Methods and systems for providing direct DMA

• US 8,112,491 B1
• Filed: 01/19/2010
• Issued: 02/07/2012
• Est. Priority Date: 01/16/2009
• Status: Active Grant

• Current Assignee: F5 Networks, Inc. (F5 Incorporated)
• Original Assignee: F5 Networks, Inc. (F5 Incorporated)
• Inventors: Michels, Timothy, Baumann, William R., Szabo, Paul I.
• Primary Examiner(s): Mesfin, Yemane
• Application Number:
  US12/690,069
• Time in Patent Office: 749 Days
• Field of Search: 709212-214, 709217-219, 709/227, 709250-253, 710/22, 710/52, 710/56, 710/59
• US Class Current: 709/212
• CPC Class Codes: H04L 49/901 using storage descriptor, e.g. read or write pointers

Abstract

A method and system for efficient direct DMA for processing connection state information or other expediting data packets. One example is the use of a network interface controller to buffer TCP type data packets that may contain connection state information. The connection state information is extracted from a received packet. The connection state information is stored in a special DMA descriptor that is stored in a ring buffer area of a buffer memory that is accessible by a host processor when an interrupt signal is received. The packet is then discarded. The host processor accesses the ring buffer memory only to retrieve the stored connection state information from the DMA descriptor without having to access a packet buffer area in the memory.

Claims

1. A method for efficiently processing a received data packet, the method comprising:

reading a received data packet to determine if the data packet contains connection state information;

extracting the connection state information from the data packet if the data packet contains the connection state information;

storing the connection state information as a special DMA descriptor in a ring buffer memory configured to be accessible by a host processor; and

notifying the host processor by an interrupt signal that the special DMA descriptor has been stored in the ring buffer memory, wherein the host processor is able to immediately access the ring buffer memory to retrieve the stored connection state information from the special DMA descriptor.

2. The method of claim 1, wherein the data packet is a TCP data packet.

3. The method of claim 1, further comprising discarding the data packet after storing the connection state information in the ring buffer memory.

4. The method of claim 1, further comprising writing the connection state information as the special DMA descriptor prior to storing the special DMA descriptor in the ring buffer memory.

5. The method of claim 1, further comprising storing the data packet into a packet buffer area if the data packet does not contain the connection state information.

6. The method of claim 5, further comprising writing and storing a descriptor corresponding to the data packet in the ring buffer area if the data packet does not contain the connection state information.

7. A non-transitory computer readable storage medium having stored thereon instructions for efficiently processing a received data packet comprising machine executable code which when executed by at least one processor, causes the processor to perform steps comprising:

reading a received data packet to determine if the data packet contains connection state information;

extracting the connection state information from the data packet if the data packet contains the connection state information;

storing the connection state information as a special DMA descriptor in a ring buffer memory configured to be accessible by a host processor; and

notifying the host processor by an interrupt signal that the special DMA descriptor has been stored in the ring buffer memory, wherein the host processor is able to immediately access the ring buffer memory to retrieve the stored connection state information from the special DMA descriptor.

8. The non-transitory computer readable storage medium of claim 7, wherein the data packet is a TCP data packet.

9. The non-transitory computer readable storage medium of claim 7, further comprising discarding the data packet after storing the connection state information in the ring buffer memory.

10. The non-transitory computer readable storage medium of claim 7, further comprising writing the connection state information as the special DMA descriptor prior to storing the special DMA descriptor in the ring buffer memory.

11. The non-transitory computer readable storage medium of claim 7, further comprising storing the data packet into a packet buffer area if the data packet does not contain the connection state information.

12. The non-transitory computer readable storage medium of claim 11, further comprising writing and storing a descriptor corresponding to the data packet in the ring buffer area if the data packet does not contain the connection state information.

13. A network traffic management device comprising:

one or more host processors;

a buffer memory coupled to the one or more processors by a bus; and

a network interface controller coupled to the one or more host processors and the buffer memory and capable of receiving and forwarding data packets from a network that relate to a plurality of applications;

at least one of the one or more host processors configured to execute programmed instructions stored in the buffer memory and including logic configured to implement a process further comprising;

reading a received data packet to determine if the data packet contains connection state information;

extracting the connection state information from the data packet if the data packet contains the connection state information;

storing the connection state information as a special DMA descriptor in a ring buffer memory configured to be accessible by the host processor; and

notifying the host processor by an interrupt signal that the special DMA descriptor has been stored in the ring buffer memory, wherein the host processor is able to immediately access the ring buffer memory to retrieve the stored connection state information from the special DMA descriptor.

14. The network traffic management device of claim 13, wherein the data packet is a TCP data packet.

15. The network traffic management device of claim 13, wherein the at least one of the one or more host processors is further configured to execute programmed instructions stored in the memory and the network interface controller with logic is further configured to implement discarding the data packet after storing the connection state information in the ring buffer memory.

16. The network traffic management device of claim 13, wherein the at least one of the one or more host processors is further configured to execute programmed instructions stored in the memory and the network interface controller with logic is further configured to implement writing the connection state information as the special DMA descriptor prior to storing the special DMA descriptor in the ring buffer memory.

17. The network traffic management device of claim 13, wherein the at least one of the one or more host processors is further configured to execute programmed instructions stored in the buffer memory and the network interface controller with logic is further configured to implement storing the data packet into a packet buffer area if the data packet does not contain the connection state information.

18. The network traffic management device of claim 17, wherein the at least one of the one or more host processors is further configured to execute programmed instructions stored in the buffer memory and the network interface controller with logic is further configured to implement writing and storing a descriptor corresponding to the data packet in the ring buffer area if the data packet does not contain the connection state information.

19. The network traffic management device of claim 13, wherein the host processor is embodied in a Field Programmable Gate Array.