Evaluation of Write Sequence Reordering Based Buffer Replacement Algorithms for Flash Memory Based Systems

Arjun Singh Saud; Hari Sharan Bhatt

Abstract

Many page replacement algorithms have been developed for disk-based systems. All of them consider the hit rate as a key performance measure. Flash memory has different characteristics than hard disks, such as asymmetric I/O latency among read, write, and erase operations. The read operation is faster than the write and erase operation, and it does not support in-place updates. Besides, write operations shorten the life of flash memories. Therefore, the number of write counts is also an important factor to be considered for flash-based systems. This research work studied WSR-based algorithms, namely the LRU-WSR and LIRS-WSR, in terms of both hit rate and write count. The trace-driven simulation is performed with four different workloads: random, read-most, write-most, and Zipf traces. The simulation result showed that LIRS-WSR is better than LRU-WSR when locality is not too strong; otherwise, the performance of LRU-WSR is better.

Abstract

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