| Summary: | 碩士 === 國立臺灣大學 === 資訊工程學研究所 === 101 === For decades, the number of devices based on flash memory increases explosively, compared with traditional disk-based storage, due to the advantages of flash memory, such as non-volatility, lower power consumption and durability. Different flash-based devices with different kinds of bus interfaces have distinct limitations such as the current limitation, the number of channels, the buffer size supported to block the requests temporarily. However, the existing schedulers wouldn''t be devised especially for all the limitations above of flash-based devices, especially the current limitation which results from the bus interface. Moreover, we also observe that in terms of users, the performance of read requests served is more important than the performance of write requests because the system should return the data to the host with read requests served. From the observations above, in this paper, we design CAS schedulers with the integrated consideration of the current limitation, the number of channels, the buffer size, and the characteristics of flash memory to maximize the performance of flash devices. To display how the efficiency and performance of CAS schedulers are in the realistic environment, we present the results of the experiments performed on the on-line environment simulated. Compared with NOOP extended to the environment of multiple channels, the most popular scheduler of Linux 2.6 for flash memory devices, the results show that the performance improvement is up to 21%.
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