The present technique provides an apparatus and method for caching data. The apparatus has a cache storage to cache data associated with memory addresses, a first interface to receive access requests, where each access request is a request to access data at a memory address indicated by that access request, and a second interface to couple to a memory controller used to control access to memory. Further, cache control circuitry is used to control allocation of data into the cache storage in accordance with a power consumption based allocation policy that seeks to select which data is cached in the cache storage with the aim of conserving power associated with accesses to the memory via the second interface. A given access request considered by the cache control circuitry is provided with associated cache hint information providing one or more usage indications for given data at the memory address indicated by that given access request, and the cache control circuitry is arranged to reference the associated cache hint information when applying the power consumption based allocation policy to determine whether to cache the given data in the cache storage.

Apparatuses and methods related to providing coherent memory access. An apparatus for providing coherent memory access can include a memory array, a first processing resource, a first cache line and a second cache line coupled to the memory array, a first cache controller, and a second cache controller. The first cache controller coupled to the first processing resource and to the first cache line can be configured to provide coherent access to data stored in the second cache line and corresponding to a memory address. A second cache controller coupled through an interface to a second processing resource external to the apparatus and coupled to the second cache line can be configured to provide coherent access to the data stored in the first cache line and corresponding to the memory address. Coherent access can be provided using a first cache line address register of the first cache controller which stores the memory address and a second cache line address register of the second cache controller which also stores the memory address.

Apparatuses and methods related to providing coherent memory access. An apparatus for providing coherent memory access can include a memory array, a first processing resource, a first cache line and a second cache line coupled to the memory array, a first cache controller, and a second cache controller. The first cache controller coupled to the first processing resource and to the first cache line can be configured to provide coherent access to data stored in the second cache line and corresponding to a memory address. A second cache controller coupled through an interface to a second processing resource external to the apparatus and coupled to the second cache line can be configured to provide coherent access to the data stored in the first cache line and corresponding to the memory address. Coherent access can be provided using a first cache line address register of the first cache controller which stores the memory address and a second cache line address register of the second cache controller which also stores the memory address.

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for a system-level cache to allocate cache resources by a way-partitioning process. One of the methods includes maintaining a mapping between partitions and priority levels and allocating primary ways to respective enabled partitions in an order corresponding to the respective priority levels assigned to the enabled partitions.

Methods, systems, and apparatus, including computer programs encoded on computer storage media, for a system-level cache to allocate cache resources by a way-partitioning process. One of the methods includes maintaining a mapping between partitions and priority levels and allocating primary ways to respective enabled partitions in an order corresponding to the respective priority levels assigned to the enabled partitions.

Some embodiments provide a program that receives a first set of data and a first greenhouse gas emission value. The program stores, in a cache, the first set of data and the first greenhouse gas emission value. The program receives a second set of data and a second greenhouse gas emission value. The program stores, in the cache, the second set of data and the second greenhouse gas emission value. The program receives a third set of data and a third greenhouse gas emission value. The program determines one of the first and second sets of data to remove from the cache based on the first and second greenhouse gas emission values. The program replaces, in the cache, one of the first and second sets of data and the corresponding first or second greenhouse gas emission value with the third set of data and the third greenhouse gas emission value.

Some embodiments provide a program that receives a first set of data and a first greenhouse gas emission value. The program stores, in a cache, the first set of data and the first greenhouse gas emission value. The program receives a second set of data and a second greenhouse gas emission value. The program stores, in the cache, the second set of data and the second greenhouse gas emission value. The program receives a third set of data and a third greenhouse gas emission value. The program determines one of the first and second sets of data to remove from the cache based on the first and second greenhouse gas emission values. The program replaces, in the cache, one of the first and second sets of data and the corresponding first or second greenhouse gas emission value with the third set of data and the third greenhouse gas emission value.

A system and method of handling data access demands in a processor virtual cache that includes: determining if a virtual cache data access demand missed because of a difference in the context tag of the data access demand and a corresponding entry in the virtual cache with the same virtual address as the data access demand; in response to the virtual cache missing, determining whether the alias tag valid bit is set in the corresponding entry of the virtual cache; in response to the alias tag valid bit not being set, determining whether the virtual cache data access demand is a synonym of the corresponding entry in the virtual cache; and in response to the virtual access demand being a synonym of the corresponding entry in the virtual cache with the same virtual address but a different context tag, updating information in a tagged entry in an alias table.

A system and method of handling data access demands in a processor virtual cache that includes: determining if a virtual cache data access demand missed because of a difference in the context tag of the data access demand and a corresponding entry in the virtual cache with the same virtual address as the data access demand; in response to the virtual cache missing, determining whether the alias tag valid bit is set in the corresponding entry of the virtual cache; in response to the alias tag valid bit not being set, determining whether the virtual cache data access demand is a synonym of the corresponding entry in the virtual cache; and in response to the virtual access demand being a synonym of the corresponding entry in the virtual cache with the same virtual address but a different context tag, updating information in a tagged entry in an alias table.

Some aspects of the disclosure relate to a pre-fetch mechanism for a cache line compression system that increases RAM capacity and optimizes overflow area reads. For example, a pre-fetch mechanism may allow the memory controller to pipeline the reads from an area with fixed size slots (main compressed area) and the reads from an overflow area. The overflow area is arranged so that a cache line most likely containing the overflow data for a particular line may be calculated by a decompression engine. In this manner, the cache line decompression engine may fetch, in advance, the overflow area before finding the actual location of the overflow data.