Method and apparatus for improving the fairness of new attaches to a weighted fair queue in a quality of service (QoS) scheduler

A network processor, comprising:

• a scheduler which includes a scheduling queue having flows attached thereto and defining a sequence in which the attached flows are to be serviced;
• and
• storage means, associated with the scheduler, for maintaining a flow queue corresponding to each flow attached to the scheduling queue;
• wherein the storage means stores, for each flow queue that has been emptied, data indicative of a last frame dispatched from the respective flow queue, and
• wherein when a new frame is received that corresponds to a flow queue that has been emptied, a flow corresponding to the new frame is attached to the scheduling queue at a distance D from a current pointer for the scheduling queue, the distance D being determined based at least in part on the stored data indicative of the size of the last frame dispatched from the flow queue that has been emptied.

A computer program product for use with a network processor, the computer program product comprising:

• a computer storage device readable by a computer, the computer storage device having program code adapted to:
• dispatch a last frame from a flow queue to empty the flow queue;
• store in a flow queue control block which corresponds to the emptied flow queue data indicative of a size of the dispatched last frame;
• receive a new frame corresponding to the emptied flow queue;
• and attach to a scheduling queue a flow corresponding to the emptied flow queue;
• wherein the flow is attached to the scheduling queue a distance D from a current pointer for the scheduling queue, the distance D being determined based at least in part on the stored data indicative of the size of the dispatched last frame.

A method of operating a network processor, comprising:

• dispatching a last frame from a flow queue maintained in the network processor, thereby emptying the flow queue;
• storing in a flow queue control block which corresponds to the emptied flow queue data indicative of a size of the dispatched last frame;
• receiving a new frame corresponding to the emptied flow queue;
• and
• attaching to a scheduling queue a flow corresponding to the emptied flow queue;
• wherein the flow is attached to the scheduling queue a distance D from a current pointer for the scheduling queue, the distance D being determined based at least in part on the stored data indicative of the size of the dispatched last frame.

A network processor, comprising:

• a scheduler which includes a scheduling queue having flows attached thereto and defining a sequence in which the attached flows are to be serviced;
• storage means, associated with the scheduler, for maintaining a flow queue corresponding to each flow attached to the scheduling queue;
• means for dispatching a last frame from a flow queue maintained in the storage means, thereby emptying the flow queue;
• means for storing, in a flow queue control block which corresponds to the emptied flow queue, data indicative of a size of the dispatched last frame;
• means for receiving a new frame corresponding to the emptied flow queue;
• and
• means for attaching to the scheduling queue a flow corresponding to the emptied flow queue;
• wherein the flow is attached to the scheduling queue a distance D from a current pointer for the scheduling queue, the distance D being determined based at least in part on the stored data indicative of the size of the dispatched last frame.

A computer program product for use with a network processor, the computer program product comprising:

• a medium readable by a computer, the computer readable medium having program code adapted to:
• dispatch a last frame from a flow queue maintained in a network processor, thereby emptying the flow queue;
• store in a flow queue control block which corresponds to the emptied flow queue data indicative of a size of the dispatched last frame;
• receive a new frame corresponding to the emptied flow queue;
• and
• attach to a scheduling queue a flow corresponding to the emptied flow queue;
• wherein the flow is attached to the scheduling queue a distance D from a current pointer for the scheduling queue, the distance D being determined based at least in part on the stored data indicative of the size of the dispatched last frame.