Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751968AbWI3U5Q (ORCPT ); Sat, 30 Sep 2006 16:57:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751969AbWI3U5Q (ORCPT ); Sat, 30 Sep 2006 16:57:16 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:14776 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S1751968AbWI3U5P (ORCPT ); Sat, 30 Sep 2006 16:57:15 -0400 Date: Sat, 30 Sep 2006 22:49:00 +0200 From: Ingo Molnar To: Linus Torvalds Cc: Andi Kleen , Eric Rannaud , Linux Kernel Mailing List , Andrew Morton , nagar@watson.ibm.com, Chandra Seetharaman , Jan Beulich Subject: Re: BUG-lockdep and freeze (was: Arrr! Linux 2.6.18) Message-ID: <20060930204900.GA576@elte.hu> References: <5f3c152b0609301220p7a487c7dw456d007298578cd7@mail.gmail.com> <200609302230.24070.ak@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: -2.8 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.8 required=5.9 tests=ALL_TRUSTED,AWL,BAYES_50 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts 0.5 BAYES_50 BODY: Bayesian spam probability is 40 to 60% [score: 0.4999] -0.0 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1111 Lines: 25 * Linus Torvalds wrote: > I mean, really: Andi, point me to anything that was a real problem > when we had no unwinder at all? personally, i like perfect stacktraces, alot. x86_64 was a huge pain for me without the unwinder. I got so used to perfect backtraces on i686 (when using %ebp frames) during the years, and i had to look at _many_ backtraces with lockdep. On x86_64 it was just constant brain-drain to think away bogus stack entries. Yes, i can do it no problem when i have to look at only a few stacktraces per day, but if it's hundreds per day it's _alot_ of brainpower wasted. (i'd have been happy with an %rbp based unwinder for x86_64, in fact i implemented it for lockdep and used it for some time on x86_64, but Andi wanted a dwarf-based, lower-overhead one. Andi also nicely integrated it into stacktrace.c.) Ingo - 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/