In a custom user space networking stack, backed by Netmap or PF_RING, is the ability to use TCP Segmentation Offload and/or Large Receive Offload lost?
The only place I can find anything that mentions NIC offloading w.r.t. Netmap or PF_RING is in Netmap: a novel framework for fast packet I/O, but it isn't apparent to me if it's usable or if it's operating transparently in the NIC:
Popular hardware features related to TCP acceleration, such as hardware checksumming or even encryption, Tx Segmentation Offloading, Large Receive Offloading, are completely orthogonal to our proposal: they reduce some processing in the host stack but do not address the communication with the device.
Thank you for your time and happy holidays!
PF_RING and netmap operates directly with NIC and its rings. Such technologies as TCO and LRO implemented in NIC dirvers (read ixgbe dirver sources for example). Only way to have such features is implement them self in you software.