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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BD4BFECAAA1 for ; Wed, 31 Aug 2022 00:51:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230453AbiHaAvY (ORCPT ); Tue, 30 Aug 2022 20:51:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60870 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229723AbiHaAvX (ORCPT ); Tue, 30 Aug 2022 20:51:23 -0400 Received: from out20-39.mail.aliyun.com (out20-39.mail.aliyun.com [115.124.20.39]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 152BB4E85E for ; Tue, 30 Aug 2022 17:51:20 -0700 (PDT) X-Alimail-AntiSpam: AC=CONTINUE;BC=0.044377|-1;CH=green;DM=|CONTINUE|false|;DS=CONTINUE|ham_regular_dialog|0.035877-0.00285441-0.961269;FP=0|0|0|0|0|-1|-1|-1;HT=ay29a033018047194;MF=wangyugui@e16-tech.com;NM=1;PH=DS;RN=4;RT=4;SR=0;TI=SMTPD_---.P3t31yZ_1661907048; Received: from 192.168.2.112(mailfrom:wangyugui@e16-tech.com fp:SMTPD_---.P3t31yZ_1661907048) by smtp.aliyun-inc.com; Wed, 31 Aug 2022 08:50:48 +0800 Date: Wed, 31 Aug 2022 08:50:50 +0800 From: Wang Yugui To: "Darrick J. Wong" Subject: Re: questions about hybird xfs wih ssd/hdd by realtime subvol Cc: Carlos Maiolino , Dave Chinner , linux-xfs@vger.kernel.org In-Reply-To: References: <20220830085718.9391.409509F4@e16-tech.com> Message-Id: <20220831085049.59BB.409509F4@e16-tech.com> MIME-Version: 1.0 Content-Type: text/plain; charset="GB2312" Content-Transfer-Encoding: 8bit X-Mailer: Becky! ver. 2.75.04 [en] Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org Hi, > On Tue, Aug 30, 2022 at 08:57:21AM +0800, Wang Yugui wrote: > > Hi, > > > > > On Mon, Aug 29, 2022 at 10:26:20AM +0800, Wang Yugui wrote: > > > > Hi, > > > > > > > > I saw some info about hybird xfs wih ssd/hdd by realtime subvol. > > > > > > > > Hybrid XFS¡ªUsing SSDs to Supercharge HDDs at Facebook > > > > https://www.usenix.org/conference/srecon19asia/presentation/shamasunder > > > > > > > > There are some questions about how to control the data to save into > > > > normal vol or realtime subvol firstly. > > > > > > > > 1, man xfsctl > > > > here is XFS_XFLAG_REALTIME in man xfsctl of xfsprogs 5.0 , > > > > but there is no XFS_XFLAG_REALTIME in xfsprogs 5.14/5.19. > > > > xfsctl(XFS_XFLAG_REALTIME) will be removed in the further? > > > > > > It's been a while since XFS uses FS_XFLAG features directly, so, what you're > > > specifically looking for is FS_XFLAG_REALTIME. xfsprogs today only has a > > > preprocessor define: > > > > > > #define XFS_XFLAG_REALTIME FS_XFLAG_REALTIME > > > > > > FS_XFLAG_REALTIME is part of the xfs realtime, unlikely it's going away without > > > the realtime filesystems going first, so, unlikely it's gonna happen. > > > > > > > > > > > 2, Is there some tool to do xfsctl(XFS_XFLAG_REALTIME)? > > > > > > You can use xfs_io's chattr command to add/remote the REALTIME attribute of a > > > file. > > > > > > > > > > > > > > 3, we build a xfs filesystem with 1G device and 1G rtdev device. and > > > > then we can save 2G data into this xfs filesystem. > > > > Sorry, I cheched again. > > This is a xfs filesystem with 2G device and 2G rtdev device > > > > > > Is there any tool/kernel option/kernel patch to control the data to save > > > > into normal vol or realtime subvol firstly? > > > > > > I didn't watch the talk you mentioned above, but when use an rt device, you > > > don't use the 'normal' one then the rt later, or vice-versa, the rt-device is > > > used to store data blocks for those files marked with the xattr above. For those > > > files you want to store in the realtime device, you should add the above xattr > > > to them. > > > > Although I still fail to check/set the attr by 'lsattr/chattr', but I > > can check the free space of 'normal' and realtime subvol now. > > > > # xfs_db -c sb -c p /dev/sdb8 |grep 'fdblocks\|frextents' > > typedef struct xfs_sb { > > ... > > uint64_t sb_fdblocks; /* free data blocks */ > > uint64_t sb_frextents; /* free realtime extents */ > > ... > > } > > > > And based the info from Carlos Maiolino > > > > FB were running a modified kernel that selected the rt dev based on > > the initial allocation size. Behaviour for them was predictable > > because they also controlled the application that was storing the > > data. See: > > > > https://lore.kernel.org/linux-xfs/20171128215527.2510350-1-rwareing@fb.com/ > > > > With a dirty patch below for test only , Now realtime subvol will be used > > as I expected, and that can be confirmed by > > #xfs_db -c sb -c p /dev/sdb8 |grep 'fdblocks\|frextents'. > > mkfs.xfs -d rtinherit=1... 'mkfs.xfs -d rtinherit=1' works very well. Thanks a lot. I noticed that 'reflink not supported with realtime devices' both in mkfs.xfs and in kernel/xfs(c14632ddac98 xfs: don't allow reflink + realtime filesystems). Is this a limit of current design? or we just disable reflink when realtime devices just for QoS/realtime? Best Regards Wang Yugui (wangyugui@e16-tech.com) 2022/08/31