| Summary: | 碩士 === 國立成功大學 === 電腦與通信工程研究所 === 93 === Compact-Flash has the advantages of small size, lightweight, shock resistant, low power consumption, and nonvolatile, thus, it shows promise for being used in storage device for embedded systems. Nowadays, Compact-Flash has been used widely in embedded multimedia applications. However, most file systems on Compact-Flash are FAT file system(FATfs), FATfs is simple, easy to implement, and widely-used, but it’s performance is poor. Performance is the most important issue for multimedia applications. So, the goal of this thesis is to implement a high performance FAT file system, we focus on three directions: 1.separate cache, 2.exploiting Compact-Flash busy waiting time, 3.direct access for burst read/write and reduce CPU loading.
We separate cache into three caches: Data Cache, FAT Cache, FDE Cache. File system can access ordinary data through Data Cache, access File Allocation Table through FAT table, and access FAT Directory Structure through FDE Cache. We use CF busy waiting time to prefetch next cluster number and replenish free clusters, and delay the execution of memory copy to the next CF busy waiting time. When large amount of access, we use CPU to access CF directly instead of accessing through cache, and we also reduce division operation to reduce CPU loading.
Experiment result show that exploiting CF busy waiting time can reduce response time in read operation but fail in write operation. And our system has good result in response time test, and has lower CF read/write times.
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