Re: Re: [virtio-comment] About adding a new device type virtio-nvme

[äèä <houyingle@sudoinfotech.com>]

On Wed, 11 Jan 2023 10:16:55 -0500, Stefan wrote:


>>On Wed, Jan 11, 2023 at 11:21:35AM +0800, äèä wrote:
>> 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. So if virtio and nvme are combined into Virtio-NvMe, Is it necessary to add a device type Virtio-NvMe ?



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>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 virtualization scenarios, NVME devices can only use PCIe pass-through . When NVME and virtio 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 are offloading virtual devices to hardware. The back-end of Virtio-blk does not support remote storage. Therefore, Virtio-Nvme-of can well combine the advantages 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-nvmeÂadvantages :
1)  live migration
2)  support remote storage



Leo Hou/äèä