Method for reducing latency in a host ethernet adapter (HEA)

• US 7,508,771 B2
• Filed: 04/01/2005
• Issued: 03/24/2009
• Est. Priority Date: 04/01/2005
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Chang, Chih-jen, Damon, Philippe, Vaidhyanathan, Natarajan, Calvignac, Jean Louis, Verplanken, Fabrice Jean, Basso, Claude, Verrilli, Colin Beaton
• Primary Examiner(s): Ngo; Ricky
• Assistant Examiner(s): Mui; Gary
• Application Number:
  US11/096,353
• Publication Number:
  US 20060221951A1
• Time in Patent Office: 1,453 Days
• Field of Search: 370/252, 370/253, 370/229, 370/398, 370/392, 370/397, 370/471, 370/393
• US Class Current: 370/252
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
• CPC Class Codes: H04L 69/12 Protocol engines
• 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 69/22 Parsing or analysis of headers
• CPC Class Codes: H04L 69/324 in the data link layer [OSI layer 2], e.g. HDLC

Abstract

A method for reducing latency in a host Ethernet adapter (HEA) includes the following. First, the HEA receives a packet with an internet protocol (IP) header and data in the HEA. The HEA parses a connection identifier from the IP header and accesses a negative cache in the HEA to determine if the connection identifier is not in a memory external to the HEA. The HEA applies a default treatment to the packet if the connection identifier is not in the memory, thereby reducing latency by decreasing access to the memory.

Claims

1. A method for reducing latency in a host Ethernet adapter (HEA) comprising:

receiving a packet with an internet protocol (IP) header and data;

parsing a connection identifier from the IP header;

accessing a negative cache in the HEA to determine if the connection identifier is not in a memory external to the HEA, the accessing a negative cache in the HEA further comprising;

hashing the connection identifier for a bit position;

accessing a bit vector in the HEA; and

determining if the connection identifier is not in the memory based on a value of the bit vector at the bit position; and

applying a default treatment to the packet if the connection identifier is not in the memory, thereby reducing latency by decreasing access to the memory.

2. The method of claim 1 further comprising:

determining if the connection identifier is in a regular cache in the HEA; and

applying a specific treatment to the packet if the connection identifier is in the regular cache.

3. The method of claim 1, further comprising:

determining if the connection identifier is in the memory;

applying a specific treatment to the packet if the connection identifier is in the memory; and

applying the default treatment to the packet if the connection identifier is not in the memory.

4. The method of claim 1, a value of zero in bit vector at the bit position indicating that the connection identifier is not in the memory.

5. The method of claim 1 wherein the negative cache is a one-bite wide hash table lacking collision resolution.

6. The method of claim 1 wherein the connection identifier includes a protocol, a source Internet protocol (IP) address, a desitination IP address, a source port, and a destination port.