On 4/1/18 6:47 PM, Md. Islam wrote:
> This patch implements IPv4 forwarding on xdp_buff. I added a new
> config option XDP_ROUTER. Kernel would forward packets through fast
> path when this option is enabled. But it would require driver support.
> Currently it only works with veth. Here I have modified veth such that
> it outputs xdp_buff. I created a testbed in Mininet. The Mininet
> script (topology.py) is attached. Here the topology is:
>
> h1 -----r1-----h2 (r1 acts as a router)
>
> This patch improves the throughput from 53.8Gb/s to 60Gb/s on my
> machine. Median RTT also improved from around .055 ms to around .035
> ms.
>
> Then I disabled hyperthreading and cpu frequency scaling in order to
> utilize CPU cache (DPDK also utilizes CPU cache to improve
> forwarding). This further improves per-packet forwarding latency from
> around 400ns to 200 ns. More specifically, header parsing and fib
> lookup only takes around 82 ns. This shows that this could be used to
> implement linerate packet forwarding in kernel.
>
> The patch has been generated on 4.15.0+. Please let me know your
> feedback and suggestions. Please feel free to let me know if this
> approach make sense.
This patch is not really using eBPF and XDP but rather trying to
shortcircuit forwarding through a veth pair.
Have you looked at the loss in performance with this config enabled if
there is no r1? i.e., h1 {veth1} <---> {veth2} / h2. You are adding a
lookup per-packet to the Tx path.
Have you looked at what I would consider a more interesting use case of
packets into a node and delivered to a namespace via veth?
+--------------------------+---------------
| Host | container
| |
| +-------{ veth1 }-|-{veth2}----
| | |
+----{ eth1 }------------------
Can xdp / bpf on eth1 be used to speed up delivery to the container?
