From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031415AbXDZSTM (ORCPT ); Thu, 26 Apr 2007 14:19:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1031418AbXDZSTM (ORCPT ); Thu, 26 Apr 2007 14:19:12 -0400 Received: from netops-testserver-4-out.sgi.com ([192.48.171.29]:53766 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1031415AbXDZSTK (ORCPT ); Thu, 26 Apr 2007 14:19:10 -0400 Date: Thu, 26 Apr 2007 11:13:49 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: Nick Piggin cc: "Eric W. Biederman" , linux-kernel@vger.kernel.org, Mel Gorman , William Lee Irwin III , David Chinner , Jens Axboe , Badari Pulavarty , Maxim Levitsky Subject: Re: [00/17] Large Blocksize Support V3 In-Reply-To: <463057D9.9030804@yahoo.com.au> Message-ID: References: <20070424222105.883597089@sgi.com> <46303A98.9000605@yahoo.com.au> <46304C74.9040304@yahoo.com.au> <46305177.7060102@yahoo.com.au> <463057D9.9030804@yahoo.com.au> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 26 Apr 2007, Nick Piggin wrote: > > But what do you mean with it? A block is no longer a contiguous section of > > memory. So you have redefined the term. > > I don't understand what you mean at all. A block has always been a > contiguous area of disk. You want to change the block layer to support larger blocksize than PAGE_SIZE right? So you need to segment that larger block into pieces. > > And you dont care about Mel's work on that level? > > I actually don't like it too much because it can't provide a robust > solution. What do you do on systems with small memories, or those that > eventually do get fragmented? You could f.e. switch off defragmentation and the large block support? > Actually, I don't know why people are so excited about being able to > use higher order allocations (I would rather be more excited about > never having to use them). But for those few places that really need > it, I'd rather see them use a virtually mapped kernel with proper > defragmentation rather than putting hacks all through the core code. Ahh. I knew we were going this way.... Now we have virtual contiguous vs. physical discontiguous.... Yuck hackidihack. > > No this has been tried before and does not work. Why should we loose the > > capability to work with 4k pages just because there is some data that has to > > be thrown around in quantity? I'd like to have flexibility here. > > Is that a big problem? Really? You use 16K pages on your IPF systems, > don't you? Yes but the processor supports 4k also. I'd rather have a choice. 16k is a choice for performance given the current kernel limitations hat wastes lots of memory.