[ovs-dev] [patch net-next v2 8/9] switchdev: introduce Netlink API

[Tom Herbert]

On Mon, Sep 22, 2014 at 3:17 PM, Thomas Graf <tgraf at suug.ch> wrote:
> On 09/22/14 at 08:10am, Tom Herbert wrote:
>> Thomas, can you (or someone else) quantify what the host case is. I
>> suppose there may be merit in using a switch on NIC for kernel bypass
>> scenarios, but I'm still having a hard time understanding how this
>> could be integrated into the host stack with benefits that outweigh
>
> Personally my primary interest is on lxc and vm based workloads w/
> end to end encryption, encap, distributed L3 and NAT, and policy
> enforcement including service graphs which imply both east-west
> and north-south traffic patterns on a host. The usual I guess ;-)
>
>> complexity. The history of stateful offloads in NICs is not great, and
>> encapsulation (stuffing a few bytes of header into a packet) is in
>> itself not nearly an expensive enough operation to warrant offloading
>
> No argument here. The direct benchmark comparisons I've measured showed
> only around 2% improvement.
>
> What makes stateful offload interesting to me is that the final
> desintation of a packet is known at RX and can be redirected to a
> queue or VF. This allows to build packet batches on shared pages
> while preserving the securiy model.
>
How is this different from what rx-filtering already does?

> Will the gains outweigh complexity? I hope so but I don't know for
> sure. If you have insights, let me know. What I know for sure is that
> I don't want to rely on a kernel bypass for the above.
>
>> to the NIC. Personally, I wish if NIC vendors are going to focus on
>> stateful offload I rather see it be for encryption which I believe
>> currently does warrant offload at 40G and higher speeds.
>
> Agreed. I would like to be see a focus on both.