Methods and systems for control of memory

摘要

Effective memory management maximizes the use of main memory in a computing system by avoiding the issuance of operating system primitives which result in overhead and increased processing time. This allows an applications program to change the state of a storage unit such as a buffer or page without requiring the issuance of an operating system primitive to change the physical state of the storage unit. A storage manager is provided for controlling the movement of data between storage units in secondary storage and storage units in main memory. A storage unit state indicator or flag is associated with each storage unit in main memory. In addition, a system state indicator for indicating the physical state of a storage unit is also associated with each storage unit. The system state indicator may be set to one of the states of fixed or pageable while the storage unit state indicator may be set to one of the states of fixed, pageable or don't care. The storage manager monitors the usage of memory to determine whether a fixed storage constraint may occur. Upon a determination that a fixed storage constraint may occur, the storage manager notifies the applications programs of the fixed storage constraint. In response, applications programs can temporarily change the state of a storage unit containing data which temporarily may not be needed by the applications program from fixed to don't care by changing the storage unit state indicator from fixed to don't care. Thus, the storage unit is available to the storage manager if needed without the need to have the storage manager issue an operating system primitive to change the system state indicator for the storage unit from fixed to pageable.