Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965668AbXEGQGP (ORCPT ); Mon, 7 May 2007 12:06:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965472AbXEGQGK (ORCPT ); Mon, 7 May 2007 12:06:10 -0400 Received: from netops-testserver-3-out.sgi.com ([192.48.171.28]:52472 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S965440AbXEGQGI (ORCPT ); Mon, 7 May 2007 12:06:08 -0400 Date: Mon, 7 May 2007 09:06:05 -0700 (PDT) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: "Eric W. Biederman" cc: David Chinner , Theodore Tso , Andrew Morton , linux-kernel@vger.kernel.org, Mel Gorman , William Lee Irwin III , Jens Axboe , Badari Pulavarty , Maxim Levitsky Subject: Re: [00/17] Large Blocksize Support V3 In-Reply-To: Message-ID: References: <20070427042046.GI65285596@melbourne.sgi.com> <20070426221528.655d79cb.akpm@linux-foundation.org> <20070427060921.GA77450368@melbourne.sgi.com> <20070427000403.6013d1fa.akpm@linux-foundation.org> <20070427080321.GG32602149@melbourne.sgi.com> <20070427014849.41f383f7.akpm@linux-foundation.org> <20070427164535.GH24852@thunk.org> <20070507042925.GT32602149@melbourne.sgi.com> <20070507052729.GV32602149@melbourne.sgi.com> 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 Content-Length: 1473 Lines: 29 On Mon, 7 May 2007, Eric W. Biederman wrote: > Yes, instead of having to redesign the interface between the > fs and the page cache for those filesystems that handle large > blocks we instead need to redesign significant parts of the VM interface. > Shift the redesign work to another group of people and call it a trivial. To some extend that is true. But then there will then also be additional gain: We can likely get the VM to handle larger pages too which may get rid of hugetlb fs etc. The work is pretty straightforward: No locking changes f.e. So hardly a redesign. I think the crucial point is the antifrag/defrag issue if we want to generalize it. I have an updated patch here that relies on page reservations. Adds something called page pools. On bootup you need to specify how many pages of each size you want. The page cache will then use those pages for filesystems that need larger blocksize. The interesting thing about that one is that it actually enables support foir multiple blocksizes with a single larger pagesize. If f.e. we setup a pool of 64k pages then the block layer can segment that into 16k pieces. So one can actually use 16k 32k and 64k block size with a single larger page size. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/