Page Replacement Control Based on Dynamic Feedback of Adequacy of the Algorithm
Original Publication Date: 1989-Feb-01
Included in the Prior Art Database: 2005-Jan-27
The function of a page replacement algorithm in a virtual storage system is to select virtual storage pages residing in processor storage to be dropped from the application's reference set so that the storage frame can be used for new allocations. Application pages which have been changed since the storage frame was assigned must be paged out to another level of the storage hierarchy. One such level is the page datasets or auxiliary storage. Since page datasets often reside on rotating DASD. such as the IBM 3380, the time to write a selected page out so that the frame can be reused is on the order of tens of milliseconds. During the time taken to write the selected page(s), there could be numerous application references to virtual storage pages that are not backed in processor storage.