System and method for snooping cache information using a directory crossbar
First Claim
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1. A directory crossbar system, comprising:
- a first crossbar coupled to a plurality of local processors;
a second crossbar coupled to at least one remote processor; and
at least one crossbar directory that tracks access of information by a remote processor in a symmetric multiprocessing (SMP) system, the remote processor in communication with at least one of the local processors via the crossbars, such that a most current location of the information can be determined by the crossbar directory.
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Abstract
A system and method for maintaining coherency in a symmetric multiprocessing (SMP) system are disclosed. Briefly described, in architecture, one exemplary embodiment comprises a first crossbar coupled to a plurality of local processors; a second crossbar coupled to at least one remote processor; and at least one crossbar directory that tracks access of information by a remote processor in a symmetric multiprocessing (SMP) system, the remote processor in communication with at least one of the local processors via the crossbars, such that a most current location of the information can be determined by the crossbar directory.
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Citations
29 Claims
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1. A directory crossbar system, comprising:
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a first crossbar coupled to a plurality of local processors;
a second crossbar coupled to at least one remote processor; and
at least one crossbar directory that tracks access of information by a remote processor in a symmetric multiprocessing (SMP) system, the remote processor in communication with at least one of the local processors via the crossbars, such that a most current location of the information can be determined by the crossbar directory. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A directory crossbar system, comprising:
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a plurality of crossbars; and
a global crossbar directory integrated with each one of the crossbars, and coupled to a plurality of processors such that ownership of information by a destination processor coupled to the crossbar directory is indicated in a database of the global crossbar directory, and wherein in response to a subsequent snoop from a requesting processor, the global crossbar directory indicates that the destination processor has current ownership of the information. - View Dependent Claims (15, 16, 17, 18, 19)
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20. A method for maintaining coherency in a symmetric multiprocessing (SMP) system, comprising:
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receiving from a requesting processor a snoop to determine location of a most current information of interest, the snoop received by a crossbar directory integrated with a crossbar;
communicating a subsequent snoop to at least one other crossbar directory integrated with another crossbar; and
receiving a response from the other crossbar directory to the subsequent snoop, the response indicating that a remote processor coupled to the other crossbar directory has current ownership of the information of interest. - View Dependent Claims (21, 22, 23, 24)
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25. A method for maintaining coherency in a symmetric multiprocessing (SMP) system with a global crossbar directory integrated with a plurality of crossbars, comprising:
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tracking ownership of information of interest accessed by a remote processor, the information of interest provided by a first processor;
receiving from a requesting processor a snoop to determine location of a most current version of the information of interest, the snoop received by the global crossbar directory;
communicating a subsequent snoop from the global crossbar directory to other processors residing in a processor cluster commonly with the requesting processor;
receiving status information from the other processors corresponding to previous access of the information of interest by the other processors; and
determining the most currently available information of interest by comparing the status information from the other processors and the access information. - View Dependent Claims (26, 27, 28)
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29. A system for maintaining coherency in a symmetric multiprocessing (SMP) system with a global crossbar directory integrated with a plurality of crossbars, comprising:
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means for tracking ownership of information of interest owned by a remote central processing unit (CPU), the information of interest provided by a first CPU;
means for receiving from a requesting CPU a snoop to determine location of a most current version of the information of interest;
means for communicating a subsequent snoop to other CPUs residing in a CPU cluster commonly with the requesting CPU;
means for receiving status information from the other CPUs corresponding to previous ownership of the information of interest by the other CPUs; and
means for determining the most currently available information of interest by comparing the status information from the other CPUs and the access information.
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Specification