Perf not resolving all symbols, showing 0x7ffffxxx

[Martin Hicks]

I've tracked the start of the strange instruction pointers in 'perf
report' to a commit by Anton:

commit 75382aa72f06823db7312ad069c3bae2eb3f8548
Author: Anton Blanchard <anton at samba.org>
Date:   Tue Jun 26 01:01:36 2012 +0000

    powerpc/perf: Move code to select SIAR or pt_regs into perf_read_regs

I don't know enough about PPC to know what's going on, but reverting
the changes to perf_instruction_pointer() gets me reasonable 'perf
report' output with 3.11.

Thanks,
mh


On Thu, Oct 3, 2013 at 10:21 AM, Martin Hicks <mort at bork.org> wrote:
> Hi,
>
> I've been trying to track down a performance regression that started
> leading up to the v3.6 kernel, and while doing this I've been
> gathering perf data on v3.6-rc and comparing it to v3.11 perf reports
> of the same workload.
>
> With v3.6-rc kernels I get all symbols resolved like this:
>
> # Events: 39K cpu-clock-msecs
> #
> # Overhead      Command           Shared Object
>             Symbol
> # ........  ...........  ......................
> ........................................
> #
>      9.69%         nfsd  [kernel.kallsyms]       [k] csum_partial
>      5.64%         nfsd  [kernel.kallsyms]       [k] __do_softirq
>      3.12%         nfsd  [sunrpc]                [k] svc_create
>      2.38%         nfsd  [kernel.kallsyms]       [k] __queue_work
>      1.91%         nfsd  [gianfar_driver]        [k] gfar_poll
>      1.73%         nfsd  [kernel.kallsyms]       [k] memset
>      1.54%         nfsd  [nfsd]                  [k] nfsd_vfs_read.isra.16
>      1.40%  ksoftirqd/0  [kernel.kallsyms]       [k] finish_task_switch.isra.54
>      1.30%         nfsd  [kernel.kallsyms]       [k] get_page_from_freelist
>      1.21%         nfsd  [gianfar_driver]        [k] gfar_start_xmit
>      1.20%         nfsd  [sunrpc]                [k] svc_xprt_received
>
>
> But when I perf on v3.11 kernels I see a lot of unresolved symbols:
>
> # Events: 69K cpu-clock-msecs
> #
> # Overhead       Command          Shared Object
>        Symbol
> # ........  ............  .....................
> ...................................
> #
>     73.80%          nfsd  [unknown]              [k] 0x7ffff7fa
>      7.57%          nfsd  [kernel.kallsyms]      [k] csum_partial
>      4.59%   kworker/0:1  [unknown]              [k] 0x7ffff832
>      3.76%   ksoftirqd/0  [unknown]              [k] 0x7ffff96e
>      0.94%       kswapd0  [unknown]              [k] 0x7ffffcc2
>      0.92%       swapper  [unknown]              [k] 0x7ffffa54
>      0.62%          nfsd  [kernel.kallsyms]      [k] __udp4_lib_lookup
>      0.49%          nfsd  [kernel.kallsyms]      [k] ip_append_page
>      0.48%          nfsd  [kernel.kallsyms]      [k] __do_softirq
>      0.36%      eventmon  [unknown]              [k] 0x7ffff9c4
>      0.32%          nfsd  [kernel.kallsyms]      [k] __getnstimeofday
>
>
> Any ideas?  Have I overlooked some necessary kernel config change?
> Does perf need some binary that I may not have installed on this
> embedded platform?
>
> Freescale mpc8379 (e300c4)
> Gcc-4.7.2 uClibC built with ct-ng 1.18.0
> binutils 2.22
>
> Thanks,
> mh
>
> --
> Martin Hicks P.Eng.      |         mort at bork.org
> Bork Consulting Inc.     |   +1 (613) 266-2296



-- 
Martin Hicks P.Eng.      |         mort at bork.org
Bork Consulting Inc.     |   +1 (613) 266-2296