From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 656202FD7D6; Wed, 29 Oct 2025 06:09:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761718173; cv=none; b=fxZuWwQ4LTFtESR+RLvu59Ur2kWq2K9qoEUXpm9woEsmlwg8VhnGdDhmQSlmYSS/ZAf+6OpayxnHs7h1WCIJ6zcGsl8MDlo0WdlOy7VVQKRUanDUY4F0hAFqQ0JicG8ljfOwXwLGw7VDS40WTHGDvJPM42lmwHSwLL2tAGGpdqs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761718173; c=relaxed/simple; bh=KhUCwoEAjcKURljQn6Z5eULKXiBUNQeiGlQ0+eSZ1+g=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=p5OpGz61FrmSNYfDViWFGRy+CsW+JStAGoxd0s7sYjP5uaf1QUpM6C3QfILWC+MoMUtMnIs6F8ehEkiESqeyP+iglffu2OZld/jd73Q6we5N/utA4IzudLdJhj0MUd4Nd3ABwFNNLXIe7d8KDhgVr66/FS+TxtBwBYyFqSW4B9Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Jv8axgsk; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Jv8axgsk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E2AD4C4CEF7; Wed, 29 Oct 2025 06:09:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761718173; bh=KhUCwoEAjcKURljQn6Z5eULKXiBUNQeiGlQ0+eSZ1+g=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Jv8axgsk0a3r/K6s7anKOkdMHyoV9M9ohNLW6Pl1/bQB2ujsqML/NoQhhejBmqaK3 86Xp9WXDrWll1/0uizzBMXVWnxjT6M1yQXWhR/dtFAgXer1cs0/+gCJokbdV+U+R7j rh+bSqMZejs5VHCLhtFXE+64+ISmcgtS1QgL9x108T5fFxUd17eLyFDWoTYmrq7fm/ VeqiahI9+MlKVwQ85vBqNlyTiOFo7DuhfqFp7iQWb7Tzt1SRshl6CLVMWIgK5bNXru C3dGfWC2R7UhQIz7c+PDEO0phQxrW7dVvcP9VhkDolbrbTYJpovNOzg2NZKZDgxt/m /E7EbpFdhc1wg== Date: Tue, 28 Oct 2025 23:09:32 -0700 From: "Darrick J. Wong" To: Kundan Kumar Cc: Christoph Hellwig , 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 Subject: Re: [PATCH v2 00/16] Parallelizing filesystem writeback Message-ID: <20251029060932.GS4015566@frogsfrogsfrogs> References: <20251014120845.2361-1-kundan.kumar@samsung.com> <20251022043930.GC2371@lst.de> Precedence: bulk X-Mailing-List: gfs2@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Oct 29, 2025 at 11:35:21AM +0530, Kundan Kumar wrote: > On 10/22/2025 10:09 AM, Christoph Hellwig wrote: > > On Tue, Oct 21, 2025 at 09:46:30AM +1100, Dave Chinner wrote: > >> Not necessarily. The allocator can (and will) select different AGs > >> for an inode as the file grows and the AGs run low on space. Once > >> they select a different AG for an inode, they don't tend to return > >> to the original AG because allocation targets are based on > >> contiguous allocation w.r.t. existing adjacent extents, not the AG > >> the inode is located in. > > > > Also, as pointed out in the last discussion of this for the RT > > subvolume there is zero relation between the AG the inode is in > > and the data placement. > > > > > I evaluated the effect of parallel writeback on realtime inodes and > observed no improvement in IOPS. We can limit writes for realtime > inodes to utilize a single default (0) writeback context. Do you > see it differently? 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) --D