Studying network protocol offload with emulation: approach and preliminary results

To take full advantage of high-speed networks while freeing CPU cycles for application processing, the industry is proposing new techniques relying on an extended role for network interface cards such as TCP offload engine and remote direct memory access. The paper presents an experimental study aimed at collecting the performance data needed to assess these techniques. This work is based on the emulation of an advanced network interface card plugged on the I/O bus. In the experimental setting, a processor of a partitioned SMP machine is dedicated to network processing. Achieving a faithful emulation of a network interface card is one of the main concerns and it is guiding the design of the offload engine software. This setting has the advantage of being flexible so that many different offload scenarios can be evaluated. Preliminary throughput results of an emulated TCP offload engine demonstrate a large benefit. The emulated TCP offload engine indeed yields 600% to 900% improvement while still relying on memory copies at the kernel boundary.