论文标题
在日志结构化商店中有效回收空间
Efficiently Reclaiming Space in a Log Structured Store
论文作者
论文摘要
一个日志结构化商店在大型缓冲区内使用单个写入I/O用于许多不同的和非连续的页面，而不是分别为每个页面使用写入I/O。这就要求将页面重新定位在每个写作上，因为页面永远不会更新到位。相反，每条写入页面都会动态重塑。日志结构是为文件系统发明并最初用于的。如今，在SSD控制器中使用了一种日志结构形式，因为SSD需要在重复使用闪存存储之前擦除大块页面。没有现场更新要求回收过时页面的存储（垃圾收集或“清洁”）。我们分析清洁性能并引入清洁策略，该策略使用一种新的方式来优先考虑收集垃圾的旧页面的顺序。我们的清洁策略近似于“最佳清洁策略”。仿真研究证实了分析的结果。该策略比以前的清洁策略有重大改进。
A log structured store uses a single write I/O for a number of diverse and non-contiguous pages within a large buffer instead of using a write I/O for each page separately. This requires that pages be relocated on every write, because pages are never updated in place. Instead, pages are dynamically remapped on every write. Log structuring was invented for and used initially in file systems. Today, a form of log structuring is used in SSD controllers because an SSD requires the erasure of a large block of pages before flash storage can be reused. No update-in-place requires that the storage for out-of-date pages be reclaimed (garbage collected or "cleaned"). We analyze cleaning performance and introduce a cleaning strategy that uses a new way to prioritize the order in which stale pages are garbage collected. Our cleaning strategy approximates an "optimal cleaning strategy". Simulation studies confirm the results of the analysis. This strategy is a significant improvement over previous cleaning strategies.
