From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: Haswell LBR call stacks - broken Date: Tue, 04 Aug 2015 11:10:32 -0700 Message-ID: <87h9oe3ox3.fsf@tassilo.jf.intel.com> References: <1682663.JO3lAz5bZo@agathebauer> <8643019.4YmQ1Xdl9W@milian-kdab2> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from mga01.intel.com ([192.55.52.88]:3736 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752247AbbHDSLo (ORCPT ); Tue, 4 Aug 2015 14:11:44 -0400 In-Reply-To: <8643019.4YmQ1Xdl9W@milian-kdab2> (Milian Wolff's message of "Tue, 04 Aug 2015 19:24:04 +0200") Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: Milian Wolff Cc: linux-perf-users@vger.kernel.org, kan.liang@intel.com Milian Wolff 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