Methods and apparatus for moving data elements within a data communications device

• US 7,395,356 B2
• Filed: 11/05/2004
• Issued: 07/01/2008
• Est. Priority Date: 01/07/2000
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Ma, Qingming, Agasaveeran, Saravanan, Gannu, Satish
• Primary Examiner(s): Jaroenchonwanit; Bunjob
• Assistant Examiner(s): Hoang; Hieu T
• Application Number:
  US10/981,815
• Publication Number:
  US 20050094559A1
• Time in Patent Office: 1,334 Days
• Field of Search: 709/240, 709/241, 709/251, 709/250, 370412-419
• US Class Current: 709/250
• CPC Class Codes: H04L 49/90 Buffering arrangements

Abstract

A method includes a step of (A) determining which of multiple network interfaces indicates readiness to transmit a data element to a network and which of the multiple network interfaces indicates receipt of a data element from the network. The method further includes a step of (B) running, for each network interface indicating readiness to transmit a data element to the network, a transmit interrupt handler to load that network interface with a data element for transmission if such a data element is available for transmission within the data communications device, in response to giving higher priority to handling transmit interrupts relative to handling receive interrupts. The method further includes a step of (C) after step B, running, for at least one network interface which indicates receipt of a data element from the network, a receive interrupt handler to process that data element.

Claims

1. In a data communications device having multiple network interfaces which are capable of transmitting and receiving data elements with a network, a method comprising the steps of:

A. determining which of the multiple network interfaces indicates readiness to transmit a data element to the network and which of the multiple network interfaces indicates receipt of a data element from the network;

B. running, for each network interface indicating readiness to transmit a data element to the network, a transmit interrupt handler to load that network interface with a data element for transmission if such a data element is available for transmission within the data communications device, in response to giving higher priority to handling transmit interrupts relative to handling receive interrupts; and

C. after step B, running, for at least one network interface which indicates receipt of a data element from the network, a receive interrupt handler to process that data element.

2. The method of claim 1 wherein more than N network interfaces indicate receipt of a data element from the network, wherein N is a positive integer, and wherein step C includes the steps of:

running, for N network interfaces indicating receipt of a data element from the network, a receive interrupt handler to process that data element; and

refraining from running receive interrupt handlers for more than the N network interfaces until step A and step B are repeated.

3. The method of claim 1 wherein the network interfaces receive more than X data elements, wherein X is a positive integer, and wherein step C includes the steps of:

running, for at least one network interface indicating receipt of a data element from the network, a receive interrupt handler to process that data element until X data elements have been processed; and

refraining from processing more than the X data elements until step A and step B are repeated.

4. The method of claim 1 wherein step C includes the steps of:

running, for a particular network interface which indicates receipt of a first data element from the network, a transmit interrupt handler to load the particular network interface with a second data element for transmission if such a second data element is available for transmission within the data communications device; and

subsequently running a receive interrupt handler to process the first data element.

5. The method of claim 1 wherein step C includes the steps of:

running, for a particular network interface which indicates receipt of a data element from the network, a receive interrupt handler to process that data element; and

running a transmit interrupt handler for another interface through which that data element is to be transmitted if a transmit interrupt is pending for that other interface.

6. The method of claim 1, further comprising the step of:

assigning weights to the network interfaces based on transmission capacities of the network interfaces such that, in step B, transmit interrupt handlers for the network interfaces run in an order determined by the assigned weights.

7. The method of claim 1, further comprising the step of:

assigning weights to the network interfaces based on numbers of data elements ready for transmission through each network interface such that, in step B, transmit interrupt handlers for the network interfaces run in an order determined by the assigned weights.

8. The method of claim 1, further comprising the step of:

assigning weights to the network interfaces based on transmission capacities of the network interfaces and numbers of data elements ready for transmission through each network interface such that, in step B, transmit interrupt handlers for the network interfaces run in an order determined by the assigned weights.

9. The method of claim 1, further comprising the step of:

assigning weights to the network interfaces based on respective numbers of processed data elements which are ready for transmission through the network interfaces such that, in step B, transmit interrupt handlers for the network interfaces run in an order determined by the assigned weights.

21. The method of claim 1 wherein:

step A includes classifying the network interfaces into a first set of interfaces with transmit interrupts and second set of interfaces with receive interrupts, each interface being capable of existing in both sets;

step B includes;

(i) selecting an unselected interface from among the first set of interfaces based on assigned weights of the interfaces in the first set;

(ii) resetting a transmit interrupt status flag of the selected interface;

(iii) if a data element exists in a software queue associated with the selected interface, moving the data element to a transmit queue of the selected interface for transmission; and

(iv) repeating the preceding steps (i)-(iii) for each unselected interface remaining in the first set before proceeding to step C; and

step C includes;

(v) selecting an unselected interface from among the second set of interfaces;

(vi) resetting a receive interrupt status flag of the selected interface;

(vii) processing one or more data elements from a receive queue of the selected interface to empty the receive queue of the selected interface; and

(viii) repeating the preceding steps (v)-(vii) for each unselected interface remaining in the second set.

10. A data communications device, comprising:

multiple network interfaces which are capable of transmitting and receiving data elements with a network; and

a controller, coupled to the multiple network interfaces, which is configured to perform a method comprising the steps of;

A. determining which of the multiple network interfaces indicates readiness to transmit a data element to the network and which of the multiple network interfaces indicates receipt of a data element from the network;

B. running, for each network interface indicating readiness to transmit a data element to the network, a transmit interrupt handler to load that network interface with a data element for transmission if such a data element is available for transmission within the data communications device, in response to giving higher priority to handling transmit interrupts relative to handling receive interrupts; and

C. after step B, running, for at least one network interface which indicates receipt of a data element from the network, a receive interrupt handler to process that data element.

11. The data communications device of claim 10 wherein more than N network interfaces indicate receipt of a data element from the network, wherein N is a positive integer, and wherein the controller is configured such that step C includes the steps of:

running, for N network interfaces indicating receipt of a data element from the network, a receive interrupt handler to process that data element; and

refraining from running receive interrupt handlers for more than the N network interfaces until step A and step B are repeated.

12. The data communications device of claim 10 wherein the network interfaces receive more than X data elements, wherein X is a positive integer, and wherein the controller is configured such that step C includes the steps of:

running, for at least one network interface indicating receipt of a data element from the network, a receive interrupt handler to process that data element until X data elements have been processed; and

refraining from processing more than the X data elements until step A and step B are repeated.

13. The data communications device of claim 10 wherein the controller is configured such that step C includes the steps of:

running, for a particular network interface which indicates receipt of a first data element from the network, a transmit interrupt handler to load the particular network interface with a second data element for transmission if such a second data element is available for transmission within the data communications device; and

subsequently running a receive interrupt handler to process the first data element.

14. The data communications device of claim 10 wherein the controller is configured such that step C includes the steps of:

running, for a particular network interface which indicates receipt of a data element from the network, a receive interrupt handler to process that data element; and

running a transmit interrupt handler for another interface through which that data element is to be transmitted if a transmit interrupt is pending for that other interface.

15. The data communications device of claim 10 wherein the controller is configured such that the method further includes the step of:

assigning weights to the network interfaces based on transmission capacities of the network interfaces such that, in step B, transmit interrupt handlers for the network interfaces run in an order determined by the assigned weights.

16. The data communications device of claim 10 wherein the controller is configured such that the method further includes the step of:

assigning weights to the network interfaces based on numbers of data elements ready for transmission through each network interface such that, in step B, transmit interrupt handlers for the network interfaces run in an order determined by the assigned weights.

17. The data communications device of claim 10 wherein the controller is configured such that the method further includes the step of:

assigning weights to the network interfaces based on transmission capacities of the network interfaces and numbers of data elements ready for transmission through each network interface such that, in step B, transmit interrupt handlers for the network interfaces run in an order determined by the assigned weights.

18. The data communications device of claim 10 wherein the controller is configured such that the method further includes the step of:

assigning weights to the network interfaces based on respective numbers of processed data elements which are ready for transmission through the network interfaces such that, in step B, transmit interrupt handlers for the network interfaces run in an order determined by the assigned weights.

22. The data communications device of claim 10 wherein the controller is further configured to perform the method such that:

step A includes classifying the network interfaces into a first set of interfaces with transmit interrupts and second set of interfaces with receive interrupts, each interface being capable of existing in both sets;

step B includes;

(i) selecting an unselected interface from among the first set of interfaces based on assigned weights of the interfaces in the first set;

(ii) resetting a transmit interrupt status flag of the selected interface;

(iii) if a data element exists in a software queue associated with the selected interface, moving the data element to a transmit queue of the selected interface for transmission; and

(iv) repeating the preceding steps (i)-(iii) for each unselected interface remaining in the first set before proceeding to step C; and

step C includes;

(v) selecting an unselected interface from among the second set of interfaces;

(vi) resetting a receive interrupt status flag of the selected interface;

(vii) processing one or more data elements from a receive queue of the selected interface to empty the receive queue of the selected intefacer; and

(viii) repeating the preceding steps (v)-(vii) for each unselected interface remaining in the second set.

19. A computer program product that includes a computer readable medium having instructions stored thereon, such that the instructions, when processed by a data communications device having multiple network interfaces which are capable of transmitting and receiving data elements with a network, cause the data communications device to perform the steps of:

A. determining which of the multiple network interfaces indicates readiness to transmit a data element to the network and which of the multiple network interfaces indicates receipt of a data element from the network;

B. running, for each network interface indicating readiness to transmit a data element to the network, a transmit interrupt handler to load that network interface with a data element for transmission if such a data element is available for transmission within the data communications device, in response to giving higher priority to handling transmit interrupts relative to handling receive interrupts; and

C. after step B, running, for at least one network interface which indicates receipt of a data element from the network, a receive interrupt handler to process that data element.

20. A data communications device, comprising:

multiple network interfaces which are capable of transmitting and receiving data elements with a network; and

a controller, coupled to the multiple network interfaces, including;

means for determining which of the multiple network interfaces indicates readiness to transmit a data element to the network and which of the multiple network interfaces indicates receipt of a data element from the network;

means for running, for each network interface indicating readiness to transmit a data element to the network, a transmit interrupt handler to load that network interface with a data element for transmission if such a data element is available for transmission within the data communications device, in response to giving higher priority to handling transmit interrupts relative to handling receive interrupts; and

means for running, for at least one network interface which indicates receipt of a data element from the network, a receive interrupt handler to process that data element after running, for each network interface indicating readiness to transmit the data element to the network, the transmit interrupt handler.