摘要:
A system and method for cache management in a data processing system. The data processing system includes a processor and a memory hierarchy. The memory hierarchy includes at least an upper memory cache, at least a lower memory cache, and a write-back data structure. In response to replacing data from the upper memory cache, the upper memory cache examines the write-back data structure to determine whether or not the data is present in the lower memory cache. If the data is present in the lower memory cache, the data is replaced in the upper memory cache without casting out the data to the lower memory cache.
摘要:
A system and method for cache management in a data processing system. The data processing system includes a processor and a memory hierarchy. The memory hierarchy includes at least an upper memory cache, at least a lower memory cache, and a write-back data structure. In response to replacing data from the upper memory cache, the upper memory cache examines the write-back data structure to determine whether or not the data is present in the lower memory cache. If the data is present in the lower memory cache, the data is replaced in the upper memory cache without casting out the data to the lower memory cache.
摘要:
A system and method of managing cache hierarchies with adaptive mechanisms. A preferred embodiment of the present invention includes, in response to selecting a data block for eviction from a memory cache (the source cache) out of a collection of memory caches, examining a data structure to determine whether an entry exists that indicates that the data block has been evicted from the source memory cache, or another peer cache, to a slower cache or memory and subsequently retrieved from the slower cache or memory into the source memory cache or other peer cache. Also, a preferred embodiment of the present invention includes, in response to determining the entry exists in the data structure, selecting a peer memory cache out of the collection of memory caches at the same level in the hierarchy to receive the data block from the source memory cache upon eviction.
摘要:
A method and an apparatus for performing just-in-time data prefetching within a data processing system comprising a processor, a cache or prefetch buffer, and at least one memory storage device. The apparatus comprises a prefetch engine having means for issuing a data prefetch request for prefetching a data cache line from the memory storage device for utilization by the processor. The apparatus further comprises logic/utility for dynamically adjusting a prefetch distance between issuance by the prefetch engine of the data prefetch request and issuance by the processor of a demand (load request) targeting the data/cache line being returned by the data prefetch request, so that a next data prefetch request for a subsequent cache line completes the return of the data/cache line at effectively the same time that a demand for that subsequent data/cache line is issued by the processor.
摘要:
A system and method of managing cache hierarchies with adaptive mechanisms. A preferred embodiment of the present invention includes, in response to selecting a data block for eviction from a memory cache (the source cache) out of a collection of memory caches, examining a data structure to determine whether an entry exists that indicates that the data block has been evicted from the source memory cache, or another peer cache, to a slower cache or memory and subsequently retrieved from the slower cache or memory into the source memory cache or other peer cache. Also, a preferred embodiment of the present invention includes, in response to determining the entry exists in the data structure, selecting a peer memory cache out of the collection of memory caches at the same level in the hierarchy to receive the data block from the source memory cache upon eviction.
摘要:
A system and method for cache management in a data processing system. The data processing system includes a processor and a memory hierarchy. The memory hierarchy includes at least an upper memory cache, at least a lower memory cache, and a write-back data structure. In response to replacing data from the upper memory cache, the upper memory cache examines the write-back data structure to determine whether or not the data is present in the lower memory cache. If the data is present in the lower memory cache, the data is replaced in the upper memory cache without casting out the data to the lower memory cache.
摘要:
A method and an apparatus for enabling a prefetch engine to detect and support hardware prefetching with different streams in received accesses. Multiple (simple) history tables are provided within (or associated with) the prefetch engine. Each of the multiple tables is utilized to detect different access patterns. The tables are indexed by different parts of the address and are accessed in a preset order to reduce the interference between different patterns. When an address does not fit the patterns of a first table, the address is passed to the next table to be checked for a match of different patterns. In this manner, different patterns may be detected at different tables within a single prefetch engine.
摘要:
A method of accessing data from a cache is disclosed. Tag bits of data among sets and ways of cache lines are divided into common subtags and remaining subtags. Similarly, an access address tag is divided into an address common subtag and address remaining tag. When the index of an access address selects a set, a match comparison of the address common subtag and the selected set common subtag is performed. Also, the address remaining tag and selected set remaining subtags are compared for matching before the selected set and associated data is supplied to the requester.
摘要:
A method and an apparatus for performing just-in-time data prefetching within a data processing system comprising a processor, a cache or prefetch buffer, and at least one memory storage device. The apparatus comprises a prefetch engine having means for issuing a data prefetch request for prefetching a data cache line from the memory storage device for utilization by the processor. The apparatus further comprises logic/utility for dynamically adjusting a prefetch distance between issuance by the prefetch engine of the data prefetch request and issuance by the processor of a demand (load request) targeting the data/cache line being returned by the data prefetch request, so that a next data prefetch request for a subsequent cache line completes the return of the data/cache line at effectively the same time that a demand for that subsequent data/cache line is issued by the processor.
摘要:
A method and an apparatus for enabling a prefetch engine to detect and support hardware prefetching with different streams in received accesses. Multiple (simple) history tables are provided within (or associated with) the prefetch engine. Each of the multiple tables is utilized to detect different access patterns. The tables are indexed by different parts of the address and are accessed in a preset order to reduce the interference between different patterns. When an address does not fit the patterns of a first table, the address is passed to the next table to be checked for a match of different patterns. In this manner, different patterns may be detected at different tables within a single prefetch engine.