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关于输入队列交换机分布式调度的RTT时延

发表时间:2016-08-31  浏览量:1634  下载量:741
全部作者: 周倩,胡冰
作者单位: 浙江大学信息与电子工程学院
摘 要: 提出一种请求预测(request prediction,RP)机制,能使得很多现存的集中式迭代调度算法扩展至分布式系统时,其最低排队时延小于往返时间(round trip time,RTT),也能直接应用于分布式迭代调度算法降低时延。应用RP 时,一个空的输出j 端通过追踪其活跃的输入端来预测请求并提前发送授权。若该预测准确,那么时延降低;否则,RP 对性能也没有任何负面影响。RP 实现简单,复杂度仅为O(1). 仿真结果表明,RP能优化现存的调度算法RR/LQF(round robin with longest queue first)和HRF/RC(highest rank first with request compression),将低负载时延降低至RTT 以下。研究还对RP 进行了理论分析,得出了低负载(p<0.4)时的理论时延。
关 键 词: 计算机网络;输入队列交换机;分布式迭代调度算法;往返时间
Title: On the delay less than a round trip time at input-queued switches with distributed schedulers
Author: ZHOU Qian, HU Bing
Organization: College of Information Science & Electronic Engineering, Zhejiang University, Hangzhou 310027, China
Abstract: This paper proposes a novel request prediction (RP) mechanism. By adopting the RP mechanism, many existing monolithic iterative scheduling algorithms can be easily extended to the distributed implementation and cut down the minimal queuing delay to less than an round trip time (RTT). To be more specific, an idle output j can smartly predict the request en route and issue a grant in advance. If this prediction is precise, the delay can be cut down. Otherwise, the performance/bandwidth is not suffered yet as output j is originally idle. RP is very simple to implement with complexity O(1). Simulation results show that RP optimizes the existing algorithms round robin with longest queue first (RR/LQF) and highest rank first with request compression (HRF/RC) to achieve the best performance under light and moderate traffic. Last but not least, the analytical results for the performance of RP are provided.
Key words: Input-queued switch; Distributed iterative scheduling algorithms; Round trip time
发表期数: 2016年8月第16期
引用格式: 周倩,胡冰. 关于输入队列交换机分布式调度的RTT时延[J]. 中国科技论文在线精品论文,2016,9(16):1636-1646.
 
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