Architectural Analysis and Instruction-Set Optimization for Design of Network Protocol Processors∗

TCP/IP protocol processing latency has been an important issue in high-speed networks. In this paper, we present an architectural study of TCP/IP protocol. We port the TCP/IP protocol stack from the 4.4 FreeBSD to the SimpleScalar simulation environment. The architectural characteristics, such as instruction level parallelism and cache behavior, are studied through simulation. We also compare the characteristics of TCP/IP protocol to that of SPECint benchmark programs. It turns out that the former is quite different from the latter due to the unique processing structure. Furthermore, in order to improve the effectiveness of instruction cache, frequent instruction pairs are analyzed, and corresponding architectural optimizations are made to the instruction set architecture. The performance is evaluated in the simulator. We find that a 23% improvement can be achieved by taking advantage of the optimization. The instruction set optimizations proposed in this paper will be helpful for the design of new programmable protocol processors in future.