On Mon, Sep 22, 2014 at 8:10 AM, Tom Herbert <therb...@google.com> wrote: > On Mon, Sep 22, 2014 at 1:13 AM, Thomas Graf <tg...@suug.ch> wrote: >> On 09/20/14 at 03:50pm, Alexei Starovoitov wrote: >>> I think HW should not be limited by SW abstractions whether >>> these abstractions are called flows, n-tuples, bridge or else. >>> Really looking forward to see "device reporting the headers as >>> header fields (len, offset) and the associated parse graph" >>> as the first step. >>> >>> Another topic that this discussion didn't cover yet is how this >>> all connects to tunnels and what is 'tunnel offloading'.
> encapsulation (stuffing a few bytes of header into a packet) is in > itself not nearly an expensive enough operation to warrant offloading > to the NIC. Personally, I wish if NIC vendors are going to focus on On contrary, generic tunneling is most important one to get right when we're talking offloads. Adding encap header is easy to do in hw, but it breaks all other offloads if hw is not generic. Consider gso packet coming from vm. Generic tunnel allows sw to add inner headers, outer headers and setup offload offsets, so that HW does segmentation, checksuming of inner packet, adjusts inner headers and adds final outer encap. And this is just tx offload. On rx smart tunnel offload in HW parses encap and goes all the way to inner headers to verify checksums, it also steers based on inner headers. Try mellanox nics with and without vxlan offload to see the difference. It looks like fm10k will be just as good, but existing encaps are not going to last forever, so RX should be improved they way John is saying. There gotta to be a 'parse graph' for HW to see past variable length encap and into inner headers. checksum_complete style of offloading checksum verification is not efficient. The cost of adjusting it over and over while parsing encaps is too high. Plus cpu steering based on outer headers is just too slow when speeds are in 40G range. > stateful offload I rather see it be for encryption which I believe > currently does warrant offload at 40G and higher speeds. encryption offload is badly needed as well. Unfortunately it's not seen as nic feature yet. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
