RFC: ATA to CAM integration patch

[Alexander Motin]

Kamigishi Rei wrote:
> Alexander Motin wrote:
>>> ahcich1: ALL SLOTS BUSY!
>>> Is it purely informational or does it indicate a problem? (I'm using 
>>> Intel Q35+ICH9 in AHCI mode.)
>> It is bad. It must never happen. It means that driver got more 
>> commands then it has empty slots available. Results can be unpredictable.
>> How have you manage it? Were there any other messages around?
> No other messages. Going to try your patch from the followup message.
> Basically, I did nothing out of the ordinary. I'm running mysqld, 
> postgres, and two lighttpds in jails, one of the lighttpds is serving 
> huge media files.
> The messages appeared mostly during "make buildworld" for one of the 
> GEOM_MIRROR drives (/usr/obj operations probably) and for one of raidz1 
> drives (where /usr/src resides).

It could be not a real bug, but incorrect diagnostic, in situation, when 
the last of 32 submitted command finishes first. NCQ in practice. :)

-- 
Alexander Motin