When does bufwaits get incremented ?

Hey, I've been trying to track down some information about when bufwaits is incremented. I found the following in the ODS Admin guide... "When a user thread needs to acquire a buffer, Online randomly selects one of the FLRU queues and uses the oldest or least-recently used entry in the list. If the least-recently used page can be latched, that page is removed from the queue. If the FLRU queue is locked, and the end page cannot be latched, Online randomly selects another FLRU queue." So my question is, Is bufwaits incremented for every time it can't find a buffer in a FLRU or when it's checked all FLRU queues ? Any ideas.... Cheers, Tony.