Memory

A deep dive into Linux Page Cache — how VFS, inode, and address_space organize cached file content, how Buffered I/O and mmap create and release cache pages, the four mmap mapping types, and the tools to observe cache hit rates.

Why modern multi-socket systems moved from UMA to NUMA — the FSB bottleneck, per-socket memory controllers, local vs remote access, and how Linux handles NUMA (plus the classic MySQL swap-insanity problem fixed by interleaving).

How Linux organizes physical memory — comparing FLATMEM, DISCONTIGMEM, and SPARSEMEM, and how each model implements pfn_to_page / page_to_pfn.

Memory consistency models define which reorderings are legal. A walk through SC, TSO (x86), PSO, and relaxed models (ARM / POWER), plus the memory barriers used to enforce ordering when it matters.