Adaptive Size-Aware Cache Insertion Policy for Content Delivery Networks
Peng Wang, Yu Liu, Zhelong Zhao, Ke Zhou, Zhihai Huang, Yanxiong Chen · 2022 IEEE 40th International Conference on Computer Design (ICCD) · 2022
Content delivery networks (CDNs) are large distributed cache systems that deliver objects with inconsistent sizes. The zero-reuse objects that are not reused in a time window but still loaded and evicted in the cache waste cache resources and result in degradation of object hit ratio (OHR) in CDNs. Although prohibiting these objects from entering the cache is a viable solution, the variable workloads and various object sizes in CDNs make the determination of zero-reuse difficult, resulting in an increased risk of bandwidth overhead in the data center by the misjudgment. To alleviate this problem, we propose to use the insertion policy to give each object at least one chance to be hit. Meanwhile, we find that the distribution of zero-reuse objects correlates with their sizes through data analysis. As a result, we propose an adaptive size-aware cache insertion policy (ASC-IP) for the OHR improvement and design an adaptive scheme to dynamically adjust the size threshold used to determine the zero-reuse objects, adapting the mutative access patterns with negligible overhead. We have deployed ASC-IP in TDC of Company-T and ASC-IP can improve the OHR by 9.6% and reduce the user access latency by 7.14ms on average and reduce the back-to-source bandwidth by 8.75Gbps. In addition, on Twitter, Wikipedia, and a real-world Trace-T, we show that ASC-IP outperforms state-of-the-art cache algorithms working on CDNs and can upgrade LRU-based replacement algorithms with negligible overheads.