SYSTEM FOR REDUCING LATENCY IN A HOST ETHERNET ADAPTER (HEA)

• US 20080317027A1
• Filed: 08/29/2008
• Published: 12/25/2008
• Est. Priority Date: 04/01/2005
• Status: Abandoned Application

• 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, Verrilli, Colin Beaton, BASSO, Claude
• Application Number:
  US12/200,970
• Publication Number:
  US 20080317027A1
• Time in Patent Office: Days
• US Class Current: 370/389
• 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 system 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 host Ethernet adapter (HEA) for reducing latency comprising:

a system for receiving a packet with an internet protocol (IP) header and data, and for parsing a connection identifier from the IP header; and

a negative cache coupled to the system, for determining if the connection identifier is not in a memory external to the HEA, the system 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,

the negative cache further for hashing the connection identifier for a bit position, accessing a bit vector in the HEA, and for determining if the connection identifier is not in the memory based on a value of the bit vector at the bit position.

2. The HEA of claim 1 further comprising:

a regular cache coupled to the system, the system further for determining if the connection identifier is in the regular cache, and for applying a specific treatment to the packet if the connection identifier is in the regular cache.

3. The HEA of claim 1, the system for applying a specific treatment to the packet if the connection identifier is in the memory.

4. The HEA of claim 3, the system for applying the default treatment to the packet if the connection identifier is not in the memory.

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

6. The HEA of claim 1, the negative cache is a one-bit wide hash table lacking collision resolution.

7. The HEA of claim 1, the connection identifier is a protocol, a source Internet protocol (IP) address, a destination IP address, a source port, and a destination port.

8. A computer readable medium encoded with computer executable instructions for reducing latency in a host Ethernet adapter (HEA), the computer executable instructions 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.

9. The computer readable medium of claim 8, the programming instructions 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.

10. The computer readable medium of claim 8, the programming instructions 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.

11. The computer readable medium of claim 8, a value of zero in bit vector at the bit position indicating that the connection identifier is not in the memory.

12. The computer readable medium of claim 8 wherein the negative cache is a one-bit wide hash table lacking collision resolution.

13. The computer readable medium of claim 8 wherein the connection identifier is a protocol, a source Internet protocol (IP) address, a destination IP address, a source port, and a destination port.