Towards Latency Awareness for Content Delivery Network Caching
Towards Latency Awareness for Content Delivery Network Caching
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发表时间：
2022
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通讯作者：
Gang Yan;Jian Li
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作者：
Gang Yan;Jian Li
缓存广泛用于内容分发网络（CDN）中，以在用户附近服务请求，从而减少内容访问延迟。然而，设计延迟最佳的缓存是具有挑战性的存在延迟命中，这发生在高吞吐量系统中，当多个请求相同的内容之前，从远程服务器获取的内容发生。在本文中，我们提出了一种新的基于计时器的机制，可证明优化的平均缓存延迟，延迟感知（LA）缓存的理解和设计提供了一个理论基础，是根本的内容交付延迟敏感的系统。我们的基于计时器的模型能够导出一个简单的排名函数，该函数可以快速通知我们内容的优先级，以最大限度地减少延迟。在此基础上提出了一种轻量级的延迟感知缓存算法LA-Cache。我们已经在流行的CDN服务器Apache Traf fic Server中实现了一个原型。我们实现的延迟与我们模型的理论预测非常一致。我们使用生产跟踪的实验结果表明，与最先进的方法相比，LA-Cache一致地减少了5%-15%的延迟，这取决于后端RTT。
Caches are pervasively used in content delivery networks (CDNs) to serve requests close to users and thus reduce content access latency. However, designing latency-optimal caches are challenging in the presence of delayed hits , which occur in high-throughput systems when multiple requests for the same content occur before the content is fetched from the remote server. In this paper, we propose a novel timer-based mechanism that provably optimizes the mean caching latency, providing a theoretical basis for the understanding and design of latency-aware (LA) caching that is fundamental to content delivery in latency-sensitive systems. Our timer-based model is able to derive a simple ranking function which quickly informs us the priority of a content for our goal to minimize latency. Based on that we propose a lightweight latency-aware caching algorithm named LA-Cache. We have implemented a prototype within Apache Traffic Server, a popular CDN server. The latency achieved by our implementations agrees closely with theoretical predictions of our model. Our experimental results using production traces show that LA-Cache consistently reduces latencies by 5%-15% compared to state-of-the-art methods depending on the backend RTTs.