The yellow line explores the relationship between the reference string of the process and certain implementation features of the virtual memory system. The implementation choices are evaluated by the performance of the virtual memory.
In a virtual memory system, a section of program code as represented by a particular reference string will produce page faults as it executes. The number of these page faults will depend on how many page frames are allotted to the process and on the choice made about which page to replace when a new page is brought in. Because the performance of the virtual memory is dependent on the number of page faults a process requires, the relationship between reference strings, replacement policies and the sizes of resident sets is an important study. Stochastic models of program behavior have been developed to determine optimal choice of page replacement algorithm and size of resident set with respect to the locality attributes exhibited by the program reference string.
The yellow line introduces several replacement policies and a method for evaluating the performance of a policy with respect to a particular reference string using various page sizes. The lifetime curve model for evaluation of program performance is presented and the model lifetime curve is described.
