Packet draining from a scheduling hierarchy in a traffic manager of a network processor

1. A method of controlling a state of each node in a scheduling hierarchy of a network processor having a plurality of processing modules and at least one shared memory with packet data, the method comprising:

generating, by a traffic manager of the network processor, a scheduling hierarchy comprising a tree structure of a root scheduler and N scheduler levels, wherein a scheduler is a branch node and a queue is a leaf node of the scheduling hierarchy, wherein N is a positive integer;

generating, by the network processor, one or more tasks corresponding to each of a plurality of received packets associated with one or more data flows of the network processor;

enqueuing, by the traffic manager, a task provided by one of the plurality of processing modules of the network processor to an associated queue of the scheduling hierarchy, wherein the queue is associated with a data flow corresponding to the received task;

maintaining one or more scheduling data structures for each node in the scheduling hierarchy, wherein the one or more scheduling data structures comprise a backpressure indicator and a timer indicator;

if the backpressure indicator is set:

setting the node as unavailable for scheduling;

removing the node from the scheduling hierarchy;

if the timer indicator is set:

setting the node as unavailable for scheduling;

otherwise, if neither the backpressure indicator nor the timer indicator is set:

setting the node as available for scheduling.

2. The method of claim 1 , further comprising:

setting the backpressure indicator of a given node based on a backpressure request by one of the processing modules to reduce a scheduling rate of the given node.

3. The method of claim 1 , further comprising:

setting the timer indicator of a given node based on a timer event request by the corresponding parent scheduler of the given node.

4. The method of claim 1 , wherein the one or more scheduling data structures comprise an in-hierarchy indicator corresponding to the given node of the scheduling hierarchy, and wherein the step of removing the node from the scheduling hierarchy comprises:

clearing the in-hierarchy indicator of the given node.

5. The method of claim 4 , wherein the step of setting the node as available for scheduling comprises:

setting the in-hierarchy indicator of the given node; and

clearing, if set, (i) the backpressure indicator of the given node and (ii) the timer indicator of the given node.

6. The method of claim 4 , further comprising:

determining a task count corresponding to the given node;

if the task count is zero, clearing the in-hierarchy indicator of the given node.

7. The method of claim 1 , further comprising:

receiving a backpressure request from one of the plurality of processing modules of the network processor, wherein the backpressure request comprises a ID value of the given node; and

setting the backpressure indicator of the given node based on the received backpressure request.

8. The method of claim 7 , further comprising:

receiving a backpressure release request from the corresponding one of the plurality of processing modules of the network processor, wherein the backpressure release request corresponds to the backpressure request; and

clearing the backpressure indicator of the given node based on the received backpressure release request.

9. The method of claim 8 , further comprising:

if the timer indicator is not set:

determining a task count corresponding to the given node;

if the task count is non-zero, setting the in-hierarchy indicator of the given node;

otherwise, if the timer indicator is set:

maintaining the in-hierarchy indicator as cleared for the given node.

10. The method of claim 1 , further comprising:

receiving a timer event from a timer module of the network processor; and

setting the timer indicator of the given node based on the received timer event.

11. The method of claim 10 , further comprising:

receiving a timer release request from the timer module, wherein the timer release request corresponds to the timer request; and

clearing the timer indicator of the given node based on the received timer release request.

12. The method of claim 11 , further comprising:

if the backpressure indicator is not set:

setting the in-hierarchy indicator of the given node;

otherwise, if the backpressure indicator is set:

maintaining the in-hierarchy indicator as cleared for the given node.

13. The method of claim 11 , further comprising:

counting, by the timer module, for a predetermined time before sending the timer release request for the given node.

14. A non-transitory machine-readable medium, having encoded thereon program code, wherein, when the program code is executed by a machine, the machine implements a method of controlling a state of each node in a scheduling hierarchy of a network processor having a plurality of processing modules and at least one shared memory with packet data, the method comprising:

generating, by a traffic manager of the network processor, a scheduling hierarchy comprising a tree structure of a root scheduler and N scheduler levels, wherein a scheduler is a branch node and a queue is a leaf node of the scheduling hierarchy, wherein N is a positive integer;

generating, by the network processor, one or more tasks corresponding to each of a plurality of received packets associated with one or more data flows of the network processor;

enqueuing, by the traffic manager, a task provided by one of the plurality of processing modules of the network processor to an associated queue of the scheduling hierarchy, wherein the queue is associated with a data flow corresponding to the received task;

maintaining one or more scheduling data structures for each node in the scheduling hierarchy, wherein the one or more scheduling data structures comprise a backpressure indicator and a timer indicator;

if the backpressure indicator is set:

setting the node as unavailable for scheduling;

removing the node from the scheduling hierarchy;

if the timer indicator is set:

setting the node as unavailable for scheduling;

otherwise, if neither the backpressure indicator nor the timer indicator is set:

setting the node as available for scheduling.

15. The non-transitory machine-readable medium of claim 14 , further comprising:

setting the backpressure indicator of a given node based on a backpressure request by one of the processing modules to reduce a scheduling rate of the given node; and

setting the timer indicator of a given node based on a timer event request by the corresponding parent scheduler of the given node.

16. The non-transitory machine-readable medium of claim 14 , wherein the one or more scheduling data structures comprise an in-hierarchy indicator corresponding to the given node of the scheduling hierarchy, and wherein the step of removing the node from the scheduling hierarchy comprises:

clearing the in-hierarchy indicator of the given node; and

wherein the step of setting the node as available for scheduling comprises:

setting the in-hierarchy indicator of the given node; and

clearing, if set, (i) the backpressure indicator of the given node and (ii) the timer indicator of the given node.

17. The non-transitory machine-readable medium of claim 16 , further comprising:

determining a task count corresponding to the given node;

if the task count is zero, clearing the in-hierarchy indicator of the given node.

18. The non-transitory machine-readable medium of claim 14 , further comprising:

receiving a backpressure request from one of the plurality of processing modules of the network processor, wherein the backpressure request comprises a ID value of the given node; and

setting the backpressure indicator of the given node based on the received backpressure request;

receiving a backpressure release request from the corresponding one of the plurality of processing modules of the network processor, wherein the backpressure release request corresponds to the backpressure request; and

clearing the backpressure indicator of the given node based on the received backpressure release request.

19. A network processor comprising:

a plurality of processing modules and at least one shared memory with packet data, wherein one of the plurality of processing modules is configured to generate one or more tasks corresponding to each of a plurality of received packets associated with one or more data flows;

a traffic manager of the network processor configured to:

receive a task corresponding to a data flow, the task provided by one of the plurality of processing modules of the network processor;

generate a scheduling hierarchy comprising a tree structure of a root scheduler and N scheduler levels, wherein a scheduler is a branch node and a queue is a leaf node of the scheduling hierarchy, wherein N is a positive integer;

enqueue each received task in a queue of the scheduling hierarchy associated with the received task, the queue having a corresponding parent scheduler at each of one or more next levels of the scheduling hierarchy up to a root scheduler of the scheduling hierarchy, wherein the queue and one or more corresponding parent schedulers at each level of the scheduling hierarchy form a branch of the scheduling hierarchy;

maintain one or more scheduling data structures for each node in the scheduling hierarchy, wherein the one or more scheduling data structures comprise a backpressure indicator and a timer indicator;

if the backpressure indicator is set, the traffic manager is configured to:

set the node as unavailable for scheduling;

remove the node from the scheduling hierarchy;

if the timer indicator is set, the traffic manager is configured to:

set the node as unavailable for scheduling;

otherwise, if neither the backpressure indicator nor the timer indicator is set, the traffic manager is configured to:

set the node as available for scheduling.

20. The network processor of claim 19 , wherein the network processor is implemented as an integrated circuit chip.