【摘要】：摘要：在服務(wù)器端實(shí)現(xiàn)比例延遲保證可以顯著提高整體網(wǎng)絡(luò)服務(wù)質(zhì)量(QoS)。Apache是世界使用第一的開源Web服務(wù)器軟件,可以運(yùn)行在大多數(shù)計(jì)算機(jī)操作系統(tǒng)上。通過修改源代碼,Apache Web服務(wù)器可以提供比例延遲區(qū)分服務(wù)。 Apache Web服務(wù)器一般采用單變量模型,其輸入為處理不同類別客戶端連接工作者線程數(shù)量比,輸出為不同類別客戶端連接延遲比。該單變量模型在處理多優(yōu)先級(jí)延遲保證時(shí)需多次建模,可擴(kuò)展性不佳。針對(duì)此情況,提出了一種ApacheWeb服務(wù)器多輸入多輸出模型,并結(jié)合分散控制理論和自校正控制理論設(shè)計(jì)分散自校正控制器。根據(jù)分散控制理論,將多變量系統(tǒng)分解為相互關(guān)聯(lián)的單變量子系統(tǒng),分別對(duì)子系統(tǒng)進(jìn)行辨識(shí)得到SISO模型,輸入為處理當(dāng)前類別客戶端連接工作者線程數(shù)量與工作者線程總量之比,輸出為當(dāng)前類別客戶端連接平均延遲與所有類別客戶端平均延遲之和之比。為了處理子系統(tǒng)之間的耦合影響,對(duì)各子系統(tǒng)應(yīng)用自校正控制器。該控制器動(dòng)態(tài)調(diào)節(jié)處理不同優(yōu)先級(jí)請(qǐng)求的工作線程數(shù)目,能保證較高優(yōu)先級(jí)請(qǐng)求更快得到處理且維持不同優(yōu)先級(jí)請(qǐng)求的平均延遲比為設(shè)定值,模型和控制器參數(shù)根據(jù)在線辨識(shí)結(jié)果實(shí)時(shí)更新。Windows平臺(tái)下,WinNT MPM是Apache唯一使用的多任務(wù)處理模塊(MPM)。修改后的WinNT MPM增加了采樣機(jī)制,連接分類器和控制線程,在Apache內(nèi)部構(gòu)建出閉環(huán)控制系統(tǒng)。 利用Vmware虛擬機(jī)搭建仿真平臺(tái),測(cè)試結(jié)果表明,過載情況下即使并發(fā)客戶連接數(shù)目急劇變化,閉環(huán)系統(tǒng)中的服務(wù)器仍能維持較好的比例延遲保證。
[Abstract]:Absrtact: the implementation of proportional delay guarantee on the server side can significantly improve the quality of service of the whole network (QoS). Apache is the world's largest open source Web server software can run on most computer operating systems. By modifying the source code, Apache Web server can provide proportional delay differentiation service. The single variable model is generally used in Apache Web servers, whose input is the ratio of the number of worker threads handling different types of clients, and the output is the connection delay ratio of different classes of clients. The single variable model needs to be modeled many times when dealing with the multi-priority delay guarantee, and the scalability is not good. In this paper, a multi-input and multi-output model of ApacheWeb server is proposed, and a decentralized self-tuning controller is designed based on decentralized control theory and self-tuning control theory. According to the decentralized control theory, the multivariable system is decomposed into interrelated single-variable subsystems, and the SISO model is obtained by identifying the subsystems respectively. The input is the ratio of the number of worker threads to the total number of worker threads in the current category client connection, and the output is the sum of the average connection delay of the current class client side and the average delay of all class clients. In order to deal with the coupling effect between subsystems, self-tuning controller is applied to each subsystem. The controller dynamically adjusts the number of worker threads processing different priority requests, which can ensure that higher priority requests can be processed faster and maintain the average delay ratio of different priority requests to set values. The model and controller parameters are updated in real time according to the on-line identification results., WinNT MPM is the only multitask processing module (MPM). Used by Apache under Windows platform. The modified WinNT MPM adds sampling mechanism, connects classifier and control thread, and constructs a closed loop control system in Apache. Using Vmware virtual machine to build a simulation platform, the test results show that even if the number of concurrent customer connections changes sharply, the servers in the closed-loop system can maintain a good proportional delay guarantee.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TP393.09;TP273

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