Victim Cache Prefetching
First Claim
1. A processing unit for a multiprocessor data processing system, said processing unit comprising:
- a processor core; and
a cache hierarchy coupled to the processor core to provide low latency data access, the cache hierarchy including an upper level cache coupled to the processor core and a lower level victim cache coupled to the upper level cache, each of the upper level cache and the lower level victim cache including a respective cache directory and a respective data array, wherein responsive to a prefetch request of the processor core that misses in the upper level cache, the lower level victim cache determines whether the prefetch request misses in the directory of the lower level victim cache and, if so, allocates a state machine in the lower level victim cache that services the prefetch request by issuing the prefetch request to at least one other processing unit of the multiprocessor data processing system.
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Accused Products
Abstract
A processing unit for a multiprocessor data processing system includes a processor core and a cache hierarchy coupled to the processor core to provide low latency data access. The cache hierarchy includes an upper level cache coupled to the processor core and a lower level victim cache coupled to the upper level cache. In response to a prefetch request of the processor core that misses in the upper level cache, the lower level victim cache determines whether the prefetch request misses in the directory of the lower level victim cache and, if so, allocates a state machine in the lower level victim cache that services the prefetch request by issuing the prefetch request to at least one other processing unit of the multiprocessor data processing system.
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Citations
20 Claims
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1. A processing unit for a multiprocessor data processing system, said processing unit comprising:
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a processor core; and a cache hierarchy coupled to the processor core to provide low latency data access, the cache hierarchy including an upper level cache coupled to the processor core and a lower level victim cache coupled to the upper level cache, each of the upper level cache and the lower level victim cache including a respective cache directory and a respective data array, wherein responsive to a prefetch request of the processor core that misses in the upper level cache, the lower level victim cache determines whether the prefetch request misses in the directory of the lower level victim cache and, if so, allocates a state machine in the lower level victim cache that services the prefetch request by issuing the prefetch request to at least one other processing unit of the multiprocessor data processing system. - View Dependent Claims (2, 3, 4, 5, 6)
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8. A data processing system, comprising:
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at least one system memory; and a plurality of processing units coupled to the system memory, wherein a processing unit among the plurality of processing units includes; a processor core; and a cache hierarchy coupled to the processor core to provide low latency data access, the cache hierarchy including an upper level cache coupled to the processor core and a lower level victim cache coupled to the upper level cache, each of the upper level cache and the lower level victim cache including a respective cache directory and a respective data array, wherein responsive to a prefetch request of the processor core that misses in the upper level cache, the lower level victim cache determines whether the prefetch request misses in the directory of the lower level victim cache and, if so, allocates a state machine in the lower level victim cache that services the prefetch request by issuing the prefetch request to at least one other processing unit of the data processing system. - View Dependent Claims (7, 9, 10, 11, 12, 13, 14)
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15. A method of data processing in a multiprocessor data processing system containing a processing unit including a processor core and a cache hierarchy coupled to the processor core to provide low latency data access, wherein the cache hierarchy includes an upper level cache coupled to the processor core and a lower level victim cache coupled to the upper level cache, each of the upper level cache and the lower level victim cache including a respective cache directory and a respective data array, said method comprising:
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the lower level victim cache receiving a prefetch request of the processor core that misses in the upper level cache; in response to receiving the prefetch request, the lower level victim cache determines whether the prefetch request misses in the directory of the lower level victim cache; and if a determination is made that the prefetch request misses in the directory of the lower level victim cache, allocating a state machine in the lower level victim cache that services the prefetch request by issuing the prefetch request to at least one other processing unit of the multiprocessor data processing system. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification