發(fā)布時間：2018-04-13 12:01

  本文選題：閃存 + 動態(tài)連續(xù)空間�。� 參考：《沈陽建筑大學(xué)》2013年碩士論文

【摘要】：Flash存儲器由于具有體積小、重量輕、低成本、高集成度、抗震動性好等優(yōu)點(diǎn)使得它被廣泛應(yīng)用于Mp3、MP4、手機(jī)等移動設(shè)備中。Flash存儲器應(yīng)用于嵌入式系統(tǒng)的最優(yōu)方法就是在Flash存儲器中構(gòu)造一個文件系統(tǒng),使得Flash存儲器管理和存儲文件時可以應(yīng)用文件代號。由于Flash存儲器中每一內(nèi)存塊不能無限擦寫,即具有有限的壽命,每一個內(nèi)存塊的擦寫次數(shù)的最大范圍一般在105～106次之間。因此在文件存儲過程中,必須采用一定的特殊機(jī)制,使得趨近于均衡使用各個內(nèi)存塊,避免某些塊提前達(dá)到損壞,以至于影響整個Flash存儲器。 連續(xù)空間等概率存儲算法只是將具有相同寫入次數(shù)且連續(xù)的內(nèi)存塊定義為連續(xù)空間,這導(dǎo)致尋找到的連續(xù)空間并不是很大,從而影響文件的查找與讀取速度。其實(shí)在龐大的數(shù)據(jù)存儲過程中,系統(tǒng)對寫入次數(shù)有一定波動范圍且連續(xù)的內(nèi)存塊并不敏感。因此本文提出了動態(tài)連續(xù)空間等概率算法,它的主要思想是在已有的連續(xù)空間等概率存儲算法的基礎(chǔ)上加入一個動態(tài)范圍,其作用是在文件存儲過程中,擴(kuò)大連續(xù)空間,使文件存儲在更大的連續(xù)空間中,進(jìn)一步解決不均衡利用存儲空間的問題。 在算法仿真的結(jié)果中,筆者發(fā)現(xiàn)加入動態(tài)范圍以后,空間利用率提高了數(shù)倍。與此同時還發(fā)現(xiàn)此算法只專注于不斷擦寫的文件。其實(shí)在文件存儲過程中,不僅包括不斷擦寫的文件,而且還包括文件存入內(nèi)存塊后長時間不被擦除導(dǎo)致所對應(yīng)的內(nèi)存塊的寫入次數(shù)非常小,從而導(dǎo)致閃存一部分充分利用,另一部分不被利用,從而整體上導(dǎo)致閃存存儲空間不被均衡利用。為了解決這種閃存存儲空問不均衡利用的問題,本文又提出一個基于靜態(tài)數(shù)據(jù)負(fù)載均衡的存儲算法,使長時間不被擦寫的文件移動到經(jīng)常擦寫以至于寫入次數(shù)很大的內(nèi)存塊中,保證閃存存儲空間利用程度最大化,優(yōu)化了Flash存儲器的整體存儲性能,延長了Flash存儲器的使用壽命。 本文在連續(xù)空間等概率存儲文件管理系統(tǒng)的基礎(chǔ)上設(shè)計(jì)了兩種算法,并通過C++程序?qū)λ惴ㄟM(jìn)行了仿真。實(shí)驗(yàn)結(jié)果表明：在相同操作的條件下,連續(xù)空間等概率存儲算法只是將具有相同寫入次數(shù)且連續(xù)的內(nèi)存塊定義為連續(xù)空間。而筆者提出的第一個算法一動態(tài)連續(xù)空間等概率存儲算法在總寫入次數(shù)方面雖略遜于連續(xù)空間等概率存儲算法,但是在文件平均斷開次數(shù)方面明顯小于連續(xù)空間等概率存儲算法,提高了文件的連續(xù)性,減少了文件的查找和讀取時間。筆者提出的第二個算法—基于靜態(tài)數(shù)據(jù)負(fù)載平衡的存儲算法,研究了將長期不移動的文件移動到寫入次數(shù)較高的內(nèi)存塊中,避免閃存一部分由于存入長期不移動的文件而不被充分利用,另一部分被不斷擦寫而提前達(dá)到損壞,延長了Flash存儲器的使用壽命。
[Abstract]:Flash memory has small size, light weight, low cost and high integration.The advantages of good vibration resistance make it widely used in MP4. The best method of using .Flash memory in embedded system in mobile devices such as mobile phone is to construct a file system in Flash memory.Enables Flash memory to apply file codes when managing and storing files.Because every memory block in Flash memory can not be erased indefinitely, that is, it has a limited lifetime, the maximum write number of each memory block is generally in the range of 105 ~ 10 ~ 6 times.Therefore, in the process of file storage, a certain special mechanism must be adopted to make the memory block use equably, so as to avoid the damage of some blocks in advance, and thus affect the whole Flash memory.The equal-probability storage algorithm of continuous space only defines the memory block with the same number of write times and continuous memory as continuous space, which leads to the finding of continuous space is not very large, thus affecting the speed of searching and reading files.In fact, in the huge data storage process, the system has a certain range of write times and continuous memory block is not sensitive.The problem of unbalanced utilization of storage space is further solved by making files stored in larger continuous space.In the algorithm simulation, the author found that the space utilization rate increased several times after the dynamic range was added.At the same time, it is also found that the algorithm only focuses on constantly erasing files.In fact, in the process of file storage, not only files that are constantly being erased, but also files stored in memory blocks are not erased for a long time, resulting in very small number of writes to the corresponding memory blocks, which results in the full use of a portion of flash memory.The other part is not used, so that the flash memory space is not balanced.In order to solve the problem of the unbalanced utilization of flash memory, a storage algorithm based on static data load balancing is proposed in this paper, in which files that are not erased for a long time are moved to memory blocks that are often erased and are written to a large number of times.It ensures the maximum utilization of flash memory space, optimizes the overall storage performance of Flash memory, and prolongs the service life of Flash memory.In this paper, two algorithms are designed based on the continuous space equal probability storage file management system, and the algorithm is simulated by C program.The experimental results show that under the same operation condition, the continuous space equal probability storage algorithm only defines the memory block with the same number of writes and continuous memory as continuous space.The first algorithm proposed by the author, the dynamic continuous space equal probability storage algorithm, is slightly inferior to the continuous space equal probability storage algorithm in terms of the total write times.However, the average number of disconnected files is obviously smaller than the probability storage algorithm such as continuous space, which improves the continuity of files and reduces the searching and reading time of files.Based on the static data load balancing storage algorithm, the second algorithm proposed by the author is to move the long-immovable files to the memory blocks with high write times.One part of the flash memory is not fully utilized because it is stored in the long-immovable files, and the other part is continuously erased and damaged in advance, thus prolonging the service life of the Flash memory.
【學(xué)位授予單位】：沈陽建筑大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2013
【分類號】：TP333

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