两级循环优先算法在PCI仲裁器上的实现

Design of PCI Arbiter based on 2-level Round-robin algorithm

循环优先仲裁算法具有现实公平的特点,介绍了两级循环优先仲裁算法,并给出了该算法在PCI总线仲裁器上的实现方案。将PCI总线主设备分为优先权不同的四个层次,通过对各层次总线主设备的检测实现仲裁。由于采用了设备申请号寄存器组记录总线状态,避免了复杂状态机的设计,该方案可灵活应用于不同数量设备的PCI系统,具有很好的可扩展性。

The paper introduces two-level round-robin arbitration algorithm which has an important characteristic of realistic fairness and presents an application of the algorithm in PCI arbiter.The arbiter divides the PCI masters into four levels,achieves arbitration through detecting bus master request in each level.With the apply number register showing the bus state,the arbiter avoids the design of complex state machine,so it can be used in PCI system with different number of bus devices and has a good scalability.