International Business Machines Corporation

Matthew Accapadi

Robert H Bell, Jr

Andrew Dunshea

Dirk Michel

Jos Manuel Accapadi

Mysore Sathyanarayana Srinivas

Hong Lam Hua

Ram Raghavan

Bret Ronald Olszewski

Mysore Sathyanaranyana Srinivas

Mark Elliott Hack

Agustin Mena, Iii

Grover C Davidson

An information handling system (IHS) includes an operating system with a release-behind component that determines which file pages to release from a file cache in system memory. The release-behind component employs a history buffer to determine which file pages to release from the file cache to create room for a current page access. The history buffer stores entries that identify respective pages for which a page fault occurred. For each identified page, the history buffer stores respective repage information that indicates if a repage fault occurred for such page. The release-behind component identifies a candidate previous page for release from the file cache. The release-behind component checks the history buffer to determine if a repage fault occurred for that entry. If so, then the release-behind component does not discard the candidate previous page from the cache. Otherwise, the release-behind component discards the candidate previous page if a repage fault occurred.

Selective release-behind of pages based on repaging history in an information handling system

A method, system and computer-usable medium are disclosed for managing prefetch streams in a virtual machine environment. Compiled application code in a first core, which comprises a Special Purpose Register (SPR) and a plurality of first prefetch engines, initiates a prefetch stream request. If the prefetch stream request cannot be initiated due to unavailability of a first prefetch engine, then an indicator bit indicating a Prefetch Stream Dispatch Fault is set in the SPR, causing a Hypervisor to interrupt the execution of the prefetch stream request. The Hypervisor then calls its associated operating system (OS), which determines prefetch engine availability for a second core comprising a plurality of second prefetch engines. If a second prefetch engine is available, then the OS migrates the prefetch stream request from the first core to the second core, where it is initiated on an available second prefetch engine.

Managing migration of a prefetch stream from one processor core to another processor core

An approach is provided that reserves a software lock for a waiting thread is presented. When a software lock is released by a first thread, a second thread that is waiting for the same resource controlled by the software lock is woken up. In addition, a reservation to the software lock is established for the second thread. After the reservation is established, if the lock is available and requested by a thread other than the second thread, the requesting thread is denied, added to the wait queue, and put to sleep. In addition, the reservation is cleared. After the reservation has been cleared, the lock will be granted to the next thread to request the lock.

Optimized preemption and reservation of software locks for woken threads

Methods, systems, and computer program products are provided for scheduling threads in a multiprocessor computer. Embodiments include selecting a thread in a ready queue to be dispatched to a processor and determining whether an interrupt mask flag is set in a thread control block associated with the thread. If the interrupt mask flag is set in the thread control block associated with the thread, embodiments typically include selecting a processor, setting a current processor priority register of the selected processor to least favored, and dispatching the thread from the ready queue to the selected processor. In some embodiments, setting the current processor priority register of the selected processor to least favored is carried out by storing a value associated with the highest interrupt priority in the current processor priority register.

Scheduling threads in a multiprocessor computer

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Austin, TX, United States of America

Matthew Accapadi