Simultaneously updating logical time of day (TOD) clocks for multiple cpus in response to detecting a carry at a pre-determined bit position of a physical clock
US7617410B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 15, 2006 |
| Grant date | Nov 10, 2009 |
| Priority date | — |
| Expiry date | Apr 24, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F1/14
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A system, method and computer program product for synchronizing adjustment of a time of day (TOD) clock for a computer system having multiple CPUs, each CPU having an associated physical clock providing a time base for executing operations that is stepping to a common oscillator, and an associated logical TOD clock. The method includes detecting propagation of a carry at a pre-determined bit position of the physical clock associated with a CPU in the computer system; and, updating, in response to the detecting of the pre-determined bit position carry, a TOD-clock offset value (d) to be added to a physical clock value (Tr) value to obtain a logical TOD clock value (Tb) for use by a CPU in the system. In this manner, each CPU computes a new logical TOD clock value in synchronization—the new logical TOD clock value taking effect simultaneously for the multiple CPUs.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.