[ntp:hackers] Of Linux and jitter

Brian Utterback brian.utterback at sun.com
Tue Oct 19 11:35:33 PDT 2004

I would suggest that you upgrade or at least dual boot the Blade to use
Solaris 10. The Dtrace facility makes debugging this kind of problem
pretty simple. Unfortunately, the Ultra-1 will not run Solaris 10, much
to my chagrin.

David L. Mills wrote:
> 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.
> 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.
> Dave
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Power corrupts. PowerPoint corrupts absolutely.
Brian Utterback - OP/N1 Revenue Product Engineering, Sun Microsystems, Inc.
Ph/VM: 877-259-7345, Em:brian.utterback-at-ess-you-enn-dot-kom

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