Timing-Driven Simulated Annealing for FPGA Placement in Neural Network Realization

The simulated annealing algorithm is an extensively utilized heuristic method for heterogeneous FPGA placement. As the application of neural network models on FPGAs proliferates, new challenges emerge for the traditional simulated annealing algorithm in terms of timing. These challenges stem from large circuit sizes and high heterogeneity in the block proportions typical in neural networks. To address these challenges, this study introduces a timing-driven simulated annealing placement algorithm. This algorithm integrates cluster criticality identification during the cluster selection phase, which enhances the probability of high-criticality cluster selection. In the cluster movement phase, the proposed method employs an improved weighted center movement for high-criticality clusters and a random movement strategy for other clusters. Experimental evidence demonstrates that the proposed placement algorithm decreases the average wire length by 1.52% and the average critical path delay by 5.03%. This improvement in performance is achieved with a marginal increase of 5.01% in runtime, as compared to VTR8.0.