[ntp:questions] Ntpd in uninterruptible sleep?

A C agcarver+ntp at acarver.net
Mon Oct 24 20:58:47 UTC 2011


On 10/24/2011 11:40, Chuck Swiger wrote:
> On Oct 24, 2011, at 7:52 AM, A C wrote:
>> The header from top when things work normally (ntpd no longer running at high priority in this capture):
>>
>>> load averages:  0.10,  0.09,  0.02;     up 14+20:55:09               14:44:43
>>> 22 processes: 21 sleeping, 1 on CPU
>>> CPU states: 10.5% user,  0.0% nice,  7.4% system,  6.4% interrupt, 75.8% idle
>>> Memory: 5048K Act, 2432K Inact, 300K Wired, 2316K Exec, 1336K File, 200K Free
>>> Swap: 128M Total, 9272K Used, 119M Free
>
> This box has ~8MB of RAM?
>
> Well, that was a reasonable amount for a ~1990-era machine, and NetBSD will still run on it today, but running X11 clients is sure to push it into swapping out other processes entirely.  That will cause ntpd (and gpsd, etc) to stop responding entirely for many seconds while the hard drive chugs-- that's the "uninterruptible sleep" you initially asked about.
>
> Put more RAM into the box, or replace it with something from this or at least the previous decade.  :-)
>
> Regards,

It has 16 MB of RAM right now (one stick).  It had 64 at one point while 
I was trying to diagnose this issue.  I thought I might have a bad stick 
of RAM so I was testing them one by one (one stick in the machine at a 
time).  I didn't reinsert the other three yet.  But it doesn't matter, 
even with 64 MB ntpd still crashes which is what started this whole 
debugging game in the first place.

Besides, I wouldn't call an Xterm and Xclock anything significant in the 
way of X11 clients.  I'm certainly not intending to run anything beyond 
those.  The Xterm is for a console and the Xclock I was using to keep an 
eye on the machine so I'd know if the system locked up.


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