RE: [chrony-users] Configuration examples and accuracy

["Charlie Laub" <charleslaub@xxxxxxxxxxxxx>]

Hello Miroslav,

Thank you for creating and publishing this new page. The info is very
helpful and demonstrates the level of accuracy that can be achieved under a
variety of configurations. I have a local GPS PPS based (via NTP running on
an R-Pi) Stratum 1 server. The other machines on my network all run chrony
and reach tens of microseconds error, which is OK but could be better. I
need to synchronize them in order to coordinate distributed audio playback,
for which 1msec is too much error between machines. But synchronicity better
than 100 usec works OK, with 10 usec being the ultimate goal. I will look at
your examples to see how I can improve the client performance, however, most
machines (not the stratum 1 server) are WiFi based so I doubt I can improve
them much more. My clients use a poll interval of 4 or 5 for the GPS based
local timeserver. No PTP or hardware timestamping is used.

Here are some examples:
1. Linux client connected via hardcable to network running version 3.5:
chronyc sourcestats:
210 Number of sources = 2
Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std
Dev
============================================================================
==
BayTrail-NTP                6   3   773     -0.151      0.053  -1643us
3658ns
PiGPS                      21  15   680     +0.001      0.032    +28ns
7283ns

2. Linux WiFi client running version 4.1:
chronyc sourcestats:
Name/IP Address            NP  NR  Span  Frequency  Freq Skew  Offset  Std
Dev
============================================================================
==
BayTrail-NTP               15  10   60m     -0.118      0.068  -2536us
73us
PiGPS                      27  17  136m     -0.000      0.017     -3ns
62us

I think this is pretty good, all things considered, and achieved without any
special setup, etc. 

Thanks for your continued work on chrony!

Best,

Charlie Laub


-----Original Message-----
From: Miroslav Lichvar <mlichvar@xxxxxxxxxx> 
Sent: Tuesday, January 25, 2022 10:43 AM
To: chrony-users@xxxxxxxxxxxxxxxxxxxx
Subject: [chrony-users] Configuration examples and accuracy

A new page was added the chrony website:
https://chrony.tuxfamily.org/examples.html

It has some example client and server configurations with measurements of
accuracy to make it easier for new users to understand what is possible with
chrony, where are the limitations, and that the offsets reported by chronyc
don't tell much about accuracy.

--
Miroslav Lichvar


-- 
To unsubscribe email chrony-users-request@xxxxxxxxxxxxxxxxxxxx 
with "unsubscribe" in the subject.
For help email chrony-users-request@xxxxxxxxxxxxxxxxxxxx 
with "help" in the subject.
Trouble?  Email listmaster@xxxxxxxxxxxxxxxxxxxx.


-- 
To unsubscribe email chrony-users-request@xxxxxxxxxxxxxxxxxxxx 
with "unsubscribe" in the subject.
For help email chrony-users-request@xxxxxxxxxxxxxxxxxxxx 
with "help" in the subject.
Trouble?  Email listmaster@xxxxxxxxxxxxxxxxxxxx.