Predicting Critical Warps in Near-Threshold GPGPU Applications using a Dynamic Choke Point Analysis.

General purpose graphics processing units (GP-GPU) can significantly improve the power consumption at the NTC operating region. However, process variation (PV) can drastically reduce its performance. In this paper, we examine choke points-a unique device-level characteristic of PV at NTC-that can exacerbate the warp criticality problem. We show that the modern warp schedulers cannot tackle the choke point induced critical warps in an NTC GPU. We propose Warp Latency Booster, a circuit-architectural solution to dynamically predict the critical warps and accelerate them in their respective execution units. Our best scheme achieves an average improvement of ~32% and ~41% in performance, and ~21% and ~19% in energy-efficiency, respectively, over two state-of-the-art warp schedulers.