What are the linux caching mechanisms?

Linux caching mechanism mainly includes page cache, directory cache, VFS index node cache, buffer cache, etc. Detailed introduction: 1. Page cache: cache the contents of the file in memory to reduce the number of reads from the disk. When a file needs to be read, the system will first check whether there is a cache for the file in the page cache. If it exists, it will read it directly from the cache. Otherwise, it will read it from the disk and cache the read data to the page cache. Medium; 2. Directory caching: cache the directory information of files in memory to reduce the number of disk accesses, etc.

Operating system for this tutorial: Windows 10 system, Dell G3 computer.

Linux caching mechanisms mainly include the following:

1. Page caching: cache the contents of files in memory to reduce the number of reads from the disk. When a file needs to be read, the system will first check whether there is a cache for the file in the page cache. If it exists, it will read it directly from the cache. Otherwise, it will read it from the disk and cache the read data to the page cache. middle.
2. Directory cache: Cache the directory information of the file in memory to reduce the number of disk accesses. When a file needs to be accessed, the system will first check whether the directory information for the file exists in the directory cache. If it exists, the file can be accessed directly. Otherwise, the entire directory tree needs to be traversed to find the file. Only directories shorter than 15 characters can be saved in the directory cache.
3. VFS index node cache: The VFS index node is a Hash table that is continuously read. The index node cache provided by VFS can speed up access to the file system. One VFS inode is read from the inode cache at a time, so that the system can save access time to read the physical device.
4. Buffer cache: When processes use a mounted file system, they generate many read and write requests for block device data blocks.

In short, Linux cache mechanisms include several types such as page cache, directory cache, VFS index node cache and buffer cache, which improve file access speed and system performance in different ways.

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