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 100F5748F; Wed, 2 Oct 2024 15:33:19 +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=1727883200; cv=none; b=fmedNMhp6Up7HCp0JdS2jxJF3ZjwlZEl8yxIaGAeqgDhC1ltfL6s3jy/hBBWWoZU6QAS2sX3OJi6jAUUFuIs31NneLW81zrLdbUzEfa2yJEx1TOi2Xccqbtn4mgQMdl+3T6xPe7FAY35S9R5oS6ajaON0Vx5+9rWQ3fL6XUDoII= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727883200; c=relaxed/simple; bh=Qu1woXcrjhp6mj151jH+MKv52DBKg49ddjc4vbsUAmQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Hguj8qyTEMoMUDnuuy+j7lNLyZRH5SESiwlb3kh7la9/VdtwT8HDfufVnbt5nQ7L7XofZGaj0WhknlAi8RbayTwDD3umKlgxZlhVKpi4dRdUKqnJWURyBupPSBM3hO8OyAdE7cEFO5YODyALIZNzRdP8SIz/fM9597DOC6Cnp14= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qLgEh+s5; 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="qLgEh+s5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3ADABC4CEC2; Wed, 2 Oct 2024 15:33:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1727883199; bh=Qu1woXcrjhp6mj151jH+MKv52DBKg49ddjc4vbsUAmQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qLgEh+s5Rk39ZYsz061N3zRQj1PrUxxnAh2ujTPzy7wuBwiCFzMzImY8PeFfsOyX+ dY3R2xMGK0UDX+Tkm+dcy1WzCapWGbN3e/kiItmXxtt5OBK1SbhLOn08jiz/3Fvlvu 2lRoONetfV0k+URzRpp3MC0UTnJELwk5dswLvGxU1dJJVun3tyUAm88GUdKcmbWnx9 rDIoyfemGaeJ8kWI5QVcWgE/Z+ZPQJfWEvX57eTHQtrwd86c+L9AzsOjFSOKpEj+CQ xC39H3wqhlT+GygAKBAYtO9N+hiy58Iezn5CbVOviY0FvYGm3JOiAMOkBfDRczf7jN hraPj+0SHpJzQ== Date: Wed, 2 Oct 2024 09:33:16 -0600 From: Keith Busch To: Christoph Hellwig Cc: Jens Axboe , Kanchan Joshi , hare@suse.de, sagi@grimberg.me, martin.petersen@oracle.com, brauner@kernel.org, viro@zeniv.linux.org.uk, jack@suse.cz, jaegeuk@kernel.org, bcrl@kvack.org, dhowells@redhat.com, bvanassche@acm.org, asml.silence@gmail.com, linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org, io-uring@vger.kernel.org, linux-block@vger.kernel.org, linux-aio@kvack.org, gost.dev@samsung.com, vishak.g@samsung.com, javier.gonz@samsung.com Subject: Re: [PATCH v7 0/3] FDP and per-io hints Message-ID: References: <20240930181305.17286-1-joshi.k@samsung.com> <20241001092047.GA23730@lst.de> <99c95f26-d6fb-4354-822d-eac94fdba765@kernel.dk> <20241002075140.GB20819@lst.de> <20241002151344.GA20364@lst.de> <20241002151949.GA20877@lst.de> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241002151949.GA20877@lst.de> On Wed, Oct 02, 2024 at 05:19:49PM +0200, Christoph Hellwig wrote: > > Nothing prevents future improvements in that direction. It just seems > > out of scope for what Kanchan is trying to enable for his customer use > > cases. This patch looks harmless. > > It's not really. Once we wire it up like this we mess up the ability > to use the feature in other ways. Additionally the per-I/O hints are > simply broken if you want a file system in the way as last time, > and if I don't misremember you acknowledged in person last week. You remember right. I also explained the use cases for per-io hints are to replace current passthrough users with generic read/write paths that have all the memory guard rails, read/write stats, and other features that you don't get with passthrough. This just lets you accomplish the same placement hints with the nvme raw block device that you get with the nvme char device.