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北美退伍军人节(Veterans Day),12 日无更新
arXiv 2003.14085cs.ITcs.PFmath.IT
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在线网络缓存的基本限制

Fundamental Limits of Online Network-Caching

Rajarshi Bhattacharjee, Subhankar Banerjee, Abhishek Sinha

摘要:

内容分发网络(CDN)中文件的最佳缓存是一个基本的和日益增长的商业利益的问题。虽然许多不同的高速缓存算法在使用中的今天,从在线学习的角度来看,网络高速缓存算法的基本性能限制仍然知之甚少。在本文中,我们解决这个问题在以下两个设置:(1)一个单一的用户连接到一个单一的缓存,(2)一组用户和一组缓存通过二分网络互连。最近,一个在线的基于梯度的编码缓存策略被证明是享受次线性遗憾。然而,由于缺乏已知的遗憾下限,所提出的政策的最优性问题是开放的。在本文中,我们解决了这个问题,在上述两个设置得到严格的非渐近遗憾下界。除此之外,我们提出了一个新的跟随扰动的领导者的未编码的缓存策略与接近最优的遗憾。从技术上讲,下界是通过将在线缓存问题与经典的概率范式(balls-into-bins)相关联来获得的。我们的证明广泛使用了一个新的结果,在人口最多的一半的箱子,这也可能是独立的利益的预期负载。我们通过对流行的MovieLens数据集进行实验来评估缓存策略的性能,并以设计建议和开放问题列表结束本文。

英文摘要:

Optimal caching of files in a content distribution network (CDN) is a problem of fundamental and growing commercial interest. Although many different caching algorithms are in use today, the fundamental performance limits of network caching algorithms from an online learning point-of-view remain poorly understood to date. In this paper, we resolve this question in the following two settings: (1) a single user connected to a single cache, and (2) a set of users and a set of caches interconnected through a bipartite network. Recently, an online gradient-based coded caching policy was shown to enjoy sub-linear regret. However, due to the lack of known regret lower bounds, the question of the optimality of the proposed policy was left open. In this paper, we settle this question by deriving tight non-asymptotic regret lower bounds in both of the above settings. In addition to that, we propose a new Follow-the-Perturbed-Leader-based uncoded caching policy with near-optimal regret. Technically, the lower-bounds are obtained by relating the online caching problem to the classic probabilistic paradigm of balls-into-bins. Our proofs make extensive use of a new result on the expected load in the most populated half of the bins, which might also be of independent interest. We evaluate the performance of the caching policies by experimenting with the popular MovieLens dataset and conclude the paper with design recommendations and a list of open problems.

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。

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