Linux Device Drivers Development

What is a cache?

A cache is temporary, small, and fast memory used to keep copies of data from larger and often very slow memory, typically placed in systems where there is a working set of data accessed far more often than the rest (for example, hard drive, memory).

When the first read occurs, let's say a process requests some data from the large and slower disk, the requested data is returned to the process, and a copy of accessed data is tracked and cached as well. Any consequent read will fetch data from the cache. Any data modification will be applied in the cache, not on the main disk. Then, the cache region whose content has been modified and differs from (is newer than) the on-disk version will be tagged as dirty. When the cache runs ...