Linux Virtualization - Oct 2018 - [RFC] VSOCK: The performance problem of vhost_vsock.

Hi Stefan & All:

Now I find vhost-vsock has two performance problems even if it
is not designed for performance.

First, I think vhost-vsock should faster than vhost-net because it
is no TCP/IP stack, but the real test result vhost-net is 5~10
times than vhost-vsock, currently I am looking for the reason.

Second, vhost-vsock only supports two vqs(tx and rx), that means
if multiple sockets in the guest will use the same vq to transmit
the message and get the response. So if there are multiple applications
in the guest, we should support "Multiqueue" feature for Virtio-vsock.

Stefan, have you encountered these problems?

Thanks,
Yiwen.

On 2018?10?15? 09:43, jiangyiwen wrote:
> Hi Stefan & All:
>
> Now I find vhost-vsock has two performance problems even if it
> is not designed for performance.
>
> First, I think vhost-vsock should faster than vhost-net because it
> is no TCP/IP stack, but the real test result vhost-net is 5~10
> times than vhost-vsock, currently I am looking for the reason.
TCP/IP is not a must for vhost-net.

How do you test and compare the performance?

Thanks
> Second, vhost-vsock only supports two vqs(tx and rx), that means
> if multiple sockets in the guest will use the same vq to transmit
> the message and get the response. So if there are multiple applications
> in the guest, we should support "Multiqueue" feature for
Virtio-vsock.
>
> Stefan, have you encountered these problems?
>
> Thanks,
> Yiwen.
>

On 2018/10/15 10:33, Jason Wang wrote:
> 
> 
> On 2018?10?15? 09:43, jiangyiwen wrote:
>> Hi Stefan & All:
>>
>> Now I find vhost-vsock has two performance problems even if it
>> is not designed for performance.
>>
>> First, I think vhost-vsock should faster than vhost-net because it
>> is no TCP/IP stack, but the real test result vhost-net is 5~10
>> times than vhost-vsock, currently I am looking for the reason.
> 
> TCP/IP is not a must for vhost-net.
> 
> How do you test and compare the performance?
> 
> Thanks
> 
I test the performance used my test tool, like follows:

Server                   Client
socket()
bind()
listen()

                         socket(AF_VSOCK) or socket(AF_INET)
Accept() <-------------->connect()
                         *======Start Record Time======*
                         Call syscall sendfile()
Recv()
                         Send end
Receive end
Send(file_size)
                         Recv(file_size)
                         *======End Record Time======*

The test result, vhost-vsock is about 500MB/s, and vhost-net is about 2500MB/s.

By the way, vhost-net use single queue.

Thanks.
>> Second, vhost-vsock only supports two vqs(tx and rx), that means
>> if multiple sockets in the guest will use the same vq to transmit
>> the message and get the response. So if there are multiple applications
>> in the guest, we should support "Multiqueue" feature for
Virtio-vsock.
>>
>> Stefan, have you encountered these problems?
>>
>> Thanks,
>> Yiwen.
>>
> 
> 
> .
>