From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755908AbaDGXQz (ORCPT ); Mon, 7 Apr 2014 19:16:55 -0400 Received: from mga09.intel.com ([134.134.136.24]:19445 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753771AbaDGXQx (ORCPT ); Mon, 7 Apr 2014 19:16:53 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,813,1389772800"; d="scan'208";a="508710477" Date: Mon, 7 Apr 2014 13:59:25 -0700 From: Andi Kleen To: Michal Marek Cc: Linus Torvalds , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [GIT] kbuild/lto changes for 3.15-rc1 Message-ID: <20140407205925.GX32556@tassilo.jf.intel.com> References: <20140407201919.GA15838@sepie.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140407201919.GA15838@sepie.suse.cz> 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 07, 2014 at 10:19:19PM +0200, Michal Marek wrote: > Hi Linus, > > besides the kbuild branch, here is the LTO build support by Andi. It is > a separate branch, because it depends on other patches by Andi which > were merged through other trees. The link-time-optimization build is an > experimental feature, so there one kconfig option to enable it and > another kconfig option to disable it (behind a door with a sign "Beware > of the Leopard"...), so that it is not enabled by > allmodconfig/allyesconfig. Thanks Michal, I should add this version builds quite a bit slower than other LTO trees, because the single pass kallsyms didn't quite make it, so the Link Time Optimization is re-done 2-3 times if KALLSYMS is enabled. That will be hopefully fixed next cycle. LTO will always be somewhat slower than a normal build, but right now it's a lot slower because of this, depending on the size of the vmlinux. -Andi