
Meanwhile in device driver land..

buffer queues are used to take buffers, send to devices. 

Could queue "infinite" writes... (Aiiee.. No Es Bueno) - I can't get
buffers because they are all mapped waiting to be written.

Limit write backlog in buffer queues

IO's could starve with traditional elevator algorithm
  replace with NSCAN

All of a sudden massive write bashing can't cripple the machine

NSCAN and queue limiting in OpenBSD 5.3


