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US 7,406,690 B2Granted
Flow lookahead in an ordered semaphore management subsystem
AssigneeInternational Business Machines Corporation
InventorsSteven Kenneth Jenkins, Ross Boyd Leavens, Robert Brian Likovich, Jr., Wesley Erich Queen, Michael Steven Siegel
Life of this patent
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Abstract
In an ordered semaphore management system a pending state allows threads not competing for a locked semaphore to bypass one or more threads waiting for the same locked semaphore. The number of pending levels determines the number of consecutive threads vying for the same locked semaphore which can be bypassed. When more than one level is provided the pending levels are prioritized in the queued order.
Claims12
An ordered semaphore management method comprising:
- providing an ordered queue, the ordered queue including a plurality of threads awaiting access to a plurality of semaphores, wherein only a thread in a semaphore head (SH) state is authorized to request access to one of the plurality of semaphores, and at any given time, only one of the plurality of threads in the ordered queue is assigned the SH state;
- and
- changing a first of the plurality of threads in the ordered queue from the SH state to a pending state and a second of the plurality of threads in the ordered queue to the SH state in response to the first thread requesting access to a semaphore in a locked state thereby allowing the second thread to gain access to another semaphore in an unlocked state,
- wherein the first thread is not changed from the SH state to the pending state if another thread is in a pending state awaiting access to the semaphore requested by the first thread.
1 more element
An ordered semaphore management method comprising:
- providing an ordered queue, the ordered queue including a plurality of threads awaiting access to a plurality of semaphores, wherein only a thread in a semaphore head (SH) state is authorized to request access to one of the plurality of semaphores, and at any given time, only one of the plurality of threads in the ordered queue is assigned the SH state;
- and
- changing a first of the plurality of threads in the ordered queue from the SH state to a pending state and a second of the plurality of threads in the ordered queue to the SH state in response to the first thread requesting access to a semaphore in a locked state thereby allowing the second thread to gain access to another semaphore in an unlocked state,
- wherein one or more other threads are in a pending state awaiting access to the semaphore requested by the first thread and the first thread is assigned a priority level based on its position in the ordered queue.
1 more element
Dependencies are inferred from the claim text.