ParaDRo: A Parallel Deterministic Router Based on Spatial Partitioning and Scheduling

Routing of nets is one of the most time-consuming steps in the FPGA design flow. Existing works have described ways of accelerating the process through parallelization. However, only some of them are deterministic, and determinism is often achieved at the cost of speedup. In this paper, we propose ParaDRo, a parallel FPGA router based on spatial partitioning that achieves deterministic results while maintaining reasonable speedup. Existing spatial partitioning based routers do not scale well because the number of nets that can fully utilize all processors reduces as the number of processors increases. In addition, they route nets that are within a spatial partition sequentially. ParaDRo mitigates this problem by scheduling nets within a spatial partition to be routed in parallel if they do not have overlapping bounding boxes. Further parallelism is extracted by decomposing multi-sink nets into single-sink nets to minimize the amount of bounding box overlaps and increase the number of nets that can be routed in parallel. These improvements enable ParaDRo to achieve an average speedup of 5.4X with 8 threads with minimal impact on the quality of results.