From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailout1.samsung.com (mailout1.samsung.com [203.254.224.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9CF832E62DA for ; Fri, 7 Nov 2025 09:25:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=203.254.224.24 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762507515; cv=none; b=VZxjcTxeF0bX67z6DREQ7ngNZ1fUsMN24e5842xXu6+gbv0qnRdO54TxzlLo13Wc4gW1Ihu/+vpLdlqDAhwokZowALDhK/nudnvFlsfa+7ifDakE5upLvUUMSVuhGGbJiDzRcKznruoNdDnDEj+DlPral9Kj9lsriQUaJl+pfw0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762507515; c=relaxed/simple; bh=Llyb6G0N3m4WlabBeyiNpWRbU+9xF3fUAQa726lzReU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:From:In-Reply-To: Content-Type:References; b=QaC9OvDRTv/MBe6DTcUcKj9N5u4spW6trvkSQwBsTTJh77crF+dMsWjvusGW2XP607wqD5TrsAoTmKGqD7T0QrMBh5EXcAZx70vo/+kFUZwrJ5AJbvhUbSb3H/+ZmDMDSyp1343GRMhLtx9MT16D36pFMBOWsxparRpcouyFw00= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com; spf=pass smtp.mailfrom=samsung.com; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b=WkyizHyt; arc=none smtp.client-ip=203.254.224.24 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=samsung.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b="WkyizHyt" Received: from epcas5p1.samsung.com (unknown [182.195.41.39]) by mailout1.samsung.com (KnoxPortal) with ESMTP id 20251107092509epoutp01809b7ff77a308ffe6e1c69740ee508c7~1rz37OpQb0498604986epoutp01u for ; Fri, 7 Nov 2025 09:25:09 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout1.samsung.com 20251107092509epoutp01809b7ff77a308ffe6e1c69740ee508c7~1rz37OpQb0498604986epoutp01u DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1762507509; bh=u8uZZ4eKtfeKdhCl1Q4zHBINNzxY5n31tzDb1+D2ZUs=; h=Date:Subject:To:Cc:From:In-Reply-To:References:From; b=WkyizHyta13iamjwW4vEYhV7pbJ4ccsfU1gtc8g9iF06s6v1ewoPf1tWE0RmZzDBq 8IrTKwbRW3EJJNRRAcc0YbZXEBZjOKLmedL0iyJ7xAD8IfLfx3GSl9U22Vc8lKAaqp 1zvpQRJd3/jzSbhjnhqRNNnd7ETs5cD4oO4MrhSI= Received: from epsnrtp02.localdomain (unknown [182.195.42.154]) by epcas5p3.samsung.com (KnoxPortal) with ESMTPS id 20251107092509epcas5p39521b5623906275347b3ec7177eac680~1rz3UXgnn2572925729epcas5p39; Fri, 7 Nov 2025 09:25:09 +0000 (GMT) Received: from epcas5p3.samsung.com (unknown [182.195.38.91]) by epsnrtp02.localdomain (Postfix) with ESMTP id 4d2tv81KkDz2SSKY; Fri, 7 Nov 2025 09:25:08 +0000 (GMT) Received: from epsmtip2.samsung.com (unknown [182.195.34.31]) by epcas5p3.samsung.com (KnoxPortal) with ESMTPA id 20251107092507epcas5p3041edfe682f64c59ac3fe0fab4b9384b~1rz1O74AD2299222992epcas5p3F; Fri, 7 Nov 2025 09:25:07 +0000 (GMT) Received: from [107.111.86.57] (unknown [107.111.86.57]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20251107092447epsmtip2e07f9528cf570ebdd336a8a4571fc676~1rzi_2xUI0827208272epsmtip2i; Fri, 7 Nov 2025 09:24:46 +0000 (GMT) Message-ID: <91367b76-e48b-46b4-b10b-43dfdd8472fa@samsung.com> Date: Fri, 7 Nov 2025 14:54:42 +0530 Precedence: bulk X-Mailing-List: gfs2@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 00/16] Parallelizing filesystem writeback Content-Language: en-US To: Christoph Hellwig , "Darrick J. Wong" Cc: Dave Chinner , jaegeuk@kernel.org, chao@kernel.org, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, miklos@szeredi.hu, agruenba@redhat.com, trondmy@kernel.org, anna@kernel.org, akpm@linux-foundation.org, willy@infradead.org, mcgrof@kernel.org, clm@meta.com, amir73il@gmail.com, axboe@kernel.dk, ritesh.list@gmail.com, dave@stgolabs.net, wangyufei@vivo.com, linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, gfs2@lists.linux.dev, linux-nfs@vger.kernel.org, linux-mm@kvack.org, gost.dev@samsung.com, anuj20.g@samsung.com, vishak.g@samsung.com, joshi.k@samsung.com From: Kundan Kumar In-Reply-To: <20251029085526.GA32407@lst.de> Content-Transfer-Encoding: 7bit X-CMS-MailID: 20251107092507epcas5p3041edfe682f64c59ac3fe0fab4b9384b X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" CMS-TYPE: 105P cpgsPolicy: CPGSC10-542,Y X-CFilter-Loop: Reflected X-CMS-RootMailID: 20251014120958epcas5p267c3c9f9dbe6ffc53c25755327de89f9 References: <20251014120845.2361-1-kundan.kumar@samsung.com> <20251022043930.GC2371@lst.de> <20251029060932.GS4015566@frogsfrogsfrogs> <20251029085526.GA32407@lst.de> On 10/29/2025 2:25 PM, Christoph Hellwig wrote: > On Tue, Oct 28, 2025 at 11:09:32PM -0700, Darrick J. Wong wrote: >> Was that with or without rtgroups? metadir/rtgroups aren't enabled by >> default yet so you'd have to select that manually with mkfs.xfs -m >> metadir=1. >> >> (and you might still not see much change because of what hch said) > > The real problem here is that even the inode number to AG association > is just a hint, and will often go wrong on an aged file system. > > Now for the zoned RT device we could probably do a thread per open > zone, as that is a very logical association. The problem with that > right now is that we only pick the zone to write to once doing > writeback, but there might be ways to lift it up. Then again > zoned writeback is so little code that I can't see how it would > saturate a single thread. > Predicting the Allocation Group (AG) for aged filesystems and passing this information to per-AG writeback threads appears to be a complex task. For write operations without pre-allocated data blocks (fallocate=none, resulting in DELALLOC), the next available AG is selected, and the XFS hook can be used to predict the AG that will be allocated. In contrast, when writing to a previously allocated data block (fallocate default, resulting in UNWRITTEN), the AG containing the data block is chosen. Large files that span multiple AGs can lead to a mix of random I/O operations (DELALLOC, UNWRITTEN, MAPPED) being directed to different AGs, while still being cached in the same page cache. To segregate these I/O requests by AG, it is necessary to associate AG-specific information with the pages/folios in the page cache. Two possible approaches are: (1) storing AG information in the folio->private field, or (2) introducing new markers in the xarray to track AG-specific data. The AG-affined writeback thread processes specific pages from the page cache marked for its AG. Is this a viable approach, or are there alternative solutions that could be more effective? >> >> --D > ---end quoted text--- >