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 9C15F986596 for ; Tue, 17 Jan 2023 16:13:21 +0000 (UTC) Date: Tue, 17 Jan 2023 11:01:37 -0500 From: Stefan Hajnoczi Message-ID: References: <961D315C9D3A523B+202301111121345064138@sudoinfotech.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="h7dX2vaWwZuF8LqF" Content-Disposition: inline In-Reply-To: Subject: Re: Re: [virtio-comment] About adding a new device type virtio-nvme To: =?utf-8?B?5L6v6Iux5LmQ?= Cc: virtio-comment , Christoph Hellwig , Keith Busch , Kevin Wolf , Klaus Jensen , sgarzare , "Michael S. Tsirkin" List-ID: --h7dX2vaWwZuF8LqF Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Jan 17, 2023 at 10:04:07AM +0800, =E4=BE=AF=E8=8B=B1=E4=B9=90 wrote: > On Wed, 11 Jan 2023 10:16:55 -0500, Stefan wrote: >=20 >=20 > >>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 = the 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 ty= pe Virtio-NvMe ? >=20 >=20 >=20 > =C2=A0 >=20 >=20 >=20 > >Hi, > >In theory, yes, virtio-nvme can be done. The question is why do it? >=20 >=20 >=20 > >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. >=20 >=20 > >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. >=20 >=20 > 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. >=20 >=20 > >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? >=20 > 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 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. 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. Maybe when you say virtio-blk doesn't support remote storage this is what you mean? Stefan --h7dX2vaWwZuF8LqF Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAmPGxmEACgkQnKSrs4Gr c8gYUAf/RvEH9HwbSl5BOzx857h0i2d4/RITquOtQ2pECr6A6b7A2Qro0b04pc84 y9Odl//CI+gM28H+flOrOW11e44maFM0KIYtRhw/YFmcd9aPwb46idXHxplWZGVw clszIPza6zOomIKOBdTJBsdCVlSAZ9gRfXG0//SShK+mXWigjLGxqbwBxOFHVTWZ Cv80wmotTpMH7BV1dxNNfT2HfjaQLqaObbh2noFDgL+SEu3PaiBH7tpEsNqIdW83 eh5X3zBh13hUw8UEdHQ4ZIffbcmOeBqQ02eysXIQHTKktmr5GPjmdd9Ha2eiROdv M08aHM1sKGqlxHPQ1GYJsHi+Mfs/8w== =6iAB -----END PGP SIGNATURE----- --h7dX2vaWwZuF8LqF--