VICTIM CACHE LATERAL CASTOUT TARGETING
First Claim
1. A method of data processing in a data processing system including a plurality of processing units including a first processing unit and a second processing unit coupled by an interconnect fabric, wherein the first processing unit has a first processor core and associated first upper and first lower level caches and the second processing unit has a second processor core and associated second upper and lower level caches, said method comprising:
- in response to a data request, selecting a victim cache line to be castout from the first lower level cache;
selecting a target lower level cache of one of the plurality of processing units based upon architectural proximity of the target lower level cache to a home system memory to which an address of the victim cache line is assigned;
the first processing unit issuing a lateral castout (LCO) command on the interconnect fabric, wherein the LCO command identifies the victim cache line to be castout from the first lower level cache and indicates that the target lower level cache is an intended destination of the victim cache line; and
in response to a coherence response to the LCO command indicating success of the LCO command, removing the victim cache line from the first lower level cache and holding the victim cache line in the second lower level cache.
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Accused Products
Abstract
A data processing system includes a plurality of processing units coupled by an interconnect fabric. In response to a data request, a victim cache line is selected for castout from a first lower level cache of a first processing unit, and a target lower level cache of one of the plurality of processing units is selected based upon architectural proximity of the target lower level cache to a home system memory to which the address of the victim cache line is assigned. The first processing unit issues on the interconnect fabric a lateral castout (LCO) command that identifies the victim cache line to be castout from the first lower level cache and indicates that the target lower level cache is an intended destination. In response to a coherence response indicating success of the LCO command, the victim cache line is removed from the first lower level cache and held in the second lower level cache.
122 Citations
20 Claims
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1. A method of data processing in a data processing system including a plurality of processing units including a first processing unit and a second processing unit coupled by an interconnect fabric, wherein the first processing unit has a first processor core and associated first upper and first lower level caches and the second processing unit has a second processor core and associated second upper and lower level caches, said method comprising:
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in response to a data request, selecting a victim cache line to be castout from the first lower level cache; selecting a target lower level cache of one of the plurality of processing units based upon architectural proximity of the target lower level cache to a home system memory to which an address of the victim cache line is assigned; the first processing unit issuing a lateral castout (LCO) command on the interconnect fabric, wherein the LCO command identifies the victim cache line to be castout from the first lower level cache and indicates that the target lower level cache is an intended destination of the victim cache line; and in response to a coherence response to the LCO command indicating success of the LCO command, removing the victim cache line from the first lower level cache and holding the victim cache line in the second lower level cache. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A data processing system, comprising:
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an interconnect fabric; a plurality of processing units coupled to the interconnect fabric, the plurality of processing units including a first processing unit and a second processing unit, wherein the first processing unit has a first processor core and associated first upper and first lower level caches, and wherein the second processing unit has a second processor core and associated second upper and lower level caches; and a home system memory coupled to the interconnect fabric, wherein the home system memory is assigned a plurality of addresses including an address; wherein the first processing unit, in response to a data request, selects a victim cache line associated with the address to be castout from the first lower level cache, selects a target lower level cache of one of the plurality of processing units based upon architectural proximity of the target lower level cache to the home system memory to which the address of the victim cache line is assigned, and issues a lateral castout (LCO) command on the interconnect fabric, the LCO command identifying the victim cache line to be castout from the first lower level cache and indicating that the target lower level cache is an intended destination of the victim cache line; and wherein responsive to a coherence response to the LCO command indicating success of the LCO command, the first processing unit removes the victim cache line from the first lower level cache and the second lower level cache holds the victim cache line. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A processing unit for a data processing system including a home system memory and a plurality of processing units coupled by an interconnect fabric, wherein the home system memory is assigned a plurality of addresses including an address, the processing unit comprising:
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the processing unit has a first processor core and associated first upper and first lower level caches; wherein the processing unit, in response to a data request, selects a victim cache line associated with the address to be castout from the first lower level cache, selects a target lower level cache of one of the plurality of processing units based upon architectural proximity of the target lower level cache to the home system memory to which the address of the victim cache line is assigned, and issues a lateral castout (LCO) command on the interconnect fabric, the LCO command identifying the victim cache line to be castout from the first lower level cache and indicating that the target lower level cache is an intended destination of the victim cache line; and wherein responsive to a coherence response to the LCO command indicating success of the LCO command, the first processing unit removes the victim cache line from the first lower level cache for storage in a second lower level cache. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification