From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751850AbaEFQag (ORCPT ); Tue, 6 May 2014 12:30:36 -0400 Received: from terminus.zytor.com ([198.137.202.10]:38208 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751774AbaEFQae (ORCPT ); Tue, 6 May 2014 12:30:34 -0400 Message-ID: <53690D97.50401@zytor.com> Date: Tue, 06 May 2014 09:28:07 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Cyrill Gorcunov , linux-kernel@vger.kernel.org CC: linux-mm@kvack.org, torvalds@linux-foundation.org, mgorman@suse.de, mingo@kernel.org, steven@uplinklabs.net, riel@redhat.com, david.vrabel@citrix.com, akpm@linux-foundation.org, peterz@infradead.org, xemul@parallels.com Subject: Re: [patch 2/2] mm: pgtable -- Require X86_64 for soft-dirty tracker References: <20140425081030.185969086@openvz.org> <20140425082042.848656782@openvz.org> In-Reply-To: <20140425082042.848656782@openvz.org> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/25/2014 01:10 AM, Cyrill Gorcunov wrote: > Tracking dirty status on 2 level pages requires very ugly macros > and taking into account how old the machines who can operate > without PAE mode only are, lets drop soft dirty tracker from > them for code simplicity (note I can't drop all the macros > from 2 level pages by now since _PAGE_BIT_PROTNONE and > _PAGE_BIT_FILE are still used even without tracker). > > Linus proposed to completely rip off softdirty support on > x86-32 (even with PAE) and since for CRIU we're not planning > to support native x86-32 mode, lets do that. > > (Softdirty tracker is relatively new feature which mostly used > by CRIU so I don't expect if such API change would cause problems > on userspace). I have to wonder which one is more likely to actually matter on whatever legacy 32-bit are going to remain. This pretty much comes down to what kind of advanced features are going to matter in deep embedded applications in the future: checkpoint/restart or NUMA. My guess is that it is actually checkpoint/restart... How much does it actually simplify to leave this feature in for PAE? I could care less about non-PAE... NX has pretty much killed that off cold. -hpa