Re: [Qemu-devel] snabbswitch integration with QEMU for userspace ethernet I/O

[Stefan Hajnoczi <stefanha@gmail.com>]

On Tue, May 28, 2013 at 12:10 PM, Luke Gorrie <lukego@gmail.com> wrote:
> On 27 May 2013 11:34, Stefan Hajnoczi <stefanha@redhat.com> wrote:
>>
>> vhost_net is about connecting the a virtio-net speaking process to a
>> tun-like device.  The problem you are trying to solve is connecting a
>> virtio-net speaking process to Snabb Switch.
>
>
> Yep!
>
>>
>> Either you need to replace vhost or you need a tun-like device
>> interface.
>>
>> Replacing vhost would mean that your switch implements virtio-net,
>> shares guest RAM with the guest, and shares the ioeventfd and irqfd
>> which are used to signal with the guest.
>
>
> This would be a great solution from my perspective. This is the design that
> I am now struggling to find a good implementation strategy for.
>
>>
>> At that point your switch is similar to the virtio-net data plane work
>> that Ping Fan Liu is working
>> on but your switch is in a separate process rather than a thread.
>
>
> Thanks for the reference! I was not aware of this work and it sounds highly
> relevant.
>
>> How does your switch talk to hardware?  If you have userspace NIC
>> drivers that bypass the Linux network stack then the approach I
>> mentioned fits well.
>
>
> The switch talks to hardware using a built-in userspace ("kernel bypass")
> device driver.

BTW there is an effort to get low-latency networking integrated into Linux:

http://thread.gmane.org/gmane.linux.kernel/1493276

Stefan