Experiments with program locality

For many years, there has been interest in "program locality" as a phenomenon to be considered in storage allocation. This notion arises from the empirical observation that it is possible to run a program efficiently with only some fraction of its total instruction and data code in main storage at any given time. That virtual memory systems can be made to run at all demonstrates that program locality can be used to advantage; and though it is certainly possible to write a program which violates the principles of locality, it seems one must go out of one's way to do so.