Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758430AbYGRNKQ (ORCPT ); Fri, 18 Jul 2008 09:10:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755099AbYGRNKE (ORCPT ); Fri, 18 Jul 2008 09:10:04 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:47005 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753574AbYGRNKD (ORCPT ); Fri, 18 Jul 2008 09:10:03 -0400 Subject: Re: [RFC] systemtap: begin the process of using proper kernel APIs (part1: use kprobe symbol_name/offset instead of address) From: Peter Zijlstra To: "Frank Ch. Eigler" Cc: Andi Kleen , James Bottomley , linux-kernel , systemtap@sourceware.org, jbeulich@novell.com, arjan , sandmann@daimi.au.dk, Ingo Molnar In-Reply-To: References: <1216146802.3312.95.camel@localhost.localdomain> <87ej5rsgk4.fsf@basil.nowhere.org> <1216373009.5232.130.camel@twins> Content-Type: text/plain Date: Fri, 18 Jul 2008 15:10:27 +0200 Message-Id: <1216386627.28405.42.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1551 Lines: 38 On Fri, 2008-07-18 at 09:02 -0400, Frank Ch. Eigler wrote: > 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? I think sysprof (kernel/trace/trace_sysprof.c) already does user-space stack unwinding. So pushing that capability further up the chain when a second user (stap) comes along makes perfect sense. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/