Achieving low grace period latencies despite energy efficiency
First Claim
1. In a computer system having one or more processors operatively coupled to one or more memory devices, a method for achieving low grace-period latencies in an energy efficient environment in which processors with Read-Copy Update (RCU) callbacks are allowed to enter low power states, comprising:
- periodically generating RCU callbacks as part of shared data element update Operations, said callbacks representing requests for deferred destruction of shared data elements following an RCU grace period;
maintaining said RCU callbacks on a per-processor basis;
for each of said one or more processors that maintains RCU callbacks, assigning different RCU grace period numbers to different groups of said processor'"'"'s RCU callbacks;
periodically starting new RCU grace periods and ending old RCU grace periods; and
as said old RCU grace periods end, invoking said groups of RCU callbacks having corresponding assigned RCU grace period numbers.
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Abstract
A technique for achieving low grace-period latencies in an energy efficient environment in which processors with Read-Copy Update (RCU) callbacks are allowed to enter low power states. In an example embodiment, for each processor that has RCU callbacks, different grace period numbers are assigned to different groups of the processor'"'"'s RCU callbacks. New grace periods are periodically started and old grace periods are periodically ended. As old grace periods end, groups of RCU callbacks having corresponding assigned grace period numbers are invoked.
89 Citations
20 Claims
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1. In a computer system having one or more processors operatively coupled to one or more memory devices, a method for achieving low grace-period latencies in an energy efficient environment in which processors with Read-Copy Update (RCU) callbacks are allowed to enter low power states, comprising:
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periodically generating RCU callbacks as part of shared data element update Operations, said callbacks representing requests for deferred destruction of shared data elements following an RCU grace period; maintaining said RCU callbacks on a per-processor basis; for each of said one or more processors that maintains RCU callbacks, assigning different RCU grace period numbers to different groups of said processor'"'"'s RCU callbacks; periodically starting new RCU grace periods and ending old RCU grace periods; and as said old RCU grace periods end, invoking said groups of RCU callbacks having corresponding assigned RCU grace period numbers. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A multiprocessor system, comprising:
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two or more processors; a memory coupled to said processors, said memory including a computer useable medium tangibly embodying at least one program of instructions executable by said processors to implement a read-copy update (RCU) subsystem and to perform operations for achieving low grace-period latencies in an energy efficient environment in which processors with Read-Copy Update (RCU) callbacks are allowed to enter low power states, said operations comprising; periodically generating RCU callbacks as part of shared data element update Operations, said callbacks representing requests for deferred destruction of shared data elements following an RCU grace period; maintaining said RCU callbacks on a per-processor basis; for each of said one or more processors that maintains said RCU callbacks, assigning different RCU grace period numbers to different groups of said processor'"'"'s RCU callbacks; periodically starting new RCU grace periods and ending old RCU grace periods; and as said old RCU grace periods end, invoking said groups of RCU callbacks having corresponding assigned RCU grace period numbers. - 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 machine-readable non-transitory data storage media; program instructions provided by said one or more data storage media for programming a multiprocessor data processing platform to implement a read-copy update (RCU) subsystem and to perform operations for achieving low grace-period latencies in an energy efficient environment in which processors with Read-Copy Update (RCU) callbacks are allowed to enter low power states, said operations comprising; periodically generating RCU callbacks as part of shared data element update Operations, said callbacks representing requests for deferred destruction of shared data elements following an RCU grace period; maintaining said RCU callbacks on a per-processor basis; for each of said one or more processors that maintains said RCU callbacks, assigning different RCU grace period numbers to different groups of said processor'"'"'s RCU callbacks; periodically starting new RCU grace periods and ending old RCU grace periods; and as said old RCU grace periods end, invoking said groups of RCU callbacks having corresponding assigned RCU grace period numbers. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification