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 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 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.
摘要:
In a data processing system capable of concurrently executing multiple hardware threads of execution, an intermediate address translation unit in a processing unit translates an effective address for a memory access into an intermediate address. A cache memory is accessed utilizing the intermediate address. In response to a miss in cache memory, the intermediate address is translated into a real address by a real address translation unit that performs address translation for multiple hardware threads of execution. The system memory is accessed with the real address.
摘要:
A mechanism is provided in a cache for providing a read and write aware cache. The mechanism partitions a large cache into a read-often region and a write-often region. The mechanism considers read/write frequency in a non-uniform cache architecture replacement policy. A frequently written cache line is placed in one of the farther banks. A frequently read cache line is placed in one of the closer banks. The size ratio between read-often and write-often regions may be static or dynamic. The boundary between the read-often region and the write-often region may be distinct or fuzzy.
摘要:
A mechanism is provided in a virtual machine monitor for fine grained cache allocation in a shared cache. The mechanism partitions a cache tag into a most significant bit (MSB) portion and a least significant bit (LSB) portion. The MSB portion of the tags is shared among the cache lines in a set. The LSB portion of the tags is private, one per cache line. The mechanism allows software to set the MSB portion of tags in a cache to allocate sets of cache lines. The cache controller determines whether a cache line is locked based on the MSB portion of the tag.
摘要:
A mechanism is provided in a virtual machine monitor for fine grained cache allocation in a shared cache. The mechanism partitions a cache tag into a most significant bit (MSB) portion and a least significant bit (LSB) portion. The MSB portion of the tags is shared among the cache lines in a set. The LSB portion of the tags is private, one per cache line. The mechanism allows software to set the MSB portion of tags in a cache to allocate sets of cache lines. The cache controller determines whether a cache line is locked based on the MSB portion of the tag.
摘要:
A virtual address scheme for improving performance and efficiency of memory accesses of sparsely-stored data items in a cached memory system is disclosed. In a preferred embodiment of the present invention, a special address translation unit is used to translate sets of non-contiguous addresses in real memory into contiguous blocks of addresses in an “intermediate address space.” This intermediate address space is a fictitious or “virtual” address space, but is distinguishable from the virtual address space visible to application programs, and in user-level memory operations, effective addresses seen/manipulated by application programs are translated into intermediate addresses by an additional address translation unit for memory caching purposes. This scheme allows non-contiguous data items in memory to be assembled into contiguous cache lines for more efficient caching/access (due to the perceived spatial proximity of the data from the perspective of the processor).