From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 19312 invoked by alias); 12 Jan 2016 05:47:54 -0000 Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org Received: (qmail 19303 invoked by uid 89); 12 Jan 2016 05:47:52 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=1.8 required=5.0 tests=AWL,BAYES_20,FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 spammy=29, Moreover, luo, hdr X-HELO: mail-pa0-f42.google.com Received: from mail-pa0-f42.google.com (HELO mail-pa0-f42.google.com) (209.85.220.42) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-GCM-SHA256 encrypted) ESMTPS; Tue, 12 Jan 2016 05:47:51 +0000 Received: by mail-pa0-f42.google.com with SMTP id uo6so317199307pac.1 for ; Mon, 11 Jan 2016 21:47:51 -0800 (PST) MIME-Version: 1.0 X-Received: by 10.66.236.69 with SMTP id us5mr69675964pac.93.1452577669978; Mon, 11 Jan 2016 21:47:49 -0800 (PST) Received: by 10.66.149.9 with HTTP; Mon, 11 Jan 2016 21:47:49 -0800 (PST) Date: Tue, 12 Jan 2016 05:47:00 -0000 Message-ID: Subject: [HELP] ubacktrace() problem From: Jinhua Luo To: systemtap@sourceware.org Content-Type: text/plain; charset=UTF-8 X-IsSubscribed: yes X-SW-Source: 2016-q1/txt/msg00020.txt.bz2 Hi All, On Debian8 (jessie), I use the sample-bt-off-cpu script to diagnose the postgresql performance. I already install the debuginfo packages of kernel, glibc and the postgresql, and I compile the systemtap 2.9 to use. See https://github.com/openresty/nginx-systemtap-toolkit#sample-bt-off-cpu for the script. It fails to unwind some user backtrace (which is a big fraction of the total samples), and just show some hex adddress, e.g. 0xb77a5d40. I check that address belongs to the vdso mapping. This issue is not specific to postgresql, but also for other programs running on the same system. I try to reinstall the debian8 in a clean box, the issue is the same. I am wondering what's wrong with debian8? And, I am also get confused about the warnings: WARNING: Too many CFI instuctions WARNING: DWARF expression stack underflow in CFI WARNING: no or bad debug frame hdr WARNING: No binary search table for eh frame, doing slow linear search for stap_b9bfb422b7bd73acc448d7f775aaacd_37477 I try to run the same script on Ubuntu 14.04 and CentOS 7. They could work and show me the correct user backtrace. But, the above warnings exist too! Moreover, the warnings does not necessarily appear at different runs of the same script! Why systemtap outputs those warnings on these popular linux distributions? The dwarf info associated with the kernel, glibc and other programs is not so qualified? Then what system we need so that we could run systemtap without any common problems? Anybody could help me out? Thanks! Regards, Jinhua Luo