Patent ID: 6434631
Filing Date: 2002-08-13
Classification: G06F,H04N

Abstract:
A method for scheduling servicing of disk I/O requests associated with a plurality of domains, each domain D having a respective quality of service guarantee including a respective reserved bandwidth weight w, the method comprising the steps of:(a) providing a queue Q for each domain D, each queue having a start tag S and a finish tag F; (b) in response to the receipt of an I/O request having a length li from a particular domain Di: appending the I/O request to the queue Qi associated with the domain Di; and updating, if the domain Di is not busy, the start tag Si and finish tag Fi of the queue Qi to indicate the time necessary to service the I/O request in accordance with the length li, the reserved bandwidth weight wi of the domain Di, and the finish tags for the other queues; (c) identifying a queue Qj having the smallest finish tag among all domains which are busy and selecting an I/O request from the queue Qj; (d) servicing the selected I/O request; and (e) in response to completion of servicing of the selected I/O request: removing the serviced I/O request from the queue Qj; and adjusting, if the queue Qj is not empty, the start tag Sj and finish tag Fj of the queue Qj to indicate the time necessary to service a next I/O request in queue Qj accordance with a length lj of the next I/O request, the reserved bandwidth weight wj of a domain Dj associated with the queue Qj, and the finish tags for the other queues.