From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiri Olsa Subject: Re: perf cannot see call graph, visible in gdb Date: Mon, 9 Sep 2013 16:35:37 +0200 Message-ID: <20130909143537.GA28036@krava.redhat.com> References: <1309051629550.29229@wes.ijneb.com> <87ioydhgs1.fsf@tassilo.jf.intel.com> <1309091326270.22075@wes.ijneb.com> <522DD5A5.70500@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mx1.redhat.com ([209.132.183.28]:5879 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751506Ab3IIOgO (ORCPT ); Mon, 9 Sep 2013 10:36:14 -0400 Content-Disposition: inline In-Reply-To: <522DD5A5.70500@gmail.com> Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: David Ahern Cc: Mark Hills , Andi Kleen , linux-perf-users@vger.kernel.org On Mon, Sep 09, 2013 at 07:05:25AM -0700, David Ahern wrote: > Adding Jiri. > > On 9/9/13 5:59 AM, Mark Hills wrote: > >On Fri, 6 Sep 2013, Andi Kleen wrote: > > > >>Mark Hills writes: > >> > >>>I have a pre-compiled .so library, which was given to me for profiling. > >>> > >>>gdb can see a complete call stack -- both the library and my own code, > >>>as expected. > >>> > >>>But in perf the callgraph for the library is not present. I'm using > >>>"perf record -g", and the callgraph for the other code is seen. > >>> > >>>In what cases could gdb see the stack, but perf cannot? > >> > >>No frame pointer. > >> > >>Recompile with -fno-omit-frame-pointer > >> > >>Or if you have a new enough perf, you can use -g dwarf to enable > >>dwarf backtracing, but it's very slow and also doesn't handle all > >>situations gdb handles. > > > >Thank you, much appreciated. > > > >A newer perf appears to need a newer kernel too, and it's not practical > >for me to break away from the RedHat kernel at the moment (currently on > >2.6.32-358.14.1.el6) > > Any updates to RHEL6 for dwarf callchains? > unfortunately no news in RHEL6 for this one jirka