System for arbitrating access from multiple requestors to multiple shared resources over a shared communications link and giving preference for accessing idle shared resources

摘要

A method and apparatus for arbitrating for access to a group of shared resources that are communicating with multiple requesters over a shared communications link while minimizing latency and maximizing link utilization is applicable to any situation where more than one device communicates with more than one resource over a single communication link and where the cycle time of the resource is greater than the time the link is needed for the transfer by the resource. The invention maintains information about the state of the shared resources. This allows the provision of an arbitration algorithm that uses the shared communications link more efficiently. A shared resource typically requires some set-up time before transferring its data and also requires some recovery time after its data are transferred before another request may be processed. The invention provides careful selection of the sequence in which requests are serviced which allows one resource to set-up while another resource is still transferring data, and which allows the first resource to complete its recovery while the second resource is transferring data.