[tlug] A Swap Question

["Stephen J. Turnbull" <stephen@example.com>]

burlingk@example.com writes:

 > I have seen some places that suggest using a swap partition equal
 >  to the size of your physical memory, and other places that 
 > say to use a swap partition equal to about twice the size of physical
 > memory.
 > 
 > Is there any reason that it would be bad, or less efficient to use a
 > larger partition for swap?

It is a bad idea to have more effective swap space than you have RAM,
usually.  If you've got that much VM active, your system will likely
be slowing to a crawl.  Why waste a couple gigabytes on swap if
touching it means you're going crazy with the slows anyway?  The
reason for the change in the recommended size is a change in the swap
allocation algorithm.  At some point in the 2.3 development series
IIRC, the algorithm was changed so that the most efficient use of swap
required a space twice as big as the desired swap.  I suppose (just
guessing!) that it's a double-buffering algorithm.