Described apparatuses and methods order memory address portions advantageously for cache-memory addressing. An address bus can have a smaller width than a memory address. The multiple bits of the memory address can be separated into most-significant bits (MSB) and least-significant bits (LSB) portions. The LSB portion is provided to a cache first. The cache can process the LSB portion before the MSB portion is received. The cache can use index bits of the LSB portion to index into an array of memory cells and identify multiple corresponding tags. The cache can also check the corresponding tags against lower tag bits of the LSB portion. A partial match may be labeled as a predicted hit, and a partial miss may be labeled as an actual miss, which can initiate a data fetch. With the remaining tag bits from the MSB portion, the cache can confirm or refute the predicted hit.

A cache control apparatus includes a data unit configured to store data on an index-specific basis, a tag unit configured to store, on the index-specific basis, a tag and a flag indicating whether the data has an uncorrectable error, and a control unit configured to refer to the flag, upon detecting a tag hit by performing a read access to the tag unit, to determine whether an uncorrectable error exists in the data corresponding to the tag hit, wherein the control unit performs process scheduling such that the read access to the tag unit and another access to the tag unit are performed simultaneously.

A cache control apparatus includes a data unit configured to store data on an index-specific basis, a tag unit configured to store, on the index-specific basis, a tag and a flag indicating whether the data has an uncorrectable error, and a control unit configured to refer to the flag, upon detecting a tag hit by performing a read access to the tag unit, to determine whether an uncorrectable error exists in the data corresponding to the tag hit, wherein the control unit performs process scheduling such that the read access to the tag unit and another access to the tag unit are performed simultaneously.

Devices and methods for cache prefetching are provided. A device is provided which comprises memory and a processor. The memory comprises a DRAM cache, a cache dedicated to the processor and one or more intermediate caches between the dedicated cache and the DRAM cache. The processor is configured to issue prefetch requests to prefetch data, issue data access requests to fetch the data and when one or more previously issued prefetch requests are determined to be inaccurate, issue a prefetch request to prefetch a tag, corresponding to the memory address of requested data in the DRAM cache. A tag look-up is performed at the DRAM cache without performing tag look-ups at the dedicated cache or the intermediate caches. The tag is prefetched from the DRAM cache without prefetching the requested data.

Devices and methods for cache prefetching are provided. A device is provided which comprises memory and a processor. The memory comprises a DRAM cache, a cache dedicated to the processor and one or more intermediate caches between the dedicated cache and the DRAM cache. The processor is configured to issue prefetch requests to prefetch data, issue data access requests to fetch the data and when one or more previously issued prefetch requests are determined to be inaccurate, issue a prefetch request to prefetch a tag, corresponding to the memory address of requested data in the DRAM cache. A tag look-up is performed at the DRAM cache without performing tag look-ups at the dedicated cache or the intermediate caches. The tag is prefetched from the DRAM cache without prefetching the requested data.

Methods, apparatus, systems and articles of manufacture are disclosed facilitate read-modify-write support in a coherent victim cache with parallel data paths. An example apparatus includes a random-access memory configured to be coupled to a central processing unit via a first interface and a second interface, the random-access memory configured to obtain a read request indicating a first address to read via a snoop interface, an address encoder coupled to the random-access memory, the address encoder to, when the random-access memory indicates a hit of the read request, generate a second address corresponding to a victim cache based on the first address, and a multiplexer coupled to the victim cache to transmit a response including data obtained from the second address of the victim cache.

Methods, apparatus, systems and articles of manufacture are disclosed facilitate read-modify-write support in a coherent victim cache with parallel data paths. An example apparatus includes a random-access memory configured to be coupled to a central processing unit via a first interface and a second interface, the random-access memory configured to obtain a read request indicating a first address to read via a snoop interface, an address encoder coupled to the random-access memory, the address encoder to, when the random-access memory indicates a hit of the read request, generate a second address corresponding to a victim cache based on the first address, and a multiplexer coupled to the victim cache to transmit a response including data obtained from the second address of the victim cache.

Methods, systems, and devices maintain state information in a shadow tag memory for a plurality of cachelines in each of a plurality of private caches, with each of the private caches being associated with a corresponding one of multiple processing cores. One or more cache probes are generated based on a write operation associated with one or more cachelines of the plurality of cachelines, such that each of the cache probes is associated with cachelines of a particular private cache of the multiple private caches, the particular private cache being associated with an indicated processing core. Transmission of the cache probes to the particular private cache is prevented until, responsive to a scope acquire operation from the indicated processing core, the cache probes are released for transmission to the respectively associated cachelines in the particular private cache.

Methods, systems, and devices maintain state information in a shadow tag memory for a plurality of cachelines in each of a plurality of private caches, with each of the private caches being associated with a corresponding one of multiple processing cores. One or more cache probes are generated based on a write operation associated with one or more cachelines of the plurality of cachelines, such that each of the cache probes is associated with cachelines of a particular private cache of the multiple private caches, the particular private cache being associated with an indicated processing core. Transmission of the cache probes to the particular private cache is prevented until, responsive to a scope acquire operation from the indicated processing core, the cache probes are released for transmission to the respectively associated cachelines in the particular private cache.

An apparatus has processing circuitry (4); memory access circuitry (15) to perform a guard tag check for a tag checking target address having an associated address tag, the guard tag check comprising comparing the address tag with a guard tag stored in a memory system in association with a block of one or more memory locations comprising an addressed location identified by the target address; and an instruction decoder (6) responsive to a random tag setting instruction specifying a tag setting target address, to control the processing circuitry (4) to set the address tag associated with the tag setting target address to a random tag value randomly selected from a set of candidate tag values.