Re: [PATCH RFC v4 7/9] tun: Introduce virtio-net RSS

Jason Wang
2024-09-25T03:31:11Z

On Tue, Sep 24, 2024 at 5:01 PM Akihiko Odaki <akihiko.odaki@daynix.com> wrote:
>
> RSS is a receive steering algorithm that can be negotiated to use with
> virtio_net. Conventionally the hash calculation was done by the VMM.
> However, computing the hash after the queue was chosen defeats the
> purpose of RSS.
>
> Another approach is to use eBPF steering program. This approach has
> another downside: it cannot report the calculated hash due to the
> restrictive nature of eBPF steering program.
>
> Introduce the code to perform RSS to the kernel in order to overcome
> thse challenges. An alternative solution is to extend the eBPF steering
> program so that it will be able to report to the userspace, but I didn't
> opt for it because extending the current mechanism of eBPF steering
> program as is because it relies on legacy context rewriting, and
> introducing kfunc-based eBPF will result in non-UAPI dependency while
> the other relevant virtualization APIs such as KVM and vhost_net are
> UAPIs.
>
> Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>

If we decide to go this way, we need to make it reusable for macvtap as well.

Thanks