Re: ntpd entered uninterruptible sleep

[Alexander Carver <agcarver%acarver.net@localhost>]

On 10/23/2011 16:13, AGC wrote:
> I sent a message over to the ntpd list about this and they seem to think
> it's a kernel issue.
>
> Anyway, so it seemed the lockups of my IPX were showing up when ntpd was
> running in high priority mode. Last week I put its priority back to
> normal and attempted to break it again by polling it every five seconds.
>
> Today I got my result, ntpd itself locked up but according to ps, its
> status was "uninterruptible sleep". This time, because the priority was
> normal, the entire machine didn't crash but the cpu was spinning wildly
> until I was able to kill and restart ntpd. I forgot to try and run a
> trace on it, but I'm sure it'll lock up again (ktrace -p <pid> does it
> correct)?
>
> Any ideas why this would happen? I'm assuming that the lower priority
> prevented the locked up code from taking over the entire system.
> Everything else stayed running but ran very slowly (five seconds from
> keypress to character on screen) until ntpd was restarted.

I should add that all the hardware seemed to be working normally 
(comment based on a question from the ntpd list that asked if the 
network hardware went bad or the device driver failed).  I've got a GPS 
receiver plugged into one serial port and am running gpsd on the 
machine.  It was still reading and processing data from the receiver and 
shipping out the data to another machine on the network.  Additionally I 
had an xclock plus an ssh-in-xterm with displays exported to another 
machine and both of those continued to work.  So the serial ports and 
the network interface were both running.  Does it eliminate a possible 
source, maybe not but they didn't seem to suffer an all out failure.