Could not create the cache used for updating
Pages of the executable file that are not executed during a particular run are never loaded into memory.This technique, sometimes also called swap prefetch, predicts which pages will be referenced soon, to minimize future page faults.For simplicity, main memory is called "RAM" (an acronym of "random-access memory") and secondary storage is called "disk" (a shorthand for "hard disk drive"), but the concepts do not depend on whether these terms apply literally to a specific computer system. A swapped-out program would be current but its execution would be suspended while its RAM was in use by another program.A program might include multiple overlays that occupy the same memory at different times.In this scheme, the operating system retrieves data from secondary storage in same-size blocks called pages. In the 1960s, swapping was an early virtual memory technique.Paging is an important part of virtual memory implementations in modern operating systems, using secondary storage to let programs exceed the size of available physical memory. An entire program would be swapped out (or rolled out) from RAM to disk, and another one would be swapped in (or rolled in).When a program tries to reference a page not currently present in RAM, the processor treats this invalid memory reference as a page fault and transfers control from the program to the operating system.
This single instruction references eight pages; if not all are in RAM, it will cause a page fault.The operating system may periodically pre-clean dirty pages: write modified pages back to disk even though they might be further modified.This minimizes the amount of cleaning needed to obtain new page frames at the moment a new program starts or a new data file is opened, and improves responsiveness.Some operating systems periodically look for pages that have not been recently referenced and perform page stealing, freeing the page frame and adding it to the free page queue.
Some operating systems support page reclamation; if a program commits a page fault by referencing a page that was stolen, the operating system detects this and restores the page frame without having to read the contents back into RAM.
When the working set is a small percentage of the system's total number of pages, virtual memory systems work most efficiently and an insignificant amount of computing is spent resolving page faults.