标题: | 在网站闸道器上提供差别服务品质之请求排程 Request Scheduling for Differentiated QoS at Website Gateway |
作者: | 温硕彦 Shuo-Yen Wen 林盈达 Ying-Dar Lin 资讯科学与工程研究所 |
关键字: | 网站服务品质;差别服务;请求排程;Web Quality of Service;Service Differentiation;Request Scheduling |
公开日期: | 2003 |
摘要: | 随着网站流量的大幅成长,网站伺服器的负载也变得愈重,进而造成使用者感受到的等待时间也愈长,网站经营者希望能够采用差别服务来改善特定使用者得到的网站吞吐量以及缩短其感受到的等待时间。本文提出一个部署在网站闸道器上的HTTP请求排程演算法来提供差别服务品质,其不需要修改任何在客户端或伺服器端的软体。以闸道器输出连结的观点来看,处理请求的时间是根据其回应的大小而不是该请求本身的大小,所以我们的演算法看起来好像是非持续传送式的¬而不像传统的封包排程演算法大部分都是持续传送式的。我们分别以回应的大小以及窗式控制的机制去仿效DRR来决定请求的顺序以及其释放的时间。此顺序是依据请求的回应大小以及事先定义让每个服务类别得到网站吞吐量的比例之服务比重,而释放时间则是依据网站伺服器的处理速度。在系统评估中,当三个服务类别的服务比重被指定为6:3:1时,不论存取网页的大小为何,此服务品质闸道器可让它们如预期般的获得网站总吞吐量的60%、30%及10%。并且,拥有最大权重之服务类别得到的网站吞吐量以及使用者感受到的等待时间分别最多改善为没有差别服务品质时的176%及69%。 With the explosive growth of Web traffic, the load on a Web server become heavier, leading to the longer user-perceived latency. Website operators would like to employ service differentiation to offer better throughput and user-perceived latency for some specific users. This work presents an HTTP request scheduling algorithm deployed at the website gateway to enable the Web quality of service without modifying any client or server software. Unlike traditional packet scheduling algorithms which are mostly work-conservative, our algorithm appears to be non-work-conservative from the viewpoint of the output link of the gateway because the service time of a request depends on the size of its response, not the size of the request itself. We emulate deficit round robin and the window control mechanism to decide the order and release time of requests, respectively. The order is according to the response size of the requests and the pre-defined service weights, to which the throughput of the service classes will be proportional, whereas the release time is according to the service rate of the Web server. In the evaluation, when the weight ratio 6:3:1 is assigned to three service classes, QoS website gateway lets them get 60%, 30%, and 10% of the overall throughput as expected, regardless whatever page sizes. In addition, the throughput and the user-perceived latency of the class with the largest weight can be improved by up to 176% and 69% of the QoS-disabled values, respectively. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#GT009123525 http://hdl.handle.net/11536/52791 |
显示于类别: | Thesis |
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