[vardump]

I write kernel mode drivers as my day job, and this is certainly the first time I've ever heard of non-swappable being called "wired".

It might be called "non-pageable", "pinned", "non-swappable", etc. Out of those, I'd prefer "non-pageable", because it's the most descriptive term for it.

Non-standard terminology is not great for communication.

[gaius]

I write kernel mode drivers as my day job, and this is certainly the first time I've ever heard of non-swappable being called "wired".

For what OS? Consider https://wiki.freebsd.org/Memory

Wired

    - Non-pageable memory: cannot be freed until explicitly released by the owner
    - Userland memory can be wired by mlock(2) (subject to system and per-user limits)
    - Kernel memory allocators return wired memory
    - Contents of the ARC and the buffer cache are wired
    - Some memory is permanently wired and is never freed (e.g., the kernel file itself)

OSX is derived from BSD.

[vardump]

> For what OS?

Check my other reply above. Did some FreeBSD work ~15 years ago, but I guess I'd already forgotten.

[Aaargh20318]

> I write kernel mode drivers as my day job, and this is certainly the first time I've ever heard of non-swappable being called "wired".

Really ? Because it's literally called that in macOS Activity Monitor app, the term is also used in Apple's kernel documentation and API's (e.g. in the `mem_and_io_snapshot` struct defined in 'debug.h' in Kernel.framework). It's also mentioned in the Kernel Programming Guide.

[vardump]

Interesting.

Never did macOS drivers, just bare metal, Windows and Linux so far, macOS is not very big in our niche. Weird that Apple's terminology is so different.

Typing this on a Macbook Pro, and I can see that Activity Monitor does mention "wired" memory.

[Aaargh20318]

I did a little googling and I see the terminology is also used in the Mach microkernel, which macOS's XNU kernel was built upon. It looks like it's not something Apple came up with.

[module0000]

It's a MacOS thing. "Wired" confused me also initially. All it means is pages marked as "Wired" can't be offloaded to swap.