From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935699AbaH0UGQ (ORCPT ); Wed, 27 Aug 2014 16:06:16 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:56006 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751731AbaH0UGP (ORCPT ); Wed, 27 Aug 2014 16:06:15 -0400 Date: Wed, 27 Aug 2014 13:06:13 -0700 From: Andrew Morton To: Matthew Wilcox Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, willy@linux.intel.com Subject: Re: [PATCH v10 00/21] Support ext4 on NV-DIMMs Message-Id: <20140827130613.c8f6790093d279a447196f17@linux-foundation.org> In-Reply-To: References: X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 26 Aug 2014 23:45:20 -0400 Matthew Wilcox wrote: > One of the primary uses for NV-DIMMs is to expose them as a block device > and use a filesystem to store files on the NV-DIMM. While that works, > it currently wastes memory and CPU time buffering the files in the page > cache. We have support in ext2 for bypassing the page cache, but it > has some races which are unfixable in the current design. This series > of patches rewrite the underlying support, and add support for direct > access to ext4. Sat down to read all this but I'm finding it rather unwieldy - it's just a great blob of code. Is there some overall what-it-does-and-how-it-does-it roadmap? Some explanation of why one would use ext4 instead of, say, suitably-modified ramfs/tmpfs/rd/etc? Performance testing results? Carsten Otte wrote filemap_xip.c and may be a useful reviewer of this work. All the patch subjects violate Documentation/SubmittingPatches section 15 ;)