MFC of "Large set of CAM improvements" breaks I/O to Adaptec 29160 SCSI controller

[Pete French]

> Thanks. First step successful - I can steadily reproduce problem on
> CURRENT. raidtest with 200 I/O streams over gmirror of two disks on same
> channel triggers issue in seconds. Any I/O on channel dying after both
> disks report "Queue full" error same time. The rest of system works
> fine. If I preliminarily manually adjust queue depth of one disk -
> everything works fine. I'll investigate it tomorrow.

Glad you have managed to dupliate it - the queue depth thing is
inetersting, what changes did you make ? I can try them here and see
if they improve the situation on either of my two machines.

-pete.