Programming language optimizations for modular router configurations

Networking systems such as Ensemble, the x-kernel, Scout, and Click achieve e xibility by building routers and other packet processors from modular components. Unfortu- nately, component designs are often slower than purpose- built code, and routers in particular have stringent e - ciency requirements. This paper addresses the e ciency problems of one component-based router, Click, through optimization tools inspired in part by compiler optimiza- tion passes. This pragmatic approach can result in signi- cant performance improvements; for example, the combi- nation of three optimizations reduces the amount of CPU time Click requires to process a packet in a simple IP router by 34%. We present several optimization tools, de- scribe how those tools a ected the design of Click itself, and present detailed evaluations of Click's performance with and without optimization.