TC queue based filtering

TC can be used for directing traffic to either a set of queues or to a single queue on both the transmit and receive side.

On the transmit side:

1. TC filter directing traffic to a set of queues is achieved using the action skbedit priority for Tx priority selection, the priority maps to a traffic class (set of queues) when the queue-sets are configured using mqprio.

2. TC filter directs traffic to a transmit queue with the action skbedit queue_mapping $tx_qid. The action skbedit queue_mapping for transmit queue is executed in software only and cannot be offloaded.

Likewise, on the receive side, the two filters for selecting set of queues and/or a single queue are supported as below:

1. TC flower filter directs incoming traffic to a set of queues using the ‘hw_tc’ option. hw_tc $TCID - Specify a hardware traffic class to pass matching packets on to. TCID is in the range 0 through 15.

2. TC filter with action skbedit queue_mapping $rx_qid selects a receive queue. The action skbedit queue_mapping for receive queue is supported only in hardware. Multiple filters may compete in the hardware for queue selection. In such case, the hardware pipeline resolves conflicts based on priority. On Intel E810 devices, TC filter directing traffic to a queue have higher priority over flow director filter assigning a queue. The hash filter has lowest priority.