[ntp:questions] Performance estimation
David Taylor
david-taylor at blueyonder.co.uk.invalid
Mon Jun 15 14:38:15 UTC 2020
On 15/06/2020 08:33, Miroslav Lichvar wrote:
> On 2020-06-14, David Taylor <david-taylor at blueyonder.co.uk.invalid> wrote:
>> When using the ntpq -crv command, which is the better measure of system
>> performance - clk_jitter or sys_jitter? I've look for the definitions
>> and I'm thinking sys_jitter but perhaps someone could please remind me
>> of the difference?
>
> clk_jitter seems to be the jitter of the system clock as it is being
> updated with offsets, and sys_jitter seems to be the jitter of the
> selected peer, or the combined peers after clustering.
>
> https://www.eecis.udel.edu/~mills/ntp/html/cluster.html
==========================================
[Been trying to send through e-mail to ntp-questions, but anything I
send gets rejected!]
Thanks, Miroslav. Right! I'm not sure which I should be measuring so I
plotted both:
https://www.satsignal.eu/mrtg/performance_ntp_jitter.php
Blue is system jitter, green is clock jitter.
The lightly-loaded Raspberry Pi cards are all showing low numbers of
jitter, and it would be really useful to get that in more than three
decimal places of milliseconds.
--
Cheers,
David
Web: http://www.satsignal.eu
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