I looked at the description for transmit and receive queue configurations in the Programmar's Guide, but was confused by how the configuration worked. I am assuming that one descriptor in the queue refers to one pktmbuf?

I am not sure what prefetch, host and writeback of queue descriptors mean for the receive and transmission queues. Can anyone explain to me what they mean?

Also tx_free_threshold is described as the number of descriptors used to transmit packets before they are freed and written back to the host memory, so in that sense what does rx_free_threshold stand for? Does that mean the NIC has to receive x number of descriptors to receive packets before moving them up to user space?

Another point of confusion is this sentence about tx_rs_threshold: "The RS bit is

set on the last descriptor used to transmit a packet if the number of descriptors

used since the last RS bit setting, up to the first descriptor used to transmit the

packet, exceeds the transmit RS bit threshold (tx_rs_thresh)"..

If anyone know what these means, it would be great!