Offloading Linux LAG Devices Via Open vSwitch and TC

Converting Open vSwitch (OVS) kernel rules to TC Flower rules has become the standard way to offload the datapath to SmartNICs and other hardware devices. Binding such TC rules to 'offloadable' ports (such as SmartNIC representers) has been shown to enable the acceleration of packet processing while saving CPU resources on the hosting server. However, one scenario not yet well defined is the case where offloadable ports are bound to a higher level Link Aggregation (LAG) netdev, such as a Linux Bond or Team device, and where this netdev is added to an OVS bridge. This talk describes an implementation that offloads rules that either ingress or egress to a LAG device. It highlights changes made to OVS (included in v2.9) as well as to core TC code and the driver layer in the Linux kernel. Rather than introduce new features into the kernel to handle LAG offload, the design expands upon recent, independently added kernel features including the concept of TC blocks. It is shown how, with slight modification, TC blocks can be used by OVS to represent LAG devices.