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 having one or more ingress ports coupled to neighboring processing units in accordance with the directed spanning tree, whereinthe 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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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
20 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 having one or more ingress ports coupled to neighboring processing units in accordance with the directed spanning tree, wherein 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A data processing system, comprising:
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a coherency network; an ordering point processing unit; 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 having one or more ingress ports coupled to the coherency network, wherein 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. - View Dependent Claims (13, 14, 15, 16, 17)
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18. 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 a first neighboring processing unit in accordance with the directed spanning tree, a coherency response in response 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 the received coherency response with a combined coherency response stored within the first entry; and providing to a second neighboring processing unit in accordance with the directed spanning tree the combined coherency response from the first entry. - View Dependent Claims (19, 20)
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Specification