Method and apparatus for coherency reporting in a multiprocessing system
AssigneeInternational Business Machines Corporation
InventorsSanjay Raghunath Deshpande, John Michael Kaiser
Life of this patent
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Abstract
An information processing system includes a plurality of bus devices coupled to at least one storage device via a bus. A first device (the "requestor") on a bus issues a request to obtain data and coherency information and monitors for the coherency information during a designated coherency response interval. A second device (the "respondant") sends a first signal during the designated coherency response interval indicating that the coherency information will be returned during a second interval, and sends a second signal providing the coherency information to the requestor during the second interval.
Claims22
In an information processing system comprising a plurality of bus devices coupled to at least one storage device via a set of buses, a method comprising the steps of:
- issuing a request on a bus by a first device for data and coherency information;
- monitoring for the requested coherency information during a designated coherency response interval;
- sending a first signal by a second device during the designated coherency response interval indicating that the coherency information will be returned during a second interval;
- and
- sending a second signal to provide the coherency information to the first device during the second interval.
In an information processing system comprising a plurality of bus devices coupled to at least one storage device via a set of buses, a method comprising the steps of:
- issuing a bus operation by a first device coupled to a set of buses directed to at least one device not directly coupled to the set of buses, including in the bus operation a tag established by the requestor;
- checking the bus operations by a second device;
- issuing a first coherency response on one of the buses during a designated coherency response interval by the second device in response to a read request directed to data residing in the at least one device;
- sending the read request to the at least one device;
- receiving the requested data from the at least one device;
- asserting the tag, the requested data and a second coherency response on one of the buses;
- and
- reading the requested data and the coherency information by the first device during a second interval.
An information processing system, comprising:
- a plurality of bus devices, including one or more processors;
- at least one storage device;
- a bus coupling said plurality of bus devices and said storage device;
- means for issuing a request on the bus by a first device for data and coherency information;
- means for monitoring by the first device for the coherency information during a designated coherency response interval;
- means for sending a first coherency response by a second device during the designated coherency response interval, indicating that the coherency information will be returned during a second interval;
- and
- means for sending a second coherency response to provide the coherency information to the first device during the second interval.
Dependencies are inferred from the claim text.