Method and apparatus for predetermining pages for swapping from physical memory in accordance with the number of accesses

Abstract

Multi-bit SP-Vectors (Shrikant Parikh Vectors) are created to record the history of each page of a process. Each time an ager scans an accessed/not accessed bit flag of page table entries, the SP-Vectors are updated to reflect whether or not the corresponding page was accessed. A table is also created to provide ready update and interpretation information for each vector depending upon whether or not the last scan indicated an accessed or not accessed status. An SP-List is created to order a predetermined number of entries from the least recently used end of an idle list. The SP-Vectors are checked for the number of accesses and a representation corresponding to the page thereof is placed into the SP-List in the order of least number of accesses to the most number of accesses. When it is necessary to remove a page from physical memory, the ager goes to the page indicated as the least number of accesses in the SP-List and swaps out that page.

Dependencies are inferred from the claim text.