發(fā)布時(shí)間：2018-12-10 11:42

【摘要】：多媒體服務(wù)器需要一個(gè)實(shí)時(shí)磁盤(pán)調(diào)度算法來(lái)為具有軟實(shí)時(shí)要求的連續(xù)多媒體流服務(wù)。由于數(shù)據(jù)傳統(tǒng)的磁盤(pán)調(diào)度算法沒(méi)有考慮磁盤(pán)請(qǐng)求的實(shí)時(shí)性,因此需要對(duì)傳統(tǒng)的磁盤(pán)調(diào)度算法SCAN進(jìn)行改進(jìn)以使其能夠應(yīng)用于多媒體服務(wù)器的磁盤(pán)請(qǐng)求。 本文提出一個(gè)新的實(shí)時(shí)磁盤(pán)調(diào)度算法,稱之為公平帶寬分配電梯調(diào)度SCAN-FBD(SCAN with Fair Bandwidth Distribution),能夠?yàn)榭勺兇a率編碼的流提供質(zhì)量保證,并且為非周期任務(wù)限制了響應(yīng)時(shí)間。SCAN-FBD算法將實(shí)時(shí)流分為保證任務(wù)和可選任務(wù)。只有當(dāng)一個(gè)流中的保證任務(wù)被滿足時(shí),接納控制才會(huì)接納這個(gè)流。通過(guò)帶寬預(yù)留和接納控制機(jī)制,SCAN-FBD算法能夠?yàn)橐呀?jīng)處于服務(wù)中的多媒體流提供質(zhì)量保證,為非實(shí)時(shí)任務(wù)也預(yù)留了帶寬以保證非實(shí)時(shí)任務(wù)具有合理的響應(yīng)時(shí)間。質(zhì)量協(xié)調(diào)機(jī)制使得系統(tǒng)能為更多的磁盤(pán)請(qǐng)求服務(wù)。負(fù)責(zé)監(jiān)測(cè)與動(dòng)態(tài)調(diào)整磁盤(pán)帶寬分配機(jī)制能夠根據(jù)實(shí)時(shí)請(qǐng)求與非實(shí)時(shí)請(qǐng)求的帶寬需求,動(dòng)態(tài)調(diào)整磁盤(pán)帶寬在兩類任務(wù)間的分配,更合理地利用磁盤(pán)帶寬并進(jìn)一步提高磁盤(pán)吞吐率。SCAN-FBD采用一種積極策略在運(yùn)行時(shí)動(dòng)態(tài)回收未用的帶寬。被回收的帶寬被用于為可選任務(wù)或者更多的非實(shí)時(shí)任務(wù)服務(wù)。 為了評(píng)價(jià)所提出的SCAN-FBD算法的性能進(jìn)行了一系列的實(shí)驗(yàn)。實(shí)驗(yàn)結(jié)果顯示,SCAN-FBD比其他算法明顯為實(shí)時(shí)流提供了更好的質(zhì)量,同時(shí)也大大縮短了非實(shí)時(shí)任務(wù)的響應(yīng)時(shí)間,是一個(gè)高效、靈活的實(shí)時(shí)磁盤(pán)調(diào)度算法。
[Abstract]:Multimedia server needs a real-time disk scheduling algorithm to serve continuous multimedia streams with soft real-time requirements. Because the traditional disk scheduling algorithm does not consider the real-time of the disk request, it is necessary to improve the traditional disk scheduling algorithm (SCAN) so that it can be applied to the disk request of the multimedia server. In this paper, a new real-time disk scheduling algorithm called Fair bandwidth allocation Elevator scheduling (SCAN-FBD (SCAN with Fair Bandwidth Distribution),) is proposed, which can provide quality assurance for variable bit-rate encoded streams. And the response time is limited for aperiodic tasks. The SCAN-FBD algorithm divides real-time flows into guaranteed tasks and optional tasks. Admission control accepts a stream only if the guaranteed task in the stream is satisfied. By means of bandwidth reservation and admission control mechanism, the SCAN-FBD algorithm can provide quality assurance for multimedia streams that are already in service, and also reserve bandwidth for non-real-time tasks to ensure a reasonable response time for non-real-time tasks. The quality coordination mechanism enables the system to serve more disk requests. Monitoring and dynamically adjusting the disk bandwidth allocation mechanism can dynamically adjust the disk bandwidth allocation between the two types of tasks according to the bandwidth requirements of real-time and non-real-time requests. Using disk bandwidth more reasonably and further improving disk throughput, SCAN-FBD adopts an active strategy to dynamically recover unused bandwidth at run time. The recovered bandwidth is used to serve optional tasks or more non-real-time tasks. A series of experiments were carried out to evaluate the performance of the proposed SCAN-FBD algorithm. Experimental results show that SCAN-FBD provides better quality for real-time stream than other algorithms, and also greatly reduces the response time of non-real-time task. It is an efficient and flexible real-time disk scheduling algorithm.
【學(xué)位授予單位】：中南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2012
【分類號(hào)】：TP333.35

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