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=-16.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 795E3C47434 for ; Mon, 28 Sep 2020 16:48:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3AA4F20717 for ; Mon, 28 Sep 2020 16:48:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727028AbgI1QsM (ORCPT ); Mon, 28 Sep 2020 12:48:12 -0400 Received: from mga12.intel.com ([192.55.52.136]:53199 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727005AbgI1QsD (ORCPT ); Mon, 28 Sep 2020 12:48:03 -0400 IronPort-SDR: 03sIbRzvAm2pqeY8sOkmI2e9IVDqsmIOIN9U2VbSQutL4WCKaBjMRKzi8mbJN86RA37zyaprXW YVPztBF27k6g== X-IronPort-AV: E=McAfee;i="6000,8403,9758"; a="141432582" X-IronPort-AV: E=Sophos;i="5.77,313,1596524400"; d="scan'208";a="141432582" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Sep 2020 09:42:00 -0700 IronPort-SDR: XQbWhO6KAZk/NW7/DnVHmkDsi3NHvQJUZzp4VEntXkFgINs7ch4KuI5QCRR6CzELcCW1goYtZE QtmsawxwcH1A== X-IronPort-AV: E=Sophos;i="5.77,313,1596524400"; d="scan'208";a="488651317" Received: from iweiny-desk2.sc.intel.com (HELO localhost) ([10.3.52.147]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Sep 2020 09:42:00 -0700 Date: Mon, 28 Sep 2020 09:42:00 -0700 From: Ira Weiny To: mtk.manpages@gmail.com Cc: linux-man@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-xfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-ext4@vger.kernel.org Subject: Re: [PATCH] man/statx: Add STATX_ATTR_DAX Message-ID: <20200928164200.GA459459@iweiny-DESK2.sc.intel.com> References: <20200505002016.1085071-1-ira.weiny@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200505002016.1085071-1-ira.weiny@intel.com> User-Agent: Mutt/1.11.1 (2018-12-01) Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Mon, May 04, 2020 at 05:20:16PM -0700, 'Ira Weiny' wrote: > From: Ira Weiny > > Linux 5.8 is slated to have STATX_ATTR_DAX support. > > https://lore.kernel.org/lkml/20200428002142.404144-4-ira.weiny@intel.com/ > https://lore.kernel.org/lkml/20200504161352.GA13783@magnolia/ > > Add the text to the statx man page. > > Signed-off-by: Ira Weiny Have I sent this to the wrong list? Or perhaps I have missed a reply. I don't see this applied to the man-pages project.[1] But perhaps I am looking at the wrong place? Thank you, Ira [1] git://git.kernel.org/pub/scm/docs/man-pages/man-pages.git > --- > man2/statx.2 | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/man2/statx.2 b/man2/statx.2 > index 2e90f07dbdbc..14c4ab78e7bd 100644 > --- a/man2/statx.2 > +++ b/man2/statx.2 > @@ -468,6 +468,30 @@ The file has fs-verity enabled. > It cannot be written to, and all reads from it will be verified > against a cryptographic hash that covers the > entire file (e.g., via a Merkle tree). > +.TP > +.BR STATX_ATTR_DAX (since Linux 5.8) > +The file is in the DAX (cpu direct access) state. DAX state 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. > +.PP > +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. > +.PP > +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. > +.PP > +While the DAX property tends to result in data being transferred synchronously, > +it does not give the same guarantees of O_SYNC where data and the necessary > +metadata are transferred together. > +.PP > +A DAX file may support being mapped with the MAP_SYNC flag, which enables a > +program to use CPU cache flush instructions to persist CPU store operations > +without an explicit > +.BR fsync(2). > +See > +.BR mmap(2) > +for more information. > .SH RETURN VALUE > On success, zero is returned. > On error, \-1 is returned, and > -- > 2.25.1 >