Managing snoop operations in a data processing apparatus

• Main Author: MANSELL DAVID H
• Format: Patent
• Language: English
• Published: 28.12.2006
• Subjects: CALCULATING; COMPUTING; COUNTING; ELECTRIC DIGITAL DATA PROCESSING; PHYSICS

A data processing apparatus and method are provided for managing snoop operations. The data processing apparatus comprises a plurality of processing units for executing a number of processes by performing data processing operations requiring access to data in shared memory. Each processing unit has a cache for storing a subset of the data for access by that processing unit, the data processing apparatus employing a snoop-based cache coherency protocol to ensure data access by each processing unit is up-to-date. Each processing unit has a storage element associated therewith identifying snoop control data, whereby when one of the processing units determines that a snoop operation is required having regard to the cache coherency protocol, that processing unit references the snoop control data in its associated storage element in order to determine which of the plurality of processing units are to be subjected to the snoop operation. This can give rise to significant energy savings by avoiding unnecessary cache tag look ups, and can also improve performance.