From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161257AbXD1GxF (ORCPT ); Sat, 28 Apr 2007 02:53:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161235AbXD1GxF (ORCPT ); Sat, 28 Apr 2007 02:53:05 -0400 Received: from smtp1.linux-foundation.org ([65.172.181.25]:59258 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161257AbXD1GxD (ORCPT ); Sat, 28 Apr 2007 02:53:03 -0400 Date: Fri, 27 Apr 2007 23:52:47 -0700 From: Andrew Morton To: Christoph Lameter Cc: David Chinner , linux-kernel@vger.kernel.org, Mel Gorman , William Lee Irwin III , Jens Axboe , Badari Pulavarty , Maxim Levitsky , Nick Piggin Subject: Re: [00/17] Large Blocksize Support V3 Message-Id: <20070427235247.3576a463.akpm@linux-foundation.org> In-Reply-To: References: <20070426195357.597ffd7e.akpm@linux-foundation.org> <20070427042046.GI65285596@melbourne.sgi.com> <20070426221528.655d79cb.akpm@linux-foundation.org> <20070426235542.bad7035a.akpm@linux-foundation.org> <20070427002640.22a71d06.akpm@linux-foundation.org> <20070427163620.GI32602149@melbourne.sgi.com> <20070427173432.GJ32602149@melbourne.sgi.com> <20070427121108.9ee05710.akpm@linux-foundation.org> <20070428031739.GK32602149@melbourne.sgi.com> <20070427215634.325606a9.akpm@linux-foundation.org> <20070427223632.52def99e.akpm@linux-foundation.org> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 27 Apr 2007 23:24:05 -0700 (PDT) Christoph Lameter wrote: > > Fact is, this change has *costs*. And you're completely ignoring them, > > trying to spin them away. It ain't working and it never will. I'm seeing > > no serious attempt to think about how we can reduce those costs while > > retaining most of the benefits. > > Well okay my work is "no serious attempt". No. My point is, you have resisted all attempts to explore less costly *alternatives* to this work. Alternatives. By misunderstanding any suggestions, misrepresenting them, making incorrect statements about them, by not suggesting any alternatives yourself, all of it buttressed by a stolid refusal to recognise that this patch has any costs. This effectively leaves it up to others to find time to think about and to implement possible alternative solutions to the problems which you're observing. The altenative which is on the table (and there may be others) is populating pagecache with physically contiguous pages. This will fix the HBA problem and is much less costly in terms of maintenance and will improve all workloads on all machines and doesn't have the additional runtime costs of pagecache wastage and more memset() overhead with small files and it doesn't require administrator intervention. OTOH (yes! there are tradeoffs!) it will consume an unknown amount more CPU and it doesn't address the large-fs-blocksize requirement, but I don't know how important the latter is and given the unrelenting advocacy storm coming from the SGI direction I don't know how to find that out, frankly.