When does swap decreases

[Francisco Reyes]

On Mon, 20 Jun 2005, Dan Nelson wrote:

> When the system is low on memory, it will force the least used blocks
> of memory to swap.  It will not free the swap space until the process
> owning them exits (even if it pages that memory back into RAM), so at
> some point the system paged out 30MB of memory, some processes exited
> and freed up 20MB, and you probably have some long-lived processes that
> account for that remaining 10MB.

Makes sense.
Any way to find out which process is using the swap?