Weighted credit-based arbitration using credit history

摘要

A system for managing data transmission from a number of queues employs a regular credit count and a history credit count for each queue. Generally, the regular credit count is used in arbitration. The count is decreased when data is transmitted from the queue and increased at given intervals if the queue is facing no transmission-blocking backpressure. The history credit count is increased in lieu of the regular credit count when transmission from the queue is blocked. Thus, the history credit count keeps track of potential transmission opportunities that would be lost due to the blocking of transmission from the queue. The history credit counts are periodically polled instead of the regular credit counts to give each queue an opportunity to catch up in its use of transmission opportunities.