Method and system for providing a deterministic virtual clock
US7921319B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 26, 2007 |
| Grant date | Apr 5, 2011 |
| Priority date | — |
| Expiry date | Feb 2, 2030 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F11/202
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and system for providing a virtual clock on a computer by multiplying the number of instructions executed by the average instruction execution time. It is however not reliable to use this generic computation for virtualization of application in a fault tolerant system because the virtual clock computed like this quickly deviates from the system clock. A virtual clock computation is provided which includes periodic readjustment of the virtual to the system clock. Also, the errors coming from rounding of the number of executing instruction are suppressed.Taking the assumption that the user instruction counters are maintained synchronized in the operational and the replication computers, replacing the system clock access by a virtual clock when virtualizing applications thus turning the system clock acquisition into a deterministic event. Replicating the system clock access can be thus done by re-executing the application code in the replication machine avoiding transfer of information at each system clock access of the virtualized application programs.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.