what is the difference between RPS and XPS technology

[dashang]

Can any one explain what is the difference between RFS(Receive Packet Steering) and XPS(Transmit Packet Steering) ...

i have read the article but still not understand the concept of XPS i think its same as RPS...please tell me what is the difference....

[coffeestayne]

I only have the sketchy understanding of this myself, but from what I've read, the difference appears to be:

XPS (Transmit Packet Steering) is a patch that selects a transmit QUEUE during packet transmission but based on configuration.
This is done by mapping the CPU 'TRANSMITTING' the packet to a queue. This is the 'TRANSIT' side analogue to RPS-- where RPS is selecting a CPU based on receive queue, XPS selects a queue based on the CPU.



RPS is a patch that distributes the load of received packet processing across multiple CPUs. RPS queues packets early on in the receive path on the backlog queues of other CPUs. This will then allow protocol processing (e.g. IP and TCP) to be
performed on packets in parallel.

Later versions allow per NAPI steering maps as well as using HW provided hash as an optimization. RPS is also the basis for per-flow steering.