Using PAGE-AHEAD for large FORTRAN programs

Virtual storage management allows an efficient use of computer memory through the cooperative actions of the computer hardware and the operating system which are completely transparent to application programs. However, when program data exceed the available memory space, the program elapsed time may be dominated by the time spent in paging I/O operations. The data transfer rate, as determined by the operating system implementation of demand paging, may be small when compared with the maximum I/O bandwidth that the I/O hardware could support. Page-ahead is a technique which complements the operating system support of demand paging on virtual storage systems in order to exploit the regularity and predictability which is typical of the data access pattern of large engineering and scientific (E/S) application programs. Application programs may exploit this regularity by using page-ahead to request paging operations from the operating system in anticipation of future needs and take full advantage of the operating systems I/O bandwidth to auxiliary paging store.