Linux虚拟文件系统层的路径检索加速

Accelerating path lookup in virtual file system of Linux

为解决Linux内核传统路径检索日益凸显的开销问题,提出Staged Lookup以加速路径检索,通过动态缓存热目录来减少文件访问的时延。Staged Lookup的核心在于缓存频繁使用的目录项,从而避免从根节点重复遍历路径。不同于从根结点开始的检索操作,Staged Lookup扩展了搜索策略,允许从最近缓存的目录项向后或向前进行路径检索。在Linux内核版本3.14和5.4上部署Staged Lookup的原型,并开展实际系统测试。实验数据显示,相比于传统的路径检索方式,Staged Lookup能实现高达46.9%的性能提升。

To solve the increasingly prominent cost of traditional path lookup strategy in the Linux kernel,Staged Lookup was proposed to accelerate path lookup by dynamically caching hot directories to reduce file access latency.The essence of Staged Lookup lay in caching frequently used directory entries,thus avoiding the repetitive traversal of paths from the root node.Unlike the retrieval operations that start from the root node,Staged Lookup expanded the search strategy to allow for forward or backward path lookup from the most recently cached directory entry.A prototype of Staged Lookup was deployed on Linux kernel versions 3.14 and 5.4 and subjected to real system tests.Experimental data indicates that Staged Lookup can achieve performance improvements of up to 46.9%compared to traditional path lookup methods.