[ntp:questions] NTP vs chrony comparison (Was: oscillations in ntp clock synchronization)

Unruh unruh-spam at physics.ubc.ca
Tue Jan 22 05:01:25 UTC 2008

mayer at ntp.isc.org (Danny Mayer) writes:

>Unruh wrote:
>>> correction applied on that sample.
>> No, this is offset as measured by the ntp procedure ( (t1+t4-t2-t3)/2 )

>No, that's wrong. It is very carefully described in the NTPv4 draft 
>section 8 (p27):

>theta = T(B) - T(A) = 1/2 * [(T2-T1) + (T3-T4)]

>Not only do you have the wrong sign, the differences must be calculated 
>first, otherwise the errors in the calculation overwhelm the resulting 
>value. That's why it's written the way it is.

I was not writing code. I was telling you what time difference  I was refering to. And
sign is a convention as to whether you are saying positive is the computer
is fast or the external source is fast. Everything I talked about is sign
independent (standard deviation uses squares), and the difference is that 
as reported by ntp or chrony and
both are careful to to do the calculations with as high an accuracy as

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