Re: [RFC] Discuss about an new idea "Vsock over Virtio-net"

Jason Wang
2018-11-15T08:27:50Z

On 2018/11/15 下午4:10, Michael S. Tsirkin wrote:
> On Thu, Nov 15, 2018 at 03:38:15PM +0800, jiangyiwen wrote:
>> On 2018/11/15 15:04, Michael S. Tsirkin wrote:
>>> On Thu, Nov 15, 2018 at 11:56:03AM +0800, jiangyiwen wrote:
>>>> Hi Stefan, Michael, Jason and everyone,
>>>>
>>>> Several days ago, I discussed with jason about "Vsock over Virtio-net".
>>>> This idea has two advantages:
>>>> First, it can use many great features of virtio-net, like batching,
>>>> mergeable rx buffer and multiqueue, etc.
>>>> Second, it can reduce many duplicate codes and make it easy to be
>>>> maintained.
>>> I'm not sure I get the motivation. Which features of
>>> virtio net are relevant to vsock? The ones that you mention
>>> all seem to be mostly of use to the networking stack.
>>>
>>>
>>>> Before the implement, I want to discuss with everyone again, and
>>>> want to know everyone's suggestions.
>>>>
>>>> After the discussion, based on this point I will try to implement
>>>> this idea, but I am not familiar with the virtio-net, that is a
>>>> pity.:(
>>>>
>>>> -------------------------Simple idea------------------------------
>>>>
>>>> 1. The packet layout will become as follows:
>>>>
>>>> +---------------------------------+
>>>> | Virtio-net header |
>>>> |(struct virtio_net_hdr_mrg_rxbuf)|
>>> Which fields in virtio_net_hdr_mrg_rxbuf are of interest to vsock?
>>>
>> Hi Michael,
>>
>> Yes, currently vsock has poor performance, first, it only support transport
>> small packet, in order to make the balance between performance and guest memory.
>>
>> In order to solve this problem, there are two features vsock can used,
>> mergeable rx buffer and multiqueue. Based on this, there are some shared
>> codes vsock can use.
>>
>> Thanks,
>> Yiwen.
> Supporting more queues with vsock is probably significantly
> less work than a completely new interface.
> For mergeable, as buffers are split arbitrarily, why can't you combine
> them within guest driver before sending them up the stack?

I don't get this question. But I think the fact that we use mergeable
buffer by default for virtio-net answer the question. Or anything
special in vsock?

Thanks

> Probably better than relying on host to do it.
>