Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758802AbYGRNbU (ORCPT ); Fri, 18 Jul 2008 09:31:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756564AbYGRNbK (ORCPT ); Fri, 18 Jul 2008 09:31:10 -0400 Received: from mx1.redhat.com ([66.187.233.31]:53182 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755035AbYGRNbJ (ORCPT ); Fri, 18 Jul 2008 09:31:09 -0400 Date: Fri, 18 Jul 2008 09:28:40 -0400 From: "Frank Ch. Eigler" To: Peter Zijlstra Cc: Andi Kleen , James Bottomley , linux-kernel , systemtap@sourceware.org, jbeulich@novell.com, arjan , sandmann@daimi.au.dk, Ingo Molnar Subject: Re: [RFC] systemtap: begin the process of using proper kernel APIs (part1: use kprobe symbol_name/offset instead of address) Message-ID: <20080718132840.GN18295@redhat.com> References: <1216146802.3312.95.camel@localhost.localdomain> <87ej5rsgk4.fsf@basil.nowhere.org> <1216373009.5232.130.camel@twins> <1216386627.28405.42.camel@twins> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1216386627.28405.42.camel@twins> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1138 Lines: 26 Hi - On Fri, Jul 18, 2008 at 03:10:27PM +0200, Peter Zijlstra wrote: > [...] > > 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. trace_sysprof relies on dump_stack, which is x86-only and does not do elf/dwarf unwinding proper. (Likewise oprofile, etc.) They can't even start, because they don't have unwind data available - something we plan to make available to the systemtap runtime. - FChE -- 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/