[dfox]

I would say that for any modern unix implementation mmaped pages are quite significant, as all the read-only copies of libc code, other shared libraries and various mmaped data files (iconv tables, locales, terminfo, gettext catalogs…) are not exactly small.

[robinsonb5]

Which is why disabling swap in the hopes of preventing the system grinding to a halt on out-of-memory doesn't work, and actually makes things worse.