Cache网络随机替换策略的性能评估
Performance Evaluation of the Random Replacement Policy for Networks of Caches
摘要：
内容分发网络以及最近提出的以信息为中心的网络的整体性能依赖于存储器和带宽容量。在这个框架中，命中率是关键的性能指标，它捕获的带宽/内存的权衡为一个给定的全局performance.This本文侧重于在网络中的高速缓存，采用随机替换策略的命中率的估计。假设请求是独立和相同分布的，提供了单个随机缓存的未命中概率的一般表达式以及特定流行度分布的精确结果。此外，对于指数$α$ > 1的任何Zipf流行度分布，我们获得了在大缓存大小的情况下的未命中概率的渐近等价物。我们扩展到网络的随机缓存的分析，当拓扑结构是一条线或一个同构树。在这种情况下，通过假设在任何节点上的未命中事件在时间上独立发生，得到整个网络的未命中概率的近似值;将所得结果与使用文献中已经提到的最近最少使用纪律的相同网络进行比较。我们进一步分析的情况下，混合串联缓存网络的两个节点采用随机或最近最少使用的政策。在所有的情况下，渐近公式和近似值进行了广泛的比较，模拟和表现非常好。最后，我们的研究结果使我们能够提出建议，在网络中的缓存替换学科专门用于内容分发。这些结果也适用于使用先进先出策略的缓存。
英文摘要：
The overall performance of content distribution networks as well as recently proposed information-centric networks rely on both memory and bandwidth capacities. In this framework, the hit ratio is the key performance indicator which captures the bandwidth / memory tradeoff for a given global performance.This paper focuses on the estimation of the hit ratio in a network of caches that employ the Random replacement policy. Assuming that requests are independent and identically distributed, general expressions of miss probabilities for a single Random cache are provided as well as exact results for specific popularity distributions. Moreover, for any Zipf popularity distribution with exponent $α$ > 1, we obtain asymptotic equivalents for the miss probability in the case of large cache size. We extend the analysis to networks of Random caches, when the topology is either a line or a homogeneous tree. In that case, approximations for miss probabilities across the network are derived by assuming that miss events at any node occur independently in time; the obtained results are compared to the same network using the Least-Recently-Used discipline, already addressed in the literature. We further analyze the case of a mixed tandem cache network where the two nodes employ either Random or Least-Recently-Used policies. In all scenarios, asymptotic formulas and approximations are extensively compared to simulations and shown to perform very well. Finally, our results enable us to propose recommendations for cache replacement disciplines in a network dedicated to content distribution. These results also hold for a cache using the First-In-First-Out policy.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
