HeteroCPPR: Accelerating Common Path Pessimism Removal with Heterogeneous CPU-GPU Parallelism

Abstract

Common path pessimism removal (CPPR) is a key step to eliminating unwanted pessimism during static timing analysis (STA). Unwanted pessimism will force designers and optimization algorithms to waste a significant yet unnecessary amount of effort on fixing paths that meet the intended timing constraints. However, CPPR is extremely time-consuming and can incur 10–100× runtime overheads to complete. Existing solutions for speeding up CPPR are architecturally constrained by CPU-only parallelism, and their runtimes do not scale beyond 8–16 cores. In this paper, we introduce HeteroCPPR, a new algorithm to accelerate CPPR by harnessing the power of heterogeneous CPU-GPU parallelism. We devise an efficient CPU-GPU task decomposition strategy and highly optimized GPU kernels to handle CPPR that scales to large numbers of paths. Also, HeteroCPPR can scale to multiple GPUs. As an example, HeteroCPPR is up to 16× faster than a state-of-the- art CPU-parallel CPPR algorithm for completing the analysis of 10K post-CPPR critical paths in a million-gate design under a machine of 40 CPUs and 4 GPUs.