for slow disk performance
Buffer cache (in memory) : cache file blocks in memory to capture locality in buffer cache or buffer cache - Idea: cache file blocks in memory to capture locality in buffer cache (or buffer cache)
- this cache is system wide, shared by all processes
- cache consistency issues can be occur
Page cache - – Caches pages rather than disk blocks using virtual memory techniques. – Memory-mapped I/O uses a page cache.
Unified Buffer cache -– A unified buffer cache uses the same page cache to cache both memory-mapped pages and ordinary file system I/O. – Avoids double caching and the possibility of inconsistencies between page caches and buffer caches.