From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755581AbcETDYD (ORCPT ); Thu, 19 May 2016 23:24:03 -0400 Received: from mail.kernel.org ([198.145.29.136]:42955 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751802AbcETDYB (ORCPT ); Thu, 19 May 2016 23:24:01 -0400 Date: Fri, 20 May 2016 12:23:50 +0900 From: Masami Hiramatsu To: Arnaldo Carvalho de Melo Cc: David Ahern , Jiri Olsa , Namhyung Kim , Linux Kernel Mailing List Subject: Re: perf probe -L on ubuntu 16.04 Message-Id: <20160520122350.74c8f2a4ef467148ef19bd9f@kernel.org> In-Reply-To: <20160519120642.GH28790@kernel.org> References: <20160517015636.GC3455@kernel.org> <20160519110039.db4a875677247fa53a17f919@kernel.org> <20160519120642.GH28790@kernel.org> X-Mailer: Sylpheed 3.4.3 (GTK+ 2.24.28; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 19 May 2016 09:06:42 -0300 Arnaldo Carvalho de Melo wrote: > Em Thu, May 19, 2016 at 11:00:39AM +0900, Masami Hiramatsu escreveu: > > On Mon, 16 May 2016 22:56:36 -0300 > > Arnaldo Carvalho de Melo wrote: > > > Have you ever tried using 'perf probe' on ubuntu? > > > > acme@ubuntu:~/git/linux$ sudo apt-cache search linux-image-$(uname -r) > > > linux-image-4.4.0-21-generic - Linux kernel image for version 4.4.0 on > > > 64 bit x86 SMP > > > linux-image-4.4.0-21-generic-dbgsym - Linux kernel debug image for > > > version 4.4.0 on 64 bit x86 SMP > > > acme@ubuntu:~/git/linux$ > > > acme@ubuntu:~/git/linux$ > > > > > > So those are installed, but then I try: > > > > > > root@ubuntu:~# perf probe -vvv -L getname_flags > > > Looking at the vmlinux_path (8 entries long) > > > Using /usr/lib/debug/boot/vmlinux-4.4.0-21-generic for symbols > > > Open Debuginfo file: /usr/lib/debug/boot/vmlinux-4.4.0-21-generic > > > fname: /build/linux-Ay7j_C/linux-4.4.0/fs/namei.c, lineno:125 > > > New line range: 125 to 2147483647 > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > > Get 3665 lines from this CU > > Ah, why do we repeat the above line that many times? Are we somehow > reading this compile unit that many times?!? Yes, because the getname_flags is inlined by compiler, depends on the parameter, some lines in the function are never compiled at some call points. In this case, we have to check every call points so that all the available lines are found. BTW, "this CU" has no meaning, it should show the diename, or remove the useless message. > > > path: /build/linux-Ay7j_C/linux-4.4.0/fs/namei.c > > > Failed to find source file path. > > > Error: Failed to show lines. Reason: No such file or directory (Code: -2) > > > root@ubuntu:~# > > > > Have to dig deeper to see where the source code is, ideas? > > > It shows the "path" is ; > > > path: /build/linux-Ay7j_C/linux-4.4.0/fs/namei.c > > > So, would you have the source code under this temporary directory? > > (yeah, I guess No) > > No, and I couldn't find a package that had it > > > Anyway, ubuntu has "linux-source" package, or apt source linux-image-`uname -r` > > will give you the source tree in current dir. > > > After you get a proper kernel source code, you can use -s to show source code. > > > -s, --source > > path to kernel source > > > I ensured it is working correctly by below command. > > $ perf probe -s ./linux-4.4.0 -L getname_flags > > Ok, how about telling the user this package is needed, since we can > figure out the distro and the package name? Did we do that already? > Couldn't it figure out where > the source code is and also not require using '-s'? No, actually, ubuntu/debian are not providing kernel source tree package as redhat/fedora do. User can only download source tarball and extract it under current working directory. There seems no standard directory where the source code is extracted to. I think it's debian/ubuntu's packaging policy. Anyway, even though we can provide how-to guide for them via Documentation. I think it's better way because we also have to add some entries to apt.conf for installing kernel debuginfo. Thank you, > > - Arnaldo -- Masami Hiramatsu