Flow Acceleration

DPDK 17.02’s rte_flow, the framework of hardware acceleration.

• flowtable-hwaccel-flowchart
  

napatech’s illustration:

• Acceleration in HW is Boosting Performance. In DPDK 17.02 rte_Flow is the Enabler
• ACL HW acceleration in VPP shows great performance improvements

DPDK’s flow acceleration framework

• flow attribute, item and action, see rte_flow.h

  • Pattern items fall in two categories:
    • Matching protocol headers and packet data, usually associated with a specification structure. These must be stacked in the same order as the protocol layers to match inside packets, starting from the lowest.
    • Matching meta-data or affecting pattern processing, often without a specification structure. Since they do not match packet contents, their position in the list is usually not relevant.
  • Supported actions, they fall in three categories:
    • Actions that modify the fate of matching traffic, for instance by dropping or assigning it a specific destination.
    • Actions that modify matching traffic contents or its properties. This includes adding/removing encapsulation, encryption, compression and marks.
    • Actions related to the flow rule itself, such as updating counters or making it non-terminating.
  • eth_filter_ctrl_t, e.g. ixgbe_dev_filter_ctrl, i40e_dev_filter_ctrl

• example of flow aaceleartion, generate_ipv4_flow

  initialize of struct rte_flow_attr
  	--> struct rte_flow_item
  		--> struct rte_flow_action
  			--> rte_flow_create()
  				--> eth_filter_ctrl_t, e.g. ixgbe_dev_filter_ctrl
  					--> struct rte_flow_ops's create, e.g. ixgbe_flow_create