157k interrupts per second causing 60% CPU load on idle system

[Matt Thyer]

On 20 March 2012 22:24, Ivan Voras <ivoras at freebsd.org> wrote:

> On 20 March 2012 12:52, Matt Thyer <matt.thyer at gmail.com> wrote:
> > On 20 March 2012 21:12, Ivan Voras <ivoras at freebsd.org> wrote:
> >>
> >> On 20/03/2012 06:26, Matt Thyer wrote:
> >> > I've upgraded my FreeBSD-STABLE NAS from r225723 (22nd Sept 2011) to
> >> > r232477 (4th Mar 2012) and am finding that a system process called
> >> > "intr"
> >> > is now constantly using about 60% of 1 CPU starting a short time after
> >> > reboot (possibly triggered by use of the samba server).
> >> >
> >> > When this starts, systat -vm 1 says that the system is 85% idle and
> 14%
> >> > interrupt handling.
> >> > It says that there's around 157k interrupts per second.
> >> >
> >>
> >> Ok, but *which* interrupt is getting triggered? Please send the output
> >> of "vmstat -i".
> >>
> >>
> > interrupt                          total       rate
> > irq16: uhci0+                 3392184862     126692
>
> Ok, something's probably wrong with USB. Can you disable it in BIOS?
>
>
> > cpu0: timer                     53549677       1999
> > irq256: mps0                     2643187         98
> > irq257: re0                      5508108        205
> > irq258: ahci0                     160717          6
> > cpu1: timer                     53525300       1999
> > cpu2: timer                     53525300       1999
> > cpu3: timer                     53525296       1999
> > Total                         3614622447     134999
> >
>

I did just update the BIOS at about the same time so the difference may be
due to that change.

I'll try a few things such as:

- Unplugging any USB things (I've only got a keyboard plugged in).
- Downgrade BIOS.

I'll get back to you all soon.