Optimizing synchronization between monitored computer system signals

• US 7,391,835 B1
• Filed: 09/29/2004
• Issued: 06/24/2008
• Est. Priority Date: 09/29/2004
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Bao, Yujuan, Gross, Kenny C.
• Primary Examiner(s): Ghayour; Mohammed
• Assistant Examiner(s): Torres; Juan Alberto
• Application Number:
  US10/955,195
• Time in Patent Office: 1,364 Days
• Field of Search: 375/354, 709/248, 713/375
• US Class Current: 375/354
• CPC Class Codes: G06F 11/2294 by remote test

Abstract

One embodiment of the present invention provides a system that optimizes synchronization between monitored signals in a computer system. During operation, the system receives a number of monitored signals. The system then forms a number of signal pairs by grouping each signal with every other signal. Next, the system optimizes synchronization between the signals by iteratively perturbing the timing of each signal in an attempt to increase the value of an objective function which reflects the overall synchronization between all the signals.

Claims

1. A method for optimizing synchronization between monitored signals in a computer system, comprising:

receiving a number of monitored signals;

forming a number of signal pairs by grouping each signal with every other signal; and

optimizing synchronization between the signals by iteratively perturbing the timing of each signal in an attempt to increase the value of an objective function which reflects the overall synchronization between all the signals.

2. The method of claim 1, wherein perturbing the timing of a signal involves generating a random lag or lead time, and shifting the timing of the signal with the random lag or lead time.

3. The method of claim 2,

wherein the objective function is the root-mean-square of the cross-correlation coefficients of all the signal pairs;

and

wherein the method further comprises;

computing the value of the objective function, which involves;

computing a cross-correlation coefficient between each signal and every other signal; and

computing the root-mean-square of all the cross-correlation coefficients; and

comparing the pre-perturbation and post-perturbation values of the objective function.

4. The method of claim 2, wherein when the perturbation increases the value of the objective function, the method further comprises retaining the lag or lead time applied to the signal;

and

wherein when the perturbation decreases the value of the objective function, the method further comprises discarding the perturbation and reverting the signal to its state prior to the perturbation.

5. The method of claim 1, further comprising stopping the iterative perturbation process when the difference of the values of the objective function between two consecutive iterations is less than a pre-determined value.

6. The method of claim 1, further comprising stopping the iterative perturbation process when the value of the objective function does not change after a pre-determined number of iterations.

7. The method of claim 6, further comprising applying an additional random lag or lead time to each signal after stopping the iterative perturbation process to ensure that a substantially optimal synchronization between all the signals has been attained.

8. The method of claim 1, further comprising selecting one of the received signals to be an anchor signal, wherein the anchor signal is not perturbed.

9. A computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for optimizing synchronization between monitored signals in a computer system, the method comprising:

receiving a number of monitored signals;

forming a number of signal pairs by grouping each signal with every other signal; and

optimizing synchronization between the signals by iteratively perturbing the timing of each signal in an attempt to increase the value of an objective function which reflects the overall synchronization between all the signals.

10. The computer-readable storage medium of claim 9, wherein perturbing the timing of a signal involves generating a random lag or lead time, and shifting the timing of the signal with the random lag or lead time.

11. The computer-readable storage medium of claim 10,

wherein the objective function is the root-mean-square of the cross-correlation coefficients of all the signal pairs;

and

wherein the method further comprises;

computing the value of the objective function, which involves;

computing a cross-correlation coefficient between each signal and every other signal; and

computing the root-mean-square of all the cross-correlation coefficients; and

comparing the pre-perturbation and post-perturbation values of the objective function.

12. The computer-readable storage medium of claim 10, wherein when the perturbation increases the value of the objective function, the method further comprises retaining the lag or lead time applied to the signal;

and

wherein when the perturbation decreases the value of the objective function, the method further comprises discarding the perturbation and reverting the signal to its state prior to the perturbation.

13. The computer-readable storage medium of claim 9, wherein the method further comprises stopping the iterative perturbation process when the difference of the values of the objective function between two consecutive iterations is less than a pre-determined value.

14. The computer-readable storage medium of claim 9, wherein the method further comprises stopping the iterative perturbation process when the value of the objective function does not change after a pre-determined number of iterations.

15. The computer-readable storage medium of claim 14, wherein the method further comprises applying an additional random lag or lead time to each signal after stopping the iterative perturbation to ensure that a substantially optimal synchronization between all the signals has been attained.

16. The computer-readable storage medium of claim 9, wherein the method further comprises selecting one of the received signals to be an anchor signal, wherein the anchor signal is not perturbed.

17. An apparatus for optimizing synchronization between monitored signals in a computer system, comprising:

a receiving mechanism configured to receive a number of monitored signals;

a grouping mechanism configured to form a number of signal pairs by grouping each signal with every other signal; and

an optimization mechanism configured to optimize synchronization between the signals by iteratively perturbing the timing of each signal in an attempt to increase the value of an objective function which reflects the overall synchronization between all the signals.

18. The apparatus of claim 17, wherein while perturbing the timing of a signal, the optimization mechanism is configured to generate a random lag or lead time, and to shift the timing of the signal with the random lag or lead time.

19. The apparatus of claim 18, wherein the objective function is the root-mean-square of the cross-correlation coefficients of all the signal pairs;

and

wherein the optimization mechanism is further configured to;

compute a cross-correlation coefficient between each signal and every other signal;

compute the root-mean-square of all the cross-correlation coefficients; and

to

compare the pre-perturbation and post-perturbation values of the objective function.

20. The apparatus of claim 18, wherein when the perturbation increases the value of the objective function, the optimization mechanism is further configured to retain the lag or lead time applied to the signal;

and

wherein when the perturbation decreases the value of the objective function, the optimization mechanism is further configured to discard the perturbation and to revert the signal to its state prior to the perturbation.

21. The apparatus of claim 17, wherein the optimization mechanism is further configured to stop the iterative perturbation process when the difference of the values of the objective function between two consecutive iterations is less than a pre-determined value.

22. The apparatus of claim 17, wherein the optimization mechanism is further configured to stop the iterative perturbation process when the value of the objective function does not change after a pre-determined number of iterations.

23. The apparatus of claim 22, wherein the optimization mechanism is further configured to apply an additional random lag or lead time to each signal after stopping the iterative perturbation process to ensure that a substantially optimal synchronization between all the signals has been attained.

24. The apparatus of claim 17, wherein the optimization mechanism is further configured to select one of the received signals to be an anchor signal, wherein the anchor signal is not perturbed.