How big should the swap partition be?

[Herb Weiner]

A/UX has eaten up all my disk and memory, so it's time to upgrade...

The question is, how do I calculate the required size for the swap
partition?  Is this a function of the amount of physical memory
installed?  Is it a function of the maximum amount of virtual memory
that all processes together will be using?  If it's too small, does
the system slow down, or die?  If I increase it, will my system
response improve?  etc.  (I will be upgrading to 20 MB of RAM.)

If this is covered in the manual(s) somewhere, I apologize; I looked,
but could not find any discussion of this topic.

Herb Weiner (herbw at midas.wr.tek.com)