Mechanism for optimizing generation of commit-signals in a distributed shared-memory system
First Claim
1. A mechanism for optimizing generation of a commit signal in response to a local memory reference operation issued by a first processor in a distributed shared memory multiprocessor system having a hierarchical switch for interconnecting a plurality of nodes, each node comprising a local switch interconnecting at least one local processor with the hierarchical switch, the mechanism comprising:
- a structure for optimizing the generation of the commit signal, the optimized commit signal being generated by control logic at a first node associated with the first processor instead of at the hierarchical switch, the structure indicating whether the memory reference operation issued by the first processor affects any non-local processor of the system, the optimized commit signal transmitted to the first processor to thereby obviate transmission of the signal to the hierarchical switch.
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Abstract
A mechanism optimizes the generation of a commit-signal by control logic of the multiprocessor system in response to a memory reference operation issued by a processor to a local node of a multiprocessor system having a hierarchical switch for interconnecting a plurality of nodes. The mechanism generally comprises a structure that indicates whether the memory reference operation affects other processors of other nodes of the multiprocessor system. An ordering point of the local node generates an optimized commit-signal when the structure indicates that the memory reference operation does not affect the other processors.
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Citations
15 Claims
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1. A mechanism for optimizing generation of a commit signal in response to a local memory reference operation issued by a first processor in a distributed shared memory multiprocessor system having a hierarchical switch for interconnecting a plurality of nodes, each node comprising a local switch interconnecting at least one local processor with the hierarchical switch, the mechanism comprising:
a structure for optimizing the generation of the commit signal, the optimized commit signal being generated by control logic at a first node associated with the first processor instead of at the hierarchical switch, the structure indicating whether the memory reference operation issued by the first processor affects any non-local processor of the system, the optimized commit signal transmitted to the first processor to thereby obviate transmission of the signal to the hierarchical switch. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for optimizing generation of a commit signal in response to a local memory reference operation issued by a first processor of a first node in a distributed shared memory multiprocessor system having a hierarchical switch for interconnecting a plurality of nodes, each node comprising a local switch interconnecting at least one local processor with the hierarchical switch, each processor employing a cache apportioned into a plurality of cache lines, the method comprising the steps of:
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providing a data structure at the first node that optimizes generation of the commit signal by storing information that indicates whether the memory reference operation issued by the first processor affects any non-local processor of the system, the memory reference operation affecting a non-local processor if the operation has a probe generated by an ordering point of the local switch at the first node;
creating an entry in the data structure for the memory reference operation in response to the operation having a probe that is transmitted to and currently outstanding at the hierarchical switch, the probe configured to invalidate a copy of data associated with the operation that is stored in the cache of a non-local processor, the entry storing an address of a cache line for the outstanding probe; and
optimizing generation of the commit signal at the first node when there is no entry in the data structure associated with the memory reference operation. - View Dependent Claims (11, 12, 13, 14, 15)
generating the commit signal at control logic of the first node; and
transmitting the commit signal to the first processor, thereby obviating transmission of the generated commit signal to the hierarchical switch.
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12. The method of claim 11 wherein the commit signal is a type 0 commit signal.
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13. The method of claim 12 further comprising the step of, in response to transmitting a probe to the hierarchical switch, totally ordering the probe at the hierarchical switch.
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14. The method of claim 13 further comprising the step of, in response to the step of totally ordering, returning an invalidate acknowledgment from the hierarchical switch.
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15. The method of claim 14 further comprising the step of, in response to the step of returning, removing the entry from the data structure.
Specification