From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 2A9169865D1 for ; Tue, 17 Jan 2023 17:20:09 +0000 (UTC) Message-ID: <40a63ca5-1273-d334-8d81-d5880e4fdff1@nvidia.com> Date: Tue, 17 Jan 2023 19:19:59 +0200 References: <961D315C9D3A523B+202301111121345064138@sudoinfotech.com> From: Max Gurtovoy In-Reply-To: MIME-Version: 1.0 Subject: Re: [virtio-comment] About adding a new device type virtio-nvme Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable To: =?UTF-8?B?5L6v6Iux5LmQ?= , Stefan Hajnoczi Cc: virtio-comment , Christoph Hellwig , Keith Busch , Kevin Wolf , Klaus Jensen , sgarzare , "Michael S. Tsirkin" List-ID: On 17/01/2023 4:04, =E4=BE=AF=E8=8B=B1=E4=B9=90 wrote: > On Wed, 11 Jan 2023 10:16:55 -0500, Stefan wrote: > > >>> On Wed, Jan 11, 2023 at 11:21:35AM +0800, =E4=BE=AF=E8=8B=B1=E4=B9=90 w= rote: >>> As we know, nvme has more features than virtio-blk. For example, with t= he development of virtualization IO offloading to hardware, virtio-blk and = NVME-OF offloading to hardware >are developing rapidly.=C2=A0 So if virtio = and nvme are combined into Virtio-NvMe, Is it necessary to add a device typ= e Virtio-NvMe ? > > > =20 > > > >> Hi, >> In theory, yes, virtio-nvme can be done. The question is why do it? > > >> NVMe already provides a PCI hardware spec for software and hardware >> implementations to follow. An NVMe PCI device can be exposed to the >> guest and modern operating systems recognize it without requiring new >> drivers. > >> The value of VIRTIO here is probably in the deep integration into the >> virtualization stack with vDPA, vhost, etc. A virtio-nvme device can use >> all these things whereas a PCI device needs to do everything from >> scratch. > > The NVME technology and ecosystem are complete. However, in virtualizatio= n scenarios, NVME devices can only use PCIe pass-through . When NVME and vi= rtio combine to connect to the vDPA ecosystem, live migration is supported. > > >> Let's not forget that virtio-blk is widely used and new commands are >> being added as needed. Which NVMe features are you missing in >> virtio-blk? > With the introduction of the concept of DPU, a large number of vendors ar= e offloading virtual devices to hardware. The back-end of Virtio-blk does n= ot support remote storage. Therefore, Virtio-Nvme-of can well combine the a= dvantages of remote storage and virtio live migration > > > >> I guess this is why virtio-nvme hasn't been done before: people who want >> NVMe can already do NVMe PCI, people who want VIRTIO can use virtio-blk, >> and so there hasn't been a great need to combine VIRTIO and NVMe yet. > >> What advantages do you see in having virtio-nvme? > > > virtio-nvme=C2=A0advantages : > 1) live migration This is WIP and will use VFIO live migration framework. > 2) support remote storage There are solutions today that can use remote storage as an NVMe=20 Namespace. For example, DPU based NVMe device such as NVIDIA'S NVMe SNAP=20 device. > > > > Leo Hou/=E4=BE=AF=E8=8B=B1=E4=B9=90 > This publicly archived list offers a means to provide input to the OASIS Virtual I/O Device (VIRTIO) TC. In order to verify user consent to the Feedback License terms and to minimize spam in the list archive, subscription is required before posting. Subscribe: virtio-comment-subscribe@lists.oasis-open.org Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org List help: virtio-comment-help@lists.oasis-open.org List archive: https://lists.oasis-open.org/archives/virtio-comment/ Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lis= ts Committee: https://www.oasis-open.org/committees/virtio/ Join OASIS: https://www.oasis-open.org/join/