From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935898AbaH0VWZ (ORCPT ); Wed, 27 Aug 2014 17:22:25 -0400 Received: from qmta11.emeryville.ca.mail.comcast.net ([76.96.27.211]:38808 "EHLO qmta11.emeryville.ca.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932146AbaH0VWX (ORCPT ); Wed, 27 Aug 2014 17:22:23 -0400 Date: Wed, 27 Aug 2014 16:22:20 -0500 (CDT) From: Christoph Lameter X-X-Sender: cl@gentwo.org To: Andrew Morton cc: Matthew Wilcox , 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 In-Reply-To: <20140827130613.c8f6790093d279a447196f17@linux-foundation.org> Message-ID: References: <20140827130613.c8f6790093d279a447196f17@linux-foundation.org> Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 27 Aug 2014, Andrew Morton wrote: > 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? Matthew gave a talk about DAX at the kernel summit. Its a great feature because this is another piece of the bare metal hardware technology that is being improved by him. > Some explanation of why one would use ext4 instead of, say, > suitably-modified ramfs/tmpfs/rd/etc? The NVDIMM contents survive reboot and therefore ramfs and friends wont work with it. > Performance testing results? This is obviously avoiding kernel buffering and therefore decreasing kernel overhead for non volatile memory. Avoids useless duplication of data from the non volatile memory into regular ram and allows direct access to non volatile memory from user space in a controlled fashion. I think this should be a priority item.