Multi-Stage Large Send Offload

1. A method for transmitting packets over a network, comprising: receiving at a first operating system operating on a computing device, an indicator of a first large segment offload (LSO) packet size wherein the first LSO packet size is a multiple of a second LSO packet size that is supported by a network interface card connected to the computing device; formatting data into a first packet of a first LSO packet size; transferring the first packet to a second operating system on the same computing device; splitting the first packet on the second operating system into multiple LSO packets of a second LSO packet size; sending the multiple LSO packets to the network interface card for transmission on the network in packets of a size supported by the network.

2. The method as recited in claim 1 comprising copying a packet header from the first packet to the multiple LSO packets.

3. The method as recited in claim 1 comprising adjusting a TCP sequence number for the multiple LSO packets.

4. The method as recited in claim 1 wherein the first LSO packet size is based at least in part on a size supported by a virtual machine management system.

5. The method as recited in claim 1 wherein the first operating system is a guest operating system executing on a virtual machine.

6. The method as recited in claim 5 wherein the transferring the first packet to the second operating system is performed by a virtual network interface card driver.

7. The method as recited in claim 1 wherein the second operating system is a host operating system.

8. The method as recited in claim 1 wherein the splitting of the first packet is performed by a virtual switch.

9. A computer-readable storage device having stored thereon computer-readable instructions, the computer-readable instructions, upon execution on a computing device causing a system at least to: receive at a first operating system operating on a computing device, an indicator of a first large segment offload (LSO) packet size wherein the first LSO packet size is a multiple of a second LSO packet size that is supported by a network interface card connected to the computing device; format data into a first packet of a first LSO packet size; transfer the first packet to a second operating system on the same computing device wherein the first packet is split on the second operating system into multiple LSO packets of a second LSO packet size and the multiple LSO packets sent to the network interface card for transmission on the network in packets of a size supported by the network.

10. The computer-readable storage device as recited in claim 9 , the computer-readable instructions, upon execution on a computing device causing the system at least to copy a packet header from the first packet to the multiple LSO packets.

11. The computer-readable storage device as recited in claim 9 , the computer-readable instructions, upon execution on a computing device causing the system at least to adjust a TCP sequence number for the multiple LSO packets.

12. The computer-readable storage device as recited in claim 9 wherein the first LSO packet size is based at least in part on a size supported by a virtual machine management system.

13. The computer-readable storage device as recited in claim 9 wherein the first operating system is a guest operating system executing on a virtual machine.

14. The computer-readable storage device as recited in claim 13 wherein the computer-readable instructions, that upon execution on a computing device cause the system at least to transfer the first packet to the second operating system is performed by a virtual network interface card driver.

15. The computer-readable storage device as recited in claim 9 wherein the second operating system is a host operating system.

16. The computer-readable storage device as recited in claim 9 wherein the computer-readable instructions, that upon execution on a computing device cause the system at least to split the first packet is performed by a virtual switch.

17. A system comprising: one or more processing devices; at least one memory in communication with the one or more processing devices when the system is operational, the at least one memory having stored thereon computer-readable instructions, the computer-readable instructions, upon execution on the one or more processing devices causing the system at least to: receive at a first operating system operating on a computing device, an indicator of a first large segment offload (LSO) packet size wherein the first LSO packet size is a multiple of a second LSO packet size that is supported by a network interface card connected to the computing device; format data into a first packet of a first LSO packet size; transfer the first packet to a second operating system on the same computing device wherein the first packet is split on the second operating system into multiple LSO packets of a second LSO packet size and the multiple LSO packets sent to the network interface card for transmission on the network in packets of a size supported by the network.

18. The system as recited in claim 17 , wherein the computer-readable instructions that upon execution on the at least one processing devices cause the system at least to copy a packet header from the first packet to the multiple LSO packets.

19. The system as recited in claim 17 , wherein the computer-readable instructions that upon execution on the at least one processing devices cause the system at least to adjust a TCP sequence number for the multiple LSO packets.

20. The system as recited in claim 17 wherein the first LSO packet size is based at least in part on a size supported by a virtual machine management system.

21. The system as recited in claim 17 wherein the first operating system is a guest operating system executing on a virtual machine.

22. The system as recited in claim 21 wherein the computer-readable instructions that upon execution on the at least one processing devices cause the system at least to transfer the first packet to the second operating system is performed by a virtual network interface card driver.

23. The system as recited in claim 17 wherein the second operating system is a host operating system.

24. The system as recited in claim 17 wherein the computer-readable instructions that upon execution on the at least one processing devices cause the system at least to split the first packet is performed by a virtual switch.