TCP performance re-visited

Abstract

Detailed measurements and analyses for the Linux-2.4 TCP stack on current adapters and processors are presented. We describe the impact of CPU scaling and memory bus loading on TCP performance. As CPU speeds outstrip I/O and memory speeds, many generally accepted notions of TCP performance begin to unravel. In-depth examinations and explanations of previously held TCP performance truths are provided, and we expose cases where these assumptions and rules of thumb no longer hold in modern-day implementations. We conclude that unless major architectural changes are adopted, we would be hard-pressed to continue relying on the 1 GHz/1 Gbps rule of thumb.