Using expedited grace periods to short-circuit normal grace-period computations
First Claim
1. A method for short-circuiting normal read-copy update (RCU) grace period computations in the presence of expedited RCU grace periods, said method comprising:
- periodically performing normal RCU grace period processing that reports normal quiescent states on behalf of CPUs in a set of CPUs until a normal quiescent state has been reported on behalf of all of said CPUs in said set of CPUs, thereby allowing a normal RCU grace period to end;
periodically performing expedited RCU grace period processing that reports expedited quiescent states on behalf of CPUs in said set of CPUs until an expedited quiescent state has been reported on behalf of all of said CPUs in said set of CPUs, thereby allowing an expedited RCU grace period to end;
said expedited grace period being of shorter duration than said normal grace period;
responsive to a condition indicating that said normal RCU grace period processing can be short-circuited by said expedited RCU grace period processing, using said expedited RCU grace period processing to report both expedited quiescent states and normal quiescent states on behalf of the same CPUs in said set of CPUs.
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Abstract
A technique for short-circuiting normal read-copy update (RCU) grace period computations in the presence of expedited RCU grace periods. Both normal and expedited RCU grace period processing may be periodically performing to respectively report normal and expedited quiescent states on behalf of CPUs in a set of CPUs until all of the CPUs have respectively reported normal or expedited quiescent states so that the normal and expedited grace periods may be respectively ended. The expedited grace periods are of shorter duration than the normal grace periods. Responsive to a condition indicating that the normal RCU grace period processing can be short-circuited by the expedited RCU grace period processing, the expedited RCU grace period processing may report both expedited quiescent states and normal quiescent states on behalf of the same CPUs in the set of CPUs.
57 Citations
20 Claims
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1. A method for short-circuiting normal read-copy update (RCU) grace period computations in the presence of expedited RCU grace periods, said method comprising:
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periodically performing normal RCU grace period processing that reports normal quiescent states on behalf of CPUs in a set of CPUs until a normal quiescent state has been reported on behalf of all of said CPUs in said set of CPUs, thereby allowing a normal RCU grace period to end; periodically performing expedited RCU grace period processing that reports expedited quiescent states on behalf of CPUs in said set of CPUs until an expedited quiescent state has been reported on behalf of all of said CPUs in said set of CPUs, thereby allowing an expedited RCU grace period to end; said expedited grace period being of shorter duration than said normal grace period; responsive to a condition indicating that said normal RCU grace period processing can be short-circuited by said expedited RCU grace period processing, using said expedited RCU grace period processing to report both expedited quiescent states and normal quiescent states on behalf of the same CPUs in said set of CPUs. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system, comprising:
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a plurality of CPUs; a memory coupled to said CPUs, said memory including a computer readable storage medium tangibly embodying at least one program of instructions executable by said CPUs to perform operations for short-circuiting normal read-copy update (RCU) grace period computations in the presence of expedited RCU grace periods, said operations comprising; periodically performing normal RCU grace period processing that reports normal quiescent states on behalf of CPUs in a set of CPUs until a normal quiescent state has been reported on behalf of all of said CPUs in said set of CPUs, thereby allowing a normal RCU grace period to end; periodically performing expedited RCU grace period processing that reports expedited quiescent states on behalf of CPUs in said set of CPUs until an expedited quiescent state has been reported on behalf of all of said CPUs in said set of CPUs, thereby allowing an expedited RCU grace period to end; said expedited grace period being of shorter duration than said normal grace period; responsive to a condition indicating that said normal RCU grace period processing can be short-circuited by said expedited RCU grace period processing, using said expedited RCU grace period processing to report both expedited quiescent states and normal quiescent states on behalf of the same CPUs in said set of CPUs. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A computer program product, comprising:
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one or more non-transitory computer readable data storage media; program instructions stored on said one or more computer readable data storage media for programming a data processing platform having a plurality of CPUs to perform operations for short-circuiting normal read-copy update (RCU) grace period computations in the presence of expedited RCU grace periods, said operations comprising; periodically performing normal RCU grace period processing that reports normal quiescent states on behalf of CPUs in a set of CPUs until a normal quiescent state has been reported on behalf of all of said CPUs in said set of CPUs, thereby allowing a normal RCU grace period to end; periodically performing expedited RCU grace period processing that reports expedited quiescent states on behalf of CPUs in said set of CPUs until an expedited quiescent state has been reported on behalf of all of said CPUs in said set of CPUs, thereby allowing an expedited RCU grace period to end; said expedited grace period being of shorter duration than said normal grace period; responsive to a condition indicating that said normal RCU grace period processing can be short-circuited by said expedited RCU grace period processing, using said expedited RCU grace period processing to report both expedited quiescent states and normal quiescent states on behalf of the same CPUs in said set of CPUs. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification