Wired Memory Limit (macOS)
The macOS system cap on maximum GPU-addressable unified RAM
Apple
In plain English
The safety barrier macOS puts up to stop one app from taking all the RAM, which can be tuned to unlock 85% of your Mac's memory for AI models.
Technically
The kernel ceiling governing maximum non-pageable memory allocatable to the Metal GPU on Apple Silicon (defaulting to ~75% of physical RAM). Can be adjusted up to ~85% via sysctl iogpu.wired_mem_limit to fit larger quantized models into unified memory.