Swap Space configuration for GRASS

[/S=E.ODOHERTY/OU=R02F06A/PRMD=USDA.FS.X400/ADMD=TELEMAIL/C=US/ at sprint.com]

Can someone tell me if there is an "ideal" setting for swap space 
(relative to the amount of RAM) for running GRASS, particularly for 
r.watershed?  I suspect I don't have mine set optimally.  I'm using 
the 2 X RAM rule-of-thumb.