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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 84D5DC4332E for ; Mon, 23 Mar 2020 00:34:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5221C20722 for ; Mon, 23 Mar 2020 00:34:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726902AbgCWAeZ (ORCPT ); Sun, 22 Mar 2020 20:34:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:47922 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726897AbgCWAeY (ORCPT ); Sun, 22 Mar 2020 20:34:24 -0400 Received: from oasis.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9861E206C3; Mon, 23 Mar 2020 00:34:23 +0000 (UTC) Date: Sun, 22 Mar 2020 20:34:21 -0400 From: Steven Rostedt To: ahmadkhorrami Cc: Linux-trace Users , Arnaldo Carvalho de Melo , Peter Zijlstra , Jiri Olsa Subject: Re: Wrong Perf Backtraces Message-ID: <20200322203421.715b32d8@oasis.local.home> In-Reply-To: References: <157597d74ff17f781d9de7e7e3defd13@ut.ac.ir> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-trace-users-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-trace-users@vger.kernel.org On Mon, 23 Mar 2020 00:54:01 +0430 ahmadkhorrami wrote: > Hi, > I used "Perf" to extract call graphs in an evince benchmark. The command > used is as follows: > sudo perf record -d --call-graph dwarf -c 10000 e > mem_load_uops_retired.l3_miss:uppp /opt/evince-3.28.4/bin/evince > > I extracted the backtraces using "perf script" and found out that there > are many corrupted backtrace instances. Some contained repeated function > calls, for example two consecutive gmallocn()s exactly at the same > offsets. There are also some backtraces where the callers and callees do > not match. Could you show some examples of the backtraces you mention? > > Note that that mappings are correct. In other words, each single line of > the reported backtraces is correct (i.e., addresses match with > functions). But is seems that there are some function calls in the > middle, which are missed by "Perf". Strangely, in all runs (and also > with different sampling frequencies) the problem occurs exactly at the > same place. > > I am really confused and looking forward to any help. I can also send > backtraces if needed. -- Steve