Glossary
Wired memory
Memory the system needs to run, which can't be compressed, swapped or given to apps.
What it is
Apple defines wired memory as memory required by the system to operate, which can't be cached and must stay in RAM. It holds the kernel, drivers and other data that must always be immediately available.
Wired memory can't be compressed or moved to swap, so every gigabyte of it is a gigabyte apps can't use.
Why it matters
Wired memory is usually stable. If it is unusually large, apps have less room and memory pressure rises sooner.
In Activity Monitor
“Wired Memory” under the Memory Pressure graph in the Memory tab.
In iKnowMyMac
The memory-by-type breakdown in the Overview and the Memory tab.
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