Operating Systems

What a process really is, why threads are cheaper, context switches, and how user code enters the kernel.

How the OS decides who runs: algorithms, starvation and priority inversion, Linux CFS, and container CPU limits.

Paging, TLBs, page faults, replacement and the OOM killer — the machinery under every malloc and mmap.

Atomic instructions, mutexes vs spinlocks, deadlock theory, condition variables and IPC — the OS view of concurrency.

The page cache, inodes and journaling, fsync and durability, epoll vs io_uring, and zero-copy — I/O from syscall to platter.