摘要:
A multi-core processing apparatus may provide a cache probe and data retrieval method. The method may comprise sending a memory request from a requester to a record keeping structure. The memory request may have a memory address of a memory that stores requested data. The method may further comprise determining that a local last accessor of the memory address may have a copy of the requested data up to date with the memory. The local last accessor may be within a local domain that the requester belongs to. The method may further comprise sending a cache probe to the local last accessor and retrieving a latest value of the requested data from the local last accessor to the requester.
摘要:
An apparatus and method is described herein for intelligently spilling cache lines. Usefulness of cache lines previously spilled from a source cache is learned, such that later evictions of useful cache lines from a source cache are intelligently selected for spill. Furthermore, another learning mechanism—cache spill prediction—may be implemented separately or in conjunction with usefulness prediction. The cache spill prediction is capable of learning the effectiveness of remote caches at holding spilled cache lines for the source cache. As a result, cache lines are capable of being intelligently selected for spill and intelligently distributed among remote caches based on the effectiveness of each remote cache in holding spilled cache lines for the source cache.
摘要:
Method and apparatus to efficiently maintain cache coherency by reading/writing a domain state field associated with a tag entry within a cache tag directory. A value may be assigned to a domain state field of a tag entry in a cache tag directory. The cache tag directory may belong to a hierarchy of cache tag directories.Each tag entry may be associated with a cache line from a cache belonging to a first domain. The first domain may contain multiple caches. The value of the domain state field may indicate whether its associated cache line can be read or changed.
摘要:
An apparatus to resolve cache coherency is presented. In one embodiment, the apparatus includes a microprocessor comprising one or more processing cores. The apparatus also includes a probe speculative address file unit, coupled to a cache memory, comprising a plurality of entries. Each entry includes a timer and a tag associated with a memory line. The apparatus further includes control logic to determine whether to service an incoming probe based at least in part on a timer value.
摘要:
A multi core processor implements a cash coherency protocol in which probe messages are address-ordered on a probe channel while responses are un-ordered on a response channel. When a first core generates a read of an address that misses in the first core's cache, a line fill is initiated. If a second core is writing the same address, the second core generates an update on the addressed ordered probe channel. The second core's update may arrive before or after the first core's line fill returns. If the update arrived before the fill returned, a mask is maintained to indicate which portions of the line were modified by the update so that the late arriving line fill only modifies portions of the line that were unaffected by the earlier-arriving update.
摘要:
Method and apparatus to efficiently organize data in caches by storing/accessing data of varying sizes in cache lines. A value may be assigned to a field indicating the size of usable data stored in a cache line. If the field indicating the size of the usable data in the cache line indicates a size less than the maximum storage size, a value may be assigned to a field in the cache line indicating which subset of the data in the field to store data is usable data. A cache request may determine whether the size of the usable data in a cache line is equal to the maximum data storage size. If the size of the usable data in the cache line is equal to the maximum data storage size the entire stored data in the cache line may be returned.
摘要:
An apparatus of an aspect includes a prefetch cache line address predictor to receive a cache line address and to predict a next cache line address to be prefetched. The next cache line address may indicate a cache line having at least 64-bytes of instructions. The prefetch cache line address predictor may have a cache line target history storage to store a cache line target history for each of multiple most recent corresponding cache lines. Each cache line target history may indicate whether the corresponding cache line had a sequential cache line target or a non-sequential cache line target. The cache line address predictor may also have a cache line target history predictor. The cache line target history predictor may predict whether the next cache line address is a sequential cache line address or a non-sequential cache line address, based on the cache line target history for the most recent cache lines.
摘要:
An apparatus and method for improving cache performance in a computer system having a multi-level cache hierarchy. For example, one embodiment of a method comprises: selecting a first line in a cache at level N for potential eviction; querying a cache at level M in the hierarchy to determine whether the first cache line is resident in the cache at level M, wherein M