Network interface device that fast-path processes solicited session layer read commands

• US 7,664,883 B2
• Filed: 10/16/2006
• Issued: 02/16/2010
• Est. Priority Date: 08/28/1998
• Status: Expired due to Fees

• Current Assignee: Alacritech, Inc.
• Original Assignee: Alacritech, Inc.
• Inventors: Philbrick, Clive M., Boucher, Laurence B., Craft, Peter K.
• Primary Examiner(s): JEAN GILLES, JUDE
• Application Number:
  US11/582,199
• Publication Number:
  US 20070067497A1
• Time in Patent Office: 1,219 Days
• Field of Search: 709/250, 709/230, 709/245, 709/204, 709/231, 709/228
• US Class Current: 709/250
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]
• CPC Class Codes: H04L 69/32 Architecture of open systems interconnection [OSI] 7-layer type protocol stacks, e.g. the interfaces between the data link level and the physical level

Abstract

A network interface device connected to a host provides hardware and processing mechanisms for accelerating data transfers between the host and a network. Some data transfers are processed using a dedicated fast-path whereby the protocol stack of the host performs no network layer or transport layer processing. Other data transfers are, however, handled in a slow-path by the host protocol stack. In one embodiment, the host protocol stack has an ISCSI layer, but a response to a solicited ISCSI read request command is nevertheless processed by the network interface device in fast-path. In another embodiment, an initial portion of a response to a solicited command is handled using the dedicated fast-path and then after an error condition occurs a subsequent portion of the response is handled using the slow-path. The interface device uses a command status message to communicate status to the host.

Claims

1. An apparatus comprising:

a host computer having a protocol stack and a destination memory, the protocol stack including a session layer portion, the session layer portion being for processing a session layer protocol; and

a network interface device coupled to the host computer, the network interface device containing an identification of a location in the destination memory and performing fast-path processing on a response received from outside the apparatus such that a data portion of the response is placed into the location in the destination memory without the protocol stack of the host computer performing any network layer processing or any transport layer processing on the response.

2. The apparatus of claim 1, wherein the host computer comprises a file system, wherein the network interface device performs some session layer processing associated with the placing of the data portion into the destination memory, and wherein once the data portion is present in the destination memory the host performs additional session layer processing by responding to the file system.

3. The apparatus of claim 1, wherein the session layer protocol is ISCSI.

4. The apparatus of claim 1, wherein the session layer protocol is SMB.

5. The apparatus of claim 1, wherein the protocol stack of the host computer can process a second response such that the protocol stack performs both network layer processing and transport layer processing on the second response and a second data portion is placed into the location in the destination memory.

6. The apparatus of claim 1, wherein the response comprises a first packet and a second packet, the first packet including first data, and second packet including second data, wherein said data portion that is placed into the destination includes both the first data and the second data, and wherein the first data and the second data are placed into the destination together in a substantially contiguous manner.

7. The apparatus of claim 1, wherein the response comprises a first packet and a second packet, the first packet including first data, and second packet including second data, wherein said data portion that is placed into the destination includes the first data and the second data, the first data being placed into the destination before the second packet is received onto the network interface device.

8. A method, comprising:

issuing a read request to a network storage device, the read request passing through a network to the network storage device;

receiving on a network interface device a packet from the network storage device in response to the read request, the packet including data, the network interface device being coupled to a host computer by a bus, the host computer having a protocol stack for carrying out network layer and transport layer processing;

performing fast-path processing on the packet such that the data is placed into a destination memory corresponding to the read request without the protocol stack of the host computer doing any network layer processing on the packet and without the protocol stack of the host computer doing any transport layer processing on the packet.

9. The method of claim 8, wherein the read request includes a header containing a session layer identification field that is used by the network interface device to associate the packet with the read request.

10. The method of claim 8, wherein the read request is an ISCSI read request.

11. The method of claim 8, wherein the destination memory is a part of the host computer.

12. The method of claim 8, wherein the destination memory is part of a second host computer, the second host computer being coupled to a second network interface device, the data and the subsequent data being sent from the network interface device to the second network interface device via a network connection.

13. The method of claim 9, wherein the identification field is an iSCSI tag.

14. The method of claim 10, wherein the network interface stores an identification of the destination memory that was provided with the read request.

15. An apparatus comprising:

a first device having a memory and a processor running a protocol processing stack, the first device establishing a transmission control protocol (TCP) connection for an application, the application sending a request to read data from outside the apparatus, for storing the data in a location in the memory; and

a second device coupled to the first device, the second device receiving control of the TCP connection from the first device and receiving an identification of the location in the memory for storing the data, the second device receiving from outside the apparatus a packet in response to the request, the second device storing data from the packet in the location without the first device performing any TCP processing on the packet.

16. The apparatus of claim 15, wherein the application is iSCSI, and the identification is sent to the second device from the first device along with the request.