On Tue, Mar 4, 2025 at 10:51 AM Aaron Conole <acon...@redhat.com> wrote: > > Jun Wang via discuss <ovs-discuss@openvswitch.org> writes: > > >> 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. > > > > Hi, I also believe that choosing a non-default command line flag to support > > this is a good option, allowing customers to decide whether or not > > to use this flag. > > However, there are still some details to consider, such as whether to allow > > users to configure the virtio-user port queue, > > and whether virtio-user usage requires affinity configuration, etc. > > ovs-tcpdump will already support using `--mirror-to` as a destination. > Wouldn't that be an appropriate flag? There's a lot involved with setup > for a successful DPDK environment, and as you note lots of user required > input.
Unfortunately, mirror-to only lets you set the interface name. It will still try to create a tap device and add it to OVS. If the interface already exists, ovs-tcpdump will quit with an error. -M > > >> 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 > > > > ------------------------------------------------------------------------------------------------------------------------- > > 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
