From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Fri, 3 May 2002 03:03:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Fri, 3 May 2002 03:03:52 -0400 Received: from penguin.e-mind.com ([195.223.140.120]:18216 "EHLO penguin.e-mind.com") by vger.kernel.org with ESMTP id ; Fri, 3 May 2002 03:03:50 -0400 Date: Fri, 3 May 2002 09:04:34 +0200 From: Andrea Arcangeli To: "Martin J. Bligh" Cc: Daniel Phillips , Russell King , linux-kernel@vger.kernel.org Subject: Re: Bug: Discontigmem virt_to_page() [Alpha,ARM,Mips64?] Message-ID: <20020503090434.C11414@dualathlon.random> In-Reply-To: <20020502180632.I11414@dualathlon.random> <3972036796.1020330599@[10.10.2.3]> <20020502184037.J11414@dualathlon.random> <143790000.1020367912@flay> <20020502205741.O11414@dualathlon.random> <150570000.1020379194@flay> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.3.22.1i X-GnuPG-Key-URL: http://e-mind.com/~andrea/aa.gnupg.asc X-PGP-Key-URL: http://e-mind.com/~andrea/aa.asc Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 02, 2002 at 03:39:54PM -0700, Martin J. Bligh wrote: > > The difference is that if you use discontigmem you don't clobber the > > common code in any way, there is no "logical/ordinal" abstraction, > > there is no special table, it's all hidden in the arch section, and the > > pgdat you need them anyways to allocate from affine memory with numa. > > I *want* the logical / ordinal abstraction. That's not a negative thing - > it reduces the number of complicated things I have to think about, > allowing me to think more clearly, and write correct code ;-) That's just overhead. you don't need an additional table ordinal/logical things. the only case nonlinear will pay off is when you have to deal with a single pgdat with physical huge holes in the middle of its per-node mem_map. You don't have those holes in the middle of the mem_map of each node, so it's cleaner and faster to avoid nonlinear for you, it's just overhead. nonlinear instead definitely pays off with the origin 2k layout shown by Ralf, or with the iseries machine if the partitioning mandates an huge number of discontigous chunks. > > Not having a multitude of zones to balance in the normal discontigmem > case also seems like a powerful argument to me ... > > M. Andrea