CoT: Decentralized Elastic Caches for Cloud Environments

TL;DR

CoT introduces a decentralized, elastic caching framework with a novel hot key tracking and replacement policy that improves hit rates and load balancing in cloud environments with skewed workloads.

Contribution

The paper presents Cache-on-Track (CoT), a new decentralized caching framework with a tailored replacement policy and hot key tracking for improved performance in cloud environments.

Findings

CoT outperforms LRU, LFU, and ARC in hit rates.

CoT slightly outperforms LRU-2 with the same tracking size.

CoT reduces front-end cache size by 50% to 93.75%.

Abstract

Distributed caches are widely deployed to serve social networks and web applications at billion-user scales. This paper presents Cache-on-Track (CoT), a decentralized, elastic, and predictive caching framework for cloud environments. CoT proposes a new cache replacement policy specifically tailored for small front-end caches that serve skewed workloads. Front-end servers use a heavy hitter tracking algorithm to continuously track the top-k hot keys. CoT dynamically caches the hottest C keys out of the tracked keys. Our experiments show that CoT's replacement policy consistently outperforms the hit-rates of LRU, LFU, and ARC for the same cache size on different skewed workloads. Also, \algoname slightly outperforms the hit-rate of LRU-2 when both policies are configured with the same tracking (history) size. CoT achieves server size load-balance with 50\% to 93.75\% less front-end cache in comparison to other replacement policies.