Abstract: System, method and computer program product for supporting a plurality of Access Control List types for a file system in an operating system in a data processing system. An Access Control List supporting system for managing access to a file system in a data processing system has at least one file system in an operating system of the data processing system, and an Access Control List management framework in the operating system and external to the at least one file system for managing access to the at least one file system. The Access Control List supporting system of the invention removes ACL management and access check-related functions from the at least one file system to an external Access Control List management framework, thus enabling an operating system to support a plurality of Access Control List types using the same Access Control List management framework and enabling new Access Control List types to be added to the operating system dynamically while the operating system is running.

Abstract: A method, information processing system, and computer readable medium for efficiently distributing a computer system's main memory among applications running in that operating system instance. More specifically, threshold values used by a page replacement algorithm of the virtual memory manager are automatically tuned in response to the load on the memory of a computer system. One such threshold value is the lower threshold of free memory which is changed as a function of the load on the memory. For example, such a load might be represented as the number of threads that were added to a waiting queue during a defined interval of time divided by the number of clock tics in that interval. This representation is known as the thread wait rate. This rate is then compared to a target rate to determine if the lower threshold value should be changed. When the free memory space falls below the lower threshold, a page replacement daemon is used to page out memory to make more memory space available.

Abstract: A method, apparatus, and computer instructions for broadcasting information. A change in data used by a number of processors in the data processing system is identified. A message is sent to the number of processors in the data processing system in which the message is sent with a priority level equal to a set of routines that use the data in response to identifying the change. This message is responded to only when the recipient is at an interrupt priority less favored than the priority of the message. A flag is set for each of the number of processors to form a plurality of set flags for the message in which the plurality of set flags are located in memory locations used by the number of processors in which the plurality of set flags remains set until a response is made to the message.

Abstract: A method (and structure) for relocating low memory for an operating system instance in a computer system includes establishing a low memory table (LMT), the LMT comprising information allocated for each of a predefined increment of the low memory to be relocated, setting the information to a first predetermined value, and copying a contents of each of the increments to a new location in a first copy operation.

Abstract: A method and apparatus for sharing memory in a multiprocessor computing system. More specifically, this invention provides a number of system buses with each bus being connected to a respective memory controller which controls a corresponding partition of the memory. Any one of the processors can use any one of the system buses to send real addresses to the connected memory controller which then converts the real addresses into physical addresses corresponding to the partition of memory that is controlled by the receiving memory controller. The processors can be dynamically assigned to different partitions of the memory by via a switching mechanism.

Abstract: A mechanism to dynamically migrate a home node of a global page to a more suitable node for improving performance of parallel applications running on a S-COMA and other DSM systems. More specifically, consultation counts are maintained at each client node of a shared memory system, where the consultation count indicates the number of times the client node has consulted the dynamic for lines a page. This information is then used along with other information to decide on whether to change the dynamic home node to a more suitable node.