Hardware method for detecting timeout conditions in a large number of data connections
Tracking several open data connections is difficult with a large number of connections. Checking for timeouts in software uses valuable processor resources. Employing a co-processor dedicated to checking timeouts uses valuable logic resources and consumes extra space. In one embodiment, a finite state machine implemented in hardware increases the speed connections can be checked for timeouts. The finite state machine stores a last accessed time stamp for each connection in a memory, and loops through the memory to compare each last accessed time stamp with a current time stamp of the system minus a global timeout value. In this manner, the finite state machine can efficiently find and react to timed out connections.
1. A method comprising:
performing a timestamp analysis by:
a) when a status property of a location indicated by a memory pointer is active
reading a last accessed timestamp corresponding to the location indicated by the memory pointer;
determining whether a timeout has occurred based on the last accessed timestamp, a current timestamp and a stored time out value; and
if a timeout has occurred, and the location of the memory pointer is active, (i) notifying a higher communication layer, and (ii) updating the status property of the location indicated by the memory pointer to inactive; and
b) incrementing the memory pointer; and
if an incoming data packet is received, handling the incoming data packet by:
a) processing the incoming data packet with an incoming data handler configured to process the incoming data packet in the higher communication layer;
b) updating the status property of the location indicated by the memory pointer to active, and setting the last accessed timestamp in one of a plurality of locations in a memory buffer.
2. The method of claim 1 further comprising determining whether a timeout has occurred by calculating an expiration timestamp based on the difference of the current timestamp and the stored time out value and triggering a timeout if the expiration timestamp is greater than the last accessed timestamp.
3. The method of claim 1 further comprising incrementing the current timestamp on a clock cycle.
4. The method of claim 1 wherein the incoming data handler is Fibre Channel.
5. The method of claim 1 wherein the memory buffer includes a connection tracking memory buffer.
6. The method of claim 5 wherein the incoming data handler processes data by detecting a new frame on a receive buffer, reading the header of the new frame to update or create timestamp data in a location in the connection tracking memory buffer, and storing the new frame in one of a plurality of data storing memory locations.
7. The method of claim 1 wherein the stored timeout value is at least one of a global timeout value based on a connection protocol and a local timeout value based on an individual connection.
8. The method of claim 1 , wherein handling the packet further includes:
if the incoming data packet is part of a new connection, a new connection status of the incoming data packet indicated by a lack of an entry corresponding to a connection of the incoming data packet in the plurality of memory locations, storing the data packet in one of the locations in the memory buffer.
9. A system comprising:
a plurality of registers, wherein the system is configured to:
when a status property of a location indicated by a memory pointer is active
reading a last accessed timestamp corresponding to the location indicated by the memory pointer;
determining whether a timeout has occurred based on the last accessed timestamp, a current timestamp and a stored time out value; and
if a timeout has occurred, and the location of the memory pointer is active, (i) notifying a higher communication layer, and (ii) updating the status property of the location indicated by the memory pointer to inactive; and
incrementing the memory pointer; and
if an incoming data packet is received, handling the incoming data packet by:
processing the incoming data packet with an incoming data handler configured to process the incoming data packet in the higher communication layer;
updating the status property of the location indicated by the memory pointer to active, and setting the last accessed timestamp in one of a plurality of locations in a memory buffer.
10. The system of claim 9 , further comprising determining whether a timeout has occurred by calculating an expiration timestamp based on a difference of the current timestamp and the stored timeout value and triggering a timeout if the expiration timestamp is greater than the last accessed timestamp.
11. The system of claim 9 further comprising a clock cycle, wherein the state machine is further configured to increment the current timestamp on each clock cycle.
12. The system of claim 9 wherein the incoming data handler is Fibre Channel.
13. The system of claim 9 wherein the memory buffer includes a connection tracking memory buffer.
14. The system of claim 9 wherein the incoming data handler processes data by detecting a new frame on a receive buffer, reading the header of the new frame to update or create timestamp data in a location in the connection tracking memory buffer, and storing the new frame in one of a plurality of data storing memory locations.
15. The system of claim 9 wherein the stored timeout value is at least one of a global timeout value based on a connection protocol and a local timeout value based on an individual connection.
16. The system of claim 9 , wherein handling the packet further includes:
if the incoming data packet is part of a new connection, a new connection status of the incoming data packet indicated by a lack of an entry corresponding to a connection of the incoming data packet in the plurality of memory locations, storing the data packet in one of the locations in the memory buffer.