What is cache tag directory?
caching, operating-system
Solution
In the memory organisation of caches, there are two blocks - one block is reserved for storing tags associated with each line of cache, and the other block is reserved for storing the cached data.
The following figure shows memory organisation in direct mapped cache.
Usually, a "cache block" refers to the block that stores the cached data and "tag directory" refers to the block that stores the tags associated with each cahe line.
Size of tag directory = (number of bits to represent 1 tag) × (number of cache lines) = tag bits × (cache size / line size)
Note: line size of cache = block size of main memory
Problem
I am studying Operating Systems and I am stuck on this term "Tag Directory". What is tag directory exactly? Where is it present? What is its role? I am a little confused. Please help.