DRIVER LEVEL SEGMENTATION

• US 20100135324A1
• Filed: 10/18/2007
• Published: 06/03/2010
• Est. Priority Date: 11/01/2006
• Status: Active Grant

• Current Assignee: Xilinx, Inc. (Advanced Micro Devices, Inc.)
• Original Assignee: SolarFlare Communications Incorporated (Advanced Micro Devices, Inc.)
• Inventors: Riddoch, David J., Pope, Steven L.
• Granted Patent: US 9,077,751 B2
• Time in Patent Office: Days
• US Class Current: 370/474
• CPC Class Codes: H04L 69/16 Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
• CPC Class Codes: H04L 69/161 Implementation details of TCP/IP or UDP/IP stack architecture; Specification of modified or new header fields
• CPC Class Codes: H04L 69/166 IP fragmentation; TCP segmentation
• CPC Class Codes: H04L 69/22 Parsing or analysis of headers

Abstract

A method for performing segmentation of a first data packet into a plurality of second data packets at a functionality of a device driver for a network interface device supported by a data processing system, each second data packet comprising a header and a segment of data from the first data packet and the network interface device being capable of supporting a communication link over a network with another network interface device, the method comprising: accepting the first data packet, the first data packet carrying data for transmission by the network interface device over the network; forming a set of headers for the plurality of second data packets; writing the set of headers to memory; forming a specification, the specification indicating the headers in memory and the segments of data in the first data packet; requesting by means of the device driver transmission by the network interface device of the headers and the respective segments of data indicated in the specification so as to effect transmission of the second data packets over the network.

Claims

1. A method for performing segmentation of a first data packet into a plurality of second data packets at a functionality of a device driver for a network interface device supported by a data processing system, each second data packet comprising a header and a segment of data from the first data packet and the network interface device being capable of supporting a communication link over a network with another network interface device, the method comprising:

accepting the first data packet, the first data packet carrying data for transmission by the network interface device over the network;

forming a set of headers for the plurality of second data packets;

writing the set of headers to memory;

forming a specification, the specification indicating the headers in memory and the segments of data in the first data packet; and

requesting by means of the device driver transmission by the network interface device of the headers and the respective segments of data indicated in the specification so as to effect transmission of the second data packets over the network.

2. A method for performing segmentation as claimed in claim 1, wherein the device driver is operable to indicate to the data processing system that the network interface device is capable of performing transmit segmentation.

3. A method for performing segmentation as claimed in claim 2, wherein the network interface is not capable of performing transmit segmentation.

4. A method for performing segmentation as claimed in claim 1, wherein the device driver is operable to indicate to the data processing system that the network interface device is capable of performing a checksum calculation on each segment of data.

5. A method for performing segmentation as claimed in claim 1, wherein TCP flow control is performed at a network protocol stack of the data processing system.

6. A method for performing segmentation as claimed in claim 1, wherein the size of the first data packet is greater than the maximum packet size allowed by the network segment to which the data processing system is connected.

7. A method for performing segmentation as claimed in claim 1, wherein the maximum size of the second packets is indicated to the device driver by the data processing system.

8. A method for performing segmentation as claimed in claim 1, wherein the maximum size of the second packets is indicated to the device driver in a header of the first data packet.

9. A method for performing segmentation as claimed in claim 1, wherein the size of each of the plurality of second data packets is not greater than the maximum packet size allowed by the network segment to which the data processing system is connected.

10. A method for performing segmentation as claimed in claim 1, wherein the size of each of the plurality of second data packets is not greater than the maximum packet size allowed over the connection over which those packets are to be sent.

13. A method for performing segmentation as claimed in claim 1, wherein the set of headers is written to a first area of the memory.

14. A method for performing segmentation as claimed in claim 13, wherein the step of accepting the first data packet includes the step of receiving the first data packet at a second area of the memory.

15. A method for performing segmentation as claimed in claim 13, wherein the first area of the memory is allocated to the device driver.

16. A method for performing segmentation as claimed in claim 14, wherein the second area of the memory is allocated to the device driver.

17. A method for performing segmentation as claimed in claim 14, wherein the first data packet is received in fragments and the fragments are enqueued at the second area of the memory.

18. A method for performing segmentation as claimed in claim 17, wherein segmentation of the first data packet starts before all the fragments of the first data packet have been received.

19. A method for performing segmentation as claimed in claim 1, wherein the step of requesting transmission of the headers and the respective segments of data indicated in the specification is by means of a single request to the network interface device.

20. A method for performing segmentation as claimed in claim 14, wherein the network interface device is operable to access the first and second areas of the memory by Direct Memory Access.

21. A method for performing segmentation as claimed in claim 1, wherein the header of the first data packet includes a first identifier and all the headers of the second data packets include the first identifier.

22. A method for performing segmentation as claimed in claim 1, wherein the step of forming a set of headers for the plurality of second data packets includes the step of calculating an offset for each header in the set, the offset of a header being the position in bytes of its respective segment of data in the first data packet.

23. A method for performing segmentation as claimed in claim 1, wherein the step of forming a set of headers for the plurality of second data packets includes the step of calculating a checksum for each header in the set, the checksum of a header being calculated using its respective segment of data.

11-12. -12. (canceled)

24. A method for transmitting data by means of a data processing system, the system being capable of supporting an operating system and at least one application and having access to a memory and a network interface device capable of supporting a communication link over a network with another network interface device, the method comprising the steps of:

an application having data for transmission requesting a functionality of the operating system to send the data to be transmitted;

responsive to that request;

forming the data into at least one first data packet at a network protocol stack of the system;

sending an indication to a device driver of the network interface device that the at least one first data packet is to be transmitted over the network;

and subsequently;

performing segmentation of each first data packet into a plurality of second data packets at a functionality of the device driver, each second data packet comprising a header and a segment of data;

the segmentation step including;

forming a set of headers for the plurality of second data packets;

writing the set of headers to memory; and

forming a specification, the specification indicating the headers in memory and the segments of data in the first data packet;

requesting by means of the device driver transmission by the network interface device of the headers and the respective segments of data indicated in the specification so as to effect transmission of the second data packets over the network.

25-32. -32. (canceled)

33. A method for performing reassembly of data packets at a functionality of a device driver for a network interface device supported by a data processing system, each data packet comprising a header and a segment of data and being received by the network interface device over a communication link with another network interface device, the method comprising:

accepting data packets from the network interface device at the functionality of the device driver;

enqueueing each data packet of a first set of the data packets at a first queue in memory, the first queue comprising at least a first data packet;

modifying the header of the first data packet in the first queue so as to include the segment of data of each newly-enqueued data packet of the first set;

defining a specification, the specification indicating the segments of data of the newly-enqueued data packets of the first set in the first queue; and

,

in response to one or more first predetermined conditions being met;

causing a superpacket comprising the header of the first data packet in the first queue and the segments of data indicated by the specification to be passed to a network protocol stack of the data processing system for subsequent protocol processing.

34. A method for performing reassembly of data packets as claimed in claim 33, wherein the step of modifying the header of the first data packet includes modifying an indication of packet size in the header of the first data packet.

35. A method for performing reassembly of data packets as claimed in claim 33, wherein the size of the superpacket is greater than the maximum packet size allowed by the network segment to which the data processing system is connected.

36. A method for performing reassembly of data packets as claimed in claim 33, wherein the first predetermined conditions include:

a) the number of data packets at the first queue is a predetermined number;

b) the total size of the data packets at the first queue is a predetermined size;

c) a predetermined time has elapsed since the first data packet was enqueued at the first queue.

37. A method for performing reassembly of data packets as claimed in claim 33, further comprising:

enqueueing each data packet of a second set of the data packets at a second queue in memory, the second queue comprising at least a first data packet;

modifying the header of the first data packet in the second queue so as to include the segment of data of each newly-enqueued data packet of the second set;

defining a specification, the specification indicating the segments of data of the newly-enqueued data packets of the second set in the second queue; and

,

in response to one or more first predetermined conditions being met;

causing a superpacket comprising the header of the first data packet in the second queue and the segments of data indicated by the specification to be passed to a network protocol stack of the data processing system for subsequent protocol processing.

38. A method for performing reassembly of data packets as claimed in claim 37, wherein data packets of the first set belong to a first data flow and data packets of the second set belong to a second data flow.

40. A method for performing reassembly of data packets as claimed in claim 33, wherein the step of accepting data packets from the network interface device includes:

if at least one data packet from the network interface device belongs to a data flow for which a queue has not yet been established, defining a new queue in memory for that data flow.

41. A method for performing reassembly of data packets as claimed in claim 40, wherein the subsequent steps of the method are performed as though the at least one data packet is the first set of data packets and the new queue is the first queue.

39. (canceled)

42. A method for performing reassembly of data packets at a functionality of a device driver for a network interface device supported by a data processing system, each data packet comprising a header and a segment of data and being received by the network interface device over a communication link with another network interface device, the method comprising:

accepting data packets from the network interface device at the functionality of the device driver;

if one or more second predetermined conditions are met, passing the data packets to the network protocol stack of the data processing system for subsequent protocol processing;

and if the one or more second predetermined conditions are not met;

enqueueing each data packet of a first set of the data packets at a first queue in memory, the first queue comprising at least a first data packet;

modifying the header of the first data packet in the first queue so as to include the segment of data of each newly-enqueued data packet of the first set; and

defining a specification, the specification indicating the segments of data of the newly-enqueued data packets of the first set in the first queue,

the method further comprising, in response to one or more first predetermined conditions being met, causing a superpacket comprising the header of the first data packet in the first queue and the segments of data indicated by the specification to be passed to a network protocol stack of the data processing system for subsequent protocol processing.

43. A method for performing reassembly of data packets as claimed in claim 42, wherein the second predetermined conditions include:

a) at least some of the data packets are fragmented;

b) at least some of the data packets are out of sequence;

c) at least some of the data packets do not contain a segment of data;

d) the data packets are TCP/IP data packets and at least some of the data packets have one of RST, SYN or URG TCP flags set.