Using Counter-Flip Acknowledge And Memory-Barrier Shoot-Down To Simplify Implementation of Read-Copy Update In Realtime Systems
First Claim
1. A method for realtime-safe detection of a grace period for deferring the destruction of a shared data element until pre-existing references to the data element are removed, comprising:
- providing a grace period identifier for readers of said shared data element to consult;
initiating a next grace period by manipulating said grace period identifier; and
requesting acknowledgement of said next grace period from processing entities capable of executing said readers before detecting when a current grace period has ended.
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Abstract
A technique for realtime-safe detection of a grace period for deferring the destruction of a shared data element until pre-existing references to the data element have been removed. A grace period identifier is provided for readers of the shared data element to consult. A next grace period is initiated by manipulating the grace period identifier, and an acknowledgement thereof is requested from processing entities capable of executing the readers before detecting when a current grace period has ended. Optionally, when the end of the current grace period is determined, arrangement is made for a memory barrier shoot-down on processing entities capable of executing the readers. Data destruction operations to destroy the shared data element are then deferred until it is determined that the memory barriers have been implemented. Data destruction operations may be further deferred until two consecutive grace periods have expired.
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Citations
20 Claims
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1. A method for realtime-safe detection of a grace period for deferring the destruction of a shared data element until pre-existing references to the data element are removed, comprising:
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providing a grace period identifier for readers of said shared data element to consult; initiating a next grace period by manipulating said grace period identifier; and requesting acknowledgement of said next grace period from processing entities capable of executing said readers before detecting when a current grace period has ended. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A data processing system having one or more processors, a memory and a communication pathway between the one or more processors and the memory, said system being adapted to implement realtime-safe detection of a grace period for deferring the destruction of a shared data element until pre-existing references to the data element are removed, and comprising:
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a grace period detection component adapted to; provide a grace period identifier for readers of said shared data element to consult; initiate a next grace period by manipulating said grace period identifier; and request acknowledgement of said next grace period from processing entities capable of executing said readers before detecting when a current grace period has ended. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A computer program product for realtime-safe grace detection of a grace period for deferring the destruction of a shared data element until pre-existing references to the data element are removed, comprising:
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one or more machine-useable media; logic provided by said one or more media for programming a data processing platform to operate as by; providing a grace period identifier for readers of said shared data element to consult; initiating a next grace period by manipulating said grace period identifier; and requesting acknowledgement of said next grace period from processing entities capable of executing said readers before detecting when a current grace period has ended. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification