[ntp:questions] Ntpd in uninterruptible sleep?

unruh unruh at physics.ubc.ca
Sun Oct 23 23:06:28 UTC 2011


On 2011-10-23, A C <agcarver+ntp at acarver.net> wrote:
> A continuation of my debugging ntpd on a sparc system running NetBSD. 
> First, using -N results in a system lockup after a period of time if I 
> am polling ntpd remotely with ntpq.  I removed the -N option from 
> startup and the system stayed stable even when querying at 5 second 
> intervals.
>
> However, I just ran into a new problem.  Here's the output of ps ax for 
> the ntpd entry:
>
> 22887 ?     Ds     20:17.58 /usr/sbin/ntpd
>
>
> Uninterruptible sleep?  The daemon is indeed asleep because it stopped 
> responding to my ntpq queries but this time the system stayed up.  I 
> suspect it was this same sleep that occurred in the other condition but 
> the high priority locked up the machine.  I was able to kill and restart 
> ntpd without having to fully reboot.  All other processes were still 
> running normally but slowly (see below).
>
> More interesting is that the cpu was pegged until I was able to kill and 
> restart ntpd.  Most of the cpu was devoted to ntpd during this locked up 
> period.  Simple things like typing at the console were difficult.  It 
> would take a few seconds for a keypress to register on the screen.  Once 
> ntpd was restarted the system responded normally and the cpu usage 
> dropped to normal levels.
>
> This is still version 4.2.6p3.  I should probably go ahead and compile 
> the most recently released version but I'm at a loss to understand why 
> it happened.

Is there some problem with your ethernet card? Is ntpd polling and
unresponsive card like mad? Ie, is hardware a problem?



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