Performance optimization of TCP/IP over 10 Gigabit Ethernet by precise instrumentation

End-to-end communications on 10 Gigabit Ethernet (10 GbE) WAN became popular. However, there are difficulties that need to be solved before utilizing Long Fat-pipe Networks (LFNs) by using TCP. We observed that the followings caused performance depression: short-term bursty data transfer, mismatch between TCP and hardware support, and excess CPU load. In this research, we have established systematic methodologies to optimize TCP on LFNs. In order to pinpoint causes of performance depression, we analyzed real networks precisely by using our hardware-based wire-rate analyzer with 100-ns time-resolution. We took the following actions on the basis of the observations: (1) utilizing hardware-based pacing to avoid unnecessary packet losses due to collisions at bottlenecks, (2) modifying TCP to adapt packet coalescing mechanism, (3) modifying programs to reduce memory copies. We have achieved a constant through-put of 9.08 Gbps on a 500 ms RTT network for 5 h. Our approach has overcome the difficulties on single-end 10 GbE LFNs.