System and method for memory failure recovery using lockstep processes

• US 7,020,800 B2
• Filed: 01/24/2002
• Issued: 03/28/2006
• Est. Priority Date: 01/24/2002
• Status: Expired due to Term

• Current Assignee: Valtrus Innovations Limited (f/k/a Dolya Holdco 9 Limited) (Key Patent Innovations Limited)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Milojicic, Dejan S., Messer, Alan, Fu, Guangrui, Bernadat, Philippe
• Primary Examiner(s): Beausoliel, Robert
• Assistant Examiner(s): Bonura, Timothy M.
• Application Number:
  US10/057,124
• Publication Number:
  US 20030140281A1
• Time in Patent Office: 1,524 Days
• Field of Search: 714/29, 714/28, 714/6, 714/8, 714/12, 714/13
• US Class Current: 714/38.13
• CPC Class Codes: G06F 11/1492 by run-time replication performed by the application software

Abstract

A system and method for memory failure recovery is disclosed. The method discloses the steps of maintaining a predetermined number of duplicate and primary processes; keeping the processes in synchronization; managing the processes so that a single process image is presented to an external environment; detecting a computer system exception which affects one of the processes; and terminating the affected process. The system discloses, a primary process memory space which hosts a primary process; a duplicate process memory space which hosts a duplicate process corresponding to the primary process; a synchronization buffer which keeps the duplicate process in synchronization with the primary process; a processor which generates an exception signal in response to detection of a memory failure condition which affects the primary process; and an operating system which receives the exception signal, terminates the affected primary process, and maintains a predetermined number of primary and duplicate processes.

Claims

1. A method for memory failure recovery in a computer, comprising:

maintaining a predetermined number of duplicate and primary processes in the computer;

keeping the processes in synchronization;

managing the processes so that a single process image is presented to an external environment;

detecting a computer exception which affects one of the processes; and

terminating the affected process.

2. The method of claim 1 wherein the detecting element includes detecting a memory failure.

3. The method of claim 1 further comprising:

allocating a new memory space in memory hardware in the computer to each of the duplicate processes, which is separate from a memory space in the memory hardware allocated to the primary process.

4. The method of claim 1 wherein the maintaining element includes:

identifying a primary process;

monitoring a fault-tolerance value corresponding to the primary process; and

setting a number of duplicate processes equal to the fault-tolerance value.

5. The method of claim 4 further comprising assigning a predetermined fault-tolerance value to a primary process.

6. The method of claim 4 further comprising dynamically modifying the fault-tolerance value of the primary process, in response to a computer command.

7. The method of claim 4 wherein the setting element includes adding one or more new duplicate processes, if the number of duplicate processes is less than the fault-tolerance value.

8. The method of claim 4 wherein the setting element includes deleting a duplicate process, if the number of duplicate processes is more than the fault-tolerance value.

9. The method of claim 1 wherein the keeping element includes synchronizing the processes upon receipt of data from an external environment.

10. The method of claim 1 wherein the keeping element includes synchronizing the processes upon receipt of signals from an external environment.

11. The method of claim 1 wherein the keeping element includes synchronizing the processes upon transmission by one of the processes to an external environment.

12. The method of claim 1 wherein the managing element includes permitting only one of the processes to transmit to an external environment.

13. The method of claim 1 wherein the managing element includes permitting only one of the processes to perform a system call to an external environment.

14. The method of claim 1 wherein the managing element includes permitting only one of the processes to perform a library call to an external environment.

15. The method of claim 1, further comprising:

the processes communicating, through a synchronization buffer, with an external environment,

wherein keeping the processes in synchronization is based on interaction between the processes and the external environment through the synchronization buffer.

16. A method for memory failure recovery, comprising:

maintaining a predetermined number of duplicate and primary processes;

keeping the processes in synchronization;

managing the processes so that a single process image is presented to an external environment;

detecting a computer system exception which affects one of the processes; and

terminating the affected process;

wherein the maintaining element includes,

identifying a primary process;

monitoring a fault-tolerance value corresponding to the primary process; and

setting a number of duplicate processes equal to the fault-tolerance value; and

wherein the managing element includes,

permitting only one of the processes to perform a system call to an external environment.

17. The method of claim 16, wherein keeping the processes in synchronization is based on data or signals received from the external environment, the external environment including computer functionality outside the processes.

18. The method of claim 16, wherein the predetermined number of duplicate and primary processes are maintained in a computer.

19. A computer-usable medium embodying computer program code for commanding a computer to perform memory failure recovery comprising:

maintaining a predetermined number of duplicate and primary processes in the computer;

keeping the processes in synchronization;

managing the processes so that a single process image is presented to an external environment;

detecting a computer system exception which affects one of the processes; and

terminating the affected process.

20. The medium of claim 19 wherein the detecting element includes detecting a memory failure.

21. The medium of claim 19 further comprising:

allocating a new memory space in memory hardware in the computer to each of the duplicate processes, which is separate from a memory space in the memory hardware allocated to the primary process.

22. The medium of claim 19 wherein the maintaining element includes:

identifying a primary process;

monitoring a fault-tolerance value corresponding to the primary process; and

setting a number of duplicate processes equal to the fault-tolerance value.

23. The medium of claim 19 wherein the managing element includes permitting only one of the processes to transmit to an external environment.

24. The medium of claim 19, wherein the computer program code is for commanding the computer to further perform:

enabling the processes to communicate, through a synchronization buffer, with an external environment,

wherein keeping the processes in synchronization is based on interaction between the processes and the external environment through the synchronization buffer.

25. A system for memory failure recovery in a computer, comprising:

means for maintaining a predetermined number of duplicate and primary processes in the computer;

means for keeping the processes in synchronization;

means for managing the processes so that a single process image is presented to an external environment;

means for detecting a computer exception which affects one of the processes; and

means for terminating the affected process.

26. A system for memory failure recovery, comprising:

a primary process memory space hosting a primary process;

a duplicate process memory space hosting a duplicate process corresponding to the primary process;

a synchronization buffer for keeping the duplicate process in synchronization with the primary process;

a processor for generating an exception signal in response to detection of a memory failure condition which affects the primary process; and

an operating system for receiving the exception signal, terminating the affected primary process, and maintaining a predetermined number of primary and duplicate processes.

27. The system of claim 26, further comprising:

a buffer controller for permitting the processes to receive communications from an external environment while permitting only one of the processes to transmit to the external environment.

28. The system of claim 26, wherein the exception signal is a machine check abort signal.

29. The system of claim 26, wherein the primary process, duplicate process, synchronization buffer, processor, and operating system are part of a computer.