New Two-Level L1 Data Cache Bypassing Technique for High Performance GPUs

초록

On-chip caches of graphics processing units (GPUs) have contributed to improved GPU performance byreducing long memory access latency. However, cache efficiency remains low despite the facts that recentGPUs have considerably mitigated the bottleneck problem of L1 data cache. Although the cache miss rate is areasonable metric for cache efficiency, it is not necessarily proportional to GPU performance. In this study, weintroduce a second key determinant to overcome the problem of predicting the performance gains from L1 datacache based on the assumption that miss rate only is not accurate. The proposed technique estimates the benefitsof the cache by measuring the balance between cache efficiency and throughput. The throughput of the cacheis predicted based on the warp occupancy information in the warp pool. Then, the warp occupancy is used fora second bypass phase when workloads show an ambiguous miss rate. In our proposed architecture, the L1 datacache is turned off for a long period when the warp occupancy is not high. Our two-level bypassing techniquecan be applied to recent GPU models and improves the performance by 6% on average compared to thearchitecture without bypassing. Moreover, it outperforms the conventional bottleneck-based bypassingtechniques.

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