Compiling packet programs to reconfigurable switches
Lavanya Jose, Lisa Jing Yan, George Varghese, Nick McKeown · Networked Systems Design and Implementation · 2015
Programmable switching chips are becoming more commonplace, along with new packet processing languages to configure the forwarding behavior. Our paper explores the design of a compiler for such switching chips, in particular how to map logical lookup tables to physical tables, while meeting data and control dependencies in the program. We study the interplay between Integer Linear Programming (ILP) and greedy algorithms to generate solutions optimized for latency, pipeline occupancy, or power consumption. ILP is slower but more likely to fit hard cases; further, ILP can be used to suggest the best greedy approach. We compile benchmarks from real production networks to two different programmable switch architectures: RMT and Intel's FlexPipe. Greedy solutions can fail to fit and can require up to 38% more stages, 42% more cycles, or 45% more power for some benchmarks. Our analysis also identifies critical resources in chips. For a complicated use case, doubling the TCAM per stage reduces the minimum number of stages needed by 12.5%.