>> Hmmm... I was under the impression that the general rule of thumb for swap
>> was 1.5 to 2 times your actual RAM.  For low RAM systems, I wouldn't use
>> any less than twice your RAM.
>
> That rule is a relic from the old vm design of 4.3BSD and before.
> It's totally irrelevant now.

To be a bit clearer:

This has to do with whether the system supports reclaiming swap pages
that back pages currently in core.  Some systems don't do this, and
therefore may keep an extra copy of everything in core even when space
is tight.  UVM supports this reclamation as of 19990326 (uvm_pdaemon.c
version 1.14, which is in the 1.4 release).