Re: Virtio testing goals for DTS

[Patrick Robb <probb@iol.unh.edu>]

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Adding Dean who I forgot to CC.

On Tue, Aug 19, 2025 at 5:48 PM Patrick Robb <probb@iol.unh.edu> wrote:

> Hi Aaron or Maxime,
>
> I want to get your perspective on our testing goals for virtio in DTS if
> you are willing.
>
> Dean, who works on DTS, has been running various PVP and PVVP virtio
> workloads on one of the SUT servers at UNH, as well as some single VM and
> double VM (with inter VM DPDK forwarding) virtio workloads just on his
> laptop, so that we can start to get an idea of how we can start validating
> DPDK virtio.
>
> We are aware that there is likely a need/desire for us to setup some
> vhost-user + virtio testsuites, i.e. there is a tester (traffic gen) server
> paired up against a SUT server, the SUT server sets up vhost-user
> device(s), creates a VM(s), and creates a virtio-net-pci device which is
> connected to the vhost socket from the host, and then we start testpmd in
> the VM using the virtio-net-pci device(s). Then we send traffic from the TG
> and assess the DPDK behavior inside the virtio VM. Or, we can run the
> testpmd inside the VM frontend in tx_only mode and transmit traffic to the
> backend vhost testpmd. In any case, these are vhost testplan specific
> details which don't really pertain to my real question which is below.
>
> The question I have for you is do you think there would be any benefit to
> producing testcases that validating DPDK usage of virtio-net-pci devices in
> a VM, but without involving Vhost, and keeping the entire "test"
> constrained to a single host. By this I mean, instead of setting up some
> vhost/testpmd application on the SUT and forwarding packets from physical
> NIC ports to the vhost vdev (which is then accessed by the VM virtio
> interfaces), the testcases would involve creating a TAP interface(s) on the
> SUT, then making a VM and accessing the TAP interfaces via a virtio
> interface in the VM, and then just starting Scapy on the SUT host and
> sending traffic at the TAP interfaces, which goes into the VM? This would
> mean that the test would not involve any physical devices, but it would
> still be validating DPDK Virtio. One reason why this is attractive is that
> it would not require particular hardware, I.e. it runs on 1 system and that
> system could even be your laptop since it only relies on virtual
> interfaces. David had asked about this possibility at Prague, and I think
> at that time Maxime piped up to say "and this would also be useful for
> virtio" or something like that. Anyhow, let me know if you think this makes
> sense or any other thoughts you may have. If it is a reasonable direction
> to go in we can start drawing up test plans.
>
> I realize this is kind of a wall of text... happy to discuss at the CI
> meeting on Thursday if that is better.
>
> Thanks,
> Patrick
>

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