From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752834AbYJYSPq (ORCPT ); Sat, 25 Oct 2008 14:15:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751053AbYJYSPi (ORCPT ); Sat, 25 Oct 2008 14:15:38 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:51218 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750960AbYJYSPh (ORCPT ); Sat, 25 Oct 2008 14:15:37 -0400 From: "Rafael J. Wysocki" To: Arjan van de Ven Subject: Re: [pull request] getting rid of __cpuinit Date: Sat, 25 Oct 2008 20:20:00 +0200 User-Agent: KMail/1.9.9 Cc: Sam Ravnborg , torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, Matt Mackall References: <20081024142056.6a2d082a@infradead.org> <20081025162116.GA13303@uranus.ravnborg.org> <20081025092942.40342ad0@infradead.org> In-Reply-To: <20081025092942.40342ad0@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200810252020.01352.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Saturday, 25 of October 2008, Arjan van de Ven wrote: > On Sat, 25 Oct 2008 18:21:16 +0200 > Sam Ravnborg wrote: > > > On Sat, Oct 25, 2008 at 08:06:38AM -0700, Arjan van de Ven wrote: > > > On Sat, 25 Oct 2008 16:35:28 +0200 > > > Sam Ravnborg wrote: > > > > So if you look at the size of the cpuinit/exit sections in the > > > > before case you get the real space saving that is lost in the > > > > embedded case after your patch is applied. > > > > The space savings that happen after early init. > > > > > > [linux.trees.git]# objdump -h vmlinux.before | grep init.text > > > 25 .init.text 00037c25 ffffffff8152a000 000000000152a000 > > > 0092a000 [inux.trees.git]# objdump -h vmlinux.after | grep > > > init.text 25 .init.text 000316c2 ffffffff81542000 > > > 0000000001542000 00942000 > > > > So with your config we will loose a saving of 25955 bytes > > of text. > > > > I tried to look a the numbers of a defconfig build here. > > cpuinit.text equals 0x5d97 = 23959 > > cpuinit.data equals 0x3574 = 13684 > > > > [objdump of vmlinux.o gives you the size of the cpuinit sections] > > > > So if we decide to drop cpuinit then it should be based on the > > above figure and not the 2k figure you gave in the original mail. > > > > Or even better we should see the difference with a typical > > embedded configuration and not some big defconfig build. > > I will assume the saving is less on a typical embedded > > configuration. > > it will be; on x86 you end up inheriting all cpu vendors init code. > on embedded you only have the dedicated CPU code. > > ... just that on x86... nobody seems to be in this position, it's > almost impossble to have HOTPLUG_CPU even be asked. FWIW, I like the idea of removing __cpuinit. It often is quite difficult to determine if given piece of code should be marked as __cpuinit and that leads to bugs that are not so easy to resolve. Thanks, Rafael