System and method for reducing latency in layered device driver architectures
US5978856A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 26, 1996 |
| Grant date | Nov 2, 1999 |
| Priority date | — |
| Expiry date | Jan 26, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F13/387
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A system and method for reducing latency in systems using layered device driver architectures. The preferred embodiment of the invention comprises a disk subsystem including a layered device driver architecture which performs various RAID operations. A plurality of the driver layers are defined to use a common request structure. The system and method of the present invention determines if a request maps unmodified to a lower driver layer and "quick launches" these requests to the lower driver layer according to the present invention. When a host request is received, the first layer device driver executing on the disk controller determines if the enqueued request is atomic, i.e., if the request maps unmodified to the next lower level driver layer. If so, then the request is dequeued from the first level queue and enqueued on the next lower level layer queue, avoiding steps of allocating and populating a new request structure for the lower level driver. This process preferably repeats for each of the device driver layers. When the last device driver layer completes, each device driver performs a completion callback to its calling driver layer. If a respective device driver layer was …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.