System and method for efficiently sorting DASD queued commands with unknown rotational latency
US6681289B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 25, 2002 |
| Grant date | Jan 20, 2004 |
| Priority date | — |
| Expiry date | Aug 4, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F3/0676
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus are provided for efficiently sorting queued commands with unknown rotational latency in a direct access storage device (DASD). For each command an initial expected access time (EAT) including a probability of success calculation is calculated and stored in a miss table. An actual starting location for the next command to be executed is identified. Utilizing the miss table, and a calculated best candidate command list for a plurality of different starting locations, a command in a command queue is selected based upon the actual starting location. The best candidate command list for a plurality of different starting locations is calculated by first sorting the miss table row by increasing EAT values and sequentially incrementing a miss time value by the predefined unit of time and updating all variable in the first row and adjusting a potential value in the second row of the miss table.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.