From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 12258 invoked by alias); 18 Jul 2008 13:04:25 -0000 Received: (qmail 12250 invoked by uid 22791); 18 Jul 2008 13:04:24 -0000 X-Spam-Status: No, hits=-2.3 required=5.0 tests=AWL,BAYES_00,KAM_MX,SPF_HELO_PASS,SPF_PASS X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (66.187.233.31) by sourceware.org (qpsmtpd/0.31) with ESMTP; Fri, 18 Jul 2008 13:04:07 +0000 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id m6ID3ucN012459; Fri, 18 Jul 2008 09:03:56 -0400 Received: from pobox-3.corp.redhat.com (pobox-3.corp.redhat.com [10.11.255.67]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id m6ID3jNh019400; Fri, 18 Jul 2008 09:03:55 -0400 Received: from touchme.toronto.redhat.com (IDENT:postfix@touchme.yyz.redhat.com [10.15.16.9]) by pobox-3.corp.redhat.com (8.13.1/8.13.1) with ESMTP id m6ID2uaU027655; Fri, 18 Jul 2008 09:03:12 -0400 Received: from ton.toronto.redhat.com (ton.yyz.redhat.com [10.15.16.15]) by touchme.toronto.redhat.com (Postfix) with ESMTP id BA7148001FF; Fri, 18 Jul 2008 09:02:39 -0400 (EDT) Received: from ton.toronto.redhat.com (localhost.localdomain [127.0.0.1]) by ton.toronto.redhat.com (8.13.1/8.13.1) with ESMTP id m6ID2NtR021413; Fri, 18 Jul 2008 09:02:23 -0400 Received: (from fche@localhost) by ton.toronto.redhat.com (8.13.1/8.13.1/Submit) id m6ID2Jvo021412; Fri, 18 Jul 2008 09:02:19 -0400 X-Authentication-Warning: ton.toronto.redhat.com: fche set sender to fche@redhat.com using -f To: Peter Zijlstra Cc: Andi Kleen , James Bottomley , linux-kernel , systemtap@sourceware.org, jbeulich@novell.com Subject: Re: [RFC] systemtap: begin the process of using proper kernel APIs (part1: use kprobe symbol_name/offset instead of address) References: <1216146802.3312.95.camel@localhost.localdomain> <87ej5rsgk4.fsf@basil.nowhere.org> <1216373009.5232.130.camel@twins> From: fche@redhat.com (Frank Ch. Eigler) Date: Fri, 18 Jul 2008 13:04:00 -0000 In-Reply-To: <1216373009.5232.130.camel@twins> (Peter Zijlstra's message of "Fri, 18 Jul 2008 11:23:29 +0200") Message-ID: User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/21.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Scanned-By: MIMEDefang 2.58 on 172.16.52.254 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 X-SW-Source: 2008-q3/txt/msg00256.txt.bz2 Peter Zijlstra writes: > [...] >> Right now x86 doesn't really have a good reliable unwinder that >> works without frame pointer. I think systemtap >> recently switched to Jan Beulich's dwarf2 unwinder. Before >> switching to the in kernel unwinder that one would need to be >> re-merged again. > > Those are two separate issues. > > 1) stap ought to use the kernel's infrastructure and not re-implement > its own. > 2) if the kernel's infrastructure doesn't meet requirements, improve > it. They are related to the extent that readers may not realize some implications of systemtap being/becoming a *kernel-resident* but not *kernel-focused* tool. For example, we're about to do unwinding/stack-traces of userspace programs. To what extent do you think the kernel unwinder (should one reappear in git) would welcome patches that provide zero benefit to the kernel, but only enable a peculiar (nonintrusive) sort of unwinding we would need for complex userspace stacks? - FChE