Apparatus and method for just-in-time transfer of transmit commands to a network interface

• US 20030058852A1
• Filed: 09/24/2001
• Published: 03/27/2003
• Est. Priority Date: 09/24/2001
• Status: Active Grant

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Connor, Patrick L., Luhmann, Patrick J.
• Granted Patent: US 7,046,628 B2
• Time in Patent Office: Days
• US Class Current: 370/389
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/29 using a combination of thresholds
• CPC Class Codes: H04L 47/50 Queue scheduling
• CPC Class Codes: H04L 47/56 implementing delay-aware scheduling
• CPC Class Codes: H04L 49/90 Buffering arrangements
• CPC Class Codes: H04L 49/901 using storage descriptor, e.g. read or write pointers
• CPC Class Codes: H04L 49/9063 Intermediate storage in different physical parts of a node or terminal

Abstract

A network driver provides additional transmit commands to a network interface when the number of transmit commands at the network interface falls below a specified threshold.

Claims

1. A method comprising:

assigning at least one descriptor to a packet;

providing the at least one descriptor to a network interface when an apparent descriptor total is less than a first threshold; and

providing the at least one descriptor to a packet descriptor queue when the apparent descriptor total is greater than the first threshold.

2. The method of claim 1, further comprising:

receiving an interrupt generated by the network interface, the interrupt indicating that an actual descriptor total is less than a second threshold; and

providing a descriptor from the packet descriptor queue to the network interface in response to the interrupt.

3. The method of claim 2, the second threshold equivalent to the first threshold.

4. The method of claim 1, further comprising recovering a processed descriptor from the network interface.

6. A method comprising:

receiving at least one descriptor from a network driver when an apparent descriptor total is less than a first threshold, the at least one descriptor associated with a packet;

transmitting the packet to a network; and

asserting an interrupt when an actual descriptor total is less than a second threshold.

7. The method of claim 6, further comprising receiving a descriptor from a packet descriptor queue in response to assertion of the interrupt.

8. The method of claim 6, further comprising:

identifying a processed descriptor, the processed descriptor associated with a transmitted packet; and

providing the processed descriptor to the network driver.

9. The method of claim 6, further comprising:

fetching the packet from a main memory, a location of the packet in the main memory identified by the at l east on e descriptor; and

placing the packet in a packet FIFO.

10. The method of claim 6, the second threshold equivalent to the first threshold.

11. A method comprising:

asserting an interrupt when an actual descriptor total is less than a second threshold; and

receiving a descriptor from a packet descriptor queue in response to assertion of the interrupt.

12. The method of claim 11, further comprising receiving another descriptor from a network driver when an apparent descriptor total is less than a first threshold.

13. The method of claim 12, the second threshold equivalent to the first threshold.

14. The method of claim 11, further comprising:

identifying a processed descriptor, the processed descriptor associated with a transmitted packet; and

providing the processed descriptor to a network driver.

15. The method of claim 11, further comprising:

fetching a packet from a main memory, a location of the packet in the main memory identified by the descriptor; and

placing the packet in a packet FIFO.

16. A system comprising:

a processor coupled with a bus;

a main memory coupled with the bus, the main memory including a packet descriptor queue;

a network interface coupled with the bus and further coupled with a network;

a network driver resident in the main memory, the network driver including a set of instructions that, when executed by the processor, cause the network driver to assign at least one descriptor to a packet;

provide the at least one descriptor to the network interface when an apparent descriptor total is less than a first threshold; and

provide the at least one descriptor to the packet descriptor queue when the apparent descriptor total is greater than the first threshold.

17. The system of claim 16, the network driver further including instructions that, when executed by the processor, cause the network driver to

receive an interrupt from the network interface, the interrupt indicating that an actual descriptor total is less than a second threshold;

and

provide a descriptor from the packet descriptor queue to the network interface in response to the interrupt.

18. The system of claim 16, the second threshold equivalent to the first threshold.

19. The system of claim 16, the network driver further including instructions that, when executed by the processor, cause the network driver to recover a processed descriptor from the network interface.

20. A system comprising:

a processor coupled with a bus;

a main memory coupled with the bus, the main memory including a packet descriptor queue and a network driver resident thereon;

a network interface coupled with the bus and further coupled with a network, the network interface to

receive at least one descriptor from the network driver when an apparent descriptor total is less than a first threshold, the at least one descriptor associated with a packet;

transmit the packet to the network; and

assert an interrupt when an actual descriptor total is less than a second threshold.

21. The system of claim 20, the network interface to receive a descriptor from a packet descriptor queue in response to assertion of the interrupt.

22. The system of claim 20, the network interface to

identify a processed descriptor, the processed descriptor associated with a transmitted packet;

and

provide the processed descriptor to the network driver.

23. The system of claim 20, the network interface to

fetch the packet from the main memory, a location of the packet in the main memory identified by the at least one descriptor;

and

place the packet in the packet FIFO.

24. The system of claim 20, the second threshold equivalent to the first threshold.

25. An article of manufacture comprising:

a machine accessible medium providing content that, when accessed by a machine, causes the machine to

assign at least one descriptor to a packet;

provide the at least on e descriptor to a network interface when an apparent descriptor total is less than a first threshold; and

provide the at least one descriptor to a packet descriptor queue when the apparent descriptor total is greater than the first threshold.

26. The article of manufacture of claim 25, wherein the content, when accessed, further causes the machine to:

receive an interrupt generated by the network interface, the interrupt indicating that an actual descriptor total is less than a second threshold; and

provide a descriptor from the packet descriptor queue to the network interface in response to the interrupt.

27. The article of manufacture of claim 26, the second threshold equivalent to the first threshold.

28. The article of manufacture of claim 25, wherein the content, when accessed, further causes the machine to recover a processed descriptor from the network interface.

29. An article of manufacture comprising:

a machine accessible medium providing content that, when accessed by a machine, causes the machine to

receive at least one descriptor from a network driver when an apparent descriptor total is less than a first threshold, the at least one descriptor associated with a packet;

transmit the packet to a network; and

assert an interrupt when an actual descriptor total is less than a second threshold.

30. The article of manufacture of claim 29, wherein the content, when accessed, further causes the machine to receive a descriptor from a packet descriptor queue in response to assertion of the interrupt.

31. The article of manufacture of claim 29, wherein the content, when accessed, further causes the machine to:

identify a processed descriptor, the processed descriptor associated with a transmitted packet; and

provide the processed descriptor to the network driver.

32. The article of manufacture of claim 29, wherein the content, when accessed, further causes the machine to:

fetch the packet from a main memory, a location of the packet in the main memory identified by the at least one descriptor; and

place the packet in a packet FIFO.

33. The article of manufacture of claim 29, the second threshold equivalent to the first threshold.

34. An article of manufacture comprising:

a machine accessible medium providing content that, when accessed by a machine, causes the machine to

assert an interrupt when an actual descriptor total is less than a second threshold; and

receive a descriptor from a packet descriptor queue in response to assertion of the interrupt.

35. The article of manufacture of claim 34, wherein the content, when accessed, further causes the machine to receive another descriptor from a network driver when an apparent descriptor total is less than a first threshold.

36. The article of manufacture of claim 35, the second threshold equivalent to the first threshold.

37. The article of manufacture of claim 34, wherein the content, when accessed, further causes the machine to:

identify a processed descriptor, the processed descriptor associated with a transmitted packet; and

provide the processed descriptor to a network driver.

38. The article of manufacture of claim 34, wherein the content, when accessed, further causes the machine to:

fetch a packet from a main memory, a location of the packet in the main memory identified by the descriptor; and

place the packet in a packet FIFO.

39. A method comprising:

maintaining a sum variable indicating a number of commands at an I/O controller;

associating a command with data;

providing the command to the I/O controller when the sum variable is less than a threshold; and

providing the command to a queue when the sum variable is greater than the threshold.

40. The method of claim 39, the act of associating a command with data comprising associating a transmit command with the data.

41. The method of claim 39, wherein the I/O controller comprises at least a portion of a network interface.

42. The method of claim 39, further comprising:

receiving an interrupt generated by the I/O controller; and

providing at least one command from the queue to the I/O controller in response to the interrupt.

43. The method of claim 39, further comprising recovering a processed command from the I/O controller.

44. A method comprising:

maintaining a sum variable indicating a number of commands;

asserting an interrupt when the sum variable is less than a threshold; and

receiving a command from a queue in response to assertion of the interrupt.

45. The method of claim 44, the act of receiving a command from a queue in response to assertion of the interrupt comprising receiving a transmit command from the queue.

46. The method of claim 44, further comprising:

identifying a processed command, the processed command associated with transmitted data; and

providing the processed command to a driver.

47. The method of claim 44, further comprising:

fetching data associated with the command from a main memory; and

placing the data in a FIFO buffer.