Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964842AbVL1PiA (ORCPT ); Wed, 28 Dec 2005 10:38:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964846AbVL1PiA (ORCPT ); Wed, 28 Dec 2005 10:38:00 -0500 Received: from waste.org ([64.81.244.121]:33199 "EHLO waste.org") by vger.kernel.org with ESMTP id S964842AbVL1Ph7 (ORCPT ); Wed, 28 Dec 2005 10:37:59 -0500 Date: Wed, 28 Dec 2005 09:34:30 -0600 From: Matt Mackall To: Andi Kleen Cc: Ingo Molnar , Linus Torvalds , Andrew Morton , Arjan van de Ven , linux-kernel@vger.kernel.org Subject: Re: [patch 02/2] allow gcc4 to optimize unit-at-a-time Message-ID: <20051228153430.GO3356@waste.org> References: <20051228114701.GC3003@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1485 Lines: 35 On Wed, Dec 28, 2005 at 04:30:49PM +0100, Andi Kleen wrote: > Ingo Molnar writes: > > > allow gcc4 compilers to optimize unit-at-a-time - which results in gcc > > having a wider scope when optimizing. This also results in smaller code > > when optimizing for size. (gcc4 does not have the stack footprint > > problem of gcc3 compilers.) > > I never had any trouble with stack footprint even with gcc 3.3 on x86-64 > and unit-at-a-time and it was always enabled. The particular offenders I remember were in lib/inflate.c running over 4K well before 4K stacks were in mainline, so I fixed it well before anyone else got to see it. > But one caveat: turning on unit-at-a-time makes objdump -S / make > foo/bar.lst with CONFIG_DEBUG_INFO essentially useless because objdump > cannot deal with functions being out of order in the object file. This > can be a big problem while analyzing oopses - essentially you have > to analyze the functions without source level information. And with > unit-at-a-time they become bigger so it's more difficult. Yeah, and it also makes stuff like bloat-o-meter output go all to hell. > But I still think it's a good idea. Indeed. -- Mathematics is the supreme nostalgia of our time. - 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/