On Mon, Feb 8, 2021 at 8:57 AM Ilya Maximets <i.maxim...@ovn.org> wrote: > > On 2/6/21 5:15 PM, William Tu wrote: > > On Mon, Feb 1, 2021 at 5:48 PM Yi Yang (杨燚)-云服务集团 <yangy...@inspur.com> > > wrote: > >> > >> Thanks Ilya, net_tap PMD is handling tap device on host side, so it can > >> leverage vnet header to do TSO/GSO, maybe net_pmd authors don't know how > >> to do this, from source code, tap fd isn't enabled vnet header and TSO. > >> > > thanks, learned a lot from these discussions. > > > > I looked at the DPDK net_tap and indeed it doesn't support virtio net hdr. > > Do you guys think it makes sense to add TSO at dpdk net_tap? > > Or simply using the current OVS's userspace-enable-tso on tap/veth is > > good enough? > > (using type=system, not using dpdk port type on tap/veth.) > > > > Regards, > > William > > > > I didn't benchmark all types of interfaces, but I'd say that, if you > need more or less high performance solution for userspace<->kernel > communication, you should, probably, take a look at virtio-user > ports with vhost kernel backend: > https://doc.dpdk.org/guides/howto/virtio_user_as_exceptional_path.html > This should be the fastest and also feature-rich solution. Thanks! I will give it a try. > > Tap devices are not designed for high performance in general, > so I'd not suggest any of them for highly loaded ports. > If it's only for some small management traffic, it should be fine > to just use netdev-linux implementation.
That's what I thought until Flavio enables vnet header. > > netdev-afxdp with pmd or non-pmd modes on a veth devices is another > (potentially high performance) solution. When testing intra-host container to container performance, Tap device becomes much faster than netdev-afxdp, especially with iperf TCP. Mostly due to vnet header's TSO and csum offload feature. It's a big limitation for XDP frame which couldn't carry large buffer or carry the partial csum information. I reach a conclusion that for intra-host container to container TCP performance, from the fastest configuration to slowest (ns: namespace) 0) dpdk vhostuser in ns0 -> vhostuer - OVS userspace (But requires TCP in userspace and application modification) 1) veth0 in ns0 -> veth with TSO - OVS kernel module - veth with TSO -> veth1 in ns1 2) tap0 in ns0 -> virtio_user - OVS userspace - virtio_user -> tap1 in ns1 3) tap0 in ns0 -> recv_tap - OVS with userspace-tso - tap_batch_send -> tap1 in ns1 4) veth0 in ns0 -> af_packet sock - OVS with userspace-tso - af_packet_sock -> veth1 in ns1 5) veth0 in ns0 -> netdev-afxdp - OVS - netdev-afxdp -> veth1 in ns1 I also tested Toshiaki's XDP offload patch, https://www.mail-archive.com/ovs-dev@openvswitch.org/msg45930.html I would guess it's between 2 to 4. Regards, William _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev
