From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 52586C43331 for ; Tue, 31 Mar 2020 12:43:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2DE742072E for ; Tue, 31 Mar 2020 12:43:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730818AbgCaMnE (ORCPT ); Tue, 31 Mar 2020 08:43:04 -0400 Received: from mail.ut.ac.ir ([80.66.177.10]:45078 "EHLO mail.ut.ac.ir" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730753AbgCaMnE (ORCPT ); Tue, 31 Mar 2020 08:43:04 -0400 Received: from localhost (localhost [127.0.0.1]) by mail.ut.ac.ir (Postfix) with ESMTP id 7E9A51DB1A5; Tue, 31 Mar 2020 17:13:01 +0430 (+0430) Received: from mail.ut.ac.ir ([127.0.0.1]) by localhost (mail.ut.ac.ir [127.0.0.1]) (amavisd-new, port 10024) with LMTP id 2IbLc7G-yzq0; Tue, 31 Mar 2020 17:13:00 +0430 (+0430) Received: from mail.ut.ac.ir (mail.ut.ac.ir [194.225.0.10]) by mail.ut.ac.ir (Postfix) with ESMTP id 4A695EC205; Tue, 31 Mar 2020 17:13:00 +0430 (+0430) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Date: Tue, 31 Mar 2020 17:13:00 +0430 From: ahmadkhorrami To: Jiri Olsa Cc: Milian Wolff , Steven Rostedt , Arnaldo Carvalho de Melo , Linux-trace Users , Peter Zijlstra , linux-trace-users-owner@vger.kernel.org, Jin Yao , Namhyung Kim , Andi Kleen Subject: Re: Wrong Perf Backtraces In-Reply-To: <8cb4f94b11fbac6ca3a44b924b6ee7b3@ut.ac.ir> References: <821540886fc57d7749edee585a50602f@ut.ac.ir> <1867036.PIDvDuAF1L@agathebauer> <20200329192010.GA2361248@krava> <2522580.mvXUDI8C0e@agathebauer> <20200330130750.GC2361248@krava> <8cb4f94b11fbac6ca3a44b924b6ee7b3@ut.ac.ir> Message-ID: X-Sender: ahmadkhorrami@ut.ac.ir User-Agent: Roundcube Webmail/1.3.6 Sender: linux-trace-users-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-trace-users@vger.kernel.org Hi, Please confirm my thought in the previous email, if it is correct. Regards. On 2020-03-30 23:35, ahmadkhorrami wrote: > Hi, > Sorry, I did not pay attention to the fact that we need debug info to > be able to decode the callchain. So, without complete debug info the > backtrace (either the symbols or the addresses) is bogus. But you say > that the backtrace portions containing binaries with full debug info > are OK. Am I right? Please confirm if this is the case. > If so, these portions may be enough for my current usecase. > Regards. > > On 2020-03-30 18:19, ahmadkhorrami wrote: > > Hi, > thanks, but I still do not understand the cause of the problem. It > seems that it is purely a software bug and the callchain addresses seem > wrong,by themselves. Am I right? > Regards. > On 2020-03-30 17:37, Jiri Olsa wrote: > > On Mon, Mar 30, 2020 at 08:09:53AM +0200, Milian Wolff wrote: On > Sonntag, 29. März 2020 21:20:10 CEST Jiri Olsa wrote: On Sun, Mar 29, > 2020 at 03:50:57PM +0200, Milian Wolff wrote: On Sonntag, 29. März 2020 > 14:39:33 CEST ahmadkhorrami wrote: Thanks. I did both of your changes. > Perhaps some outputs are revised. > But I still have repeated function calls and the script detects them. > Here is one of them when the sampling period is 1000 events: > > Here, we have two consecutive "7f91788120b5 > gtk_widget_propagate_state+0x195 > (/usr/lib/x86_64-linux-gnu/libgtk-3.so.0.2200.30) gtkwidget.c:0" lines, > while "gtk_widget_propagate_state+0x195" is not recursive. It should > call "gtk_container_forall", which does not occur even after the second > (inner) call. > Potentially you are just lacking some debug symbols here for this GTK > library. note that "gtkwidget.c:0" is bogus already - the line numbers > start with 1, so could we just skip those then? pass on all zero lined > inlines > and not add/display them > I guess so - but quite frankly I'm a bit uneasy to do this without > further > exploration about the actual causes here. Afaik DWARF does not say > anything > about the validity, so in theory there might be some language/compiler > that > encodes valid DWARF locations with line 0? > > Generally, it would be quite interesting to figure out why there is > /some/ > DWARF data here such that the code thinks it's able to decode the > inline frame > but then fails and leads to this confusing result? > right, but it's beyond my DWARF expertise ;-) we'll need > to wait till one of you guys could take a look on it > > thanks, > jirka