Patent US 9,201,816

A data processing apparatus and method for setting priority levels for transactions has a shared resource for processing transactions, and at least one master device for issuing the transactions to the shared resource. The master device provides a plurality of sources of the transactions, and each of the transactions has a priority level associated therewith. Arbitration circuitry applies an arbitration policy to select a transaction from amongst multiple transactions issued to the shared resource. Adaptive priority circuitry is associated with at least one of the sources and monitors throughput indication data for previously issued transactions from the associated source. For each new transaction from the associated source, the circuitry sets the priority level to one of a plurality of predetermined priority levels dependent on the throughput indication data. The adaptive priority circuitry sets the lowest priority level from amongst the plurality of predetermined priority levels.