Tagged: #virtual-memory

The kernel's own malloc — a hierarchy of zone allocators, the kalloc heap, and slab caches for specific types. Different from user-side VM, and just as important.

How XNU responds when memory gets tight — the four-stage pressure pipeline from free pages through compression to swap to process termination, and what each stage costs.

Walk a single mmap call from libc, through BSD into Mach VM, the lazy first-touch fault, and the pmap entry that finally makes the file accessible as memory.

Every system dylib pre-linked into one giant memory-mappable file, shared across every process on the system. Why a fresh process has 1 GB of virtual size but tiny resident memory.

Every macOS process gets a private address space it can't possibly afford. Here's how XNU gives it one anyway — pmap, vm_map, the compressor, and jetsam.