acpi_task_0 consuming cpu resource

[Robert Noland]

On Fri, 2009-08-07 at 12:11 +0800, C. C. Tang wrote:
> > I have one of these boards, but I haven't seen this with -CURRENT.
> > There are known fan issues with some of the BIOS revisions for these
> > boards.  I would make sure you have the latest BIOS update and see if it
> > resolves your issue.
> 
> I have updated the BIOS to rev.0182(20090528). It seems that new rev. 
> has been released about 2 weeks ago but I haven't updated it yet.
> 
> I am using 7.2-RELEASE. In fact this problem exists when the board is 
> newly bought(BIOS rev.099 if I remembered correctly). But at that time I 
> didn't have case fan so I simply disabled that.
> 
> And it seems that the problem may not always happen. (happen when fan 
> speed need to change?) I rebooted once an hour ago when the system 
> temperature become stable and the problem does not happed till now.

Not sure then... I've got that board swapped out for a VIA board right
now.  It tends to be noisy enough in my office with all the other fans
running that I really can't hear that one.  I did have the smart fan
control enabled on both the case fan and cpu fan.  It also periodically
rebuilds lots of ports or kernels with -j 5, so if it was going to heat
up, that should do it...  If I can dig up a spare case and power, I'll
hook it back up and see if I can break it.  Otherwise it will have to
wait until I get done with the VIA driver...  I haven't really had any
issues that I can think of with that board, other than it is a bit slow
for compiling.  It runs amd64 just fine.

Just remembering an issue that I had with some old p4 boxes though.  On
those boxes, when they got hot, they would trigger an acpi message that
was picked up by devd.  There was no way to throttle the messages, so it
would work the cpu as hard as it could, processing the messages.  The
only solution at that point was to power it off for a few minutes while
it cooled off and not work it too hard.  That sounds like what you are
seeing.  Are you seeing messages in syslog?

# Notify all users before beginning emergency shutdown when we get
# a _CRT or _HOT thermal event and we're going to power down the system
# very soon.
notify 10 {
        match "system"          "ACPI";
        match "subsystem"       "Thermal";
        match "notify"          "0xcc";
        action "logger -p kern.emerg 'WARNING: system temperature too high, shut
ting down soon!'";
};

robert.

> Thanks,
> C.C.
> 
-- 
Robert Noland <rnoland at FreeBSD.org>
FreeBSD