Swap Usage

[Doug Hardie]

I have several FreeBSD 9.3 systems that are using swap and I can’t figure out what is doing it.  The key system has 6GB swap and currently it has over 2GB in use.  ps shows only a kernel module [intr] with a W status.  Obviously that isn’t using the space.  No other process shows a W in its status.  I suspect this is somewhat related to the use of mmap in one application.  However, all of the mmaps in that application are file backed and thus shouldn’t use swap.  How do I figure out what that swap space is being used for?