Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759288AbZCWUpu (ORCPT ); Mon, 23 Mar 2009 16:45:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753266AbZCWUpl (ORCPT ); Mon, 23 Mar 2009 16:45:41 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:58684 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750711AbZCWUpk (ORCPT ); Mon, 23 Mar 2009 16:45:40 -0400 Date: Mon, 23 Mar 2009 13:39:22 -0700 (PDT) From: Linus Torvalds X-X-Sender: torvalds@localhost.localdomain To: "Frank Ch. Eigler" cc: Ingo Molnar , Andrew Morton , Roland McGrath , Steven Rostedt , utrace-devel@redhat.com, linux-kernel@vger.kernel.org, Peter Zijlstra , Thomas Gleixner Subject: Re: [PATCH 3/3] utrace-based ftrace "process" engine, v2 In-Reply-To: <20090323202503.GD18774@redhat.com> Message-ID: References: <20090321014244.9ADF1FC3AB@magilla.sf.frob.com> <20090321074301.GA19384@elte.hu> <20090321013912.ed6039c9.akpm@linux-foundation.org> <20090321091235.GA29678@elte.hu> <20090321041954.72b99e69.akpm@linux-foundation.org> <20090321115141.GA3566@redhat.com> <20090321050422.d1d99eec.akpm@linux-foundation.org> <20090321154501.GA2707@elte.hu> <20090321214852.GA5262@redhat.com> <20090322120811.GD19826@elte.hu> <20090323202503.GD18774@redhat.com> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1461 Lines: 40 On Mon, 23 Mar 2009, Frank Ch. Eigler wrote: > > I have CONFIG_DEBUG_INFO turned off in 99.9% of my kernel builds, > > because it slows down the kernel build times significantly: [...] > > OK, 15% longer time. It's way more than that if you don't have tons of memory and excessive amounts of CPU power. > > 2) > > > > When the kernel build becomes IO-bound [...] > > without: 870.36 user 292.79 system 3:32.10 elapsed 548% CPU > > with: 929.65 user 384.55 system 8:28.70 elapsed 258% CPU > > OK, lots of network traffic. This is the _normal_ situation for a debug info build. If it's not network traffic (distcc), it's just disk IO. Have you tried it on a laptop? Ingo is not the only one that turns off DEBUG_INFO in disgust. It's totally useless for any sane kernel developer - the costs are excessive. Adn that's totally ignoring the disk usage of multiple debug info kernels. > Note that this backs away from earlier claims that we can make do > without debuginfo, or that the compiler can't be trusted to build the > stuff. We all agree it'd be nice if made it better and made a little > less. Gaah. I'd wish you all agreed that DEBUG_INFO is just TOTALLY UNREALISTIC. Linus -- 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/