CTPIO transmission mode:
sf- store and forward
The NIC will buffer the entire packet before starting to send it on the wire.
sf-np- store and forward, no poison
sfmode but the NIC will guarantee never to emit a poisoned frame under any circumstances. This will force store-and-forward semantics for all users of CTPIO on the same port.
The NIC will start to send the outgoing packet onto the wire before it has been fully received, improving latency at the cost of occasionally transmitting a poisoned frame under some circumstances (such as the process being descheduled before it has finished writing the packet to the NIC).