From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933102AbXDZGqJ (ORCPT ); Thu, 26 Apr 2007 02:46:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933084AbXDZGqJ (ORCPT ); Thu, 26 Apr 2007 02:46:09 -0400 Received: from netops-testserver-4-out.sgi.com ([192.48.171.29]:40679 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S933094AbXDZGqH (ORCPT ); Thu, 26 Apr 2007 02:46:07 -0400 Date: Wed, 25 Apr 2007 23:46:06 -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: <463048FE.5000600@yahoo.com.au> Message-ID: References: <20070424222105.883597089@sgi.com> <463048FE.5000600@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: > Yeah. IMO anti-fragmentation and defragmentation is the hack, and we > should stay away from higher order allocations whenever possible. Right and we need to create series of other approaches that we then label "non-hack" to replace it. > Hardware is built to handle many small pages efficintly, and I don't > understand how it could be an SGI-only issue. Sure, you may have an > order of magnitude or more memory than anyone else, but even my lowly > desktop _already_ has orders of magnitude more pages than it has TLB > entries or cache -- if a workload is cache-nice for me, it probably > will be on a 1TB machine as well, and if it is bad for the 1TB machine, > it is also bad on mine. There have been numbers of people that have argued the same point. Just because we have developed a way of thinking to defend our traditional 4k values does not make them right. > If this is instead an issue of io path or reclaim efficiency, then it > would be really nice to see numbers... but I don't think making these > fundamental paths more complex and slower is a nice way to fix it > (larger PAGE_SIZE would be, though). The code paths can stay the same. You can switch CONFIG_LARGE pages off if you do not want it and it is as it was. If you would have a look the patches: The code is significantly cleanup and easier to read.