IB QoS的带宽分配机制研究  

Research on Bandwidth Allocation Mechanism of IB QoS

作　　者：郑霄[1] 陈忠平[1] 吴志兵[1] 

机构地区：[1]江南计算技术研究所,无锡214083

出　　处：《计算机科学》2012年第4期127-130,134,共5页Computer Science

基　　金：国家科技支撑计划项目(2011BAH04B03)资助

摘　　要：InfiniBand(简称IB)网络的质量服务策略(简称IB QoS)能有效地分离和控制在IB网络上并发传输的不同应用负载的带宽,从而为基于InfiniBand网络互连的高性能计算(简称HPC)平台和数据中心平台用户提供网络服务的质量保障。但在IB QoS机制下,高优先级权值、低优先级权值和QoS因子3个关键参数究竟如何影响带宽分配,"IBA规范"并没有明确规定,目前也缺少相关的文档说明。首先在基于当前主流IB产品的实验平台上进行大量的IBQoS带宽测试实验,总结出IB QoS带宽分配机制的重要特性:当QoS因子和高优先级权值取值确定时,随着低优先级权值的增长,高优先级VL和低优先级VL的带宽比呈锯齿形增长,锯齿的偏幅逐渐减小,且周期性达到某一定值;接着根据测试数据推测出带宽分配与高优先级权值、低优先级权值和QoS因子等3个关键变量之间的量化关系式,并通过随机抽样检测的方式验证了该关系式的正确性;最后从量化关系式出发,用数学证明的方式为前面总结的带宽分配特性找到了理论依据。The quality of service mechanism supported by the InfiniBand network is an important technique to effectively separate and control the bandwidth allocation between the multiple data-flows on the network,which provides a gua-ranteed transportation service to applications concurrently running in the HPC or datacenters interconnected by IB network.But the ＂InfiniBand architecture specification＂ does not propose demand for the IB device manufacturers how to implement IB QoS in detail,especially for the three key components（High-Priority,Low-Priority and Limit of High-Priority） how to numerically control the bandwidth allocation between Virtual Lanes（VL for short） in different priority-ranked queues and with different priority values,and also no documents have closed expatiation on it by now.In this paper,a quantitative formula to compute the ratio of bandwidth between high-and low-priority VLs according the three key components was presented.It was brought forward based on abundant results of bandwidth allocation experiments done on the most popular IB devices and proved to be true by random sample verification.We also found that the bandwidth ratio would change in zigzag shape with the increase of the Low-Priority value and periodically reach a stable value on condition that both High-Priority and Limit of High-Priority are certain.These characteristics were verified by mathematical reasoning method.

关 键 词：INFINIBAND网络 质量服务 虚通道 带宽分配 优先级权值 

分 类 号：TP393.03[自动化与计算机技术—计算机应用技术]