Abstract: Techniques for simulating exclusive use of a processor core amongst multiple logical partitions (LPARs) include providing hardware thread-dependent status information in response to access requests by the LPARs that is reflective of exclusive use of the processor by the LPAR accessing the hardware thread-dependent information. The information returned in response to the access requests is transformed if the requestor is a program executing at a privilege level lower than the hypervisor privilege level, so that each logical partition views the processor as though it has exclusive use of the processor. The techniques may be implemented by a logical circuit block within the processor core that transforms the hardware thread-specific information to a logical representation of the hardware thread-specific information or the transformation may be performed by program instructions of an interrupt handler that traps access to the physical register containing the information.

Abstract: A system, and computer usable program product for a dual mode reader writer lock are provided. A contention condition is determined in using an original lock. The original lock manages read and write access to a resource by several processes executing in the data processing system. The embodiment creates a set of expanded locks for use in conjunction with the original lock. The original lock and the set of expanded locks forming the dual mode reader writer lock, which operates to manage the read and write access to the resource. Using an index within the original lock, each expanded lock is indexed such that each expanded lock is locatable using the index. The contention condition is resolved by distributing requests for acquiring and releasing the read access and write access to the resource by the several processes across the original lock and the set of expanded locks.

Abstract: A method for a dual mode reader writer lock is provided. A contention condition is determined in using an original lock. The original lock manages read and write access to a resource by several processes executing in the data processing system. The embodiment creates a set of expanded locks for use in conjunction with the original lock. The original lock and the set of expanded locks forming the dual mode reader writer lock, which operates to manage the read and write access to the resource. Using an index within the original lock, each expanded lock is indexed such that each expanded lock is locatable using the index. The contention condition is resolved by distributing requests for acquiring and releasing the read access and write access to the resource by the several processes across the original lock and the set of expanded locks.

Abstract: A method, system, and computer usable program product for retooling lock interfaces for using a dual mode reader writer lock. An invocation of a method is received using an interface. The method is configured to operate on a lock associated with a resource in a data processing system. A determination is made whether the lock is an upgraded lock. The upgraded lock is the DML operating in an upgraded mode. An operation corresponding to the method is executed on the DML, if the lock is the upgraded lock.

Abstract: Memory page de-duplication in a computer system that includes a plurality of virtual machine partitions managed by a hypervisor, where each virtual machine is assigned a different dedicated memory partition, may include: identifying, by the hypervisor, a plurality of identical memory pages in memory of one or more dedicated memory partitions; assigning, by the hypervisor, one of the identical memory pages as a master page; mapping, for each virtual machine having an identical memory page, each of the identical memory pages to the master page; and directing, by the hypervisor, reads of the memory page to the master page.

Abstract: Memory page de-duplication in a computer system that includes a plurality of virtual machine partitions managed by a hypervisor, where each virtual machine is assigned a different dedicated memory partition, may include: identifying, by the hypervisor, a plurality of identical memory pages in memory of one or more dedicated memory partitions; assigning, by the hypervisor, one of the identical memory pages as a master page; mapping, for each virtual machine having an identical memory page, each of the identical memory pages to the master page; and directing, by the hypervisor, reads of the memory page to the master page.

Abstract: A method, a system and a computer program product for controlling the hardware priority of hardware threads in a data processing system. A Thread Priority Control (TPC) utility assigns a primary level and one or more secondary levels of hardware priority to a hardware thread. When a hardware thread initiates execution in the absence of a system call, the TPC utility enables execution based on the primary level. When the hardware thread initiates execution within a system call, the TPC utility dynamically adjusts execution from the primary level to the secondary level associated with the system call. The TPC utility adjusts hardware priority levels in order to: (a) raise the hardware priority of one hardware thread relative to another; (b) reduce energy consumed by the hardware thread; and (c) fulfill requirements of time critical hardware sections.

Abstract: Embodiments of the disclosure relate to the management of memory pages available for pin operations by groups of processors in a multiprocessor system to reduce cache contention and improve system performance. An exemplary embodiment comprises a system that may include interconnected processors, a global count of the number of pages available for pinning, and a plurality of local counts of pages available for pinning by groups of processors. Each local count may be in proximity to a processor group and include a subset of the pages allocated from the global count that are available for pinning by processors in the group. The local counts are adjusted accordingly in response to page pinning and unpinning by processors in the respective processor groups.

Abstract: A method, system, and computer usable program product for using a dual mode reader writer lock. A contention condition is detected in the use of a lock in a data processing system, the lock being used for managing read and write access to a resource in the data processing system. A determination of the data structure used for implementing the lock is made. If the data structure is a data structure of a reader writer lock (RWL), the data structure is transitioned to a second data structure suitable for implementing the DML. A determination is made whether the DML has been expanded. If the DML is not expanded, the DML is expanded such that the data structure includes an original lock and a set of expanded locks. The original lock and each expanded lock in the set of expanded locks forms an element of the DML.

Abstract: A method for a dual mode reader writer lock is provided. A contention condition is determined in using an original lock. The original lock manages read and write access to a resource by several processes executing in the data processing system. The embodiment creates a set of expanded locks for use in conjunction with the original lock. The original lock and the set of expanded locks forming the dual mode reader writer lock, which operates to manage the read and write access to the resource. Using an index within the original lock, each expanded lock is indexed such that each expanded lock is locatable using the index. The contention condition is resolved by distributing requests for acquiring and releasing the read access and write access to the resource by the several processes across the original lock and the set of expanded locks.

Abstract: Software components “self-scrub” to improve software reliability, serviceability and availability (RAS). Each component designates a routine to perform a component level consistency check on major data structures and to verify the state of component. This is performed as an on-going task during the life of the component. The component registers an entry point with the system to receive notification of scrubbing parameter changes. The entry point is also called with the request to perform component-scrubbing operations. The entry point functions are responsible for executing within limitations on central processing unit (CPU) usage and memory footprint when performing scrubbing operations.

Abstract: Embodiments of the disclosure relate to the management of memory pages available for pin operations by groups of processors in a multiprocessor system to reduce cache contention and improve system performance. An exemplary embodiment comprises a system that may include interconnected processors, a global count of the number of pages available for pinning, and a plurality of local counts of pages available for pinning by groups of processors. Each local count may be in proximity to a processor group and include a subset of the pages allocated from the global count that are available for pinning by processors in the group. The local counts are adjusted accordingly in response to page pinning and unpinning by processors in the respective processor groups.

Abstract: A method, system, and computer usable program product for using a dual mode reader writer lock. A contention condition is detected in the use of a lock in a data processing system, the lock being used for managing read and write access to a resource in the data processing system. A determination of the data structure used for implementing the lock is made. If the data structure is a data structure of a reader writer lock (RWL), the data structure is transitioned to a second data structure suitable for implementing the DML. A determination is made whether the DML has been expanded. If the DML is not expanded, the DML is expanded such that the data structure includes an original lock and a set of expanded locks. The original lock and each expanded lock in the set of expanded locks forms an element of the DML.

Abstract: A method, system, and computer usable program product for using a dual mode reader writer lock. A contention condition is detected in the use of a lock in a data processing system, the lock being used for managing read and write access to a resource in the data processing system. A determination of the data structure used for implementing the lock is made. If the data structure is a data structure of a reader writer lock (RWL), the data structure is transitioned to a second data structure suitable for implementing the DML. A determination is made whether the DML has been expanded. If the DML is not expanded, the DML is expanded such that the data structure includes an original lock and a set of expanded locks. The original lock and each expanded lock in the set of expanded locks forms an element of the DML.

Abstract: A method, system, and computer usable program product for a dual mode reader writer lock. A contention condition is determined in using an original lock. The original lock manages read and write access to a resource by several processes executing in the data processing system. The embodiment creates a set of expanded locks for use in conjunction with the original lock. The original lock and the set of expanded locks forming the dual mode reader writer lock, which operates to manage the read and write access to the resource. Using an index within the original lock, each expanded lock is indexed such that each expanded lock is locatable using the index. The contention condition is resolved by distributing requests for acquiring and releasing the read access and write access to the resource by the several processes across the original lock and the set of expanded locks.

Abstract: A method, system, and computer usable program product for retooling lock interfaces for using a dual mode reader writer lock. An invocation of a method is received using an interface. The method is configured to operate on a lock associated with a resource in a data processing system. A determination is made whether the lock is an upgraded lock. The upgraded lock is the DML operating in an upgraded mode. An operation corresponding to the method is executed on the DML, if the lock is the upgraded lock.

Abstract: A method, system, and computer usable program product for using a dual mode reader writer lock. A contention condition is detected in the use of a lock in a data processing system, the lock being used for managing read and write access to a resource in the data processing system. A determination of the data structure used for implementing the lock is made. If the data structure is a data structure of a reader writer lock (RWL), the data structure is transitioned to a second data structure suitable for implementing the DML. A determination is made whether the DML has been expanded. If the DML is not expanded, the DML is expanded such that the data structure includes an original lock and a set of expanded locks. The original lock and each expanded lock in the set of expanded locks forms an element of the DML.

Abstract: A processing unit includes an authority check for controlling access by the processing unit to pages of memory according to whether a hardware protection key set currently loaded in an authority mask register allows access to the pages. In particular, each page of memory is assigned a page key number that indexes into the hardware protection key set. The currently loaded hardware protection key set specifies those page key numbers that are currently accessible to the processing unit for the execution context. Each hardware key within the hardware protection key set is associated with a particular data object or group of data objects. Thus, effectively, the currently loaded hardware protection key set identifies which data objects or groups of data objects are currently accessible.

Abstract: A method, computer program product, and data processing system for preventing the occurrence of undetectable dangling pointers through memory reallocation are disclosed. Allocated memory regions that are no longer needed are deallocated but are not immediately freed for reallocation, being designated as “retained.” A memory retention metric is computed as a measure of an extent of the retained memory regions in the computer's memory space. Once the memory retention metric exceeds a pre-determined threshold, some or all of the retained memory regions are freed for reuse. In this manner, improper accesses to deallocated memory regions can be detected more easily, since reuse of those regions is delayed, while at the same time excessive resource usage and heap fragmentation is avoided by only retaining deallocated regions for a limited time (determined by the threshold and retention metric chosen).

Abstract: Software components “self-scrub” to improve software reliability, serviceability and availability (RAS). Each component designates a routine to perform a component level consistency check on major data structures and to verify the state of component. This is performed as an on-going task during the life of the component. The component registers an entry point with the system to receive notification of scrubbing parameter changes. The entry point is also called with the request to perform component-scrubbing operations. The entry point functions are responsible for executing within limitations on central processing unit (CPU) usage and memory footprint when performing scrubbing operations.