> Memory pressure is an internal macOS system metric Interesting. That'll probab...

> Memory pressure is an internal macOS system metric

Interesting. That'll probably mean it's in the source code Apple publishes for macOS:

https://github.com/apple-oss-distributions/distribution-macO...

Doing a search for the phrase "memory pressure" in the containing organisation (apple-oss-distributions) shows some relevant stuff:

https://github.com/search?q=org%3Aapple-oss-distributions+%2...

• memorystatus.md : https://github.com/apple-oss-distributions/xnu/blob/94d3b452...

    # Memorystatus Subsystem

    Dealing with memory pressure by forcibly recovering pages.
    (etc)

• memory_pressure.1 : https://github.com/apple-oss-distributions/system_cmds/blob/...

    Looks like the man page for a `memory_pressure` command

• freezer.md : https://github.com/apple-oss-distributions/xnu/blob/94d3b452...

    # Freezer

    Details of how some processes can be swapped out to disk.

    [...] The freezer is a limited form of swap on embedded. Under memory pressure,
    the freezer picks apps to freeze.
    (etc)

And a whole bunch more. With some digging, it should be possible to find the exact info. :)