From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7E5E1C33CAF for ; Thu, 16 Jan 2020 18:52:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5DD3D2053B for ; Thu, 16 Jan 2020 18:52:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2436944AbgAPSwj (ORCPT ); Thu, 16 Jan 2020 13:52:39 -0500 Received: from mga01.intel.com ([192.55.52.88]:8245 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2437111AbgAPSwh (ORCPT ); Thu, 16 Jan 2020 13:52:37 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 16 Jan 2020 10:52:36 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,327,1574150400"; d="scan'208";a="214192638" Received: from iweiny-desk2.sc.intel.com ([10.3.52.157]) by orsmga007.jf.intel.com with ESMTP; 16 Jan 2020 10:52:36 -0800 Date: Thu, 16 Jan 2020 10:52:36 -0800 From: Ira Weiny To: "Darrick J. Wong" Cc: Dan Williams , Jan Kara , Linux Kernel Mailing List , Alexander Viro , Dave Chinner , Christoph Hellwig , "Theodore Y. Ts'o" , linux-ext4 , linux-xfs , linux-fsdevel Subject: Re: [RFC PATCH V2 01/12] fs/stat: Define DAX statx attribute Message-ID: <20200116185235.GE24522@iweiny-DESK2.sc.intel.com> References: <20200110192942.25021-1-ira.weiny@intel.com> <20200110192942.25021-2-ira.weiny@intel.com> <20200115113715.GB2595@quack2.suse.cz> <20200115173834.GD8247@magnolia> <20200115194512.GF23311@iweiny-DESK2.sc.intel.com> <20200115223821.GG23311@iweiny-DESK2.sc.intel.com> <20200116053935.GB8235@magnolia> <20200116175501.GC24522@iweiny-DESK2.sc.intel.com> <20200116180421.GD8235@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200116180421.GD8235@magnolia> User-Agent: Mutt/1.11.1 (2018-12-01) Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Thu, Jan 16, 2020 at 10:04:21AM -0800, Darrick J. Wong wrote: > On Thu, Jan 16, 2020 at 09:55:02AM -0800, Ira Weiny wrote: > > On Wed, Jan 15, 2020 at 09:39:35PM -0800, Darrick J. Wong wrote: > > > On Wed, Jan 15, 2020 at 02:38:21PM -0800, Ira Weiny wrote: > > > > On Wed, Jan 15, 2020 at 12:10:50PM -0800, Dan Williams wrote: > > > > > On Wed, Jan 15, 2020 at 11:45 AM Ira Weiny wrote: > > > > > > > > > > > > On Wed, Jan 15, 2020 at 09:38:34AM -0800, Darrick J. Wong wrote: > > > > > > > On Wed, Jan 15, 2020 at 12:37:15PM +0100, Jan Kara wrote: > > > > > > > > On Fri 10-01-20 11:29:31, ira.weiny@intel.com wrote: > > > > > > > > > From: Ira Weiny > > > > > > > > > > > > > > > > > [snip] > > > > > > > > > > Sure, but for now I think referencing mmap for details on MAP_SYNC works. > > > > > > > > I suspect that we may have some word smithing once I get this series in and we > > > > submit a change to the statx man page itself. Can I move forward with the > > > > following for this patch? > > > > > > > > > > > > STATX_ATTR_DAX > > > > > > > > The file is in the DAX (cpu direct access) state. DAX state > > > > > > Hmm, now that I see it written out, I kind of like "DAX mode" > > > better now. :/ > > > > > > "The file is in DAX (CPU direct access) mode. DAX mode attempts..." > > > > Sure... now you tell me... ;-) > > > > Seriously, we could use mode here in the man page as this is less confusing to > > say "DAX mode". > > > > But I think the code should still use 'state' because mode is just too > > overloaded. You were not the only one who was thrown by my use of mode and I > > don't want that confusion when we look at this code 2 weeks from now... > > > > https://www.reddit.com/r/ProgrammerHumor/comments/852og2/only_god_knows/ > > > > ;-) > > Ok, let's leave it alone for now then. Cool could I get a reviewed by? And Jan is this reword of the man page/commit ok to keep your reviewed by? > > I'm not even sure what 'DAX' stands for. Direct Access to ... > Professor Xavier? 8-) That is pronounced 'Direct A'Xes' you know, for chopping wood! Thanks everyone, Ira > > > > > > > > attempts to minimize software cache effects for both I/O and > > > > memory mappings of this file. It requires a file system which > > > > has been configured to support DAX. > > > > > > > > DAX generally assumes all accesses are via cpu load / store > > > > instructions which can minimize overhead for small accesses, but > > > > may adversely affect cpu utilization for large transfers. > > > > > > > > File I/O is done directly to/from user-space buffers and memory > > > > mapped I/O may be performed with direct memory mappings that > > > > bypass kernel page cache. > > > > > > > > While the DAX property tends to result in data being transferred > > > > synchronously, it does not give the same guarantees of > > > > synchronous I/O where data and the necessary metadata are > > > > transferred together. > > > > > > (I'm frankly not sure that synchronous I/O actually guarantees that the > > > metadata has hit stable storage...) > > > > I'll let you and Dan work this one out... ;-) > > Hehe. I think the wording here is fine. > > --D > > > Ira > >