Application behavior aware re-reference interval prediction for shared LLC

摘要

In modern CMPs, Last Level Cache (LLC) is shared among cores for better utilization. Interference among data, mapped from multiple cores, increases conflict misses in shared LLCs. Such interference is highly dependent on cache behavior of applications and access rate difference among them. We observe that interference among applications is not eliminated completely even using existing state-of-the-art mechanism for applications having high cache access rate difference and different memory characteristic. Applications with highly diverse cache behavior can be observed in homogeneous as well as heterogeneous multicore processors. Streaming applications, having high access rate, can still interfere with cache friendly applications having low access rate. We propose Application behavior aware replacement policy that predicts re-reference interval of the block based on block locality as well as application behavior. By providing more priority to application behavior over cache block locality, we reduce interference between streaming applications and cache friendly applications. Our evaluation on set of SPEC CPU2006 workloads running on CMP with shared LLC shows that proposed replacement policy outperforms the state-of-the-art replacement policy, on throughput metric. We achieve performance gain up to 16.2% over SRRIP for application mixes of cache-friendly and streaming applications. Our replacement policy achieves maximum of 59.9% reduction in number of misses as compared to SRRIP with average misses per kilo instructions (mpki) reduction of 5.9% over SRRIP.