A technique for prefetching data for a cache is provided. The technique includes detecting access to a data block. In response to the detection, a prefetch block generates proposed blocks for prefetch. The prefetch block also examines prefetch tracking data to determine whether a prefetch group including the proposed blocks is marked as already having been prefetched. If the group has been marked as already having been prefetched, then prefetch block does not prefetch that data, thereby avoiding traffic between the prefetch block and the cache memory. Using this technique, unnecessary requests to prefetch data into the cache memory are avoided.

A computing system, method and apparatus to cache a portion of a data block. A processor can access data using memory addresses in an address space. A first memory can store a block of data at a block of contiguous addresses in the space of memory address. A second memory can cache a first portion of the block of data identified by an item selection vector. For example, response to a request to cache the block of data stored in the first memory, the computing system can communicate the first portion of the block of data from the first memory to the second memory according to the item selection vector without accessing a second portion of the block of data. Thus, different data blocks in the first memory of a same size can be each cached in different cache blocks of different sizes in the second memory.

A computing system using a bit counter may include a host device; a cache configured to temporarily store data of the host device, and including a plurality of sets; a cache controller configured to receive a multi-bit cache address from the host device, perform computation on the cache address using a plurality of bit counters, and determine a hash function of the cache; a semiconductor device; and a memory controller configured to receive the cache address from the cache controller, and map the cache address to a semiconductor device address.

A computing system using a bit counter may include a host device; a cache configured to temporarily store data of the host device, and including a plurality of sets; a cache controller configured to receive a multi-bit cache address from the host device, perform computation on the cache address using a plurality of bit counters, and determine a hash function of the cache; a semiconductor device; and a memory controller configured to receive the cache address from the cache controller, and map the cache address to a semiconductor device address.

A memory device comprises a memory bank comprising a plurality of addressable memory cells, wherein the memory bank is divided into a plurality of segments. Further, the device comprises a cache memory operable for storing a second plurality of data words, wherein each data word of the second plurality of data words is either awaiting write verification associated with the memory bank or is to be re-written into the memory bank. The cache memory is divided into a plurality of primary segments, wherein each primary segment of the cache memory is direct mapped to a corresponding segment of the plurality of segments, wherein each primary segment is sub-divided into a plurality of secondary segments, and wherein each of the plurality of secondary segments comprises at least one counter for tracking a number of entries stored therein.

A memory device comprises a memory bank comprising a plurality of addressable memory cells, wherein the memory bank is divided into a plurality of segments. Further, the device comprises a cache memory operable for storing a second plurality of data words, wherein each data word of the second plurality of data words is either awaiting write verification associated with the memory bank or is to be re-written into the memory bank. The cache memory is divided into a plurality of primary segments, wherein each primary segment of the cache memory is direct mapped to a corresponding segment of the plurality of segments, wherein each primary segment is sub-divided into a plurality of secondary segments, and wherein each of the plurality of secondary segments comprises at least one counter for tracking a number of entries stored therein.

An apparatus and method are provided for decoding instructions. The apparatus has fetch circuitry for fetching instructions from memory, where each instruction is from a fetch granule comprising P instructions at sequential addresses in the memory. Decode circuitry is then used to decode fetched instructions in order to produce a stream of decoded instructions for execution by the execution circuitry, and a decoded instruction cache is provided to store decoded instructions produced by the decode circuitry. The decoded instruction cache comprises a plurality of cache lines, where each cache line is arranged to store decoded instructions from at least one fetch granule allocated to that cache block, for each fetch granule allocated to the cache block the cache block being able to store up to P decoded instructions from that fetch granule. When the corresponding decoded instruction for a required instruction for execution by the execution circuitry is subsequently determined to already be stored in the decoded instruction cache, then the corresponding decoded instruction from the decoded instruction cache may be output in the stream of decoded instructions, thereby avoiding the need to re-decode the required instruction. Allocation circuitry is provided to allocate cache blocks for storing the decoded instructions, and is arranged, when a cache block is already allocated for a number of existing decoded instructions from a particular fetch granule due to a first path through the fetch granule being taken, and then a number of additional decoded instructions from that particular fetch granule are subsequently produced by the decode circuitry due to a second path different to the first path being taken through the fetch granule, to update the already allocated cache block to provide both the existing decoded instructions and the additional decoded instructions. As a result, more efficient utilisation of the available resources within the decoded instruction cache can be achieved.

A system comprises a processor including a CPU core, first and second memory caches, and a memory controller subsystem. The memory controller subsystem speculatively determines a hit or miss condition of a virtual address in the first memory cache and speculatively translates the virtual address to a physical address. Associated with the hit or miss condition and the physical address, the memory controller subsystem configures a status to a valid state. Responsive to receipt of a first indication from the CPU core that no program instructions associated with the virtual address are needed, the memory controller subsystem reconfigures the status to an invalid state and, responsive to receipt of a second indication from the CPU core that a program instruction associated with the virtual address is needed, the memory controller subsystem reconfigures the status back to a valid state.

In one example, a system for managing encrypted memory comprises a processor to store a first MAC based on data stored in system memory in response to a write operation to the system memory. The processor can also detect a read operation corresponding to the data stored in the system memory, calculate a second MAC based on the data retrieved from the system memory, determine that the second MAC does not match the first MAC, and recalculate the second MAC with a correction operation, wherein the correction operation comprises an XOR operation based on the data retrieved from the system memory and a replacement value for a device of the system memory. Furthermore, the processor can decrypt the data stored in the system memory in response to detecting the recalculated second MAC matches the first MAC and transmit the decrypted data to cache thereby correcting memory errors.

In one example, a system for managing encrypted memory comprises a processor to store a first MAC based on data stored in system memory in response to a write operation to the system memory. The processor can also detect a read operation corresponding to the data stored in the system memory, calculate a second MAC based on the data retrieved from the system memory, determine that the second MAC does not match the first MAC, and recalculate the second MAC with a correction operation, wherein the correction operation comprises an XOR operation based on the data retrieved from the system memory and a replacement value for a device of the system memory. Furthermore, the processor can decrypt the data stored in the system memory in response to detecting the recalculated second MAC matches the first MAC and transmit the decrypted data to cache thereby correcting memory errors.