| 摘要 |
A data processing apparatus and method for setting priority levels for transactions is provided. The data processing apparatus has a shared resource for processing transactions, and at least one master device for issuing the transactions to the shared resource. The at least one master device provides a plurality of sources of the transactions, and each of the transactions has a priority level associated therewith. Arbitration circuitry is used to apply an arbitration policy to select a transaction from amongst multiple transactions issued to the shared resource, the arbitration policy using the priority level associated with each of the multiple transactions when performing the selection. Adaptive priority circuitry is associated with at least one of the sources, the adaptive priority circuitry monitoring throughput indication data for previously issued transactions from the associated source, and for each new transaction from the associated source, setting the priority level to one of a plurality of predetermined priority levels dependent on the throughput indication data. Through such a mechanism, the adaptive priority circuitry sets the lowest priority level from amongst the plurality of predetermined priority levels that will enable a specified target throughput to be achieved. The adaptive priority circuitry hence uses a feedback mechanism to control the priority level assigned to each new transaction from a source in order to target a specified throughput for the source, and through this mechanism finds the lowest priority necessary to achieve the throughput objectives independent of the activity of other sources within the system. |
