A Survey of Swarm Intelligence Techniques in VLSI Routing Problems <s> e: OPTIMIZATION STRATEGIES <s> Routing FPGAs is a challenging problem because of the relative scarcity of routing resources, both wires and connection points. This can lead either to slow implementations caused by long wiring paths that avoid congestion or a failure to route all signals. This paper presents PathFinder, a router that balances the goals of performance and routability. PathFinder uses an iterative algorithm that converges to a solution in which all signals are routed while achieving close to the optimal performance allowed by the placement. Routability is achieved by forcing signals to negotiate for a resource and thereby determine which signal needs the resource most. Delay is minimized by allowing the more critical signals a greater say in this negotiation. Because PathFinder requires only a directed graph to describe the architecture of routing resources, it adapts readily to a wide variety of FPGA architectures such as Triptych, Xilinx 3000 and mesh-connected arrays of FPGAs. The results of routing ISCAS benchmarks on the Triptych FPGA architecture show an average increase of only 4.5% in critical path delay over the optimum delay for a placement. Routes of ISCAS benchmarks on the Xilinx 3000 architecture show a greater completion rate than commercial tools, as well as 11% faster implementations. <s> BIB001 </s> A Survey of Swarm Intelligence Techniques in VLSI Routing Problems <s> e: OPTIMIZATION STRATEGIES <s> This paper presents a fast and accurate solution, namely Fashion, to routability-driven global routing problem. Fashion is based on two efficient yet effective techniques: 1) dynamic pattern routing (DPR) and 2) movable-segment-driven DPR. These two techniques enable Fashion to explore large solution space to achieve high routability with low time complexity. Compared with BoxRouter, Fashion has a shorter wire length and reduces overflow and runtime by 5 and 15 times, respectively. Compared with FastRoute, Fashion has similar runtime but 90% smaller overflow and 1.9% shorter wire length. Fashion is significantly better than Labyrinth and Fengshui in terms of overflow, wire length, and runtime. <s> BIB002
In order to improve the quality of solutions, researchers have put forward various optimization strategies. Rip-up and reroute BIB002 allows the nets passing through congested regions be ripped up and rerouted for finding alternative routes. And negotiated congestion routing can balance the competing goals of eliminating congestion and minimizing the performance degrading due to timing critical paths BIB001 . This idea based on negotiation mechanism has been widely used in the design of routing system.