead  Command                            Shared Object  Symbol
> >   # ........  .......  .......................................  ......
> >   #
> > 
> >   [ Note: the jato executable doesn't appear anywhere in the trace. I'm
> >     pretty sure the libzip functions, for example, are from jato, not perf.  ]
> > 
> >       36.14%     perf  /home/penberg/bin/perf                   [.] dso__synthesize_plt_symbols
> >       35.20%     perf  /home/penberg/bin/perf                   [.] dso__new
> >        3.57%     perf  /home/penberg/bin/jato                   [.] 0x0000000000c910
> 
> Perhaps it's this commit:
> 
> 4d1e00a: perf symbol: Fix symbol parsing in certain cases: use the build-id as a symlink
> 
> it does not revert cleanly, so you might want to check out these two 
> commits:
> 
>   4d1e00a
>   4d1e00a~1
> 
> and build perf on both, and check with your anomalous perf.data 
> (without changing it) whether the output makes most sense.

The commit seems fine. Like I said, the perf.data file is busted even
with 2.6.31-rc4 userspace so I think it's a kernel bug.

			Pekka

4d1e00a~1:

penberg@...berg-laptop:~/testing/jato$ perf report
# Samples: 57821
#
# Overhead  Command                            Shared Object  Symbol
# ........  .......  .......................................  ......
#
    73.55%     perf  /home/penberg/bin/perf                   [.] dso__synthesize_plt_symbols
     6.54%     perf  /lib/tls/i686/cmov/libc-2.8.90.so        [.] 0x0000000014b8c0
     3.31%     perf  /home/penberg/bin/jato                   [.] 0x0000000000c910
     1.37%     perf  [kernel]                                 [k] get_page_from_freelist
     1.05%     perf  /home/penberg/bin/perf                   [.] dso__load_sym
     0.91%     perf  /usr/lib/libzip.so.1.0.0                 [.] _zip_get_name
     0.59%     perf  /lib/tls/i686/cmov/libc-2.8.90.so        [.] __GI_strcmp
     0.57%     perf  /usr/lib/libfontconfig.so.1.3.0          [.] 0x00000000019700
     0.53%     perf  /usr/lib/libz.so.1.2.3.3                 [.] 0x0000000000f0c5
     0.49%     perf  /home/penberg/bin/perf                   [.] dso__load_kernel

4d1e00a:

penberg@...berg-laptop:~/testing/jato$ perf report
# Samples: 57821
#
# Overhead  Command                            Shared Object  Symbol
# ........  .......  .......................................  ......
#
    73.55%     perf  /home/penberg/bin/perf                   [.] dso__synthesize_plt_symbols
     6.53%     perf  /lib/tls/i686/cmov/libc-2.8.90.so        [.] 0x0000000014b8c0
     3.31%     perf  /home/penberg/bin/jato                   [.] 0x0000000000c910
     1.37%     perf  [kernel]                                 [k] get_page_from_freelist
     1.05%     perf  /home/penberg/bin/perf                   [.] dso__load_sym
     0.91%     perf  /usr/lib/libzip.so.1.0.0                 [.] _zip_get_name
     0.59%     perf  /lib/tls/i686/cmov/libc-2.8.90.so        [.] __GI_strcmp
     0.57%     perf  /usr/lib/libfontconfig.so.1.3.0          [.] 0x00000000019700
     0.53%     perf  /usr/lib/libz.so.1.2.3.3                 [.] 0x0000000000f0c5
     0.49%     perf  /home/penberg/bin/perf                   [.] dso__load_kernel
     0.43%     perf  /home/penberg/bin/perf                   [.] cmd_stat
     0.35%     perf  /home/penberg/bin/perf                   [.] store_aux
     0.34%     perf  [kernel]                                 [k] kunmap_atomic
     0.33%     perf  /home/penberg/bin/perf                   [.] quote_c_style_counted
     0.31%     perf  /lib/tls/i686/cmov/libc-2.8.90.so        [.] _int_malloc
     0.29%     perf  /home/penberg/bin/perf                   [.] 0x00000000026951
     0.29%     perf  /home/penberg/bin/perf                   [.] strbuf_addf
     0.28%     perf  /usr/lib/libzip.so.1.0.0                 [.] _zip_name_locate


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