Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754220AbaDOJgr (ORCPT ); Tue, 15 Apr 2014 05:36:47 -0400 Received: from eddie.linux-mips.org ([78.24.191.182]:48175 "EHLO cvs.linux-mips.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753775AbaDOJgn (ORCPT ); Tue, 15 Apr 2014 05:36:43 -0400 Date: Tue, 15 Apr 2014 11:36:22 +0200 From: Ralf Baechle To: Josh Triplett Cc: Ingo Molnar , Markus Trippelsdorf , Andi Kleen , Linus Torvalds , Michal Marek , Linux Kbuild mailing list , Linux Kernel Mailing List , Sam Ravnborg , John Crispin Subject: Re: [GIT] kbuild/lto changes for 3.15-rc1 Message-ID: <20140415093622.GB27556@linux-mips.org> References: <20140407201919.GA15838@sepie.suse.cz> <20140408204906.GA3616@cloud> <20140409013557.GA32556@tassilo.jf.intel.com> <20140409060133.GA6766@gmail.com> <20140409081709.GA283@x4> <20140414103205.GA2846@gmail.com> <20140415010003.GA2765@jtriplet-mobl1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140415010003.GA2765@jtriplet-mobl1> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 14, 2014 at 06:00:04PM -0700, Josh Triplett wrote: > > and it slows down > > kernel development'. > > No, it doesn't slow down development builds; it makes kernel builds > slower if and only if LTO is turned on, which most kernel developers > won't need to do. On the other hand, distro and embedded kernels can do > so for final builds, and developers pushing to minimize the kernel can LTO inherently is going to slow down development because it does inflate the testing matrix - a developer really should test an LTO build. That said, the increased checking of the source code for validity across compilation units done by the LTO final link is a benefit by itself. With my MIPS maintainer head on I can say it's required fixes / cleanups of several thousand lines which have already been merged several kernel versions ago because they all were beneficial even without LTO. A mere three small commits preparing arch/mips for LTO support and that don't make sense without LTO are remaining. So it's not a support/testing nightmare. And while the code size reduction is less for MIPS than what others have reported for their platforms (I'm still investigating) is still is enough that embedded developers would commit murder for. Ralf -- 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/