Summary: Re: Spin down HDD after disk sync or before power off

[Alexander Motin]

Bruce Cran wrote:
> On Tue, 16 Nov 2010 20:40:00 +0000
> Bruce Cran <bruce at cran.org.uk> wrote:
> 
>> One problem with the code that's been committed is that the shutdown
>> event handler doesn't get run during a suspend operation so an
>> emergency unload still gets done when running "acpiconf -s3".
> 
> Something else I noticed today: I've just got a new disk that supports
> NCQ and found the kern.cam.ada.ada_send_ordered sysctl that appears to
> enable/disable its use (?).  

ada_send_ordered controls periodical non-queued commands insertion to
avoid possible infinite commands starvation and timeouts as result. NCQ
can't be disabled now.

> But the shutdown handler that spins
> the disk down only gets initialized if ada_send_ordered is enabled. I
> was wondering what the reason for this is?

Interesting question. That code came as-is from "da" driver and I can't
explain it. I have feeling that it's wrong.

-- 
Alexander Motin