Improve GPGPU Latency Hiding with a Hybrid Recovery Stack and a Window Based Warp Scheduling Policy

Branch divergence phenomenon usually has very serious impact on SIMD pipeline´s efficiency. However Dynamic Warp Subdivision´s branch method utilizes the branch divergence phenomenon to hide memory latency by interleaving issue among all branch paths of a warp. But this method may experience serious over-subdivision problem. So, we propose a hybrid stack mechanism that enables the PDOM stack can issue any ready sub-warps without losing the logical structure of PDOM stack. To maximize our hybrid stack´s potential we propose a window based scheduling policy to reinforce the memory latency hiding. The experiment result shows that our window based scheduling policy and the hybrid stack hardware´s combination can improve the performance by 10% compared with the baseline configuration with PDOM loose round-robin method and 6.8% over DWS-PC with our window based scheduling policy in our selected 7 benchmark programs.