From mboxrd@z Thu Jan 1 00:00:00 1970 From: Milian Wolff Subject: Re: Trying to understand some strange samples in a perf profile Date: Thu, 04 Jan 2018 23:08:17 +0100 Message-ID: <10526114.Hqjjc3tiqt@agathebauer> References: <2337765.oK3dqqyzHo@milian-kdab2> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart4891992.Xyebzi2WkP"; micalg="sha256"; protocol="application/pkcs7-signature" Return-path: Received: from mail.kdab.com ([176.9.126.58]:43580 "EHLO mail.kdab.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752344AbeADWIW (ORCPT ); Thu, 4 Jan 2018 17:08:22 -0500 In-Reply-To: Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: David Hinkle Cc: Hadrien Grasland , linux-perf-users@vger.kernel.org --nextPart4891992.Xyebzi2WkP Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" On Friday, December 29, 2017 12:31:41 AM CET David Hinkle wrote: > > - build a minimal "unwinder" application for libunwind e.g. > > - notify libunwind about all mmap events > > - install the register and stack state from the per.data file > > - try to unwind, see what happens > > I'm having some problems with perf dwarf stack unwindings that stop at > the kernel/userspace boundary and some userspace stacks that aren't > unwinding at all on 4.9.70 I'd really love to shed some light on. > Similar situation, in my case the stacks are in libc-2.17.so, which I > think is symbolized properly (Other traces are unwinding through this > library fine). I'm also using libdw for unwinding and not libunwind. > > I'd love to be able to do the above 4 things in an app and see if I > can figure out why it's not unwinding properly. Do you have some > example code that can do that? If you do now or you write it please > share. I don't have anything ready-made, otherwise I'd have shared it already. The example code for what needs to be done would be the perf code base. I.e. have a look at tools/perf/util/unwind-{libunwind-local,libdw}.c Cheers -- Milian Wolff | milian.wolff@kdab.com | Senior Software Engineer KDAB (Deutschland) GmbH, a KDAB Group company Tel: +49-30-521325470 KDAB - The Qt, C++ and OpenGL Experts --nextPart4891992.Xyebzi2WkP Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCDEIw ggXmMIIDzqADAgECAhBqm+E4O/8ra58B1dm4p1JWMA0GCSqGSIb3DQEBDAUAMIGFMQswCQYDVQQG EwJHQjEbMBkGA1UECBMSR3JlYXRlciBNYW5jaGVzdGVyMRAwDgYDVQQHEwdTYWxmb3JkMRowGAYD VQQKExFDT01PRE8gQ0EgTGltaXRlZDErMCkGA1UEAxMiQ09NT0RPIFJTQSBDZXJ0aWZpY2F0aW9u IEF1dGhvcml0eTAeFw0xMzAxMTAwMDAwMDBaFw0yODAxMDkyMzU5NTlaMIGXMQswCQYDVQQGEwJH QjEbMBkGA1UECBMSR3JlYXRlciBNYW5jaGVzdGVyMRAwDgYDVQQHEwdTYWxmb3JkMRowGAYDVQQK ExFDT01PRE8gQ0EgTGltaXRlZDE9MDsGA1UEAxM0Q09NT0RPIFJTQSBDbGllbnQgQXV0aGVudGlj 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