From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758978AbXJJVzb (ORCPT ); Wed, 10 Oct 2007 17:55:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757496AbXJJVrA (ORCPT ); Wed, 10 Oct 2007 17:47:00 -0400 Received: from gw.goop.org ([64.81.55.164]:35271 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757651AbXJJVq7 (ORCPT ); Wed, 10 Oct 2007 17:46:59 -0400 Message-ID: <470D4826.2060903@goop.org> Date: Wed, 10 Oct 2007 14:46:14 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.5 (X11/20070727) MIME-Version: 1.0 To: Christoph Lameter CC: Andi Kleen , William Lee Irwin III , Ingo Molnar , Thomas Gleixner , Andrew Morton , Linux Kernel Mailing List Subject: Re: [PATCH] i386: remove dead code in pgtable_cache_init References: <470D3846.1000209@goop.org> In-Reply-To: X-Enigmail-Version: 0.95.3 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Christoph Lameter wrote: > I believe that virtualization support needed a full pgd. > Yes, Xen requires it for PAE pgds, at least at the moment. But native, lguest, vmi and kvm don't. I'd made it so that the memory overhead was only paid in the Xen case. Allocating a whole page all the time certainly simplifies things, but at the cost of more overhead for everyone. If we move away from using the page->private field to link the pgds together, then I can probably remove Xen's need to allocate a whole page for PAE pgds. J