標題: | Eager Synching: A Selective Logging Strategy for Fast fsync() on Flash-Based Android Devices |
作者: | Chang, Li-Pin Sung, Po-Han Chen, Po-Tsang Chen, Po-Hung 資訊工程學系 Department of Computer Science |
關鍵字: | Design;Performance;Algorithm;Android;file system;fsync();eMMC;flash storage |
公開日期: | 1-Apr-2017 |
摘要: | Flash storage has been a standard component in Android devices. Recent research has reported that application data management in Android involves frequent fsync() operations. The current fsync() implementations, including those of ext4 and F2FS, have several common drawbacks. Specifically, ext4 commits a transaction every time to sync a file, whereas F2FS commits a checkpoint to sync a directory. Committing a transaction or checkpoint flushes all dirty data from the page cache to the flash storage via many small, random block write requests. The resultant high I/O frequency and excessive write traffic cause a high fsync() latency. This study presents an efficient fsync() method, called eager synching, which is based on a simple idea: write less, and write sequentially. To sync a file, eager synching writes only a subset of all dirty data in the page cache to a sequential log space using a few sequential block write requests. It does not involve transaction or checkpoint committing. We successfully implemented eager synching in ext4 and F2FS, and our experimental results show that, compared with the original fsync() methods of ext4 and F2FS, eager synching reduced the average and maximum fsync() latencies by up to 72% and 91%, respectively, block-level write traffic by up to 35%, and I/O frequency by up to 66%. Through enhanced crash recovery procedures, eager synching can successfully recover all previously synched files while still guaranteeing the file system integrity. We also conducted live application replays using the proposed eager synching approach and observed that this approach significantly improved the application frame updating rate and application execution time. |
URI: | http://dx.doi.org/10.1145/2930668 http://hdl.handle.net/11536/145408 |
ISSN: | 1539-9087 |
DOI: | 10.1145/2930668 |
期刊: | ACM TRANSACTIONS ON EMBEDDED COMPUTING SYSTEMS |
Volume: | 16 |
Appears in Collections: | Articles |