| US 7,475,272 B2 | ||
| Method for calculating clock offset and skew | ||
| Scott M. Carlson, Tucson, Ariz. (US); Michel Henri Theodore Hack, Cortlandt Manor, N.Y. (US); and Li Zhang, Yorktown Heights, N.Y. (US) | ||
| Assigned to International Business Machines Corporation, Armonk, N.Y. (US) | ||
| Filed on Sep. 09, 2005, as Appl. No. 11/223,577. | ||
| Prior Publication US 2007/0061607 A1, Mar. 15, 2007 | ||
| Int. Cl. G06F 1/04 (2006.01) | ||
| U.S. Cl. 713—503 [713/500; 370/503; 707/100] | 2 Claims |
| 2. A method of calculating clock offset and skew in a computer system, the method comprising the steps of:
sending data packets from a first processing unit in the computer system to a second processing unit in the computer system;
sending the data packets from the second processing unit to the first processing unit;
providing first time stamps to indicate when the packets leave the first processing unit;
providing second time stamps to indicate when the packets arrive at the second processing unit;
providing third time stamps to indicate when the packets leave the second processing unit;
providing fourth time stamps to indicate when the packets arrive at the first processing unit;
defining a set of backward delay points using the fourth time stamps; and
calculating a clock offset between clocks on the first and second processing units and clock skews of said clocks using said
set of backward delay points;
wherein the step of defining a set of backward delay points includes the step of defining a set of negative backward delay
points using the fourth time stamp.
|