[Cryptography] swap needed, or not

[CodesInChaos]

If you have no swap space available (even if never used in practice)
you need to either overcommit or you waste RAM, since you need to
reserve physical memory for every potential copy in a copy-on-write
scenario. While that memory can still be used as read cache (since
those can be discarded at will), it can still be limiting when you
have a lot of sharable memory.

Windows chose to reserve commited memory, unixy systems usually overcommit.