For best latency the application should call
onload_delegated_send_complete() as soon as a delegated send is complete. This allows Onload to continue if retransmissions are required.
When a link partner has already acknowledged data before complete has been called, Onload will not have to copy the sent data to the TCP retransmit queue. So delaying the complete call might avoid a data copy, but latency might suffer in the event of packet loss.