Patent application number | Description | Published |
20080229070 | Cache circuitry, data processing apparatus and method for prefetching data - Cache circuitry, a data processing apparatus including such cache circuitry, and a method for prefetching data into such cache circuitry, are provided. The cache circuitry has a cache storage comprising a plurality of cache lines for storing data values, and control circuitry which is responsive to an access racquet issued by a device of the data processing apparatus identifying a memory address of a data value to be accessed, to cause a lookup operation to be performed to determine whether the data value for that memory address is stored within the cache storage. If not, a linefill operation is initiated to retrieve the data value from memory. Further, prefetch circuitry is provided which is responsive to a determination that the memory address specified by a current access request is the same as a predicted memory address, to perform either a first prefetch linefill operation or a second prefetch linefill operation to retrieve from memory at least one further data value in anticipation of that data value being the subject of a subsequent access request. The selection of either the first prefetch linefill operation or the second prefetch linefill operation is performed in dependence on an attribute of the current access request. The first prefetch linefill operation involves issuing a sequence of memory addresses to memory, and allocating into a corresponding sequence of cache lines the data values returned from the memory in response to that sequence of addresses. The second prefetch linefill operation comprises issuing a selected memory address to memory, and storing in a linefill buffer the at least one data value returned from the memory in response to that memory address, with that at least one data value only being allocated into the cache when a subsequent access request specifies the selected memory address. By such an approach, the operation of the prefetch circuitry can be altered to take into account the type of access request being issued. | 09-18-2008 |
20110231633 | Operand size control - A data processing system | 09-22-2011 |
20140201447 | DATA PROCESSING APPARATUS AND METHOD FOR HANDLING PERFORMANCE OF A CACHE MAINTENANCE OPERATION - A data processing apparatus has data processing circuitry for performing data processing operations on data, and a hierarchical cache structure for storing at least a subset of the data for access by the data processing circuitry. The hierarchical cache structure has first and second level caches, and data evicted from the first level cache is routed to the second level cache under the control of second level cache access control circuitry. Cache maintenance circuitry performs a cache maintenance operation in both the first level cache and the second level cache. The access control circuitry is responsive to maintenance indication data to modify the eviction handling operation performed in response to the evicted data, so as to cause the required cache maintenance for the second level cache to be incorporated within the eviction handling operation. | 07-17-2014 |
20140258622 | PREFETCHING OF DATA AND INSTRUCTIONS IN A DATA PROCESSING APPARATUS - A data processing apparatus includes a processor and a hierarchical data storage system, including a memory and a cache, for storing the data and the instructions in storage locations identified by physical addresses. The apparatus includes address translation circuitry for mapping the virtual addresses to the physical addresses and load store circuitry receiving access requests from the processor. The store circuitry accesses the translation circuitry to identify physical addresses that correspond to virtual addresses of the received data access requests, and to access the corresponding physical addresses in the hierarchical data storage system. Preload circuitry receives preload requests from the processor indicating virtual addresses storage locations that are to be preloaded. Prefetch circuitry monitors at least some of the accesses performed by the load store circuitry and predicts addresses to be accessed subsequently, and transmits the predicted addresses to the preload circuitry as preload requests. | 09-11-2014 |
20140310480 | DATA PROCESSING APPARATUS AND METHOD FOR PERFORMING LOAD-EXCLUSIVE AND STORE-EXCLUSIVE OPERATIONS - A data processing apparatus is provided in which a processor unit accesses data values stored in a memory and a cache stores local copies of a subset of the data values. The cache maintains a status value for each local copy stored in the cache. When the processor unit executes a load-exclusive operation, a first data value is loaded from a specified memory location and an exclusive use monitor begins monitoring the specified memory location for accesses. When the processor unit executes a store-exclusive operation, a second data value is stored to the specified memory location if the exclusive use monitor indicates that the first data value has not been modified since the load-exclusive operation was executed. When a local copy of the first data value is stored in the cache and the status value for the local copy of the first data value indicates that the processor unit has exclusive usage of the first data value, the data processing apparatus is configured to prevent modification of the status value for a predetermined time period after the processor unit has executed the load-exclusive operation. | 10-16-2014 |