[ntp:hackers] Of Linux and jitter

mayer at gis.net mayer at gis.net
Tue Oct 19 11:48:20 PDT 2004


----- Original Message Follows -----
> Guys,
> 
> 1. All the backroom and campus machines are now running ntp-dev and
> all  seem to work except Linux albert on the campus wire. It segfaults
> after  a few minutes. I am dumb with Linux debugging tools, so I'll
> leave the  carcass on the hope some Linux jockey can look at it.
>

We've seen that. We suspect a bad resolver library. Harlan may have
more to say about this.
 
> 2. I'm very suspicious about the Solaris jitter using a serial port
> and  any of several radios. The jitter can be over one second(!) and
> varies  in intensity with time. I can't believe the port interrupt
> routine can  have jitter that high. The jitter does not occur with a
> SunOS SPARC IPC  running ntp-dev, which is now the best timekeeper we
> have. The jitter  first showed up on Ultra-1 pogo running Solaris 8/9
> and Blade 1500  running Solaris 9. Could there be something in the
> ntpd I/O code causing  this? It's only in the serial port code; there
> is no such jitter in the  packet I/O code.
> 

I haven't touch ANY of the serial port code, on the packet code. Maybe
changes in one of the refclocks affects this?

Danny

> Dave
> 
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