[chrony-users] Why doesn't chrony provide a "maximum error" like ntpd does?

[Xuehan Xu]

Hi, everyone.

It seems there is no "maximum error" of the system time in chrony like
the one in ntpd, is this right? If it is, why?

Thanks:-)

[Miroslav Lichvar]

Post by Xuehan Xu
Hi, everyone.
It seems there is no "maximum error" of the system time in chrony like
the one in ntpd, is this right? If it is, why?

I'm not sure which "maximum error" do you mean. chrony provides root
dispersion and root delay in the chronyc tracking report, similarly to
the ntpq readvar command.

[Xuehan Xu]

Post by Miroslav Lichvar
I'm not sure which "maximum error" do you mean. chrony provides root
dispersion and root delay in the chronyc tracking report, similarly to
the ntpq readvar command.

Thanks, Miroslav:-)

By the way, by "maximum error", I mean the maximum uncertainty of the
local system time, or the maximum error between local system time and
the time server's system time:-)

[Bill Unruh]

William G. Unruh __| Canadian Institute for|____ Tel: [phone]
Physics&Astronomy _|___ Advanced Research _|____ Fax: [phone]
UBC, Vancouver,BC _|_ Program in Cosmology |____ ***@physics.ubc.ca
Canada V6T 1Z1 ____|____ and Gravity ______|_ www.theory.physics.ubc.ca/

Post by Xuehan Xu

Post by Miroslav Lichvar
I'm not sure which "maximum error" do you mean. chrony provides root
dispersion and root delay in the chronyc tracking report, similarly to
the ntpq readvar command.

Thanks, Miroslav:-)
By the way, by "maximum error", I mean the maximum uncertainty of the
local system time, or the maximum error between local system time and
the time server's system time:-)

Sounds like it basically the roundtrip-time/2 +max uncert in the server time.
Not that that is a terribly useful number.

Post by Xuehan Xu
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[Miroslav Lichvar]

Post by Bill Unruh

Post by Xuehan Xu

Post by Miroslav Lichvar
I'm not sure which "maximum error" do you mean. chrony provides root
dispersion and root delay in the chronyc tracking report, similarly to
the ntpq readvar command.

Thanks, Miroslav:-)
By the way, by "maximum error", I mean the maximum uncertainty of the
local system time, or the maximum error between local system time and
the time server's system time:-)

Sounds like it basically the roundtrip-time/2 +max uncert in the server
time. Not that that is a terribly useful number.

That would be the root distance (root delay/2 + root dispersion).

There is also a "maximum error" field in the timex structure returned
by the ntp_adjtime()/adjtimex() call, which includes a 500ppm drift
and is set by chronyd on each clock update, similarly to ntpd.