BSDCan2013 - Final

BSDCan 2013
The Technical BSD Conference

Bob Beck
Day Talks - Day 2 - 2013-05-18
Room MNT 202
Start time 10:00
Duration 01:00
ID 396
Event type Lecture
Track Hacking
Language used for presentation English

The Buffer Cache in OpenBSD

This talk goes over recent changes to the OpenBSD Midlayer and Buffer Cache.

OpenBSD has moved to a model where we support large buffer caches with a limited amount of kernel memory mapping. Buffers are mapped when in use, and unmapped when not in use. Buffers are flipped to/from DMA accessible regions when needed for io, but may be read from non DMA accessible memory.

This talk goes over the changes that have been made and the evolution of the OpenBSD buffer cache from a small fixed allocated array to it's current incarnation, and the interesting bugs and challenges that working in this area has exposed.