Efficient coherency response mechanism
First Claim
1. A data processing system, comprising:
- a plurality of processing units interconnected by a coherency network in accordance with a directed spanning tree in which the plurality of processing units comprises a first processing unit characterized as a root of the directed spanning tree, a first set of processing units each characterized as a leaf of the directed spanning tree, and a remaining set of processing units, exclusive of the first processing unit and first set of processing units, whereineach processing unit of the first set comprises;
processing circuitry configured to provide a coherency response in response to a snoop request, andeach processing unit of the remaining set comprises;
switch point circuitry comprising;
one or more ingress ports coupled to neighboring processing units in accordance with the directed spanning tree,a coherency tracking table configured to store a combined coherency response in response to a particular snoop request based on one or more coherency responses received at the one or more ingress ports from the neighboring processing units,an egress port toward the first processing unit characterized as the root of the directed spanning tree, wherein the egress port is coupled to the coherency network, andcoherency logic configured to provide the combined coherency response for the particular snoop request on the egress port when a corresponding coherency response for the particular snoop request has been received from every one of the neighboring processing units in accordance with the directed spanning tree.
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Abstract
A plurality of processing units are interconnected by a coherency network in accordance with a directed spanning tree. Each processing unit that is a leaf of the directed spanning tree includes processing circuitry to provide a coherency response in response to a snoop request. Each processing unit which is not a root or leaf of the directed spanning tree includes switch point circuitry having one or more ingress ports coupled to neighboring processing units in accordance with the directed spanning tree. The switch point circuitry includes a coherency tracking table configured to store a combined coherency response in response to a particular snoop request based on one or more coherency responses received at the one or more ingress ports from the neighboring processing units.
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Citations
17 Claims
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1. A data processing system, comprising:
a plurality of processing units interconnected by a coherency network in accordance with a directed spanning tree in which the plurality of processing units comprises a first processing unit characterized as a root of the directed spanning tree, a first set of processing units each characterized as a leaf of the directed spanning tree, and a remaining set of processing units, exclusive of the first processing unit and first set of processing units, wherein each processing unit of the first set comprises; processing circuitry configured to provide a coherency response in response to a snoop request, and each processing unit of the remaining set comprises; switch point circuitry comprising; one or more ingress ports coupled to neighboring processing units in accordance with the directed spanning tree, a coherency tracking table configured to store a combined coherency response in response to a particular snoop request based on one or more coherency responses received at the one or more ingress ports from the neighboring processing units, an egress port toward the first processing unit characterized as the root of the directed spanning tree, wherein the egress port is coupled to the coherency network, and coherency logic configured to provide the combined coherency response for the particular snoop request on the egress port when a corresponding coherency response for the particular snoop request has been received from every one of the neighboring processing units in accordance with the directed spanning tree. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A data processing system, comprising:
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a coherency network; an ordering point processing unit; and a plurality of processing units, wherein the ordering point processing unit and the plurality of processing units are interconnected by the coherency network, wherein the plurality of processing units comprises a set of trunk processing units, wherein each of the set of trunk processing units comprises; switch point circuitry comprising; one or more ingress ports coupled to the coherency network, a coherency tracking table configured to store a combined coherency response in response to a particular snoop request based on one or more coherency responses received at the one or more ingress ports, an egress port toward the ordering point processing unit, wherein the egress port is coupled to the coherency network, and coherency logic configured to provide the combined coherency response for the particular snoop request on the egress port when a corresponding coherency response for the particular snoop request has been received from every one of the one or more ingress ports. - View Dependent Claims (12, 13, 14, 15)
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16. In a data processing system having multiple processing units interconnected via a coherency network in accordance with a directed spanning tree, a method comprising:
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receiving, at a processing unit from each of one or more ingress neighboring processing units in accordance with the directed spanning tree, a corresponding coherency response responsive to a first snoop request; updating a first entry corresponding to the first snoop request in a coherency tracking table of the processing unit, wherein the updating comprises accumulating each corresponding coherency response into a combined coherency response stored within the first entry; and providing to an egress neighboring processing unit in accordance with the directed spanning tree the combined coherency response from the first entry, wherein the providing is performed after each corresponding coherency response to the first snoop request has been received from all of the one or more ingress neighboring processing units and accumulated into the combined coherency response of the first entry. - View Dependent Claims (17)
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Specification