System for coordinating coherency of cache memories of multiple host computers of a distributed information system
First Claim
1. A system for coordinating cache coherency in a distributed information system, comprising:
- at least one main storage memory;
a plurality of host computers, each having a cache memory add a host cache controller;
a main memory controller connected between said at least one main storage memory and said plurality of host computers;
each said host cache controller providing the means for communicating with said main memory controller and for participating in the control of the coordinated reading and writing of blocks of data between said host cache memories and said at least one main storage memory.
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Abstract
Apparatus and method for coordinating cache coherency between host cache memories in a distributed information system in a system which comprises at least one main storage memory coupled to a plurality of host computers through controllers. Each host computer includes a host cache controller which maintains the state of the data stored in its associated memory and maintains communicating with a main memory controller for participating in the control of coordinated reading and writing of data between the host cache memories and the main storage memory. The system maintains cache coherency by the exchange of commands between the main memory controller and the hosts cache controllers each of which define the state of the blocks of data stored in the host cache memories.
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Citations
20 Claims
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1. A system for coordinating cache coherency in a distributed information system, comprising:
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at least one main storage memory; a plurality of host computers, each having a cache memory add a host cache controller; a main memory controller connected between said at least one main storage memory and said plurality of host computers; each said host cache controller providing the means for communicating with said main memory controller and for participating in the control of the coordinated reading and writing of blocks of data between said host cache memories and said at least one main storage memory. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A distributed processing system having a plurality of independently operable host computers arranged to share a main memory and maintain data coherency in the system, comprising;
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main memory means comprising at least one main storage medium, a plurality of host computers each having an associated cache memory and a cache controller, a main controller coupled to said main memory means and to each of each cache controllers for maintaining cache coherency in said distributed processing system, said main controller having a directory for recording and maintaining the global status of data in all of said cache memories, and said main controller querying said directory in response to a command from a cache controller of a host computer in order to maintain coherency of data in the cache memories of the other host computers. - View Dependent Claims (14, 15, 16, 17)
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18. A method of maintaining cache coherence between a plurality of host computers in a distributed processing system each having a cache memory and access to a shared main memory, comprising the steps of:
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coupling the main memory to a main memory controller, coupling said main memory controller to a plurality of individual cache controllers, coupling each of said cache controllers to a host computer of the typed adapted to serve clients requests, providing in said main memory controller a global directory for maintaining the state of said cache memories, defining the state of each of said cache memories in one of four states, changing the state of a cache memory in said global directory in response to a cache controller request, and subsequently changing the state of the plural cache memories in response to the same request. - View Dependent Claims (19, 20)
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Specification