From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965929AbXCPU7z (ORCPT ); Fri, 16 Mar 2007 16:59:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965930AbXCPU7y (ORCPT ); Fri, 16 Mar 2007 16:59:54 -0400 Received: from dvhart.com ([64.146.134.43]:50412 "EHLO dvhart.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965926AbXCPU7x (ORCPT ); Fri, 16 Mar 2007 16:59:53 -0400 Message-ID: <45FB0548.5070909@mbligh.org> Date: Fri, 16 Mar 2007 13:59:52 -0700 From: Martin Bligh User-Agent: Thunderbird 1.5.0.9 (X11/20070104) MIME-Version: 1.0 To: Christoph Lameter Cc: Andi Kleen , Steven Rostedt , Linus Torvalds , Ingo Molnar , linux-kernel@vger.kernel.org, Andrew Morton , Chris Wright , Rusty Russell , Glauber de Oliveira Costa , Andy Whitcroft Subject: Re: [PATCH 00/18] Make common x86 arch area for i386 and x86_64 - Take 2 References: <20070314050819.536207642@goodmis.org> <20070314125330.GA13168@elte.hu> <45F96B57.10206@mbligh.org> <20070315160648.GA11812@one.firstfloor.org> <1173977264.7922.24.camel@localhost.localdomain> <20070316114415.GA26403@one.firstfloor.org> <45FAFD57.90601@mbligh.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Christoph Lameter wrote: > On Fri, 16 Mar 2007, Martin Bligh wrote: > >> You have to do some sort of lookup anyway, and Andy seemed to have them >> all folded into one. > > What lookup would you need to do? On x86_64 even the TLB use is > hidden by the existing 2M entries for 1-1 mappings. > >> Or are you trying to avoid this by going to back to the crud we had >> in 2.4 where we pretend mem_map is one big array, indexed by pfn with >> huge sparsely mapped holes in it? > > Yes that the advanced way of doing it rather than adding useless custom > lookups. For starters, you can't do that sparse a mapping on a 32 bit system. I'll let Andy explain the rest of it. >> Would be nice to work out (and document somewhere) what the pros and >> cons of virtual memmap vs sparsemem were - ISTR one of the arguments >> was extremely sparsely layed out machines, and you needed sparsemem >> for that. But right now we have 3 solutions, which is not a good >> situation. > > Please read my posts to linux-mm on that subject. We discussed it last > year in detail and the agreement was that the sparsemem crud needs to be > taken out. Kame-san posted patches to do that. "the agreement"? So Andy agreed to taking it out? Or you and Kame did? M.