| 摘要 |
<p>A data processing apparatus 10, 20 is provided in which a processor unit 11, 21 accesses data values stored in a memory 30 and a cache 12, 22 stores local copies of a subset of these values. The cache maintains a status value 13, 23 for each local copy stored. 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 14, 24 begins monitoring this 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 its status value indicates that the processor unit has exclusive usage of it, the apparatus is configured to prevent modification of the status value for a predetermined time period after execution of the load exclusive operation. Such modification may be prevented by stalling certain instructions. A timer 15, 25 may run for the predetermined time period. The cache may administer a MESI protocol.</p> |
