What is dentry cache?

Similarly, what is an inode cache?

VFS inode cache can be described as a hashtable whose entries point to other VFS inode with the same hash value. An inode's hash value is determined by its inode number, and the device identifier of the physical device that contains the file system.

What is SReclaimable, you ask? This means that Reclaimable refers to memory that kernel uses (for instance, as a filesystem memory cache), but that could be used in other ways, such as to fulfill memory requests from user apps that cannot be fulfilled by other methods, for example, by using MemFree (free) memory.

Similar to the above, one might ask: What are Dentries?

A directory is represented by a dentry, which is a data structure. These structures can be used to create a memory cache which represents the file structure of a disk. The OS could list the contents of the directory directly by going to its dentries (if it is present) and listing them (a series inodes).

What are dentries and inodes?

Inodes and dentries are used to represent a filesystem in memory. Inodes represent the files and directories. A dentry object has a string name (d_name), an inode pointer (d_inode) and a parent dentry pointer (d_parent).