Description: The distance (in pages) between front and back pageout daemon hands. The pageout daemon manages two hands on the clock. The front hand moves through memory, clearing the reference bit, and stealing pages from processes that exceed the value maxrss. The back hand travels behind the front hand, freeing pages that have not been referenced since the front hand passed. If the pages have been modified, they are pushed to the swap space before being freed. After pageout examines a page of memory, the amount of time that is needed to reclaim the page increases as the distance increases between the two hands, and decreases as the scan rate rises.