Data sharing using difference-on-write
US9471244B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 9, 2012 |
| Grant date | Oct 18, 2016 |
| Priority date | — |
| Expiry date | Oct 12, 2032 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02D10/00
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
When a virtual machine writes to a page that is being shared across VMs, a share value is calculated to determine how different the page would be if the write command were implemented. If the share value is below a predefined threshold (meaning that the page would not be “too different”), then the page is not copied (as it would be in a standard copy-on-write operation). Instead, the difference between the contents of the pages is stored as a self-contained delta. The physical to machine memory map is updated to point to the delta, and the delta contains a pointer to the original page. When the VM needs to access the page that was stored as a delta, the delta and the page are then fetched from memory and the page is reconstructed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.