From: Andi Kleen <andi@firstfloor.org>
To: Milian Wolff <mail@milianw.de>
Cc: linux-perf-users@vger.kernel.org, kan.liang@intel.com
Subject: Re: Haswell LBR call stacks - broken
Date: Tue, 04 Aug 2015 11:10:32 -0700 [thread overview]
Message-ID: <87h9oe3ox3.fsf@tassilo.jf.intel.com> (raw)
In-Reply-To: <8643019.4YmQ1Xdl9W@milian-kdab2> (Milian Wolff's message of "Tue, 04 Aug 2015 19:24:04 +0200")
Milian Wolff <mail@milianw.de> writes:
>
> OK, with a more recent perf v4.2.rc5 on a Intel(R) Core(TM) i7-4770 CPU @
> 3.40GHz it actually works. Somewhat :) It is much faster, but the callstacks
> don't terminate properly, and are sometimes not correctly demangled. I observe
> the following behavior:
>
> 15.56% ex_string_compa libQt5Core.so.5.5.0 [.] QString::compare_helper
> |
> |--5.84%--
> _ZN7QString14compare_helperEPK5QChariS2_iN2Qt15CaseSensitivityE@plt
Maybe the demangler doesn't like the @plt.
> | QString::compare_helper
> | main
> | |
> | |--4.24%-- main
> | | |
> | | |--1.60%-- main
> | | | |
> | | | |--1.07%-- main
Yes that looks like a bug.
Adding Kan.
-Andi
> | | | | |
> | | | | |--0.54%-- main
> | | | | | main
> | | | | |
> | | | | --0.53%--
> QString::compare_helper
> | | | | main
> | | | |
> | | | --0.53%--
> QString::compare_helper
> | | | main
> | | | main
> | | |
> QString::compare_helper
> | | | main
> | | |
> QString::compare_helper
> ...
>
> The correct callgraph, as shown by --call-graph dwarf, is:
>
> 21.62% ex_string_compa libQt5Core.so.5.5.0 [.] QString::compare_helper
> |
> ---QString::compare_helper
> main
>
> Is this a known (undocumented) limitation or a bug? Is there anything I could
> do to get this fixed?
>
> Thanks
--
ak@linux.intel.com -- Speaking for myself only
next prev parent reply other threads:[~2015-08-04 18:11 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-14 11:02 Haswell LBR call stacks Milian Wolff
2015-08-04 17:24 ` Haswell LBR call stacks - broken Milian Wolff
2015-08-04 18:10 ` Andi Kleen [this message]
2015-08-04 21:41 ` Liang, Kan
2015-08-05 9:02 ` Milian Wolff
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