Method To Support Lossless Real Time Data Sampling And Processing On Rapid I/O End-Point

• US 20090225770A1
• Filed: 03/06/2008
• Published: 09/10/2009
• Est. Priority Date: 03/06/2008
• Status: Active Grant

• Current Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Original Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Inventors: Tezcan, Bertan, Wang, Chi-Lie, Mo, Jason Z., Nguyen, Calvin
• Granted Patent: US 8,213,448 B2
• Time in Patent Office: Days
• US Class Current: 370/412
• CPC Class Codes: H04L 1/0082 fields explicitly indicating existence of error in data being transmitted, e.g. so that downstream stations can avoid decoding erroneous packet; relays
• CPC Class Codes: H04L 47/22 Traffic shaping
• CPC Class Codes: H04L 49/90 Buffering arrangements

Abstract

A serial buffer monitors an incoming stream of packets to identify single missing packets and multiple consecutive missing packets. Upon detecting multiple consecutive missing packets, an interrupt is generated, thereby stopping the data transfer. Upon detecting a single missing packet, a single missing packet identifier is inserted into the packet header of the packet that resulted in identification of the single missing packet. The incoming packets, including any inserted single missing packet identifiers, are written to a queue. When the water level reaches the water mark of the queue, the stored packets are read to create an outgoing packet stream. When a packet read from the queue includes an inserted single missing packet identifier, a dummy packet (e.g., a packet having a data payload of all zeros) is inserted into the outgoing packet stream. As a result, real-time applications are capable of processing the outgoing packet stream in a constant fashion.

Claims

1. A method of operating a serial buffer to provide a data offload function, the method comprising:

monitoring an incoming stream of packets to identify single missing packets in the incoming stream of packets;

inserting a single missing packet identifier into each of the packets that results in the identification of a single missing packet;

writing the incoming stream of packets, including any inserted single missing packet identifiers, to a queue;

reading the packets, including any inserted single missing packet identifiers, from the queue to provide an outgoing stream of packets;

inserting a dummy packet into the outgoing stream of packets in response to each of the packets read from the queue having an inserted single missing packet identifier.

2. The method of claim 1, wherein the step of monitoring the incoming stream of packets to identify single missing packet comprises comparing addresses associated with the packets with expected addresses of the packets.

3. The method of claim 1, wherein the step of inserting a single missing packet identifier comprises writing the single missing packet identifier to an unused location of a packet header.

4. The method of claim 1, wherein the step of reading the packets from the queue is initiated when a water level of the queue reaches a water mark of the queue.

5. The method of claim 4, further comprising incrementing the water level of the queue by two when a single missing packet identifier is inserted into a packet.

6. The method of claim 1, further comprising inserting an interval between packets in the outgoing stream of packets.

7. The method of claim 1, further comprising controlling each dummy packet to have the same predetermined data payload.

8. The method of claim 1, wherein each of the packets in the incoming stream and each of the packets in the outgoing stream have the same size.

9. The method of claim 1, further comprising monitoring the incoming stream of packets to identify multiple consecutive missing packets in the incoming stream of packets.

10. The method of claim 9, further comprising interrupting operation of the serial buffer upon identifying multiple consecutive missing packets in the incoming stream of packets.

11. A serial buffer comprising

a first port configured to receive an incoming stream of packets;

missing packet detection logic coupled to the first port and configured to identify single missing packets in the incoming stream of packets, and in response, insert corresponding single missing packet identifiers into packets that resulted in identification of the single missing packets;

write control logic coupled to the first port and the missing packet detection logic, and configured to write the packets, including the inserted single missing packet identifiers, to a queue; and

read control logic configured to read the packets from the queue, and in response, provide an outgoing stream of packets, the read control logic being configured to insert a dummy packet into the outgoing stream of packets in response to reading a packet having an inserted single missing packet identifier.

12. The serial buffer of claim 11, wherein the first port comprises a serial rapid IO (sRIO) interface.

13. The serial buffer of claim 11, wherein each of the packets in the incoming stream of packets and the outgoing stream of packets has the same size.

14. The serial buffer of claim 11, wherein the missing packet detection logic includes means for identifying multiple consecutive missing packets in the incoming stream of packets.

15. The serial buffer of claim 14, further comprising means for interrupting operation of the serial buffer upon identifying multiple consecutive missing packets in the incoming stream of packets.

16. The serial buffer of claim 11, wherein the missing packet detection logic includes means for incrementing a water level of the queue by two upon inserting a single missing packet identifier.

17. The serial buffer of claim 11, wherein the missing packet detection logic includes comparison logic configured to compare memory addresses of packets in the incoming stream with expected memory addresses.

18. The serial buffer of claim 11, wherein the dummy packet comprises a predetermined data payload.

19. A serial buffer comprising:

a plurality of queues, each configurable to support or not support missing packet detection, and including a first queue configured to support missing packet detection, and a second queue not configured to support missing packet detection;

a first port configured to receive an incoming stream of packets, wherein different packets specify different queues;

missing packet detection logic coupled to the first port and configured to identify single missing packets in the incoming stream of packets, wherein the missing packet detection logic is configured to insert single missing packet identifiers into packets that specify the first queue and are associated with single missing packets, and wherein the missing packet detection logic is configured to not insert single packet identifiers into packets that specify the second queue.