Hello, Yes, this will result in better ovs-tcpdump performance. The reason why it hasn't been added so far is because we can't guarantee or even check for the existence of any given DPDK driver at runtime in a generic fashion.
One option would be to select this type of interface with a non-default command line flag. What do you think? M On Mon, Feb 24, 2025 at 2:25 AM Jun Wang via discuss <ovs-discuss@openvswitch.org> wrote: > > Hi,team. > In OVS-DPDK scenarios, using ovs-tcpdump for packet capture can > significantly impact forwarding performance due to the packet processing > between user space and kernel space. > This impact is especially noticeable when there is high traffic or when > multiple capture ports are started, causing the performance to degrade > drastically. > Therefore, the question is whether we have considered improving the packet > capture capability of ovs-tcpdump in OVS-DPDK scenarios. Based on my analysis, > I believe replacing the default ovs-tcpdump mirror port with the DPDK > virtio-user interface would greatly enhance processing performance. > > https://doc.dpdk.org/guides-24.11/howto/virtio_user_as_exception_path.html > > Command to create a virtio-user port on an OVS-DPDK bridge： > > ovs-vsctl --may-exist add-port br-tun veth1 -- set interface veth1 type=dpdk > -- set interface veth1 > options:dpdk-devargs="vdev:virtio_user0,path=/dev/vhost-net,iface=veth1" > > After creation, the corresponding interface veth1 is bound to PMD： > [root@compute0-dpdk /]# ovs-appctl dpif-netdev/pmd-rxq-show > pmd thread numa_id 1 core_id 21: > isolated : false > port: tun_port_p0 queue-id: 0 (enabled) pmd usage: 0 % > port: vh-userclient-e5281ddf-c8 queue-id: 0 (enabled) pmd usage: 0 % > overhead: 0 % > pmd thread numa_id 1 core_id 22: > isolated : false > port: tun_port_p0 queue-id: 1 (enabled) pmd usage: 0 % > port: veth1 queue-id: 0 (enabled) pmd usage: 0 % > overhead: 0 % > pmd thread numa_id 1 core_id 23: > isolated : false > port: tun_port_p1 queue-id: 0 (enabled) pmd usage: 0 % > overhead: 0 % > pmd thread numa_id 1 core_id 24: > isolated : false > port: tun_port_p1 queue-id: 1 (enabled) pmd usage: 0 % > overhead: 0 % > > And the corresponding veth1 kernel interface can be seen in the kernel： > [root@compute0-dpdk /]# ip ad|grep veth1 > 700: veth1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group > default qlen 1000 > > So, we only need to redirect the mirrored traffic to the virtio-user port, > which significantly improves performance compared to the default kernel-space > mirror port. > > ________________________________ > Jun Wang > _______________________________________________ > discuss mailing list > disc...@openvswitch.org > https://mail.openvswitch.org/mailman/listinfo/ovs-discuss _______________________________________________ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
