Lazy-RTGC: A Real-Time Lazy Garbage Collection Mechanism with Jointly Optimizing Average and Worst Performance for NAND Flash Memory Storage Systems
Lazy-RTGC: A Real-Time Lazy Garbage Collection Mechanism with Jointly Optimizing Average and Worst Performance for NAND Flash Memory Storage Systems
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DOI：
10.1145/2746236
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发表时间：
2015-06
期刊：
影响因子：
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通讯作者：
Qi Zhang-;Xuandong Li;Linzhang Wang;Tian Zhang;Yi Wang;Z. Shao
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文献类型：
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作者：
Qi Zhang-;Xuandong Li;Linzhang Wang;Tian Zhang;Yi Wang;Z. Shao
由于NAND闪存具有许多独特的性能，已被广泛应用于关键任务的硬实时系统和一些软实时系统。然而，NAND闪存中的非确定性垃圾收集操作使得难以预测每个数据请求的系统响应时间。本文介绍了一种用于NAND闪存存储系统的实时惰性垃圾收集机制Lazy-RTGC。Lazy-RTGC采用了两种设计优化技术：按需页面级地址映射和部分垃圾收集。按需页级地址映射可以实现高性能的地址转换，并且可以以最小的RAM成本有效地管理闪存空间。另一方面，部分垃圾收集可以提供有保证的系统响应时间。通过采用这些技术，Lazy-RTGC联合优化了平均和最差的系统响应时间，并提供了回收的空闲空间的下限。在FlashSim中实现了Lazy-RTGC，并与典型的实时NAND闪存管理方案进行了比较。实验结果表明，我们的技术可以显着提高平均和最坏的系统性能，非常低的额外闪存空间的要求。
Due to many attractive and unique properties, NAND flash memory has been widely adopted in mission-critical hard real-time systems and some soft real-time systems. However, the nondeterministic garbage collection operation in NAND flash memory makes it difficult to predict the system response time of each data request. This article presents Lazy-RTGC, a real-time lazy garbage collection mechanism for NAND flash memory storage systems. Lazy-RTGC adopts two design optimization techniques: on-demand page-level address mappings, and partial garbage collection. On-demand page-level address mappings can achieve high performance of address translation and can effectively manage the flash space with the minimum RAM cost. On the other hand, partial garbage collection can provide the guaranteed system response time. By adopting these techniques, Lazy-RTGC jointly optimizes both the average and the worst system response time, and provides a lower bound of reclaimed free space. Lazy-RTGC is implemented in FlashSim and compared with representative real-time NAND flash memory management schemes. Experimental results show that our technique can significantly improve both the average and worst system performance with very low extra flash-space requirements.