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  本文選題：嵌入式系統(tǒng)　切入點：NAND　出處：《中南大學》2013年碩士論文　論文類型：學位論文

【摘要】：摘要：在會議評審輔助支撐系統(tǒng)中海量數(shù)據(jù)的存取對嵌入式終端的性能提出了很高的要求,尤其需要大量數(shù)據(jù)快速讀寫,并保證有較高的可靠性,而應用于嵌入式系統(tǒng)的閃存芯片本身具有讀寫不平衡和異地更新等特點,需要進行系統(tǒng)的數(shù)據(jù)管理研究。 論文針對實際問題提出了基于熱度優(yōu)先級的改進置換算法,以及基于該算法的兩級cache映射粒度交換的FTL(閃存轉(zhuǎn)換層)算法-CEFTL。該算法將NAND閃存劃分為數(shù)據(jù)塊和轉(zhuǎn)換塊,頁映射表保存在轉(zhuǎn)換塊,地址映射機制則采用塊映射和頁映射兩種不同的粒度,通過全局轉(zhuǎn)換字典(GTD)進行交換,從而提高cache命中率。 通過研究LRU-WSR算法,論文借鑒其中提出的冷熱檢測算法,并對LRU-WSR的置換劃分進行改進,根據(jù)訪問數(shù)據(jù)在NAND閃存存儲中的訪問頻率和存儲特點將數(shù)據(jù)塊標記成四種不同優(yōu)先級級別,通過這種優(yōu)先級的劃分構(gòu)建兩級置換算法,以此解決NAND閃存中數(shù)據(jù)訪問的特殊性帶來的置換開銷。 論文以兩級置換算法為基礎構(gòu)建CEFTL映射算法,針對RFTL算法在可靠性和磨損均衡上的不足,改變其混合映射中頁映射存儲位置,借鑒CDFTL提出的兩級cache機制,減少RAM空間消耗,從而使OOB可存儲碼長更長的BCH校驗碼,提高可靠性。對RFTL的分段垃圾回收策略中的交換操作和移位操作進行改進,加入基于熱度的塊映射交換,使系統(tǒng)在運行過程中,閃存物理塊的擦除次數(shù)相近。通過優(yōu)先級置換的策略,使CEFTL的系統(tǒng)平均響應時間接近RFTL的最佳響應時間。
[Abstract]:Absrtact: the access of massive data in the conference review support system requires high performance of embedded terminals, especially requires a large number of data to read and write quickly, and to ensure high reliability. The flash memory chip used in the embedded system has the characteristics of unbalanced reading and writing and remote updating, so it is necessary to study the data management of the system. In this paper, an improved permutation algorithm based on heat priority is proposed to solve practical problems, and an FTL (flash memory conversion layer) algorithm based on two-level cache mapping granularity exchange is proposed. The algorithm divides NAND flash memory into data blocks and conversion blocks. The page mapping table is stored in the translation block, and the address mapping mechanism uses block mapping and page mapping two different granularity, which is exchanged by the global translation dictionary, so as to improve the hit rate of cache. By studying the LRU-WSR algorithm, this paper uses the proposed cold and heat detection algorithm for reference, and improves the permutation partition of LRU-WSR. According to the access frequency and storage characteristics of access data in NAND flash memory, the data block is marked into four different priority levels. In this way, the permutation overhead caused by the particularity of data access in NAND flash memory is solved. In this paper, we construct CEFTL mapping algorithm based on two-level permutation algorithm. Aiming at the deficiency of RFTL algorithm in reliability and wear equalization, we change the storage location of page mapping in its hybrid mapping, draw lessons from the two-level cache mechanism proposed by CDFTL, and reduce the space consumption of RAM. So that OOB can store longer code length BCH check code, improve the reliability, improve the switching operation and shift operation in the section garbage collection strategy of RFTL, add block mapping exchange based on heat, make the system run in the process. The average response time of CEFTL system is close to the optimal response time of RFTL.
【學位授予單位】：中南大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：TP333

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本文編號：1564952