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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,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 97EABC33CAF for ; Thu, 16 Jan 2020 18:05:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6F795217F4 for ; Thu, 16 Jan 2020 18:05:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="P/xpYMzs" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406949AbgAPSE7 (ORCPT ); Thu, 16 Jan 2020 13:04:59 -0500 Received: from userp2120.oracle.com ([156.151.31.85]:37778 "EHLO userp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406927AbgAPSEv (ORCPT ); Thu, 16 Jan 2020 13:04:51 -0500 Received: from pps.filterd (userp2120.oracle.com [127.0.0.1]) by userp2120.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 00GI3d2x032053; Thu, 16 Jan 2020 18:04:29 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2019-08-05; bh=Wz0bfYpv6qVBxaaDhPfuHMj6fRJ3/Ll2i4XCWCEkzKU=; b=P/xpYMzsQBE5bSIf2S5Rqg1imFhX6WSs+gM+2vlJjnEuX8CqmY+cnCyTLYqeL+nk6jJK JhEyImmV4seyD2OKgOsPG9vPvMbtqliB0wCrQgMlRgaia8zGn55X8/0qBAKoBu+tFf/j EGCnwUI/eE/YKnzFFyDulMHUTfZBKon5j4hwvQZpbRp71xa/v95DvKjA3dPwvf3XGxFd rdWyTXu+2UuJcb0UfglLCJOhdZzBbBKLnX9GeUDxxH5VU5aj6MxUK+putiEf6vO+Uu+v fmhY9Mnhg6L481saVULx+u4dmOsR2ydOneEQXD7B26uNZk595wXKPoG9TCeTUZtuGT0h yA== Received: from aserp3030.oracle.com (aserp3030.oracle.com [141.146.126.71]) by userp2120.oracle.com with ESMTP id 2xf73yv695-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 16 Jan 2020 18:04:29 +0000 Received: from pps.filterd (aserp3030.oracle.com [127.0.0.1]) by aserp3030.oracle.com (8.16.0.27/8.16.0.27) with SMTP id 00GI46wZ100800; Thu, 16 Jan 2020 18:04:28 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserp3030.oracle.com with ESMTP id 2xj61n0etc-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 16 Jan 2020 18:04:28 +0000 Received: from abhmp0008.oracle.com (abhmp0008.oracle.com [141.146.116.14]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 00GI4NWO015447; Thu, 16 Jan 2020 18:04:23 GMT Received: from localhost (/67.169.218.210) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 16 Jan 2020 10:04:22 -0800 Date: Thu, 16 Jan 2020 10:04:21 -0800 From: "Darrick J. Wong" To: Ira Weiny 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: <20200116180421.GD8235@magnolia> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200116175501.GC24522@iweiny-DESK2.sc.intel.com> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9502 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001160146 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9502 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1911140001 definitions=main-2001160146 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. I'm not even sure what 'DAX' stands for. Direct Access to ... Professor Xavier? 8-) > > > > > 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 >