Browsing by Author "Tien, Ching-Ming"

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Multiple-resource request scheduling for differentiated QoS at website gateway
(2008-06-25)
Lin, Ying-Dar
;
Tien, Ching-Ming
;
Tsao, Shih-Chiang
;
Feng, Ruo-Hua
;
Lai, Yuan-Cheng
Differentiated quality of service is a way for a website operator to provide different service levels to its clients. Traditional HTTP request scheduling schemes can achieve this, but they schedule requests to manage only one server resource, such as CPU or disk I/O. Actually, processing a request on the server will consume multiple resources. This paper presents a multiple-resource request scheduling algorithm, called mQoS, for differentiating the utilization of the server resource. The mQoS scheduler consists of several sub-schedulers and a main scheduler. Each sub-scheduler manages a server resource to differentiate its utilization among the classes. The main scheduler checks the availability of every server resource and triggers an appropriate sub-scheduler to balance the utilization of server resources. The implementation of the mQoS gateway is based on Squid and Linux. The evaluation compares the mQoS scheduling with no scheduling (nQoS) and single-resource request scheduling (sQoS). The mQoS scheduling reveals the accurate differentiation oil every server resource. In addition, the total server throughput in the mQoS scheduling is improved by 21%, compared with the sQoS scheduling. The average user-perceived latency of the mQoS scheduling is also shorter than other scheduling. (C) 2008 Elsevier B.V. All rights reserved.
Request scheduling for differentiated QoS at website gateway
(2006)
Tien, Ching-Ming
;
Wen, Shuo-Yen
;
Lin, Ying-Dar
;
Lai, Yuan-Cheng
;
資訊工程學系
With the explosive growth of Web traffic, the load on a Web server becomes heavier, leading to the longer user-perceived latency. Website operators would like to employ service differentiation to offer better throughput and shorter user-perceived latency to some specific users. This paper presents an HTTP request scheduling algorithm deployed at the website gateway to enable the Web quality of service without any modification to client or server software. A variation of the deficit round robin scheduling algorithm and a window control mechanism are presented to decide the order and the releasing time of requests, respectively. The order is decided by the response size of the requests and the pre-defined service weights. The ratio of the bandwidth throughput of the service classes is determined by the weights, whereas the releasing time is decided by the service rate of the Web server. The evaluation reveals the scheduling algorithm can provide service differentiation and improve server throughput and user-perceived latency.
Request Scheduling for Differentiated QoS at Website Gateway
(2008)
Lin, Ying-Dar
;
Tien, Ching-Ming
;
Tsao, Shih-Chiang
;
Wen, Shuo-Yen
;
Lai, Yuan-Cheng
With the explosive growth of Web traffic, the load on a Web server becomes heavier, leading to the longer user-perceived latency. Website operators would like to employ service differentiation to offer better throughput and shorter user-perceived latency to some specific users. This paper presents an HTTP request scheduling algorithm deployed at the Website gateway to enable the Web quality of service without any modification to client or server software. A variation of the deficit round robin algorithm for packet scheduling and a window control mechanism are presented to decide the order and the releasing time of requests, respectively. The order is decided by the response size of the requests and the pre-defined service weights. The ratio of the service rate got by the service classes is determined by the weights, whereas the releasing time is decided by the service rate of the Web server. The evaluation shows the scheduling algorithm can provide service differentiation and improve server throughput and user-perceived latency. When the weight ratio 6:3:1 is assigned to three service classes, the QoS Website gateway makes 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.