From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-99.freemail.mail.aliyun.com (out30-99.freemail.mail.aliyun.com [115.124.30.99]) (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 1DACB38FA6; Mon, 16 Dec 2024 12:07:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.99 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734350843; cv=none; b=n/2JycBHXmxakdm9iEiAtVNKcR3jb9RcYdeuMFZ07qQ4Y8uQNV6bpwsTYgjfP2eiepYlQjeLI0YVPEcQYG8GK4hItUNwjlWQKTy4x26n8A10nFGLMgovncrcAmHpC8KOBY3wdiL82NU1/BENxfXKIdSW6uXGY3xyqiyvsgxq40c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734350843; c=relaxed/simple; bh=iqh5XOjrIPBtDSeYr9JPy6x0FGs3THMaULE0vFFzThQ=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=f2uIaCe3APA2iiwtOjZnE0PS0Iul08Q6rRKAEwSit8NbMA75DuHUtWYV1fs6OLTk/S9Vi5KNKL3dvNdrfvYeVtNZcnzUmuPI6aKT1jbE+V2qm8eJ86yDYNeI2KeUDBzst7WPvjRoogV6cF9Jos4RiE10ECfOne0nGNrPnDFkKPk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=B0m6Ufqb; arc=none smtp.client-ip=115.124.30.99 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="B0m6Ufqb" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1734350832; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=1OmVpZqZxthyjz0j/R+PbOfKwTbA3aCpAvSvnBaqQIs=; b=B0m6UfqbZvOm6pH/oHifyK8Cuqod1lUEKNN7L7R0PgpptP9LXuThSg4okyO3zVvImDFNzD+llOaCEcO65fYaGINp/kG9h0GGtjrCSAncp4PO5CQYQ9WgDCezfyDDTIkZkIjE7sLvhKSYVFBFRFcROD4hatRLTHoBSGwkx9t0zIk= Received: from 30.221.131.67(mailfrom:mengferry@linux.alibaba.com fp:SMTPD_---0WLazs5j_1734350830 cluster:ay36) by smtp.aliyun-inc.com; Mon, 16 Dec 2024 20:07:11 +0800 Message-ID: <60fd6f1a-ddf5-4b53-8353-18dcd8f6f93c@linux.alibaba.com> Date: Mon, 16 Dec 2024 20:07:09 +0800 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 0/3][RFC] virtio-blk: add io_uring passthrough support for virtio-blk To: Jason Wang Cc: "Michael S . Tsirkin" , linux-block@vger.kernel.org, Jens Axboe , virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, io-uring@vger.kernel.org, Joseph Qi , Jeffle Xu References: <20241203121424.19887-1-mengferry@linux.alibaba.com> <2d4ad724-f9da-4502-9079-432935f5719d@linux.alibaba.com> Content-Language: en-US From: Ferry Meng In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 12/16/24 3:38 PM, Jason Wang wrote: > On Mon, Dec 16, 2024 at 10:01 AM Ferry Meng wrote: >> >> On 12/3/24 8:14 PM, Ferry Meng wrote: >>> We seek to develop a more flexible way to use virtio-blk and bypass the block >>> layer logic in order to accomplish certain performance optimizations. As a >>> result, we referred to the implementation of io_uring passthrough in NVMe >>> and implemented it in the virtio-blk driver. This patch series adds io_uring >>> passthrough support for virtio-blk devices, resulting in lower submit latency >>> and increased flexibility when utilizing virtio-blk. >>> >>> To test this patch series, I changed fio's code: >>> 1. Added virtio-blk support to engines/io_uring.c. >>> 2. Added virtio-blk support to the t/io_uring.c testing tool. >>> Link: https://github.com/jdmfr/fio >>> >>> Using t/io_uring-vblk, the performance of virtio-blk based on uring-cmd >>> scales better than block device access. (such as below, Virtio-Blk with QEMU, >>> 1-depth fio) >>> (passthru) read: IOPS=17.2k, BW=67.4MiB/s (70.6MB/s) >>> slat (nsec): min=2907, max=43592, avg=3981.87, stdev=595.10 >>> clat (usec): min=38, max=285,avg=53.47, stdev= 8.28 >>> lat (usec): min=44, max=288, avg=57.45, stdev= 8.28 >>> (block) read: IOPS=15.3k, BW=59.8MiB/s (62.7MB/s) >>> slat (nsec): min=3408, max=35366, avg=5102.17, stdev=790.79 >>> clat (usec): min=35, max=343, avg=59.63, stdev=10.26 >>> lat (usec): min=43, max=349, avg=64.73, stdev=10.21 >>> >>> Testing the virtio-blk device with fio using 'engines=io_uring_cmd' >>> and 'engines=io_uring' also demonstrates improvements in submit latency. >>> (passthru) taskset -c 0 t/io_uring-vblk -b4096 -d8 -c4 -s4 -p0 -F1 -B0 -O0 -n1 -u1 /dev/vdcc0 >>> IOPS=189.80K, BW=741MiB/s, IOS/call=4/3 >>> IOPS=187.68K, BW=733MiB/s, IOS/call=4/3 >>> (block) taskset -c 0 t/io_uring-vblk -b4096 -d8 -c4 -s4 -p0 -F1 -B0 -O0 -n1 -u0 /dev/vdc >>> IOPS=101.51K, BW=396MiB/s, IOS/call=4/3 >>> IOPS=100.01K, BW=390MiB/s, IOS/call=4/4 >>> >>> The performance overhead of submitting IO can be decreased by 25% overall >>> with this patch series. The implementation primarily references 'nvme io_uring >>> passthrough', supporting io_uring_cmd through a separate character interface >>> (temporarily named /dev/vdXc0). Since this is an early version, many >>> details need to be taken into account and redesigned, like: >>> ● Currently, it only considers READ/WRITE scenarios, some more complex operations >>> not included like discard or zone ops.(Normal sqe64 is sufficient, in my opinion; >>> following upgrades, sqe128 and cqe32 might not be needed). >>> ● ...... >>> >>> I would appreciate any useful recommendations. >>> >>> Ferry Meng (3): >>> virtio-blk: add virtio-blk chardev support. >>> virtio-blk: add uring_cmd support for I/O passthru on chardev. >>> virtio-blk: add uring_cmd iopoll support. >>> >>> drivers/block/virtio_blk.c | 325 +++++++++++++++++++++++++++++++- >>> include/uapi/linux/virtio_blk.h | 16 ++ >>> 2 files changed, 336 insertions(+), 5 deletions(-) >> Hi, Micheal & Jason : >> >> What about yours' opinion? As virtio-blk maintainer. Looking forward to >> your reply. >> >> Thanks > If I understand this correctly, this proposal wants to make io_uring a > transport of the virito-blk command. So the application doesn't need > to worry about compatibility etc. This seems to be fine. > > But I wonder what's the security consideration, for example do we > allow all virtio-blk commands to be passthroughs and why. About 'security consideration', the generic char-dev belongs to root, so only root can use this passthrough path. On the other hand, to what I know, virtio-blk commands are all related to 'I/O operations', so we can support all those opcodes with bypassing vfs&block layer (if we want). I just realized the most  basic read/write in this RFC patch series, others will be considered later. > Thanks >