Patent ID: 9223701
Filing Date: 2015-12-29
Classification: G06F

Abstract:
1. A data processing apparatus comprising: a processor configured to perform data processing operations by executing instructions, said data processing operations comprising accessing data values stored in a memory; a cache configured to store local copies of a subset of said data values, wherein said cache is configured to maintain a status value for each local copy stored in said cache; and an exclusive use monitor configured to monitor a selected memory location for accesses, wherein said processor is configured to execute a load-exclusive operation, said load-exclusive operation comprising loading a first data value from a specified memory location and causing said exclusive use monitor to begin monitoring said specified memory location, wherein said processor is configured to execute a store-exclusive operation, said store-exclusive operation comprising storing a second data value to said specified memory location if said exclusive use monitor indicates that said first data value at said specified memory location has not been modified since said load-exclusive operation was executed, and wherein, when a local copy of said first data value is stored in said cache and said status value for said local copy of said first data value indicates that said processor has exclusive usage of said first data value, said data processing apparatus is configured to prevent modification of said status value for a predetermined time period after said processor has executed said load-exclusive operation, a pending instruction queue populated by pending instructions which have been decoded but not yet executed, wherein said data processing apparatus is configured to prevent modification of said status value with reference to said pending instructions, wherein said data processing apparatus is configured to identify a first set of pending instructions in said pending instruction queue when an instruction configured to cause execution of at least part of said load-exclusive operation is in said pending instruction queue, wherein execution of said first set of pending instructions must be completed before execution of said store-exclusive operation completes, and said data processing apparatus is configured to prioritize execution of said first set of pending instructions.