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 421C89862AE for ; Sun, 5 Feb 2023 12:33:25 +0000 (UTC) Date: Sun, 5 Feb 2023 07:33:17 -0500 From: "Michael S. Tsirkin" Message-ID: <20230205073219-mutt-send-email-mst@kernel.org> References: <961D315C9D3A523B+202301111121345064138@sudoinfotech.com> <06E22D1C69A02418+2023011810492308135755@sudoinfotech.com> MIME-Version: 1.0 In-Reply-To: <06E22D1C69A02418+2023011810492308135755@sudoinfotech.com> Subject: Re: Re: [virtio-comment] About adding a new device type virtio-nvme Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable To: =?utf-8?B?5L6v6Iux5LmQ?= Cc: Stefan Hajnoczi , virtio-comment , Christoph Hellwig , Keith Busch , Kevin Wolf , Klaus Jensen , sgarzare List-ID: On Wed, Jan 18, 2023 at 10:49:23AM +0800, =E4=BE=AF=E8=8B=B1=E4=B9=90 wrote= : > On Tue, 17 Jan 2023 11:01:37 -0500, Stefan wrote: >=20 > >On Tue, Jan 17, 2023 at 10:04:07AM +0800, =E4=BE=AF=E8=8B=B1=E4=B9=90 wr= ote: >=20 > >> 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 wrote: > >> >> As we know, nvme has more features than virtio-blk. For example, wi= th the development of virtualization IO offloading to hardware, virtio-blk = and NVME-OF offloading to hardware >are developing rapidly.=C2=A0 So if vir= tio and nvme are combined into Virtio-NvMe, Is it necessary to add a device= type Virtio-NvMe ? > >> > >> > >> > >> =C2=A0 > >> > >> > >> > >> >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 virtualiza= tion scenarios, NVME devices can only use PCIe pass-through . When NVME and= virtio combine to connect to the vDPA ecosystem, live migration is support= ed. > >> > >> > >> >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= are offloading virtual devices to hardware. The back-end of Virtio-blk doe= s not support remote storage. Therefore, Virtio-Nvme-of can well combine th= e advantages of remote storage and virtio live migration > > > >virtio-blk is just a storage interface, whether that storage is local or > >remote is up to the device implementation. The block device could be > >located on Ceph, NFS, etc. > >=C2=A0 > >Each virtio-blk device is a single block device. There is no > >standardized management protocol in virtio-blk for connecting to remote > >block devices. I'm aware of hardware virtio-blk devices that connect to > >remote storage. Configuration is performed through an out-of-band > >management interface. > >=C2=A0 > >Maybe when you say virtio-blk doesn't support remote storage this is > >what you mean? >=20 >=20 >=20 > Yes, virtio-blk devices offlaod to hardware, For example, DPU and SmartNI= C. > So, compare virtio-nvme with virtio-blk and NVME. >=20 >=20 >=20 >=20 >=20 > Stefan >=20 Let's circle back a bit. You asked: =09So if virtio and nvme are combined into Virtio-NvMe, Is it =09necessary to add a device type Virtio-NvMe ? And the answer seems to be: =09not without much more in the way of motivation. --=20 MST 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/