Towards socket-level network header caching

In recent years, we are seeing an important increase in network interface transmission rates. This poses a challenge to come up with better methods of mitigating latency at all levels in a computer system. In this paper, we propose an approach that works well in systems where scatter-gather transfers are fast compared to memory accesses. We note that, in a Transport level flow, a large part of the Network and Data Link layer headers do not vary. As a result, we assert that it is favorable to store the parts of the header that do not vary, instead of copying them from the socket data structure to the packet buffer for each packet transmission. The network interface then uses scatter-gather to assemble the network packet without explicitly copying data in memory. This approach was partially implemented, but we propose extending it from the Data Link to the superior Network level, hoping that it will aid in lessening the load on legacy hardware at high packet transmission rates.